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Written by: A J Scarlett (Scarlett Research Ltd), I M Knight(Apollo Vehicle Safety Ltd) and P A Morgan (TRL Limited)August – 2017

Study on the availability ofanti-lock braking systems for

agricultural and forestryvehicles with a maximum

design speed between40 km/h and 60 km/h

Final Report

August 2017

EUROPEAN COMMISSION

Directorate-General for Internal Market, Industry, Entrepreneurship and SMEsDirectorate C — Industrial Transformation and Advanced Value ChainsUnit C.4 — Automotive and Mobility Industries

Contact: Andreas Vosinis

E-mail: [email protected]

European CommissionB-1049 Brussels

EUROPEAN COMMISSION

Directorate-General for Internal Market, Industry, Entrepreneurship and SMEs

2017

Study on the availability ofanti-lock braking systems for

agricultural and forestryvehicles with a maximum

design speed between40 km/h and 60 km/h

Final Report

August 2017

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Luxembourg: Publications Office of the European Union, 2017

ISBN 978-92-79-70240-2doi:10.2873/580390

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This report has been produced by the Transport Research Laboratory under a contract with the EuropeanCommission. Any views expressed in this report are not necessarily those of the European Commission.The information contained herein does not necessarily reflect the views or policies of the customer for whomthis report was prepared. Whilst every effort has been made to ensure that the matter presented in thisreport is relevant, accurate and up-to-date, TRL Limited cannot accept any liability for any error oromission, or reliance on part or all of the content in another context.

Framework Contract No: 470/PP/2015/FCSpecific Contract No: SI2.741735Document Number: PPR831Prepared By: TRL Limited.Quality approved: Phil Morgan (Project Manager), Richard Cuerden (Technical Referee)

Study on the availability of anti-lock braking systems for agricultural and forestry vehicles with amaximum design speed between 40 km/h and 60 km/h

August 2017 1

Table of contentsTable of contents ............................................................................................. 1

Executive summary ......................................................................................... 3

Glossary of symbols, abbreviations and industry body acronyms ........................... 5

Introduction ............................................................................................. 71

Background to the investigation ......................................................... 71.1

Information gathering methodology .................................................... 81.2

Structure of the report ...................................................................... 91.3

Classification and selection of agricultural vehicles, trailers and2interchangeable towed equipment .............................................................. 11

Agricultural vehicle, trailer and interchangeable towed equipment2.1categories ....................................................................................... 11

Vehicle categories excluded from the investigation scope ...................... 122.2

Vehicle categories included in the investigation scope .......................... 172.3

Summary of vehicle categories .......................................................... 282.4

Current and future usage of agricultural vehicles in the EU ............................ 293

Changes in the nature of agricultural operations and farming ................ 293.1

The rationale for increased speed ...................................................... 323.2

The EU agricultural vehicle fleet......................................................... 353.3

Existing legislation and policy regarding on-road use of agricultural3.4vehicles .......................................................................................... 47

Accidents related to agricultural vehicles ..................................................... 514

Influence of speed on injury risk ........................................................ 514.1

Effect of Mass on Injury Severity ....................................................... 554.2

Review of accident data for all agricultural vehicles .............................. 564.3

Accidents involving SbS and ATVs ...................................................... 744.4

Overview of anti-lock braking systems (ABS) .............................................. 775

Current use of ABS on agricultural vehicles ......................................... 775.1

The effectiveness of ABS .................................................................. 855.2

Perception of benefits and impacts of implementing ABS on agricultural5.3vehicles ........................................................................................ 100

Issues affecting the wider implementation of ABS systems on agricultural6vehicles ................................................................................................ 107

Technical availability ...................................................................... 1076.1

Practical issues associated with ABS installation / implementation ....... 1106.2

Potential benefits of ABS installation / implementation on agricultural6.3vehicles ........................................................................................ 116

Practical availability and economic availability ................................... 1196.4

Summary ..................................................................................... 1216.5

Possible alternative criteria for ABS implementation ................................... 1237


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Cost benefit analysis .............................................................................. 1298

Overview of CBA methodology ........................................................ 1298.1

Development of CBA scenarios ........................................................ 1298.2

Costs of ABS when fitted to a new vehicle ......................................... 1318.3

The benefits of ABS ....................................................................... 1328.4

Forecasting the distribution of sales by vehicle type and how the fleet8.5changes as a consequence .............................................................. 134

Developing the business as usual baseline (option 1- remove8.6requirement for ABS) ..................................................................... 137

Estimating and valuing casualty reductions ....................................... 1398.7

Results of the CBA ......................................................................... 1408.8

Analysis and discussion .......................................................................... 1479

Conclusions ........................................................................................... 15110

Possible options for amendment of Regulation (EU) 2015/68 ....................... 15511

Agricultural Tractors (Category Tb) .................................................. 15511.1

Agricultural trailers and interchangeable towed equipment11.2(Categories R3, R4 & S2) ................................................................ 156

Acknowledgements ....................................................................................... 157

References................................................................................................... 157

Annex 1 Review of alternative measures ....................................................... 161

Annex 1.1 Braking measures already in the RVBR ................................. 162

Annex 1.2 Control of trailer braking system via drive stick input (CVTTransmission/vehicle travel speed control ......................................... 162

Annex 1.3 Seat belts ......................................................................... 163

Annex 1.4 Roll-Over Protective Structures (ROPS) ................................. 163

Annex 1.5 Electronically controlled braking systems (EBS) for trailers ...... 164

Annex 1.6 Vehicle to Vehicle (V2V) Communication ............................... 164

Annex 1.7 Electronic Stability Control (ESC) for towing vehicles .............. 166

Annex 1.8 Improved Lighting/Signalling ............................................... 166

Annex 1.9 Improved conspicuity (by means other than lighting) ............. 167

Annex 1.10 Improved field of vision for tractor driver (e.g. mirrors, closeproximity or junction cameras, blind spot proximity alarms) ............... 167

Annex 1.11 Driver assist systems – collision warnings or avoidancesystems 168

Annex 1.12 Improved maintenance & roadworthiness checks ................... 168

Annex 1.13 Driver training/education (for drivers of both agriculturalvehicles and other vehicles) ............................................................ 169


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Executive summaryRegulation (EU) No 167/2013 sets out in Article 17, together with its delegated actRegulation (EU) 2015/68, the braking safety requirements necessary for EU type-approval of all categories of agricultural and forestry vehicle (AFV). This includesprovisions for the use of ABS on such vehicles, set out in Delegated Regulation (EU)2015/68.

TRL was commissioned by the European Commission to undertake an assessmentaddressing Recital (6) of Regulation (EU) 2015/68 to provide the Commission with theinformation necessary to amend, as appropriate, the Delegated Regulation for AFVs witha maximum design speed of 40 < Vmax ≤ 60 km/h.

It was agreed with the Commission that there was the opportunity to refine the focus ofthe investigation by excluding those vehicles where ABS is deemed either not to beapplicable or is unlikely to be technically supported. This excluded consideration ofdedicated forestry vehicles and included agricultural tractors under Category T1, T2 andT4.3, Side-by-Side vehicles or All-Terrain Vehicles when type-approved as agriculturaltractors, Category R3 and R4 trailers and Category S2 interchangeable towed equipment.

Data to inform the investigation was collated using a multi-faceted approach, comprisingstakeholder surveys, face-to-face discussions with stakeholders, and reviews of technicaland manufacturer literature, vehicle fleet data, legislation and policy regarding on-roadusage of agricultural vehicles, cost data related to ABS development / installation /implementation for agricultural vehicles, and data related to accidents involvingagricultural vehicles. However, in some cases the information available was very limited,identifying vehicles by speed capability in fleet and accident data was problematic andcost information relied on responses from a relatively small set of stakeholders.

The investigation identified the following

· Technical availability: ABS is technically feasible and available for nearly allrelevant agricultural vehicle types (Categories Tb, R3b, R4b and S2b). However,the ease and economic feasibility of their installation is currently dependent uponthe brake application method / medium used on the vehicle and the physicalspace available to accommodate system components. Mature pneumatically-basedABS technology is readily-available for use on agricultural tractors (T1b) and alsoon agricultural trailers/towed equipment (R3b, R4b and S2b). Such ABS systemsare already in commercial use on a limited number of T1 tractor models, whilsthydraulic (mineral oil) ABS systems are at advanced stages of productdevelopment. Commercially-available hydraulic (brake fluid)-based light / mediumtruck systems are, based on discussions with industry, understood to be suitablefor installation on Category T4.3b vehicles. ABS for other (tractor) categories areeither at a proof-of-concept stage or in development (e.g. a commercial hydraulicsystem for ATVs is expected to be marketed in the very near future).

Whilst ABS is readily-available for trailers / towed equipment fitted withpneumatic braking systems, it is not currently available for such vehicles whichemploy hydraulically-actuated braking systems and may not be brought to themarket in the foreseeable future. Such (typically lower-mass, less expensive)trailers / towed equipment would therefore require conversion to pneumaticbraking systems to permit ABS installation. However, most trailers / towedequipment intended for V > 40 km/h use tends to feature pneumatic brakingsystems.

· Practical availability and applicability: Vehicle braking system actuationmethod and/or medium is significant in determining the complexity andassociated cost of ABS system installation on agricultural vehicles, particularly asthe majority of tractors employ hydraulic (mineral oil) brake actuation systems.The diverse nature of tractor design may well require ABS installation to beapproached on a model-range by model-range basis. The space available for


August 2017 4

installation of some current ABS system components may also present achallenge. ABS implementation also requires installation of wheel speed sensors,but this appears to be a surmountable engineering challenge. For larger(pneumatically-braked) agricultural trailers and interchangeable towed equipment,ABS systems may be installed without difficulty. Smaller vehicle applications arelikely to be more costly. ABS systems are not currently available for hydraulically-braked trailers. Valid concerns regarding ABS behaviour during off-road brakinghave been addressed by the provision of manual or automatic system disablementfunctionality and/or alternative (slower speed) operating characteristics.

· Economic availability: The likely system diversity for ABS implementation onagricultural tractors will potentially increase system installation and developmentcosts, thereby increasing cost to the vehicle user. For reasons of commercialconfidentiality it has only been possible for this investigation to estimate potentialoverall system costs. ABS suppliers have commented that, depending uponproduction volumes, tractor system costs to Original Equipment (vehicle)Manufacturers (OEMs) may be in the region ~€1000 – €1300, to which installationand vehicle-based development costs must be added. Where offered as optionalequipment, tractor manufacturers currently retail ABS at ~€4000–€5000. Foragricultural trailers and interchangeable towed equipment, mature pneumatic ABSsystems are readily available at an OEM cost of ~€500.

· Cost benefit analysis: Based on the net (benefits minus costs) present valuefigures, removing the requirement to fit ABS to agricultural vehicles (40 < Vmax ≤60 km/h) would result in the best monetary gain (from between €1.3 billion - 3.0billion). Within this net gain, the ‘cost’ is an increase in the number of fatalitiesfrom collisions involving agricultural vehicles. There is substantial uncertainty inthe analysis which results in a wide range of estimated effects. However, it can beseen that even at the extremes of the possible ranges, the overall effect of thisoption is always beneficial with respect to the benefit to cost ratios (BCRs), whichare always substantially in excess of 1. This option introduces some non-monetised risks around future investment in agricultural vehicle safetytechnology.

The best BCR is achieved by mandating the fitment of ABS on T1b tractors ofMPM ≥11.5 tonnes and either all R3b and R4b trailers or just those ofMPMaxles≥ 12tonnes. Such options would lessen the overall net gain to between€0.55 billion and 1.1 billion. However, the improved BCR comes from the fact thatthe associated increase in casualties is lessened by proportionally more than thecost of fitting the systems is increased.

The only new policy options that achieve a BCR of less than one are to fit ABS onall 40 < Vmax ≤ 60 km/h Category T1b, R3b and R4b vehicles or to fit ABS onCategory T1b and Categories R3b and R4b vehicles of MPMaxles > 12tonnes.

Considering how to balance the overall monetary value, benefit to cost ratio, andnon-monetised risks to conclude which option is best overall is a matter for theCommission.

The investigation concluded the following:

· Technical Availability of ABS: In the majority of instances, systems are readilyavailable for relevant agricultural vehicles.

· Applicability of ABS: Systems are applicable for use on relevant agriculturalvehicles deemed likely to undertake agricultural transport operations on-road.

· Cost Benefit Analysis: The likely costs of ABS implementation on relevantagricultural vehicles of 40 < Vmax ≤ 60 km/h capability are high and are unlikely tobe outweighed by monetised savings resulting from reduction in casualty numbersduring the 15-year evaluation period.


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Glossary of symbols, abbreviations and industry body acronymsABS Anti-Lock Braking System (singular)

ADAS Advanced Driver-Assistance System

AFV Agricultural or Forestry Vehicle

AoH Air-over-Hydraulic

ATV All-Terrain Vehicle

ATVEA All-Terrain Vehicle Industry European Association

AWU Agricultural Work Unit

BCR Benefit to Cost Ratio

CAP Common Agricultural Policy

CBA Cost Benefit Analysis

cc Cubic Capacity

CEMA European Agricultural Machinery Manufacturers Association

CLEPA European Association of Automotive Suppliers

CoG Centre-of-Gravity

CVT Continuously-Variable Transmission

delta_V Change in velocity

EBS Electronically-controlled Braking System

ESC Electronic Stability Control

EU European Union

GB Great Britain (i.e. England, Scotland and Wales)

GVW Gross Vehicle Weight

HGV Heavy Goods Vehicle

hp Horse power

IIHS Insurance Institute for Highway Safety

KE Kinetic Energy

KSI Killed and Seriously Injured

MPM (Vehicle) Maximum Permissible Mass

MPMaxles Sum of Technically Permissible Masses per axle

NAAC National Association of Agricultural Contractors (UK)

NTT Narrow-Track Tractors

OEM Original Equipment Manufacturer

PTW Powered Two Wheeler

RAV Relevant Agricultural Vehicle

ROPS Roll-Over Protective Structure

RVBR Regulation with regards to Vehicle Braking Requirements ((EU) 2015/68)

SbS Side-by-Side vehicle

TRS Technology Readiness Stage


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UK United Kingdom (i.e. England, Scotland, Wales and Northern Ireland)

ULM (Vehicle) Unladen mass

V2V Vehicle 2 Vehicle

Vmax (Vehicle) Maximum design speed


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Introduction1

Background to the investigation1.1Transport, both in terms of commodity haulage and travel to/from fields, has long beenrecognised as an important activity for vehicles such as agricultural tractors. However, inrecent decades, rationalisation has led to the creation of larger farm units, each with agreater geographic spread of land. This trend, together with sales of fewer but largertractors, has resulted in a reduced labour force being required to travel further from/tothe base farmstead to perform operations. Additionally, the scope of application forvehicles such as agricultural tractors has also changed, transportation of goods to/fromrenewable energy generation plants being an increasingly common operation. As a resultof these factors, the prevalence of such vehicles on the highway network has increasedsignificantly. In turn, this has led to the introduction of faster tractors, capable of greaterproductivity during transport operations. As such, the risks posed to other road users bysuch vehicles have potentially risen. Low speeds relative to other road traffic, poormaintenance and a lack of visibility are all common factors. The parties most commonlykilled or injured are those outside of the agricultural or forestry vehicle (AFV) rather thanits occupants.

Braking performance is fundamental in ensuring the drivability and functional safety ofAFVs during both on-road and off-road operations. One means of potentially improvingthe braking performance of AFVs is through the use of anti-lock braking systems (ABS),as already demonstrated through their implementation on heavy goods vehicles, wherethis is now a mature technology.

Whilst the speed and mass of these agricultural vehicles has increased over the lastdecade, improvements in safety systems have not necessarily kept pace with thesechanges and the use of ABS technology is still not widespread, despite certain similaritieswith commercial vehicles in terms of, for example, large laden / unladen ratio, varyingwheel load distribution, and vehicle combinations with up to two trailers and manydegrees of freedom.

Regulation (EU) No 167/2013 (European Union, 2013) sets out in Article 17, togetherwith its delegated act Regulation (EU) 2015/68 (European Union, 2015), the brakingsafety requirements necessary for EU type-approval of all categories of AFV (as definedin Article 4 of Regulation (EU) No 167/2013). These categories are:

· Category T: Wheeled tractors.

· Category C: Track-laying tractors propelled by endless tracks or a combination of wheels and endless tracks.

· Category R: Agricultural trailers.

· Category S: Interchangeable towed equipment.

This includes provisions for the use of ABS on AFVs, set out in Delegated Regulation (EU)2015/68 as follows:

· Clause 2.2.1.21.1 of Annex 1 of Delegated Regulation (EU) 2015/68 states that"tractors of category Tb with a maximum design speed exceeding 60 km/h shallbe equipped with anti-lock braking systems of category 1 in accordance with therequirements of Annex XI."

· Clause 2.2.2.16 of Annex 1 of the same Delegated Regulation states that "towedvehicles with a maximum design speed exceeding 60 km/h of categories R3b, R4band S2b shall be equipped with an anti-lock braking system in accordance withAnnex XI."

However, no mention is made regarding the use of ABS systems on Category C tractors.This is due to there being practically no (if any) 'fast' (Category Cb) tractors of this typecurrently available in the European Union (see Section 2.2).


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Delegated Regulation (EU) 2015/68 also states in Annex 1, Clause 2.2.1.21.2 that"tractors of category Tb with a maximum design speed exceeding 40 km/h and notexceeding 60 km/h shall be equipped with anti-lock braking systems of category 1 inaccordance with the requirements of Annex X

a) for new vehicle types as from 1 January 2020; and

b) for new vehicles as from 1 January 2021."

Recital (6) of the Delegated Regulation states that "while anti-lock braking systems arewide-spread for vehicles with a maximum design speed of above 60 km/h and could thusbe considered as appropriate and made compulsory as of its application by thisRegulation, such systems are not yet widely available for vehicles with a design speedbetween 40 km/h and 60 km/h. For those vehicles, the introduction of anti-lock brakingsystems should thus be confirmed after a final assessment by the Commission of theavailability of such systems… Should this assessment not confirm that such technology isavailable or applicable, the Commission should amend this Regulation in order to providethat these requirements will not become applicable to vehicles with a design speedbetween 40 km/h and 60 km/h."

TRL was commissioned by the European Commission to undertake an investigationaddressing Recital (6) to provide the Commission with the information necessary toamend, as appropriate, Delegated Regulation (EU) 2015/68. This report presents thefindings from that investigation.

The investigation was to consider three areas, namely:

· The availability of ABS on AFVs, i.e. the technical availability and/or thereadiness of ABS technologies for application on AFVs.

· The applicability of ABS on AFVs, i.e. both the practical applicability andeconomic feasibility of installing ABS technologies and the likely practicaladvantages (and/or disadvantages).

· A cost-benefit assessment to determine whether benefits from vehicle safetyimprovements using ABS technologies may counterbalance systemimplementation costs.

Information gathering methodology1.2The data required to inform the investigation into ABS technology availability andapplicability and to provide input to the Cost Benefit Analysis was collated using a multi-faceted approach, since it was considered that the breadth of information required couldnot be addressed by a single methodology. The different approaches are summarised asfollows:

· Stakeholder surveys: Three separate questionnaires were developed, eachdesigned for a different target audience and seeking to gather informationrelevant to that audience. These were disseminated both online and in MS Wordformat.

o National Approval Authorities, Enforcement Authorities and TechnicalServices): A total of 140 parties from all EU Member States were contacted.At least six parties reviewed the questionnaire but no completedquestionnaires were received; it is suspected that this was due in part to alack of named contacts within these organisations.

Subsequently a modified version of the questionnaire was sent by theEuropean Commission directly to named contacts within National TransportAuthorities in all 28 EU Member States. Responses were received from fiveMember States.

o Manufacturers of agricultural tractors (or vehicles type-approved astractors), agricultural trailers and towed equipment, trailer or trailedequipment axles, and vehicle braking equipment systems: A total of 72


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manufacturers were contacted. Responses were received from 33manufacturers across all of the product groups.

o Industry Bodies and Social Partners: A total of 156 parties werecontacted. Only 12 responses were received.

· Stakeholder discussions: To supplement the information from the surveys andmanufacturers, these discussions were held between members of the project teamand both industry bodies and manufacturers as set out below. These discussionswere expected to provide the most useful information for the investigation:

o Face-to-face meetings were held with CEMA, CLEPA and ATVEA in March 2017.

o Face-to-face meetings, detailed conversations and telephone discussions wereheld with a range of manufacturers of braking systems and agriculturaltractors, side-by-side vehicles, all-terrain vehicles, agricultural trailers andinterchangeable towed equipment.

· Literature review: A review of technical and manufacturer literature on ABSsystems in relation to agricultural vehicles.

· Data reviews: These data were sourced directly by the project team or providedby stakeholders and included vehicle fleet data, legislation and policy regardingon-road usage of agricultural vehicles, cost data related to ABSdevelopment/installation/implementation for agricultural vehicles, and datarelated to accidents involving on-road use of agricultural vehicles.

The scale and quality of the data available varied. Where this has impacted on theinvestigation or required assumptions to be made, this is reflected in the text ofthis report.

Structure of the report1.3The structure of the report is as follows:

· Section 2 presents the agricultural vehicle categories defined by EU legislation,and highlights those which the investigation focusses upon and those which havebeen excluded.

· Section 3 discusses changes in the nature of agricultural operations and farmingover the last 20 years, presents the rationale for increased on-road agriculturalvehicle speeds, and presents overviews of the EU agricultural vehicle fleet andexisting legislation / policy regarding on-road use of agricultural vehicles.

· Section 4 discusses accidents related to agricultural vehicles, including theinfluence of speed and vehicle mass, and a review of accident data related to theon-road use of agricultural vehicles.

· Section 5 presents an overview of ABS systems, addressing the current use ofABS on agricultural vehicles, the effectiveness of ABS and the perceived safetybenefits and impacts of implementing ABS on agricultural vehicles. It alsoidentifies those alternative measures perceived by stakeholders as potentiallyoffering equivalent or greater safety benefits with regards to accident reductionwhen compared to ABS.

· Section 6 addresses the wider implementation of ABS on agricultural vehicles,taking into account technical availability, practical issues associated with ABSimplementation and installation, the potential practical benefits of ABS fitment,and both the practical and economic availability of ABS systems for agriculturalvehicles.

· Section 7 outlines possible alternative criteria for ABS implementation such asmass and speed thresholds.

· Section 8 presents the Cost Benefit Analysis (CBA), addressing the methodology,scenarios used and inputs. It also presents the full results of the CBA.


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· Section 9 presents analysis and discussion of the findings from Sections 2-8.

· Section 10 presents the conclusions of the project, based on the findingspresented in Section 9.

· Annex 1 discusses the alternative measures to ABS, as identified in Section 5,that are perceived to offer equivalent or greater safety benefits with regard toaccident reduction.


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Classification and selection of agricultural vehicles, trailers2and interchangeable towed equipment

Agricultural vehicle, trailer and interchangeable towed equipment categories2.1The vehicle types initially included in the scope of the investigation are defined inArticle 3 of Regulation (EU) No 167/2013 (European Union, 2013) as follows:

· Tractor: Any motorised, wheeled or tracked agricultural or forestry vehicle havingat least two axles and a maximum design speed of not less than 6 km/h. It isdesigned to pull, push, carry and actuate certain interchangeable equipmentdesigned to perform agricultural or forestry work, or to tow agricultural or forestrytrailers or equipment; it may be adapted to carry a load in the context ofagricultural or forestry work.

· Trailer: Any agricultural or forestry vehicle intended mainly to be towed by atractor and intended mainly to carry loads or to process materials and where theratio of the technically permissible maximum laden mass to the unladen mass ofthat vehicle is equal to or greater than 3.0.

· Interchangeable towed equipment: Any vehicle used in agriculture or forestrywhich is designed to be towed by a tractor, changes or adds to its functions,permanently incorporates an implement or is designed to process materials, whichmay include a load platform designed and constructed to receive any tools andappliances needed for those purposes and to store temporarily any materialsproduced or needed during work and where the ratio of the technically permissiblemaximum laden mass to the unladen mass of that vehicle is less than 3.0.

The vehicle categories included in the scope of the investigation are defined withinArticle 4 of Regulation (EU) No 167/2013, noting that each category is supplemented bythe index ‘a’ (for vehicles with a maximum design speed (Vmax) below or equal to 40km/h), or ‘b’ (for vehicles with a maximum design speed above 40 km/h). The categoriescan be summarised as follows:

· Category T1: Wheeled tractors of > 600 kg unladen mass (ULM), in runningorder, and a minimum wheel track width of ≥ 1,150 mm.

· Category T2: Wheeled tractors of > 600 kg ULM (in running order), but withnarrow wheel track widths, i.e. < 1,150 mm.

· Category T3: Wheeled tractors of ≤ 600 kg ULM.

· Category T4.1: High-clearance wheeled tractors.

· Category T4.2: Extra-wide wheeled tractors.

· Category T4.3: Low-clearance, low centre-of-gravity tractors, of ≤ 10,000 kgmaximum permissible mass.

· Category C: Track-laying tractors propelled by endless tracks or by acombination of wheels and endless tracks (Subcategories areanalogous to Category T).

· Category R1: Trailers with a sum of technically permissible masses per axle(MPMaxles) of £ 1,500 kg.

· Category R2: Trailers with a sum of technically permissible masses peraxle > 1,500 kg but £ 3,500 kg.

· Category R3: Trailers with a sum of technically permissible masses peraxle > 3,500 kg but £ 21,000 kg.


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· Category R4: Trailers with a sum of technically permissible masses peraxle > 21,000 kg.

· Category S1: Interchangeable towed equipment with a sum of technicallypermissible masses per axle £ 3,500 kg.

· Category S2: Interchangeable towed equipment with a sum of technicallypermissible masses per axle > 3,500 kg.

In addition the following vehicle categories are also included within the study:

· Side-by-Side Vehicles (SbSs) type-approved either as Category T1 or T3(depending upon vehicle mass). These are small motorised vehicles, with at leastfour wheels, with two or more seating positions intended for a variety of usesprimarily on unpaved surfaces and equipped with a steering wheel.

· All-Terrain Vehicles (ATVs) type-approved as Category T3. These are motorisedvehicles designed to travel on four low pressure tyres on unpaved surfaces,having a seat designed to be straddled by the operator and handlebars forsteering control.

Vehicle categories excluded from the investigation scope2.2Whilst the initial scope of the investigation covered all categories of agricultural andforestry vehicles, it was agreed with the Commission at the commencement of the workthat there was the opportunity to narrow the focus of the investigation, by excludingthose vehicles where ABS is deemed either not to be applicable or is unlikely to betechnically supported. The following exclusions were agreed with the Commission:

· Dedicated forestry vehicles: Whilst agricultural tractors are sometimes used(with appropriate protective guarding) for farm-based forestry activities, modernforestry vehicles are generally considered as off-road / Non-Road Mobile Machines,are therefore not categorised as tractors and are outside of the scope of Regulation(EU) No 167/2013. Dedicated tree harvesters, incorporating timber processingheads (Figure 2.1 (left)), are used to fell, de-limb and cut timber to length, prior toits extraction to the roadside by specialist forwarder vehicles (Figure 2.1 (right)).Onward transportation is then undertaken by road vehicles. As these specialistforestry machines are not tractors and are not used for on-road transportation offorest products, they and related vehicles (i.e. self-propelled, vehicles designed foruse solely in forestry) were excluded from the study.

Figure 2.1: Dedicated forestry harvester (left) and forwarder (right) vehicles(Copyright Ponsse)


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· Category T3 tractors: These vehicles are not of high mass, are generally not usedfor road transport operations and in most instances are unlikely to incorporatesufficient build-complexity to support the installation of ABS technology. The masslimitation (≤ 600 kg) of the T3 vehicle category primarily restricts it to what areusually known as “Lawn Tractors” (Figure 2.2 (left)), which frequently incorporatemid-mounted grass cutting equipment for use in larger residential ground careapplications. Such vehicles do not generally have > 30 km/h max design speedcapability. However it should be noted that ATVs type-approved as Category T3bvehicles were included in the study.

Figure 2.2: Category T3 lawn tractor (left) & Category T4.1 high-clearance tractor (right)(Copyright Kubota & Tecnoma)

· Category T4.1 tractors: These specialist vehicles incorporate raised chassis toenable them to straddle and travel along rows of tall growing crops (> 1 m high)such as vines, olives and field-scale soft-fruit (Figure 2.2 (right)). Such tractors arespecifically designed for specialist in-field working and are unlikely to be used forroad transport operations; additionally they are likely to suffer from poor stability ifused at speeds > 40 km/h. It is also worthwhile noting that, as EU type-approval ofCategory T4.1 vehicles is not mandatory, manufacturers may alternatively chooseto comply with the national regulatory requirements of individual Member States;consequently the installation of ABS may not be a requirement.

Figure 2.3: Category T4.2 tractor in-work (left) and travelling on-road (right)

(Copyright CNH Industrial)

· Category T4.2 tractors: These ‘extra-wide’ tractors are characterised by theirhigh engine power and large dimensions. They are primarily intended for in-fieldoperations, are unlikely to undertake any significant road transport, except for


August 2017 14

travel between field sites (Figure 2.3) and are unlikely to have Vmax > 40 km/hcapability. Once again it is worthwhile noting that, as EU type-approval of CategoryT4.2 vehicles is not mandatory, manufacturers may alternatively choose to complywith the national regulatory requirements of individual Member States.Consequently the installation of ABS may not be a requirement.

· Category C tractors: Historically, track-laying (crawler) tractors were slow speedvehicles fitted with steel tracks (Figure 2.4) and were unsuitable for on-highwayuse due to the damage caused to the road surface. The small numbers of thesevehicles sold today tend to be used for specialist applications and/or in hilly areas.They are not used for transport applications and/or at high speeds.

Figure 2.4: Steel-tracked Category C track-laying tractors(Copyright SDF)

The introduction of rubber-tracked crawlers in the late-1980s enhanced the on-roadmobility of track-laying vehicles, but generally they are designed as high-poweralternatives to Category T4.2 tractors, intended for in-field heavy draughtoperations (Figure 2.5). On-road use tends to be limited to travel between the farmand fields. Rubber track or half-track conversions have been developed forwheeled tractors (Figure 2.6), but they are primarily intended to enhance in-fieldtractive performance. Absence of track / axle suspension tends to limit Vmax to≤ 40 km. In common with vehicle Categories T4.1 and T4.2, the EU type-approvalof Category C vehicles is not mandatory under Regulation (EU) No 167/2013:manufacturers may instead elect to comply with the relevant national regulatoryrequirements of individual Member States for this vehicle type which, in any case,tends only to be sold in relatively small numbers.

Figure 2.5: Rubber-tracked Category C track-laying tractors

(Copyright Scarlett Research & AGCO)


August 2017 15

Figure 2.6: Rubber half-track Category C track-laying tractors


· Category R1 trailers: This vehicle category, of MPMaxles ≤ 1500 kg, primarilyincludes small single-axle trailers of up to 1500 – 1750 kg carrying capacity.Smaller capacity trailers, intended for use with ATV and SbS vehicles, tend to limitthe vertical drawbar loading applied to the towing vehicle, whereas those designedfor use with conventional tractors often increase this parameter by locating thetrailer axle towards the rear of the chassis (Figure 2.7 (right)). Regulation(EU) 2015/68 (European Union, 2015) stipulates that all Category R1a trailers andR1b vehicles of MPMaxles ≤ 750 kg are not required to be fitted with a brakingsystem (Table 2.1). R1b vehicles of 750 < MPMaxles ≤ 1500 kg may be fitted witheither an inertia or power-operated braking system. ABS technology is not availablefor such lightweight, inertia-braked vehicles and so Category R1 vehicles wereexcluded from the investigation.

Figure 2.7: Example Category R1 agricultural trailers(Copyright Logic & Fleming)

Figure 2.8: Example Category R2 agricultural trailers(Copyright Fliegl & Fleming)


August 2017 16

Table 2.1: Trailed vehicle braking systems permitted by Regulation (EU) 2015/68(RVBR)

Trailed VehicleCategory

Sum of Technically-Permissible Axle Loads

(kg)

Max. Design Speed(km/h)

Required BrakingSystem

R1a m ≤ 1500 Vmax ≤ 40

NONES1a m ≤ 3500 Vmax ≤ 40

R1b / S1b m ≤ 750 Vmax ≤ 40

R1b 750 < m ≤ 1500 Vmax > 40Inertia or Power-

operatedS1b m ≤ 3500 Vmax > 40

R2 1500 < m ≤ 3500

ANYR3 3500 < m ≤ 21000

Power-operated(continuous or semi-

continuous)R4 m > 21000

S2 m > 3500

R3a 3500 < m ≤ 8000Vmax ≤ 30 (brakes not onall wheels) / 40 (brakes

on all wheels)

Inertia-operated(derogation)

· Category R2 trailers: Agricultural trailers of 1500 < MPMaxles ≤ 3500 kg which,in single-axle form, typically equates vehicles of 1500 – 1750 kg to 3000 –4000 kg carrying capacity (Figure 2.8): this being dependent upon axle locationon the chassis and the magnitude of mass transfer to the towing vehicle. CategoryR2 trailers may be fitted with either an inertia or power-operated braking system(Table 2.1). Consequently they were excluded from the investigation for thereasons given above.

· Category S1 interchangeable towed equipment: This vehicle categoryencompasses a wide range of trailed agricultural implements ofMPMaxles ≤ 3500 kg. S1a vehicles (Vmax ≤ 40 km/h) are not required to be fittedwith a braking system (Table 2.1), whereas S2b vehicles (Vmax > 40 km/h) maybe fitted with either an inertia or power-operated braking system. As explainedabove, ABS technology was not found to be available for inertia-braked vehiclesand, in any case, the gross mass and likely on-road usage of Category S1 vehiclesis likely to be limited. They were therefore excluded from the investigation.

Figure 2.9: Category S1 interchangeable towed equipment: Round baler (left) and trailedmower-conditioner (right)

(Copyright Kverneland / CEMA)


August 2017 17

Vehicle categories included in the investigation scope2.3Article 17 of Regulation (EU) No 167/2013 refers to ensuring that agricultural andforestry vehicles "with a maximum design speed of more than 40 km/h meet anequivalent level of functional safety with regard to brake performance and, whereappropriate, anti-lock braking systems as motor vehicles and their trailers."

The above statement focuses on on-road use of vehicles. It was therefore agreed withthe Commission that the focus of this investigation should be further-refined toconcentrate upon agricultural tractors, trailers and towed equipment used on-road for operations necessary to agricultural purposes, with an emphasis on largermass vehicle combinations. The vehicle categories included in the investigation scopewere therefore as follows:

2.3.1 Category T1 tractors

These wheeled vehicles of > 600 kg ULM and ≥ 1150 mm minimum wheel track widthrepresent the vast majority of ‘conventional’ agricultural tractors sold in the EU.However, due to the broad spectrum of demands placed upon them by users, T1 tractorsare manufactured in a very wide range of sizes and capabilities, both in terms of physicaldimensions, engine sizes and rated power outputs; such variation also extends tomaximum design speed (Vmax) capability.

It has been found that current production T1 tractors may be reliably placed in one of arange of generic size categories (Table 2.2, Figure 2.10 & Figure 2.11), these beingbased primarily upon vehicle rated engine power, but also considering vehicle wheelbase,unladen mass, max permissible mass, payload and 3-point linkage lift capacity. Thisinvestigation has found that, currently, 40 < Vmax ≤ 60 km/h capability is widely availableas a customer-specified option on tractors in the High-Power 4 cylinder and Lightweight6 cylinder categories (generally those of > 130 hp / 97 kW rated engine power) and alsoin all larger vehicle categories (Lower Middleweight 6 cylinder, Upper Middleweight 6cylinder and Heavyweight 6 cylinder). These basically cover the rated power range of130 – 500 hp (97 – 375 kW). The market availability of such vehicles in certain MemberStates may currently be limited by national road usage legislation (see Section 3.4), butthese higher-speed tractors have been offered in certain EU markets since 2003 – 2006(depending upon vehicle size / power). They therefore represent a key area of focus forthis investigation.


August 2017 18

Table 2.2: Generic T1 tractor size categories (Source: Scarlett Research Ltd)

Size CategoryTypical Rated

Power Range (hp/ kW)

Wheelbase(m)

UnladenMass (kg)

Max.PermissibleMass (kg)

Vmax > 40 km/havailable?

Low-Power3 & 4 cylinder

50 – 75 hp(37 – 56 kW)

1.9 – 2.15 1600 - 3000 4000 – 5500 No

Med-Power3 & 4 cylinder

75 – 100 hp(56 – 75 kW)

2.3 ± 0.2 3000 - 4500 5000 – 8500 No

High-Power4 cylinder

100 – 150 hp(75 – 112 kW)

2.55 ±0.15 4500 - 7000 8000 – 10000

Yes(≥130 hp / 97 kW)

Lightweight6 cylinder

100 – 150 hp(75 – 112 kW)

2.6 ± 0.1 6000 - 7000 8000 – 10000Yes

(≥130 hp / 97 kW)

LowerMiddleweight

6 cylinder

150 – 230 hp(112 – 172 kW)

2.9 ± 0.1 7300 - 9000 11500 – 13500 Yes

UpperMiddleweight

6 cylinder

230 – 320 hp(172 – 239 kW)

3.0 ± 0.1 9500 -11500 14000 - 17000 Yes

Heavyweight6 cylinder

320 – 500 hp(239 – 375 kW)

3.1 ± 0.05 11500 -14000 17000 - 22000 Yes

Figure 2.10: Initial generic categories of T1 tractors: Low-power 3 & 4 cylinder (top left),Medium power 3 & 4 cylinder (top right), High-power 4 cylinder (bottom left) and

Lightweight 6 cylinder (bottom right)

(Copyright Deere & Co, Claas & CNH Industrial)


August 2017 19

Figure 2.11: Remaining T1 tractor categories: Lower Middleweight 6 cylinder (top left),Upper Middleweight 6 cylinder (top right) and Heavyweight 6 cylinder (bottom)

(Copyright SDF, CNH Industrial & Deere & Co.)

2.3.2 Category T2 tractors

Category T2 tractors are characterised by their narrow overall width and narrow wheeltrack widths (minimum track width ≤ 1150 mm). Within the industry, T2 tractors areusually referred to as Narrow-Track Tractors (NTT) and are primarily intended for use inapplications which require a vehicle of limited overall width. These are often areas ofsemi-permanent cropping where moderately-tall (> 1 m high) plants are grown in arectilinear arrangement and tractors are required to travel between each crop row on aregular basis, to perform crop treatment and harvesting operations. Typical examplesfound within the EU and worldwide include vineyards, orchards, field-scale soft fruit(e.g. raspberries, blackcurrants) and hops (Nathanson, Scarlett, & Barlow, 2014).

Figure 2.12: Example T2 tractors performing crop treatment operations in avineyard (left) and an orchard (right)



August 2017 20

Figure 2.13: Example articulated-chassis (left) and rigid chassis (right) Category T2tractors

(Copyright Scarlett Research)

Whilst in-field / vineyard / orchard work typically represents a substantial proportion ofthe activities undertaken by T2 tractors, during the harvest season they would also beexpected to transport the crop back to the farm / processing plant. The time spent duringthe growing season travelling between the farm and field during crop treatmentoperations (e.g. agrochemical application) also detracts from daily work output.Consequently rapid and comfortable on-road transport capabilities are desirable T2vehicle features. To this end the majority of current T2 tractors are offered withVmax = 40 km/h transmissions either as optional or standard equipment but, at present,no Vmax > 40 km/h T2b tractors are marketed. This is possibly due in part to the virtualnecessity of a front axle suspension system to maintain both driver comfort levels andvehicle drivability on rural roads at speeds above 40 km/h. Few T2 tractor manufacturerscurrently offer this feature, but it may become more widespread in the future and Vmaxcapability may increase, hence the inclusion of T2 vehicles in this investigation.

2.3.3 Category T4.3 tractors

Regulation (EU) No 167/2013 defines T4.3 vehicles as

“low-clearance four-wheel drive tractors whose interchangeable equipment isintended for agricultural or forestry use and which are characterised by asupporting frame, equipped with one or more power take-offs, having atechnically permissible mass of ≤ 10,000 kg, for which the ratio of this mass tothe maximum unladen mass in running order is < 2.5 and having the centre ofgravity, measured in relation to the ground using the tyres normally fitted, of lessthan 850 mm.”

These rather specialised transporter-type vehicles are characterised by their low centreof gravity and consequent very favourable stability characteristics. Whilst they are usedboth in agricultural and municipal applications, the niche area they fill in agricultureprimarily involves operations to support livestock-based farming systems on steeply-sloping fields in Alpine regions. The vehicle’s frame-type chassis accepts alternativebodies for fodder collection, manure / slurry distribution and other purposes (Figure2.14). The capability of the braking systems offered on these machines reflects theirfrequent operation on steeply-sloping ground. Both T4.3a (Vmax ≤ 40 km/h) and T4.3b(Vmax ≤ 50 km/h) versions are available, but none are currently offered with ABS. TheirVmax > 40 km/h capability and the fact that they are required to be subject to EU type-approval, resulted in their inclusion within the investigation.


August 2017 21

Figure 2.14: Example T4.3 low-clearance, transporter-type tractors (Copyright Aebi-Schmidt)

2.3.4 Side-by-Side (SbS) vehicles

ATVEA (the All-Terrain Vehicle Industry European Association) describes SbS vehicles assmall motorised vehicles with at least four wheels, equipped with a steering wheel andwith two or more seating positions. They are intended for a variety of uses includingleisure and utility / work tasks (e.g. agriculture and forestry applications), primarily onunpaved surfaces. In agricultural and forestry applications, SbS utility vehicles aredesigned to perform light-duty tasks for which conventional tractors are too heavy,inconvenient or inefficient.

Whilst used for similar purposes and utilising some similar components, SbS vehicles(Figure 2.15) differ from All-Terrain Vehicles (ATVs) due to their size, seating position,and the presence of a rear load-carrying platform and a roll-over protective structure(ROPS). Indeed in certain EU markets (e.g. the United Kingdom (UK; i.e. England,Scotland, Wales and Northern Ireland) agricultural market) SbS utility vehicles aredisplacing ATVs to an extent, partly because of their greater capability (passenger & loadcarrying), greater operator comfort (partly or totally enclosed cab) and improved stabilityon sloping ground.

Figure 2.15: Example SbS vehicles(Copyright ATVEA)


August 2017 22

SbS vehicles come in a wide range of sizes, including 4-wheel and larger 6-wheelvariants, but their typical masses and payloads may be summarised as follows:

· Unladen Mass: ~450 – 870 kg.

· Payload: ~400 – 700 kg (4 wheel) or ~900 kg (6 wheel).

· Towing Capacity: ~500 – 900 kg.

Current SbS engine capacities range from ~400 – 1100 cc, but the larger capacityengines (the most popular in agriculture) are diesel rather than petrol-powered. All SbSmakes / models encountered by the investigation were fitted with mechanically-controlled, belt-type continuously-variable transmissions (CVTs). Vehicle suspension andbraking system designs were found to be similar to those of ATVs, with independent frontand rear wheel suspension being most prevalent and external automotive-type, non-servo-assisted ‘dry’ disc and caliper brakes usually being mounted at the wheel ends.

Due to their range of unladen masses, when type-approved as agricultural tractors,individual SbS vehicles may be classified either as Category T3 (ULM ≤ 600 kg) orCategory T1 (ULM > 600 kg); in practice the majority fall into the T1 category.Interestingly their (unrestricted) max speed capability can be as high as 90 km/h, butwhen type-approved as tractors their Vmax is limited electronically (via engine &transmission management systems) to 40 or 60 km/h, depending upon the manufacturerand whether type-approved as Ta or Tb. At the time of writing this report, ABS systemsare not currently offered on SbS vehicles; however, their potential high-speed capabilityand inclusion within the tractor type-approval system resulted in their consideration bythe investigation.

2.3.5 All-Terrain Vehicles (ATVs)

ATVEA describes ATVs as motorised vehicles fitted with four low pressure tyres, designedto travel on unpaved surfaces, having a seat designed to be straddled by the operatorand handlebars for steering control (Figure 2.16). ATVs are subdivided into two types asdesigned by the manufacturer:

· Type I: Intended for use by a single operator and no passenger.

· Type II: Intended for use by an operator and a passenger.

ATVs are rider-active vehicles, meaning operators are required to shift their body weightto enhance the performance capabilities of the vehicle. This requires special skills andtraining to ensure safe operation, especially when on challenging off-road terrain. ATVsare widely-sold for leisure and sporting purposes. However within agriculture in additionto being utilised as a convenient form of off-road transport around the farm, often tosupport livestock rearing activities (Figure 2.16 (right)), they are also utilised with a widerange of mounted or trailed implements to perform tasks for which the physical sizeand/or mass of a conventional tractor may cause it to be less suitable (Figure 2.17).

Due to their low unladen mass (typically ~250 – 325 kg), when type-approved asagricultural vehicles ATVs tend to be classified as Category T3 tractors. Petrol enginecapacities vary from ~270 – 950 cc, but most vehicles intended for agricultural use tendto fall within the ~550 – 750 cc range. Independent front and rear wheel suspension isnow the most common design. Front wheel brakes tend to be automotive-type ‘dry’ discand caliper units mounted at the wheel ends, whereas rear brakes are of a similar type oroil-immersed ‘wet’ multi-disc-type fitted in the rear axle / transmission. All are actuatedby conventional non-servo-assisted automotive-type hydraulic systems employing brakefluid. At the time of writing, ABS systems are not offered, irrespective of the max speedcapability of the vehicles. However, the investigation has been advised that an ATVmanufacturer intends to market a Vmax > 60 km/h vehicle, type-approved as anagricultural tractor. This will be fitted with an ABS system to comply with the currentrequirements of Regulation (EU) 2015/68.


August 2017 23

Figure 2.16: Example single-seat ATV and a typical agricultural use (inspecting livestock)(Copyright KYMCO & ATVEA)

Figure 2.17: Example agricultural uses of ATVs: slug pellet application (top left), fieldspraying (top right), timber extraction (bottom left) and mowing (bottom right)

(Copyright Stocks AG & Logic)


August 2017 24

2.3.6 Category R3 trailers

This grouping encompasses agricultural trailers and tractor-towed load carrying vehiclesof 3500 < MPMaxles ≤ 21,000 kg. In practice this corresponds to a very wide range ofvehicle carrying capacity and consequent design complexity. However, it is important toappreciate that whilst trailers are normally marketed in terms of their carrying capacity,the manner in which this relates to the parameter chosen to categorise such vehicleswithin the EU type-approval process (sum of the technically-permissible masses per axle,MPMaxles), is very dependent upon vehicle design configuration.

Regulation (EU) 2015/68 (European Union, 2015) further sub-divides Category R and Stowed vehicles into one of the following designs categories:

· Drawbar Towed Vehicle: A towed vehicle with at least two axles of which atleast one is a steered axle, equipped with atowing device which can move vertically inrelation to the towed vehicle and which transmitsno significant static vertical load to the tractor.

· Centre-axle Towed Vehicle: A towed vehicle where one or more axles arepositioned close to the centre of gravity of thevehicle so that, when uniformly loaded, only asmall vertical static load, not exceeding 10% ofthe maximum mass of the towed vehicle or a loadof 1000 daN, whichever is less, is transmitted tothe tractor.

· Rigid drawbar Towed Vehicle: A towed vehicle with one axle or group of axles,fitted with a drawbar which transmits significant(vertical) static load to the tractor due to itsconstruction. The coupling used for a vehiclecombination shall not consist of a king pin and afifth wheel. Some slight vertical movement mayoccur at a rigid drawbar.

These somewhat lengthy definitions are largely derived from on-road truck-trailerterminology and in this instance have been adapted to suit agricultural trailers and towedequipment. Previous terminology referred to ‘Balanced’ trailers / towed equipment whichdo not impose a vertical load on the towing vehicle and ‘Unbalanced’ trailers / towedequipment which do transfer mass onto the towing vehicle. In practice few, if anyexamples of agricultural towed vehicles fall within the ‘Centre-Axle’ definition.

The reason for highlighting these definitions and vehicle design variations at this point isas follows. The vast majority of larger (Category R3 and R4) trailers used in the EU are ofthe Rigid Drawbar / Unbalanced type (Figure 2.18 (left)) which, depending upon theirspecific design may transfer up to 3000 – 4000 kg of vertical loading onto the towingtractor when fully-laden, thereby greatly assisting in-field tractive performance.‘Drawbar’ or ‘Balanced’ trailers (Figure 2.18 (right)) are still popular in certain EUmember states (mainly Germany), primarily for on-road transport but, it will beappreciated that, for a given MPMaxles value, they generally offer lower carrying capacities(Table 2.3).

As Rigid Drawbar-type trailers transfer a significant vertical load onto the towing tractor,for a given MPMaxles value, their total (gross) laden mass will be higher than that of aDrawbar-type trailer of an identical MPMaxles level. The mass-transfer nature of theirdesign requires a more robust construction, which is reflected in a higher unladen massbut, overall, the carrying capacity of the Rigid Drawbar-type vehicle is greater (Table2.3). This is important to appreciate, particularly given the potential influence of trailer-imposed loadings on the tractor during transport operations.


August 2017 25

Figure 2.18: Example Category R3 trailers: rigid drawbar / unbalanced (left) anddrawbar / balanced (right)

(Copyright Fliegl / CEMA)

Table 2.3: Influence of agricultural trailer design / configuration upon carrying capacity

Trailer Type MPMaxles(kg)

Total (Gross)Laden Mass

(kg)

Unladen Mass(kg)

DrawbarVertical Load

(kg)

CarryingCapacity (kg)

R3 Drawbar(Balanced) 18,000 18,000 4200 0 13,800

R3 Rigid Drawbar(Unbalanced) 18,000 21,000 5800 3000 15,200

As mentioned previously, the Category R3 trailer 3500 < MPMaxles ≤ 21,000 kg rangecorresponds to a very wide range of vehicle carrying capacity and design complexity,potentially from a relatively simplistic ~4000 kg carrying capacity single-axle trailer(Figure 2.8 (right)) up to a ~18,000 kg capacity tandem-axle trailer of similar design tothat depicted in Figure 2.18 (left). It should also be appreciated that the power outputand the Vmax capabilities of the tractors likely to be towing these trailers from either endof the Category R3 range are also likely to be significantly different. Category R3 trailersprobably represent the largest proportion of the current EU-28 agricultural trailer fleetwhich is in regular / frontline use, in many cases at speeds above 40 km/h. Theirconsideration by this investigation was therefore essential.

2.3.7 Category R4 trailers

The R4 category encompasses agricultural or forestry trailers and tractor-towed loadcarrying vehicles of MPMaxles > 21,000 kg. The national legislation of most EU MemberStates does not permit such loadings to be carried on only two axles, so Category R4trailers are generally of tri-axle design (Figure 2.19). In order to enable the towingtractor to generate sufficient tractive effort to effectively tow these large trailers in-field,the majority of vehicle designs are of the Rigid Drawbar type. Given that the vertical loadwhich may be imposed on the tractor is usually limited to ~3000 – 4000 kg by thetractor manufacturer and that few Member States permit imposed loadings of greaterthan 8000 kg per axle for close-spaced tri-axle trailer bogies (MPMaxles ≤ 24,000 kg), thetotal laden mass of such Category R4 vehicles is generally limited to ~28,000 kg,resulting in a max carrying capacity of ~21,500 kg.

The axles and foundation braking equipment used on such vehicles are very similar if notidentical to that found on on-road truck trailers. However, given that the ‘flotation’-type


August 2017 26

tyres used on agricultural trailers (in order to minimise in-field soil compaction) havevery much larger ground contact areas than those used on truck trailers of comparableaxle loadings, tri-axle agricultural trailers are frequently fitted with steerable axles (eitherthe rear or both the front & rear axles of the bogie) to improve vehicle manoeuvrabilityand to reduce turning forces and tyre wear due to scrubbing.

Figure 2.19: Example Category R4 agricultural trailers(Copyright Fliegl / CEMA & Claas / Joskin)

It should also be remembered that Regulation (EU) No 167/2013 defines a trailer as

“any agricultural or forestry vehicle intended mainly to be towed by a tractor andintended mainly to carry loads or to process materials and where the ratio of thetechnically permissible maximum laden mass to the unladen mass of that vehicleis equal to or greater than 3.0.”

Consequently the Category R definition includes what may be regarded as trailedagricultural implements, if their primary purpose is either:-

(i) to carry loads, or

(ii) to process materials and their Laden : Unladen mass ratio is ≥ 3.0.

Therefore trailed equipment such as those vehicles shown in Figure 2.20 are classified asCategory R vehicles. It should be noted that this arrangement applies across the entireCategory R vehicle mass range and not just within Category R4.

Figure 2.20: Trailed agricultural implements classified as Category R4 trailers: Tri-axleself-loading forage wagon (left) and slurry tanker (right)

(Copyright Pöttinger / CEMA & CNH Industrial / Joskin)


August 2017 27

2.3.8 Category S2 interchangeable towed equipment

This vehicle category potentially encompasses an extremely wide range of semi-mountedand trailed agricultural implements (Figure 2.21), from ploughs and cultivators, toseeders, agrochemical application equipment (sprayers), and to a wide variety of trailed,crop-specific harvesting machinery such as mowers, tedders & rakes, balers, forage,potato and sugar beet harvesters. Given that in 2016, in a number of EU Member States≥ 35% of tractors sold were of ≥ 150 hp / 112 kW rated power (see Section 3.3), thecorresponding implements required to effectively utilise these power levels will becapable of considerable work output. This requires a robust implement constructionand/or a substantial working width: factors which both contribute to an increase inimplement mass. Consequently it is not unrealistic to suggest that the majority of trailedor semi-mounted implements used in modern European agriculture will exceed theMPMaxles > 3500 kg threshold and fall within the S2 vehicle category. However, it shouldbe remembered that the primary purpose of this equipment is in-field or off-road use andthat on-road travel should (in all probability) comprise only a limited amount of theirdaily operation.

Figure 2.21: Examples of Category S2 interchangeable towed equipment: Semi-mountedreversible plough (top left), seeder (top right), crop sprayer (bottom left) and large square

baler (bottom right) (Copyright CEMA & Valtra / Amazone)

To aid practical interpretation of which trailed agricultural machinery may be consideredas Category R vehicles and which as Category S, CEMA (European Agricultural MachineryManufacturers Association) have produced a useful guidance document (CEMA, 2016a;CEMA, 2016b) which illustrates a wide range of modern agricultural trailers and trailedimplements and provides pertinent vehicle data.


August 2017 28

Summary of vehicle categories2.4

Table 2.4 summarises which vehicle categories are included and excluded from furtherconsideration within the investigation.

Table 2.4: Vehicle categories included and excluded from the investigation

Included in the investigation

Category T1 tractors

Category T2 tractors

Category T4.3 tractors

Side-by-side (SbS) vehicles type-approved asCategory T3 or T1 tractors

All-terrain vehicles (ATVs) type-approved asCategory T3 tractors

Category R3 trailers


Category S2 interchangeable towed equipment

Excluded from the investigation

Dedicated forestry vehicles

Category T3 tractors (except for those SbSsand ATVs type approved as Category T3b)



Category C tractors



Category S1 interchangeable towed equipment


August 2017 29

Current and future usage of agricultural vehicles in the EU3

Changes in the nature of agricultural operations and farming3.1The last 20 years has witnessed significant changes to European agriculture. Whilst EUCommon Agricultural Policy (CAP) support systems were in place throughout the period,substantial fluctuations in agricultural commodity prices, coupled with significantincreases in input costs such as energy and fertilisers, have adversely affectedprofitability. One of the few options available to counteract these trends was to reducefarm labour overhead costs, either by reducing staff numbers or by increasing the size ofthe farm enterprise. In either case greater levels of productivity were required, both ofthe labour force and the equipment operated by it.

The expansion of farm enterprises led to the creation of larger farm units, which hasresulted in a greater geographic spread of land and associated farming activities.Particularly in the case of arable farming operations, fewer workers were required to usefewer but larger tractors to travel further away from the base farmstead to performoperations. Associated rationalisation of farming enterprises frequently resulted ingreater reliance being placed upon the services of specialist agricultural contractorswhose tractors, by the very nature of the businesses, have to travel substantial distancesto perform their duties. In recent years, the subsidised development of anaerobicdigestion plants for renewable energy generation in a number of EU Member States hasfurther increased the geographic spread of agricultural activities and the associated on-road transport workload of agricultural tractors and trailers. These changingrequirements have placed greater emphasis upon the productivity, operator comfort androad transport capabilities of modern agricultural tractors (Scarlett, 2013).

These assertions are supported by EU agricultural statistics relating to the period inquestion. It is noteworthy that just six Member States (France, Germany, Italy, Spain,the United Kingdom and the Netherlands) together generate over 68% of EU-28 totalagricultural output (Figure 3.1). These Member States also account for the majority ofnew agricultural tractor sales in the EU (see Section 3.3). Over the 1997–2013 period thedomestic agriculture of these Member States all demonstrated the trends outlined above,namely:

· No. of Agricultural Holdings: Decreased by an average of 36% (Figure 3.2).Italy demonstrated the largest reduction (56%),followed by Germany (47%): Spain and the UKreturned the smallest changes (21%).

· Average Farm Size: Increased on average by 32% (Figure 3.3).Italian and German farm size increased by thelargest margin (~46%), Spanish farm size bythe smallest amount (13%).

· Farm Labour Force: Decreased by an average of 32% (Figure 3.4).Italy demonstrated the largest reduction (54%),followed by the UK (34%): Germany returnedthe smallest change (20%).

Generally, over the last 20 years, the share of utilised agricultural area within the EUcultivated by smaller farms has decreased and that of larger farms has grown. Thischange is reflected in the size and/or work capacity of agricultural machinery utilised(see Section 3.3).


August 2017 30

Figure 3.1: Output of EU Member States agricultural industries: Contribution to the EU-28total (in %)

Source: (European Union, 2016)

Figure 3.2: Change in the number of agricultural holdings in selected EU Member States Source: Analysis of Eurostat database (Eurostat, 2017)


August 2017 31

Figure 3.3: Change in average agricultural holding size (area) in selected EU MemberStates

Source: Analysis of Eurostat database (Eurostat, 2017)

Figure 3.4: Change in the size of the farm labour force in selected EU Member States.(AWU = Agricultural Work Unit = the work of one full-time employee)

Source: Analysis of Eurostat database (Eurostat, 2017)


August 2017 32

The rationale for increased speed3.2

Modern agriculture is very firmly run as a business and so it can be safely assumed thatthe purchase of an agricultural vehicle is in most instances economically rational. Thus,the changes described above in farming will create a different set of requirements that afarmer might have for their machine. That is to say, a fast agricultural vehicle purchasewill in most cases be motivated by an economic benefit brought about because of thehigher speed and not because, for example, the driver is a thrill seeker who likes to drivefast.

A full economic analysis of agricultural transport operations is beyond the scope of thisresearch. However, some existing research evidence exists that allows a simplisticillustration of the order of magnitude of the potential effect that increased tractor speedcan have on the economics of farming. This should not be taken as a robustquantification, merely an indication of the order of magnitude and the type of informationthat would be required if it was considered beneficial to undertake a robust analysis atsome future time.

It is generally accepted that the quantity of road transport undertaken with agriculturalvehicles is increasing. (Gotz, Holzer, Winkler, Bernhardt, & Engelhardt, 2011) citedexamples of the reason for such growth as including increasing size of individualagricultural businesses, centralisation of processes, closing of sugar beet refineries andincreasing demand for biogas. (European Union, 2016) showed that the average farmsize increased from 12.6 ha to 16.1 ha between 2007 and 2013. (Gotz, Zimmerman,Engelhardt, & Bernhardt, 2014) also cited increasing productivity in terms of tonnes ofproduct per hectare of field and an increased utilisation area per active farm. However,the distances that goods are moved within agriculture are relatively short, thoughgrowing. Many operations will transport goods from field to farm which can be a veryshort distance up to around 20-30 km (Gotz, Zimmerman, Engelhardt, & Bernhardt,2014). Where markets are national or international, those products may well be takenfrom farm to market in a road-going HGV because the distances are large and HGVs aremore fuel efficient. Thus, the additional costs of transhipping goods from the tractor toan HGV are reversed by the reduction in the onward transport costs. If the product isstored at the farm for any length of time then there is no additional trans-shipment costof loading onto a specialist transport vehicle (HGV). However, in more local or morespecialist operations (e.g. biomass, sugar beet, etc.) the farmer may transport productsdirect from field to market and the distances involved in this can be longer. (Gotz,Zimmerman, Engelhardt, & Bernhardt, 2014) cites distances to sugar beet refineries ofup to around 100 km.

In Germany, the distribution of freight transport in agriculture is compared to standardroad, rail and barge freight in Figure 3.5.

Although only a relatively small fraction of all road freight traffic (1.2% of tonne kms),agricultural transport is still significant at 5 billion tonne kms in a year. Dividing the totalfreight traffic (tonne kms) by the total freight lifted (tonnes) shows that the averagelength of haul is short at just under 12 km. Unfortunately, no information was presentedon the total vehicle kms and there was no information on the average load per vehicle soit cannot be calculated from the data that was presented. If the average load per vehiclewas 5 tonnes then there would have been 1 billion vehicle kms by agricultural vehicles. Ifit was 10 tonnes then there would only have been around 0.5 billion vehicle kms byagricultural vehicles.

(Gotz, Zimmerman, Engelhardt, & Bernhardt, 2014) tested a range of different vehicleson a real road route containing a mixture of different urban and rural road types thatthey considered representative of an agricultural transport operation in Germany. Thevehicles were two agricultural tractors (one 121 kW and Vmax of 40 km/h, the other243 kW and Vmax 50 km/h) a Unimog (210 kW and Vmax of 80 km/h) and a standardarticulated truck (310 kW and Vmax of 90 km/h). All but the truck was tested with anagricultural trailer and a semi-trailer. The results for average speeds achieved are shownin Figure 3.6.


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Figure 3.5: Inland goods transport volumes in GermanySource: (Gotz, Zimmerman, Engelhardt, & Bernhardt, 2014)

Figure 3.6: Average speeds achieved by different test vehicles in public road trials ofdifferent vehicles on a route designed to be representative of German agricultural

transport operations.

It can be seen that the increases in average speed were of course less than the increasesin maximum speed, likely reflecting the fact that other factors than Vmax constrain theactual travel speed. This can also be seen in the fact that urban speeds were lower thanrural speeds (likely a consequence of lower speed limits and increased traffic congestionin many urban areas) and also that the difference between vehicles was less (alsocontributed to by engine power considerations with increased frequency ofacceleration/deceleration cycles). The data was also presented separated by whether thevehicle was full or empty but averaged across both road types. Based on this dataincreasing the maximum speed of an agricultural tractor from 40 km/h to 50 km/h (with

3209

428 341 235398

5 92 64

Road Haulage Agriculture Rail Barge

Transport quantity (million t)

Traffic performance (billion tkm)

33.21

32.54

39.00

39.02

40.93

42.29

45.02

22.99

22.54

26.69

24.82

25.15

24.37

27.03

0 10 20 30 40 50

Tractor (121 kW) agricultural trailer

Tractor (121 kW) semitrailer

Tractor (243 kW) agricultural trailer

Tractor (243 kW) semitrailer

Unimog agricultural trailer

Unimog semitrailer

Truck

Series2 Series1


August 2017 34

associated power increase) raised average speed from 29.33 km/h to 35.39 km/h (21%)when empty and from 26.88 km/h to 30.01 km/h (12%) when fully loaded.

(Mederle, Urban, Fischer, Hufnagel, & Bernhardt, 2015) undertook similar tests ondifferent vehicles with a different route with the aim of optimising standard tractors fortransport. They found that increasing the maximum speed from 50 km/h to 60 km/hresulted in time savings of 8.5%.

So, in terms of the average 12 km trip then the time taken can be calculated. Whencombined with labour costs per hour (c €16/h taken from (DfT, 2015) representing UKlevels in 2015) the cost saving per trip can be calculated. Similarly, for Germany it ispossible to give a crude estimate of the total vehicle kms travelled in agriculturaltransport (based on a crude estimate of an average load of between 5 and 10 tonnes anddata presented by (Gotz, Zimmerman, Engelhardt, & Bernhardt, 2014)). This can beconverted to travel times and labour cost savings. The results are shown in Figure 3.1.

Table 3.1: Speeds, travel times and costs for different agricultural vehicle trip scenarios

Scenario Distance(km)

Max Speed(km/h)

Averagespeed

(km/h)1

Travel time(hours)

Travel cost(€)

Singlevehicle trip

Baseline 12 40 26.88 0.45 7.2

High speed 12 50 30.01 0.40 6.4

Difference 0 10 3.13 -0.05 -0.8

Estimatedannual

agriculturetransport inGermany

Baseline 0.5billion 40 26.88 18.6m 297.6m

High speed 0.5 billion 50 30.01 16.7m 266.6m

Difference 0 10 3.13 -1.9m -31m

Baseline 1billion 40 26.88 37.2m 595.2m

High speed 1billion 50 30.01 33.4m 533.2m

Difference 0 10 3.13 -3.8m -62m

No easily available data quantifying the road transport vehicle kms by agriculturalvehicles across Europe has been identified. It is not, therefore possible at this time to doa reliable analysis of the likely cost savings for the EU as a whole. However, as a crudeproxy measure, (European Union, 2016) shows that agricultural output in Germany wasapproximately 12% of that of the whole EU in 2015. If agricultural vehicle kms on theroad was assumed to correlate with overall output, then the labour saving as a result ofreduced travel time by increasing maximum speed from 40 to 50 km/h is up to betweenaround €258million and €516m2. Offsetting this benefit, there would be an increase infuel consumption. This has not been quantified at this time because the analysis is only asimplistic indication of effects. Consideration of variable fuel cost and machine efficiencyadd substantially to the complexity of the issue. Additionally, the fact that, whereavailable, tractors capable of exceeding 40 km/h are becoming much more popular,shows that the benefits of the increase substantially outweigh the direct perceived cost tothe end-user.

1 Note: Average speeds are those for the fully loaded case so likely to be conservative in practice.2 The wide range of values relates principally to the need to assume a range of likely average loadscarried because this data was required for the analysis but unavailable.


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The EU agricultural vehicle fleet3.3The primary focus of this investigation is agricultural vehicles of 40 < Vmax ≤ 60 km/h. Inmost supply industries, development of the product occurs over time in response tocustomer / market demand, whether this be predicted or demonstrated. Manufacturers ofpremium products tend to lead the field with the introduction of new features; othersfollow once a clear market demand is evident. These trends apply to most products, bethey cars, trucks, lawnmowers, vacuum cleaners or agricultural tractors and trailers.

Consequently the composition of the EU agricultural vehicle fleet reflects changes inagricultural requirements. The change in fleet composition over time is progressive, asnew machines replace older versions. However, it is important to appreciate that whilstolder vehicles may be retained within the fleet for back-up / reserve purposes, due inpart to the unpredictability and weather-dependency of farming operations, it is thenewer ‘frontline’ machines (e.g. ≤ 15 years old) which perform the majority of the work.The following Sections (3.3.1 & 3.3.2) consider EU agricultural vehicle fleet composition,particularly regarding those types deemed likely to travel on-road at higher speeds (T1b,R3b, R4b & S2b) and therefore perhaps benefit most from adoption of ABS technology.

3.3.1 Category T1 wheeled tractors

As stated in Section 3.1, changes in EU farm structure have placed greater emphasisupon the productivity of agricultural tractors. Whilst some may suggest that tractorsspend the majority of their operating hours in-field, it is a widely-acknowledged fact thattransport activities and (depending upon farm business structure) travel between thefarmstead and field make up a substantial proportion of total operating time (Gotz,Holzer, Winkler, Bernhardt, & Engelhardt, 2011). The provision of tractors with greatermaximum speed capability has long been recognised as a means of reducing theproportion of unproductive time spent travelling between fields and also improvingoverall efficiency during material transport operations.

Reviewing European tractor development, in the mid-1980s the majority of tractors wereof Vmax ≤ 30 km/h capability: by the mid-1990s Vmax = 40 km/h tractors were widelyavailable and by the mid-2000s Vmax = 50 km/h tractors were available from the majorityof global manufacturers. Given this progressive increase in tractor maximum designspeed capability over a relatively limited time, it appears reasonable to conclude that asignificant market demand exists for such vehicles from farmers and agriculturalcontractors. Given that such higher speed capability is only of benefit during on-roadtransport and general travel activities, these must represent a significant proportion ofoverall vehicle use (at least a sufficient proportion of usage to justify the purchase of atractor with higher Vmax capability).

With the notable exception of the Mercedes-Benz Unimog, Vmax > 40 km/h tractorsbecame available from specialist and premium brand manufacturers (JCB and Fendt) inthe early 1990s. As market demand developed, global T1 tractor manufacturers releasedVmax = 50 km/h models across their ≥ 100 hp / 75 kW model ranges by 2003 - 2006.Today two manufacturers (Fendt and SDF) offer Vmax = 60 km/h versions of certain(higher-power) T1 tractor models, in addition to Vmax = 40 km/h or 50 km/h variants;one manufacturer (JCB) offers Vmax > 60 km/h vehicles, but of more specialistdesigns (Figure 3.7). As commented in Section 2.3.1, at present Vmax > 40 km/hcapability is generally only offered on T1 tractor models of > 130 hp / > 97 kW ratedengine power (Table 2.1).

Vmax = 50 km/h remains the most popular and widely available Vmax > 40 km/h version ofT1 ‘conventional’ tractors, being offered as a customer-specified option on ‘standard’Vmax = 40 km/h vehicles. Some early Vmax = 50 km/h tractors were fitted with highercapacity service braking systems but, for sake of product-build commonality, suchcapability is often now fitted to Vmax = 40 km/h vehicles. For reasons of both drivercomfort and practical drivability on uneven rural roads, Vmax > 40 km/h tractors requiresuspension on at least one axle (usually the front); the national legislation of some


August 2017 36

Member States mandates this requirement (see Section 3.4). However, the benefits offront axle and driver cab suspension are now widely appreciated in the marketplace andso are regularly specified by the customer, irrespective of vehicle Vmax capability.

Figure 3.7: Fendt 900 Vario series Vmax ≤ 60 km/h T1 tractor (left) and JCB Fastrac 8000series Vmax ≤ 70 km/h T1 tractor (right)

(Copyright AGCO GmbH & JCB)

It is important to appreciate that, with the widespread introduction of electronic engineand transmission control systems on modern tractors, the former in response to engineexhaust emissions requirements, the option of Vmax = 40 km/h or Vmax = 50 km/h on aT1 tractor may frequently be selected by configuration of the vehicle’s control software,potentially post-production. This is particularly the case given the increasing availability /popularity of electronically-controlled continuously-variable transmissions (CVTs) uponhigher-powered tractors. These transmissions can offer a very wide range ofinput : output speed ratios and consequently high Vmax capability, if so configured.

Despite the widespread availability of Vmax > 40 km/h T1 tractors since 2003-2006(depending upon rated engine power), not all EU Member States permit the sale and/orthe use of such vehicles at their maximum speed (see Section 3.4). Additionally, whilstnew tractors sales in individual Member States are normally recorded, these tend to becategorised on the basis of engine power output and Vmax capability is not alwaysrecorded; fortunately there are some exceptions (e.g. Germany (Kraftfahrt-Bundesamt,2016)). Consequently, in order to gain a reliable insight into the presence and usage ofVmax > 40 km/h tractors in the EU, it has been necessary to compile data from multiplesources and also to make certain assumptions / estimations.

As previously stated (Section 2.3.1), Vmax > 40 km/h capability is generally only offeredon T1 tractor models of > 130 hp / > 97 kW rated engine power (Table 2.1), thisprimarily being due to the minimum level of engine power required for effective tractor-trailer transport operations at speeds above 40 km/h. Whilst certain manufacturers havemarketed Vmax > 40 km/h tractors from the early 1990s, such vehicles have been widelyproduced by all major T1 manufacturers since 2003-2006. Also, just six Member States(France, Germany, Italy, Spain, the United Kingdom and the Netherlands) togethergenerate over 68% of EU-28 total agricultural output (Figure 3.1) and between themaccount for a similar proportion of new tractor sales in the EU. It is therefore appropriateto consider the vehicle fleets in these Member States in greater detail, from 2006 to thepresent day, a period over which (if permitted by national legislation) Vmax > 40 km/htractors would potentially have been available in those countries.

Over the 2006–2016 period sales of new > 50 hp (37 kW) tractors in the six selected EUMember States declined, on average, by ~18%. However, over the same period, salesof > 125 hp (93 kW) tractors increased by 35% (Figure 3.8) and salesof > 150 hp (112 kW) tractors increased by ~52% (Figure 3.9). It is noteworthy that in


August 2017 37

2016 > 125 hp (93 kW) machines accounted for ≥ 60% of new tractor sales in Germany,the UK and the Netherlands.

Consequently, it would appear that over the 2006-2016 period, in an otherwise decliningmarket, increasing numbers of more powerful tractors were sold. This corroborates thestatements made earlier regarding the rationalisation of EU farm businesses (seeSection 3.1). It would appear that, particularly in these Member States, fewer farmholdings of increased size are utilising fewer, larger tractors operated by a reducedlabour force. This cannot fail to increase on-road travel distances for individual vehicles.

Figure 3.8: Proportion of new tractors of > 125 hp / 93 kW rated engine power sold inselected EU Member States over the 2006 – 2016 period

Source: AEA data

Figure 3.9: Proportion of new tractors of > 150 hp / 112 kW rated engine power sold inselected EU Member States over the 2006 – 16 period

Source: AEA data


August 2017 38

Whilst these tractor sales data present reliable information showing a distinct increase inthe population of annual tractor sales which could be of Vmax > 40 km/h capability, itdoes not quantify the proportion of vehicles with such capability. Industry stakeholders(CEMA) estimate that approx. 17,000 tractors of 40 < Vmax ≤ 60 km/h capability weresold in the EU during 2016 and that these represented approximately 10% of total EUtractor sales, suggesting a total of approximately ~170,000 vehicles for that year.However, (Jorgensen & Persson, 2013) reported an EU agricultural tractor market of150,000 in 2011 and it is known that market volumes declined between 2011 and 2016.Other stakeholders suggest that EU total new tractor sales (> 50 hp) in 2016 were morelikely to be in the range 125,000 – 135,000 units, as CEMA statistics may have includedseveral non-EU European countries, such as Turkey. If this is the case,40 < Vmax ≤ 60 km/h tractors would potentially have represented ~13% of the total EUmarket in 2016; still hardly a large proportion.

However, at present not all Member States permit the sale of such vehicles (seeSection 3.4) and also this value makes no allowance for the number of vehicles sold inpreceding years. Fortunately the German authorities (Kraftfahrt-Bundesamt, 2016) dorecord both the engine power ratings and Vmax capability of new tractors sold. It wouldappear that 40 < Vmax ≤ 60 km/h tractors currently comprise ~6% of the German tractorfleet (Figure 3.15), which is not a large proportion. However, during the 2010-2015period, the number of these vehicles increased by over 23,000 units or by ~42% toapproximately 79,000 units, representing ~40% of the German > 90 kW tractor fleet.Arguably this is a significant value.

Taking the UK market as an example (one of the six example Member Statesconsidered), agricultural tractors of up to Vmax = 40 mph (64 km/h) may be placed onthe market, but if driven / used on-road at speeds exceeding 25 mph / 40 km/h theymust comply with more stringent constructional requirements, including greater brakingsystem performance (including ABS) and the provision of front and rear axle suspension.However, as the UK does not implement a formal national type-approval scheme, butrather relies upon enforcement of regulations whilst vehicles are in-use, Category T1tractors of Vmax > 40 km/h capability and ‘conventional’ construction (front axlesuspension only and no ABS installed) have found a ready market in the UK.

A recent survey of UK agricultural contractors (NAAC, 2017) highlighted the degree ofVmax > 40 km/h tractor operation by this type of user (Figure 3.10). Tractors in the‘Lower Middleweight’ (151-230 hp) power range were the most numerous, followed byvehicles in the ‘Upper Middleweight (231-320 hp) range; the proportion of these tractorswith Vmax > 40 km/h capability was ~85% and ~89% respectively. Perhaps surprisingly,an even greater proportion (100%) of 321-400 hp ‘Heavyweight’ tractors hadVmax > 40 km/h capability, highlighting the importance to this user group, for what maybe regarded as an in-field, heavy-draught operations tractor, to be able to travel quicklyon-road between jobs.

The survey asked UK agricultural contractors to estimate the proportion of time theirvarious-sized tractors spent whilst engaged in the following basic operations:

· In-Field Work: e.g. cultivations, material application, crop harvesting.

· Material Transport: e.g. transport of crop / other materials to/from the fieldand/or the farmstead / elsewhere.

· General Travel to/from the Field: Not involving transport of consumablematerials.

Additionally, the times spent by each tractor size range during ‘Material Transport’ and‘General Travel’ operations were summed to create a ‘Total Travel’ category whichpotentially estimates the total time a tractor may spend travelling. It should of course be


August 2017 39

emphasized that a proportion of ‘Material Transport’ activities will be undertaken in-fieldas opposed to on-road, but nonetheless these may well be at speeds above 20 km/h.

Figure 3.10: Power distribution and Vmax capability of tractors currently operated by UKagricultural contractors

Source: (NAAC, 2017)

Figure 3.11: Breakdown of tractor time utilisation by UK agricultural contractorsSource: (NAAC, 2017)

It would appear that, of all the tractor size categories, vehicles in the 151-230 hp and230-320 hp ranges perform the largest proportion of ‘Material Transport’ operations(31-32%: see Figure 3.11) and, perhaps understandably, > 320 hp tractors undertake


August 2017 40

the least (~3%). However, it was estimated that these large tractors still spend ~13% oftheir time engaged in ‘General Travel’, no doubt reflecting the distances these vehiclesare required to travel for agricultural contracting businesses in order to perform their(primary) in-field tasks (~83%).

This was however in stark contrast to tractors of 151-230 hp and 230-320 hp, whichwere estimated to spend 50% and 47% of their total operating time, respectively,engaged either in ‘Material Transport’ or ‘General Travel’: hardly a small proportion.

Agricultural contractors are known to be intensive users of the machinery at theirdisposal. The survey found that vehicles of > 150 hp were, on average, worked for 1200– 1500 hours per year and were replaced approximately every 5 years. Such contractingbusinesses are also highly likely to operate over larger geographic areas than normalfarms and so, potentially, would be more likely to purchase Vmax > 40 km/h tractors.

Figure 3.12: Breakdown (by engine power) of proportion of new Vmax ≤ 40 km/h andVmax = 50 km/h T1 tractors sold by a major East Anglian (UK) tractor dealer during the

2013 – 17 periodSource: Anonymous UK tractor dealer

However, the tractor sales data of a typical UK main franchised dealer suggests that thepenetration of Vmax > 40 km/h tractors into the UK market is very substantial and isequally due to purchases by normal farmers rather than just by agricultural contractors.T1 tractor sales averaged over the 2013 – 2017 period show a very high proportion(~88-89%) of Vmax = 50 km/h vehicles sold in the 151-230 hp and 230-320 hp powerranges and over 70% in the 125-150 hp and > 320 hp ranges (Figure 3.12).

Analysis of vehicle sales over time (Figure 3.13) shows a steady increase in sales ofVmax = 50 km/h tractors in all categories above 100 hp / 75 kW to the extent that, forwheeled tractors above 150 hp / 112 kW engine power, Vmax = 50 km/h is almost thedefault customer choice. This is compelling data, but it can be argued with somejustification that the UK is but one market within the EU-28 and that, at present, manyMember States do not accept Vmax > 40 km/h tractors (see Section 3.4). It also relatesonly to sales on new vehicles and, unlike the German data presented in Figure 3.15, itdoes not indicate the proportion of vehicles in the total UK fleet.


August 2017 41

Figure 3.13: Variation of Vmax ≤ 40 km/h and Vmax = 50 km/h new tractor sales by amajor East Anglian (UK) tractor dealer during the 2012 – 17 period

Source: Anonymous UK tractor dealer

Figure 3.14: Proportion Vmax > 40 km/h T1 tractors produced during 2016 by two globaltractor manufacturers

Source: Anonymous tractor manufacturers

The recent Vmax > 40 km/h tractor production data of two major global manufacturerspotentially provides a more reliable indication of the current situation across the entireEU (Figure 3.14). As previously discussed, the EU-wide demand for Vmax > 40 km/htractors is without question dependent upon vehicle power, not only because such


August 2017 42

capability is not readily available on < 130 hp (< 97 kW) machines, but also becausehigher tractor power : mass ratios are required for effective performance during higher-speed transport operations. Figure 3.14 indicates that ≥ 50% of tractor production fromthese particular manufacturers in the important, farm transport-orientated 151-230 hpand 230-320 hp power ranges would appear to be of Vmax > 40 km/h capability. Giventhe final implementation of Regulation (EU) No 167/2013 (European Union, 2013) inJanuary 2018, from which date all Member States cannot refuse the sale / registration ofVmax > 40 km/h tractors (although they can prohibit their higher-speed use -see Section 3.4), it would be surprising if the sales proportions of such vehicles acrossthe EU did not increase in the future.

Figure 3.15: Variation in the population of 40 < Vmax ≤ 60 km/h tractors in the Germanagricultural tractor fleet during the 2010 – 15 period

Source: (Kraftfahrt-Bundesamt, 2016)

However, the Vmax > 40 km/h tractor data presented for the UK in Figure 3.11 and Figure3.12 only relates to new vehicle sales. In order to analyse the possible effects ofVmax > 40 km/h tractor operation upon road accident numbers in the UK, this beingconsidered to be a market with high Vmax > 40 km/h penetration and one for whichdetailed accident data was available (see Section 4), it was necessary to estimate theproportion of such vehicles currently present in the UK tractor fleet and also how thispopulation has changed over time since their first widespread release onto the market(2003-2006).

Vehicle registration data was obtained, which specified the number and historical agebreakdown of agricultural tractors in use in the UK over the period in question. Thesedata were segregated for each year (on the basis of historical sales vs. engine powerdata) to reflect the proportion of registered vehicles in each of three major power (100-200 hp, 200-300 hp & 300-400 hp) present in the total tractor fleet. These data werethen factored by the proportion of vehicles sold in each year (in each power band), whichwere deemed likely to have Vmax > 40 km/h. This was considered to be ~1% prior to2003-2006 (depending upon the power band), increasing progressively to theproportions indicated by Figure 3.13 for recent years. By this method the total number of


August 2017 43

Vmax > 40 km/h tractors currently present in the UK fleet was reliably estimated, both asa proportion of the total tractor fleet and also of the vehicles of less than 20 years age,the latter being deemed to reflect tractors which are still likely to be in intensive /frontline use upon farms. Figure 3.16 shows the estimated variation of these vehiclepopulations to the present time.

Figure 3.16: Estimated increase in the proportion of 40 < Vmax ≤ 60 km/h tractors in UKagricultural tractor fleet

3.3.2 Agricultural trailers and interchangeable towed equipment

As highlighted at the beginning of this section, the primary focus of this investigation isagricultural vehicles of 40 < Vmax ≤ 60 km/h. In practice, agricultural trailers andinterchangeable towed equipment are not able to control the speed at which they areoperated; they travel at the speed of the vehicle which is towing them. Whilst design-speed or maximum operating speed-related national regulations / requirements do existin some EU Member States, the implementation of Regulation (EU) No 167/2013 hasprovided the first route by which agricultural trailers and interchangeable towedequipment may be granted EU type-approval. Additionally, for the first time, thisregulation introduces the concept of such vehicles being recognised as suitablefor > 40 km/h operation on an EU-wide basis.

However, with regard to the timing of this investigation, Regulation (EU) No 167/2013 isstill in its first implementation period (2016–2018) and few Category R or S vehicles haveyet to receive type-approval, let alone be placed on the market in significant numbers toinfluence the nature of the EU vehicle fleet. Additionally, as highlighted in Section 2.3, EUtype-approval of Category R and S vehicles is not a mandatory requirement of Regulation(EU) No 167/2013. Vehicle manufacturers may instead choose to comply with therelevant national regulatory requirements of individual Member States for the foreseeablefuture. In time, these national requirements may possibly tend to become aligned withthose of Regulation (EU) No 167/2013, but this is as yet uncertain. For these reasons,this investigation has largely viewed the EU trailed agricultural vehicle fleet as it iscontrolled by current national requirements as opposed to harmonised EU legislation.


August 2017 44

As highlighted in Section 2.3, this investigation has focussed upon Category R3, R4 andS2 trailed agricultural vehicles, namely those of MPMaxles > 3500 kg. Additionally, asexplained in Section 2.3.7, if the ratio of Laden : Unladen mass of trailed equipment(i.e. Category S vehicles) is ≥ 3.0, it is classified as a Category R vehicle; consequently,Category R3 and R4 vehicles are of primary importance.

However, if these vehicles are towed by agricultural tractors (assumed to be the caseduring normal agricultural operations), they are only likely to be used above 40 km/h ifthe towing vehicle is of > 130 hp / 97 kW engine power, simply because (i) extremelyfew Vmax > 40 km/h tractors exist below this power level and (ii) these and higher enginepower levels are a practical pre-requisite for effective tractor-trailer transport operationsabove 40 km/h. Given that the towing vehicle is likely to be > 130 hp / 97 kW andprobably even > 150 hp / 112 kW in order to ensure reliable Vmax > 40 km/h operation(see Figure 3.10), it is highly likely that the user will wish to operate a trailer of sufficientcarrying capacity to fully-utilise this size of tractor. These predictions are confirmed bydata from a recent survey of UK agricultural contractors (NAAC, 2017) which suggeststhat 10-14 tonne capacity trailers are the most numerous (55%) in the UK fleet, followedby 14-17 tonne capacity vehicles (32%). However, whilst over 70% of 10-14 tonnetrailers were considered likely to be operated with Vmax > 40 km/h tractors, almost 100%of trailers of more than 14 tonne capacity were likely to be used above 40 km/h (Figure3.17). This very much confirms the theory that, in the main, larger capacity trailers tendto be used behind higher-powered tractors capable of Vmax > 40 km/h.

Figure 3.17 Trailers operated by UK agricultural contractors: vehicle size (carryingcapacity) distribution and proportion used with Vmax > 40 km/h tractors


The same survey also demonstrated a change in agricultural trailer size (carryingcapacity) over time (Figure 3.18); trailers of ≤ 14 tonnes were generally much older(~5 – 20 years), whereas newer trailers (~0 – 10 years) were mainly of 14.1 –17 tonnes or larger capacity. This correlates well with information gained from UK trailermanufacturers, who claim that the most popular sizes of monocoque (bulk) trailercurrently sold are 16 and 18 tonnes capacity, followed by 14 tonnes, followed


August 2017 45

by > 20 tonnes. This incidentally is in the face of UK national road legislation which(theoretically) does not permit the use of > 13.5 tonne capacity trailers!

In truth, trailer carrying capacity is very much influenced by the holding tank capacity ofmodern (larger) harvesting machinery, which has developed to such an extent over thelast 5-10 years that a 14 tonne capacity vehicle is, in many cases, no longer adequate forefficient materials transport without constraining harvesting output. During harvestingoperations it is highly desirable that haulage trailers have sufficient carrying capacity toaccommodate one or more complete discharges of the harvesting machine’s holdingtank. Combine harvester tank capacity now frequently exceeds ~8 tonnes; sugar beetharvester bunker capacity can exceed ~16 tonnes: hence the need for large capacitytrailers.

It may be argued that the equipment used by agricultural contractors is not necessarilyentirely representative of that operated by normal farmers, the former perhaps beinggenerally larger / of greater capacity. However, as discussed in Section 3.3.1, EU salesstatistics of tractors do not support this viewpoint, but rather underline the fact that theagricultural equipment market is moving towards fewer, but larger / higher capacitymachines. Agricultural contractors frequently have to operate in the smaller and lessaccessible fields of smaller-farm customers and so will select adaptable equipment withhigh potential output. Additionally, in other cases, farmers have expanded theiroperations to ‘contract-farm’ neighbouring land under rental agreements, therebyimproving the economic viability of their businesses. Irrespective of the identity of thepurchaser, the requirement for larger, more productive agricultural machinery is thesame and it would appear to represent an increasing proportion of the market.

Figure 3.18: Trailers operated by UK agricultural contractors: population breakdown bycarrying capacity and age


Regulation (EU) No 167/2013 defines trailer size categories not by carrying capacity, butrather in terms of the sum of the technically-permissible masses per axle (MPMaxles).Given the wide variety of trailer sizes and configurations, this is entirely understandable.However, for Category R3 and R4 trailers of the common, rigid drawbar monocoque-bodydesign (see Section 2.3.6), a reliable correlation exists between MPMaxles and carrying


August 2017 46

capacity. This is further illustrated by Table 3.2, together with the proportion of such (UKcontractor-operated) vehicles likely to be used at speeds of > 40 km/h.

These data (Figure 3.17 and Figure 3.18) provide a quite convincing insight into likelyagricultural trailer usage within the UK, particularly at Vmax > 40 km/h, but what aboutpractices in other EU Member States? It is known that the use of Vmax > 40 km/h tractorsis only permitted at present in certain Member States (Germany, Austria, UK, Spain,Finland, Ireland, plus certain others – see Section 3.4). Trailer size is also influenced bynational road legislation which, again, is not harmonised throughout the EU.

However, it is known that the use of large-capacity (R4-type) rigid drawbar trailers ispermitted in Germany, France, Belgium, the Netherlands, Ireland, and in a number ofother Member States. In many instances the permitted operating masses of thesevehicles are larger than are permitted in the UK. Consequently, whilst the marketpenetration of Vmax > 40 km/h tractors in some of these countries may not be as great asthat in UK at present, the use of larger, heavier trailers is potentially greater.

Figure 3.19: Correlation between MPMaxles and carrying capacity of monocoque (fixed-side) Category R3 and R4 agricultural trailers

Source: Manufacturer data

Table 3.2: Tandem and tri-axle (rigid drawbar) trailers used by UK agriculturalcontractors: correlation between carrying capacity, axle loading and use at > 40 km/h.


Trailer Carrying Capacity(kg)

MPMaxles(kg)

Proportion of trailers usedat > 40 km/h (%)

< 10,000 <11,000 33

10,000 – 14,0000 11,000 – 16,000 71

14,001 – 17,0000 ~16,000 – 20,000 97

17,001 – 20,0000 ~20,000 – 23,650 100

> 20,000 > 23.650 100


August 2017 47

Existing legislation and policy regarding on-road use of agricultural vehicles3.4As discussed in Section 3.3, the use of Vmax > 40 km/h agricultural vehicles is far from anew phenomenon in many EU Member States, but most enact their own legislationregarding the maximum operating speeds and masses of vehicles used on-road:agricultural vehicles, whilst sometimes treated favourably, are rarely exempted fromsuch requirements.

Prior to the introduction of Regulation (EU) No 167/2013, the system of EU whole-vehicletype-approval of agricultural tractors was defined by Directive 2003/37/EC (EuropeanCommunity, 2003), technical requirements and test procedures being specified by awhole range of separate Directives. Directive 2003/37/EC was far-sighted in so much as,in addition to the ‘conventional’ T1, T2 and T3 vehicle categories, it also defined adedicated category (T5) for Vmax > 40 km/h agricultural tractors. Unfortunately thisadvantage was never realised in practice because, critically, the technical requirementsfor T5 tractor type-approval were never entirely finalised and defined (Scarlett, 2015).This effectively meant that, prior to the introduction and implementation ofRegulation (EU) No 167/2013 (i.e. 1st Jan 2016), it was not possible to obtain EU type-approval for agricultural tractors of Vmax > 40 km/h.

Until now this issue has posed quite a significant barrier to the use of Vmax > 40 km/htractors in certain EU Member States. However, as discussed in Section 3.3.1, suchtractors have been widely available from all major manufacturers since 2003–2006 and,in a number of cases, up to a decade previously. So prior to the implementation of (EU)No 167/2013, by what means were these vehicles placed on the market?

With no EU type-approval route available, tractor manufacturers had no option otherthan to consider each Member State on a case-by-case basis and, where possible,comply with national legislative requirements, if these permitted or did not preclude thesale of Vmax > 40 km/h tractors. Alternatively national type-approval could be sought forthe vehicles in question, if this route existed. A minority of Member States operatednational approval schemes for agricultural trailers (particularly larger capacity examples),but > 40 km/h operation of such vehicles was, of course, dependent upon the acceptanceof Vmax > 40 km/h tractors in the market. Where the latter was possible, regulations /requirements normally existed to permit the use of Vmax > 40 km/h trailers, subject toenhanced braking and (possibly) suspension system performance requirements.

The influence of specific national requirements for the sale / use of Vmax > 40 km/htractors have tended to be reflected in the specifications of vehicles offered by globalmanufacturers in other EU Member States. For instance, Germany is both the largestmarket for agricultural tractors in the EU-28 and is also a major centre for tractorproduction. German road regulations permit tractors of Vmax > 40 km/h to be sold / usedon-road, subject to a number of requirements, including the installation of front axlesuspension, but ABS is not required unless Vmax > 60 km/h. By comparison, the UKpermits agricultural tractors of up to Vmax = 40 mph (~65 km/h) to be placed on themarket, but if driven / used on-road at speeds exceeding 25 mph / 40 km/h they mustcomply with more stringent constructional requirements, including greater brakingsystem performance (including ABS) and the provision of front and rear axle suspension.These constructional requirements have not been reflected in the products of globaltractor manufacturers, whereas those of the German national market, perhapsunderstandably, have been.

So at the time of writing, the regulation of the EU tractor and agricultural vehicle marketis in a state of transition. Regulation (EU) No 167/2013 has defined both vehiclecategories and respective technical requirements for the EU type-approval ofVmax ≤ 40 km/h and Vmax > 40 km/h agricultural vehicles, including both trailers andinterchangeable towed equipment. Critically, following the 1st January 2018implementation date of the regulation for existing types (as opposed to new types) ofvehicle, no Member State can prohibit the placing on the market, the registration or theentry into service of vehicles which comply with the requirements of the regulation.Essentially this means that, importantly, EU Member States which previously refused to


August 2017 48

accept Vmax > 40 km/h agricultural vehicles will no longer be able to do so if the saidvehicles have been type-approved in accordance with the requirements ofRegulation (EU) No 167/2013.

Theoretically this could lead to a significant increase in the market for Vmax > 40 km/hagricultural vehicles. Individual Member States will, of course, still be entitled to limit thespeed of use of such vehicles by means of national speed restrictions enforced by thePolice and other enforcement methods. However, it is not permitted for thespecification / construction or the performance of the vehicle to be modified or restrictedfollowing type-approval. Subject to the existence and degree of enforcement of any suchnational speed restrictions, it is therefore highly probable that such vehicles will beregularly used at their maximum design speed, where vehicle power : weight ratio andthe mass of any attached trailer permits. Indeed, in certain countries where the use ofVmax ≥ 40 km/h tractors is currently permitted, in appropriate road conditions, operationat higher forward speeds is considered to cause less delay and frustration to other roadusers and reduce the likelihood of dangerous overtaking manoeuvres by them, therebyactually reducing overall accident risk. However, no evidence exists to support this view.

It is also appropriate to highlight that some Member States impose periodicroadworthiness assessment (testing) requirements on agricultural tractors and trailersused at speeds above 40 km/h. Austria is known to operate such a system, whereas it isbelieved certain other Member States (e.g. Germany) are considering doing so.Directive 2014/45/EU (European Union, 2014) specifies these requirements, but permitsindividual Member States to exempt agricultural and forestry vehicles from therequirements if they consider it appropriate.

As commented in Section 1.2, this investigation went to considerable lengths to surveythe National Approval Authorities, Enforcement Authorities, Technical Services and (withthe further assistance of the European Commission) the National Transport Authorities ofEU Member States, to identify current and forthcoming (post-January 2018) nationalrequirements for the operation of Vmax > 40 km/h agricultural vehicles. Unfortunately,the overall response received was low. The following tabular summaries of the nationalrequirements of Member States have therefore been compiled with the information whichis currently at our disposal and are not deemed to be either exhaustive or error-free.


August 2017 49

Table 3.3: Current national transport policies of EU Member States regarding the on-roaduse of Vmax > 40 km/h agricultural vehicles (where known)

MemberState

> 40 km/h operationpermitted Conditions / requirements for sale and/or use

> 40 km/hTractor Trailer

Germany Yes YesVmax ≤ 60 km/h tractors permitted (if fitted with frontaxle suspension). ABS braking system only required ifVmax > 60 km/h

France No No Operation > 40 km/h not permitted

Italy No No Operation > 40 km/h not permitted

Spain Yes NoSolo tractors may operate between 40 – 70 km/h,depending upon specification, but are restricted to ≤ 25km/h if towing a trailer

UnitedKingdom

Yes(≤ 65km/h)

Yes

Tractors must feature enhanced braking systems(UNECE Reg 13 or 71/320/EEC-compliant) and ABS,front & rear axle suspension plus other requirements.Vmax > 40 km/h trailers must comply with Category Ovehicle requirements.

Netherlands Unclear UnclearVmax ≤ 25 km/h has been mentioned, but otherssuggest Vmax > 40 km/h may be permitted undercertain national regulations

AustriaYes

(≤ 50km/h)

Yes(≤ 50km/h)

Vmax ≤ 50 km/h tractors permitted (if fitted with frontaxle suspension). ABS system required > 50 km/h.Vehicles restricted to agricultural and forestry uses.Vmax > 40 km/h trailers must comply with Category Ovehicle requirements (Directive 2007/46/EC, Annex IV)

Republic ofIreland Yes Yes

Vmax > 40 km/h tractors must be plated & meet higherbraking performance requirements ABS required ifVmax > 60 km/h. Similar speed-related requirementsfor trailers plus suspension & minimum tyre sizestipulations. Vmax > 40 km/h trailers must be fitted withpneumatic braking systems

Belgium No No -

Denmark No No -

FinlandYes

(≤ 50km/h)

Yes(≤ 50km/h)

Precise requirements not known

Sweden No No -

Portugal No No -

Poland Unclear Unclear Information suggests Vmax > 40 km/h operation may bepermitted under certain national regulations

CzechRepublic Unclear Unclear Information suggests Vmax > 40 km/h operation may be

permitted under certain national regulations

Hungary No No -

Bulgaria Unclear Unclear Information suggests Vmax > 40 km/h operation may bepermitted under certain national regulations

Romania Unclear Unclear Information suggests Vmax > 40 km/h operation may bepermitted under certain national regulations

Latvia Yes (Noupper limit)

Yes (Noupper limit)

Vehicles must comply with general road traffic rulesincluding posted speed limits


August 2017 50

Table 3.4: Likely future national transport policies of EU Member States (post-Regulation(EU) No 167/2013 implementation) regarding the on-road use of Vmax > 40 km/h

agricultural vehicles (where known)

MemberState

> 40 km/h operationpermitted

Conditions / requirements for sale and/or use> 40 km/h

Tractor Trailer

Germany Yes YesNational requirements largely unchanged: already inagreement with category ‘b’ requirements of (EU) No167/2013 & associated Delegated Acts

France No No Operation > 40 km/h will not permitted

Italy No No Operation > 40 km/h will not permitted

Spain Yes No Unclear

UnitedKingdom

Yes(≤ 65 km/h) Yes

National requirements largely unchanged: already ingeneral agreement with category ‘b’ requirements of(EU) No 167/2013 & associated Delegated Acts

Netherlands Unclear UnclearVehicles must comply with category ‘b’ requirements of(EU) No 167/2013 & associated Delegated Acts, butnational speed limitations may be imposed

Austria Yes YesTractors and trailers must comply with category ‘b’requirements of (EU) No 167/2013 & associatedDelegated Acts

Republic ofIreland Yes Yes

Vmax > 40 km/h tractors must be plated & meet higherbraking performance requirements ABS required ifVmax > 60 km/h. Similar speed-related requirementsfor trailers plus suspension & minimum tyre sizestipulations. Vmax > 40 km/h trailers must be fitted withpneumatic braking systems. Assume compliance with(EU) No 167/2013 category ‘b’ requirements will alsobe deemed acceptable

Belgium No No -

Denmark Unknown Unknown -

Finland

Yes(≤ 50 km/h,but possibly

higher)

Yes(≤ 50 km/h,but possibly

higher)

Precise requirements not known, but harmonisationwith (EU) No 167/2013 category ‘b’ requirements likely

Sweden Unknown Unknown -

Portugal No No -

Poland Unclear Unclear Information suggests Vmax > 40 km/h operation may bepermitted under certain national regulations

CzechRepublic Unclear Unclear Information suggests Vmax > 40 km/h operation may be

permitted under certain national regulations

Hungary No No -

Bulgaria Unknown Unknown -

Romania Unknown Unknown -

Latvia Yes (Noupper limit)

Yes (Noupper limit)

Vehicles must comply with general road traffic rulesincluding posted speed limits


August 2017 51

Accidents related to agricultural vehicles4

Influence of speed on injury risk4.1

4.1.1 Effect on collision frequency

Many research studies have examined the relationship between speeds and collisionrisks. In general, the conclusion is clear, higher speeds increase risk. Historically,agricultural tractors were restricted to very low speeds. However, a wide range ofdifferent ways of characterising speeds and different changes to speed have beenconsidered in different studies. The available research is dominated by collisions involvingpassenger cars with contributions considering the effect of differential speeds for trucksand buses. It is also possible to separately consider the effect of speed on crashfrequency or on crash severity (i.e. injury outcome). At this stage, no research has beenfound directly studying the relationship, if any, between maximum design speed ofagricultural tractors and collision risk. (Greenan, Toussaint, Peek-Asa, Rohlman, &Ramirez, 2016) did find (in Iowa, US) that agricultural vehicle collisions were more likelyto occur on roads with higher speed limits (≥ 80 km/h) but if it is assumed that thetractor speed capability remained low, this is more likely to be associated with theincreased speed of other traffic.

When considering the effect of speed on the frequency of collisions, results are oftenquoted as showing that a 1% change in average speed is associated with a 5% change inaccident frequency. However, (Taylor, Lynam, & Baruya, 2001) explored this genericrelationship in more detail. They noted that there is a fundamental difference in studyapproaches; many use a road-based approach examining different measures of speed ona given road or road type and the average crash frequency on that road. Others use adriver-based approach, examining the speed that drivers chose to drive in differentcircumstances and their personal collision history.

In combination, the analyses of (Taylor, Lynam, & Baruya, 2001) found that whateverthe study method or speed criteria, there was a strong relationship with collisionfrequency. However, they found that both increases in average speed and increases inthe spread of speeds around the average both separately increased collision frequencyand this applied to both urban and high speed rural roads. If the contribution ofincreasing agricultural tractor speeds to this were considered then, in the absence ofother changes, it would increase the average speed on that road by an extent dependingon relative density of agricultural vehicle and other traffic, probably a small amount inmost cases. However, it would reduce the spread of speed around the average in mostcases because it would be likely that agricultural tractors would be at the bottom of thespeed range. It was also found that the influence of speed on accident frequency wasslightly less (4% compared to an average 5%) on lower speed rural roads and less again(3%) for higher speed rural roads.

The concept of the spread of speed around the average has been raised by stakeholdersduring both the consultations and face-to-face discussions, highlighting that a significantnumber of agricultural vehicle collisions occur because a higher speed vehicle such as acar or a truck collides with the rear of a much slower moving tractor ahead. It is arguedthat if this differential speed is reduced, the probability of such collisions will be reduced,as would the severity. (Greenan, Toussaint, Peek-Asa, Rohlman, & Ramirez, 2016) notedthis as a possible explanatory variable for a high proportion of rear end crashes wherefarm equipment was involved in Iowa. However, no scientific study has directlyattempted to measure the effect of tractor speed capability on crash frequency.

Heavy Goods Vehicles (HGVs) in Europe are typically subjected to differential speedlimits. That is, on many higher speed roads, the maximum permitted speed for HGVs willbe less than for passenger cars. This could be considered broadly analogous to thedifferential speeds observed as a consequence of low speed capability, though the


August 2017 52

hypotheses are reversed (improve truck safety by reducing maximum speed, improvetractor safety by increasing maximum speed). (Harkey & Mera, 1994) studied differentialcar/truck speed limits in the USA and found that overall, they made little difference tosafety in terms of either collision frequency or severity. However, they did find that thetype of collision sustained might change. Where trucks were restricted to a lower speedthan cars, rear end shunt type collisions were more likely to involve a car colliding withthe rear of a truck. However, where the speed limit was uniform, all car to truckaccidents were more likely to involve trucks striking cars. There was little difference insingle vehicle collisions.

These overall findings were consistent with (Neeley & Richardson, 2009) who found thatincreasing the truck speed limit correlated closely with increasing collision rates but thathaving different speed limits for different vehicle types did not. It was suggested that thisfinding may have been at least partially because the compliance with differential speedlimits was not as good as for uniform limits such that the actual difference in speedbetween trucks and cars would be less than suggested by the posted limit alone. (Neeley& Richardson, 2009) did also cite other studies that had found a beneficial effect ofdifferential speed limits.

When considering how these results might be applied to agricultural vehicle collisions, itis important to note that the distribution of agricultural vehicle traffic by road class willbe different to trucks and that the differential speeds reviewed for trucks were in therange of 55-75 mile/h (88-120 km/h). Thus, the speed differential between agriculturalvehicles at 40-60 km/h and other traffic will be much greater than for trucks. In additionto this, the difference relates to the maximum speed capability of tractors, not the postedspeed limit. Therefore, the compliance element is much less relevant because drivers of aT1 tractor physically cannot drive it in excess of 40 km/h (in most circumstances). If thevehicle is upgraded to be capable of 60 km/h, then in many jurisdictions there will be nolegal impediment to using it to its maximum speed on many road classes. Thus, thedifference in actual speeds may be proportionally greater when comparing low speed andhigh speed tractors than when comparing the actual average speed of trucks (with verysimilar maximum speeds) in different speed limit regimes.

Thus, in summary, there is clear evidence to suggest that increasing average speedsincreases collision risk across a range of vehicle types and across all road types. Theinfluence of speed differentials and the spread of speeds around the average allows thepossibility that the effect of increasing the speed of low speed agricultural vehicles mightbe mitigated to some extent by a reduction in differential speed. However, the evidencein respect of this is somewhat ambiguous and difficult to directly transfer to agriculturalvehicles. It is possible that it would not mitigate risks overall, merely change the riskfrom one type to another (for example car front to tractor rear becomes tractor front tocar rear).

4.1.2 Effect on collision severity

In addition to the potential effect on the probability of becoming involved in a collision inthe first place, speed can have an influence on the severity of injury outcome in acollision. Again, evidence related specifically to collisions involving agricultural vehicles isextremely limited, so comparison must be based on theory and evidence from analysesof other vehicle types.

With respect to collisions, a range of speeds can be defined:

· Travel speed: the speed at which an individual vehicle is travelling immediatelyprior to the start of the sequence of events leading to a collision. In most cases,this is the speed at the start of emergency avoidance action.

· Impact speed: the speed of an individual vehicle at the moment it first makescontact with a collision partner (e.g. another vehicle, pedestrian, or roadsideobject).


August 2017 53

· Closing speed: the relative speed between a vehicle and its collision partner asthey approach impact. If a car travelling 60 km/h approaches the rear of a tractortravelling at 30 km/h in the same direction then the closing speed is 30 km/h. If acar travelling 60 km/h approaches the front of a tractor travelling at 30 km/h inthe opposite direction then the closing speed is 90 km/h.

· Change in velocity (often known as delta-V): The change in speedexperienced by a vehicle during the impact itself. Assuming equal mass andperfect impact conditions, a head on collision between two cars each travelling at30 km/h would see a closing speed of 60 km/h but a delta-V of 30 km/h. A car tocar rear collision where one car had an impact speed of 30 km/h and the otherwas stationary would see a closing speed of 30 km/h and a delta-V of 15 km/h(that is the impacting vehicle would get closer to the stationary vehicle at a speedof 30 km/h and when it collided with the stationary vehicle both would end upmoving at 15 km/h, a deceleration for the impacting vehicle and an accelerationfor the vehicle hit from behind).

The fundamental property influencing the effect of speed on collision severity is thekinetic energy, which increases in proportion to vehicle mass and the square of speed.Thus, increasing vehicle mass by 50% would increase kinetic energy by 50% butincreasing speed by 50%, for example from 40 km/h to 60 km/h would increase kineticenergy by 125%.

When considering how injury severity relates to speed, there is a well-documentedcorrelation between severity and the change in velocity (delta-V) experienced during acollision. The relationship varies for different types of crashes. Many such examples ofthese relationships can be found in the literature; Figure 4.1 shows examples produced by(Richards, 2010).

The pedestrian example in Figure 4.1 is the only one that uses the speed of a single car atimpact as the measure of risk. This is because the speed of the pedestrian will be lowand combined with the very low mass of a pedestrian this makes the influence ofpedestrian speed relatively negligible. In the relationships for car occupants, the measureused is ‘delta-V’, the change in velocity experienced by the car the occupant wastravelling in. This will depend on the impact speed not only of the vehicle the occupantwas travelling in but also the impact speed of the other vehicle that was struck and anydifference in mass between the two.

In some tractor accidents, for example where they are struck from behind by anothervehicle due to the impacting vehicle failing to react appropriately to their low speed,increasing tractor speed would actually reduce the delta-V experienced by both parties inthe collision. Thus, the net effect of increased tractor speed on injury severity is not assimple as it may first appear and it will depend strongly on how speed affects thedifferent types of collisions that are prevalent in any individual territory. That is, ifcollision patterns are substantially different in different member states, then the effect oninjury severity of increasing speed in those member states may also differ.


August 2017 54

Figure 4.1: Relationship between delta-v and risk of fatality for car drivers in frontalimpacts (top), side impacts (middle) and pedestrians in collision with a car (bottom)

[dashed lines indicate statistical confidence limits around the central estimate of probability indicated by thesolid blue line]

Source: (Richards, 2010)

0%10%20%30%40%50%60%70%80%90%

100%

0 10 20 30 40 50 60 70 80

Risk

of c

ar d

river

fata

lity

Delta-v (mph)

Car drivers in frontal impacts (all ages, belted, impacts with another car, n = 620)

0%10%20%30%40%50%60%70%80%90%

100%

0 10 20 30 40 50 60 70 80

Risk

of c

ar d

river

fata

lity

Delta-v (mph)

Car drivers in side impacts (all ages, belted, impacts with another car, n = 118)

0%10%20%30%40%50%60%70%80%90%

100%

0 10 20 30 40 50 60 70

Risk

of p

edes

tria

n fa

talit

y

Impact speed (mph)

OTS and Police fatal file data (all ages, front of cars, n = 197)


August 2017 55

Effect of Mass on Injury Severity4.2It has been shown in the preceding section that the change of velocity seen by eachindividual party involved in a collision is likely to strongly influence the probability thatthey will suffer a serious injury as a consequence. For a given set of impact speeds, thedifference in mass between a vehicle and its collision partner will strongly affect thechange of velocity seen by each vehicle in the crash. For example, if two cars of equalmass collide head on each with an impact speed of 30 km/h, both will be stationary postcollision and both will see an equal change in velocity and a nominally equal risk ofserious injury to the occupants. However, if a 44-tonne truck collides with a 1.5 tonnecar head-on each with an impact speed of 30 km/h, then immediately post-collision thetruck will be travelling at around 28 km/h in its original direction of travel (delta-V2 km/h) and the car will be travelling backwards at a speed of around 28 km/h (delta-V58 km/h). Thus, the risk of injury for the occupant of the heavy vehicle is reduced andthe risk for the occupant of the light vehicle is increased.

The probability of serious injury with respect to delta-V is non-linear. Thus, the benefitattributable to mass, to the occupant of the heavy vehicle might be less than the penaltyfor the occupant of the light vehicle. Thus, in addition to shifting the balance of risk fromoccupants of tractors to collision partners, the higher mass of tractors compared withmost other vehicles also leads to the possibility of more severe outcomes overall.

The effect of mass on delta-V is illustrated across a spread of different vehicle massconfigurations in Figure 4.2. This shows that the proportion of the closing velocityexperienced as a change in velocity by the lighter vehicle increases rapidly when the ratiobetween vehicle masses is small. For example, a vehicle colliding with another vehicle alittle more than double its mass will already see 70% of the closing speed as its changein velocity (with the heavier vehicle experiencing 30% of the closing speed). Once themass ratio exceeds around 10 to one, then the change in velocity experienced by thelighter vehicle changes relatively little in response to further increases in the mass ratio.

Figure 4.2: Proportion of change of velocity seen by the lighter vehicle as a function ofmass ratio between the vehicles

Source: (FHWA, 2000)

If collisions between vehicles and pedestrians are considered, then the mass ratio isusually well in excess of 10, so differences in mass between vehicles are not particularlysignificant in the injury risk to the pedestrian. However, if the risk to car occupants incollision with agricultural vehicles is considered, the mass ratio may be significant. Themass of All-Terrain Vehicles (ATVs) and Side-by-Side (SbS) vehicles will be lower than


August 2017 56

the mass of the cars in many instances and in either direction the mass ratio will berelatively small. However, even relatively lightweight solo tractors will be 3 or 4 timesheavier than many passenger cars. Passenger cars will usually be in the range of 1 tonneto 3 tonnes. The 10 to 1 weight ratio where further increases in mass have little effect oninjury risk is therefore between around 10 tonnes and 30 tonnes.

Although many factors will influence the severity of collisions, the accident datapresented in section 4.3.1 is consistent with this theory showing both that accidentsinvolving agricultural vehicles are more likely to be fatal than other crash types and thatthe fatalities are more likely to be a collision opponent than an occupant of theagricultural vehicle.

Review of accident data for all agricultural vehicles4.3

4.3.1 Collision frequency and severity

The main source of accident data for Europe is the CARE database (the EC database onroad traffic accidents resulting in death or injury; (European Commission, 2017). This iscompiled from statistics supplied by the relevant Government departments in eachMember State. However, although the standardisation of data has been steadilyimproving since the database began, differences in the extent of data captured bydifferent Member States and in the way it is coded and categorised means that the detailavailable can be limited. Considerably more detailed data is available for collisionsoccurring in Great Britain (GB; i.e. England, Scotland and Wales), from the Stats19database (i.e. the database of road traffic accidents reported to the police (Departmentfor Transport (UK), 2016a)). Thus, high level statistics have been produced based onCARE data for the EU as a whole. Data for GB has been compared to that for the EU at ahigh level to assess the degree to which GB might be considered representative of theEU. Then more detailed analyses have been based mainly on GB analyses, supplementedwith detailed evidence from other Member States where available and applicable.

In 2015, just over 1.45 million casualties from road traffic collisions in the EU-28 wererecorded on the CARE database. Of these, 26,165 (1.8%) were fatally injured. Table 4.1shows the number of casualties that arose specifically from collisions where at least oneagricultural tractor was involved.

Table 4.1: Casualties from EU collisions involving agricultural tractors by injury severityand year. Source: Analysis of CARE database

YearsNumber of casualties

Fatal Serious Slight Unknown Total

2005 563 2053 5324 802 8742

2006 471 1850 4739 789 7849

2007 557 1916 5098 782 8353

2008 449 1698 4660 720 7527

2009 478 1765 4826 695 7764

2010 460 1654 4832 733 7679

2011 441 1651 4677 710 7479

2012 393 1540 4514 686 7133

2013 386 1412 4311 665 6774

2014 404 1515 4515 708 7142

2015 395 1499 4301 547 6742


August 2017 57

It can be seen that in 2015, 395 people were killed in collisions involving agriculturalvehicles in the EU. This is a significant number, and one would be one too many. It alsorepresents 5.9% of all those injured in collisions involving agricultural vehicles, asubstantially higher fatality rate then for all vehicles (1.8%). It is also slightly higherthan the equivalent rate for collisions involving HGVs (5.7% in 2015).

However, 395 remains a small proportion of the total road toll in Europe and it can alsobe seen that the absolute number of casualties from these collisions has typically seen along term decline, with some evidence of a recent slowing or stagnating of that decline(since 2012), in common with all collision types. A more detailed comparison with allcrashes is shown in Figure 4.3.

Figure 4.3: Casualties from collision involving agricultural vehicles as a proportion of allroad casualties in the EU-28

Source: Analysis of CARE Database

Again, this reflects the relatively small proportion of all accidents that involve agriculturalvehicle and the fact that when an agricultural vehicle becomes involved in a collision ittends to be more severe than average (~0.4% of slight casualties but ~1.5% offatalities). However, it can also be seen that as a proportion of the total road casualtyproblem, slight and serious casualties from collisions involving agricultural vehiclesappear to have remained approximately constant but fatalities are representing asubstantially growing proportion. Combined with the absolute numbers this shows thatfatalities from collision involving agricultural vehicles are falling but they are not falling asfast as in other areas of road transport as a whole. This is true if specifically comparing tocollisions involving HGVs (Figure 4.4), probably the closest comparator group in thewider road vehicle fleet. The proportion involving an HGV is much larger because of thegreater number and greater distance travelled on the road but the trend over time is asmall decline in the proportion of all fatalities that arise from collisions involving an HGV.


August 2017 58

Figure 4.4: Casualties from collision involving HGVs as a proportion of all road casualtiesin the EU-28

Source: Analysis of CARE Database

Equivalent data for agricultural vehicles in Great Britain has been sourced from theStats19 database (Department for Transport (UK), 2016b). In 2015 there were a total of1730 fatalities, 22,144 serious injuries and 162,135 slightly injured casualties on GBroads. Data with respect to those collisions that involved at least one agricultural vehicleis reproduced in Table 4.2.

Table 4.2: Casualties from GB collisions involving agricultural tractors by injury severityand year. Source: Analysis of Stats19 database

YearsNumber of casualties

Fatal Serious Slight Unknown Total

2005 37 158 844 1039 37

2006 26 176 752 954 26

2007 34 133 814 981 34

2008 21 139 696 856 21

2009 18 129 629 776 18

2010 22 127 649 798 22

2011 21 126 570 717 21

2012 25 157 655 837 25

2013 23 134 567 724 23

2014 31 118 597 746 31

2015 24 128 491 643 24

In terms of fatalities from agricultural vehicle collisions, Great Britain sustains on average5.6% of all those occurring in the EU, though in individual years this varies from 3.8% to7.7%. The proportion of those involved in agricultural vehicle collisions that are killedwas on average 3.1%, compared to an average for all GB collisions of (1%) over thewhole time period studied. Thus, collisions involving agricultural vehicles in Great Britain

0.0%2.0%4.0%6.0%8.0%

10.0%12.0%14.0%16.0%18.0%

2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015

Prop

ortio

n fo

all

casu

altie

s tha

t aro

sefr

om a

colli

sion

invo

lvin

g an

HG

V (%

)

Year

Fatalities Seriously injured Slightly injured KSI


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are considerably more (approximately 3 times more) likely to be fatal than all collisions.The absolute fatality rate (3.1%) is about half of the equivalent value for the EU (5.9%).However, the ratio between the fatality rate for agricultural accidents and all accidents isabout the same, at approximately 3, in Great Britain and the EU. Fatality rates dependstrongly on the extent of under-reporting of low severity collisions, which is known tovary quite substantially across Europe and is likely to explain this difference.

A more detailed comparison of the number of casualties from GB collisions involvingagricultural vehicles to all casualties is shown in Figure 4.5.

Figure 4.5: Casualties from collision involving agricultural vehicles as a proportion of allroad casualties in GB

Source: Analysis of Stats19 Database

It can be seen that the scale of agricultural vehicle collisions in Great Britain is similar tothe EU and that the same trend is observed; fatalities from collisions involvingagricultural vehicles appear to be representing a growing proportion of all road fatalities.This trend appears slightly more pronounced in Great Britain than in the EU.

Thus, based on these high-level figures and trends, it can be concluded that collisionsinvolving agricultural vehicles represent only a small proportion of the EU road safetyproblem. However, they are around 3 times more likely to result in fatality than allcollisions and there is evidence to suggest that fatalities from collisions involvingagricultural vehicles have started to represent an increasing proportion of the fatalitiesfrom all collisions. In short, they are much less frequent than crashes involving othervehicles and the absolute number is reducing. However, when they do occur, they aremuch more severe than average and the frequency of fatalities from agricultural vehiclecollisions is reducing more slowly than for other vehicle types such that they represent anincreasing proportion of the total. At a high level, GB collisions involving agriculturalvehicles are broadly representative of the EU as a whole.

4.3.2 Casualty rates

The number of collisions that a particular type of vehicle is involved in will not onlydepend on the safety performance of that type of vehicle but also the exposure to risk.For example, silver cars will be involved in many more collisions than luminous yellowcars, not because silver cars are less conspicuous or more dangerous in other ways butsimply because there are more of them. The most commonly used measure of exposureto risk is the number of kms driven on the public road. However, data on the vehicle kms


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travelled by agricultural vehicles is not available. Data on the number of vehiclesregistered is often taken as the next best proxy for exposure to risk. Agricultural vehicleregistration data has not been identified on a cross EU basis but was available for the UK.It has been combined with the casualty data produced above to derive the casualty ratesshown in Figure 4.6.

Figure 4.6: GB casualty rates per 100,000 registered vehicles for all collisions andcollisions involving agricultural vehicles

Source: Analysis of Stats19 and DfT licensing data

It can be seen that agricultural vehicles cause casualties at less than half the rate perregistered vehicle than all vehicles do, taken as a whole. This appears logical whencombined with the anecdotal expectation that agricultural vehicles would do far fewerroad kilometres than most other vehicle types, spending a significant amount ofoperating time off-road etc. It is also worth noting that this rate has declined over theperiod by 46% for agricultural vehicles compared to only 35% for all vehicles, which willbe numerically dominated by passenger cars. However, the outcome is quite different ifonly fatalities are considered, as shown in Figure 4.7 on the following page.

It can be seen that the fatality rate per registered vehicle is actually higher foragricultural vehicles than it is for all vehicle types despite the anecdotal expectation ofsubstantially lower road kilometres driven by agricultural vehicles. In addition to this, theevidence of a decline in the risk presented is much weaker and, if there has been astatistically significant decline then at best it would appear to have ended in 2009 and atworst to have turned to a slight increase since then.

The number of vehicles registered is a relatively weak measure of the ‘exposure to risk’for a given vehicle type. This is because, for example, it takes no account of the distancetravelled on the roads. In freight terms, the most important parameter to measureperformance is the quantity of goods moved because this is the underlying size of the jobthat must be done to support the economy, regardless of how many vehicles, or whattype of vehicles, are required to achieve it. Goods moved is usually defined as the massof goods carried multiplied by the distance that they were transported and is, therefore,measured in tonne.kms.


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Figure 4.7: GB fatality rates per 100,000 registered vehicles for all collisions andcollisions involving agricultural vehicles

Source: Analysis of Stats19 and DfT licensing data

Although these measures are commonly available for heavy goods vehicles they are nottypically available in agriculture. However, (Gotz, Zimmerman, Engelhardt, & Bernhardt,2014) presented comparative data for Germany looking at the freight tasks undertakenby road transport (HGVs) and in agriculture (Tractors). The data is understood to relateto the year 2011 and casualty data for the two groups for that year has been obtainedfrom the CARE database. The results are shown in Table 4.3.

Table 4.3: Casualties, goods moved and casualty rates for agricultural transport and roadtransport by HGVs in Germany 2011. Sources: (European Commission, 2017) & (Gotz,

Zimmerman, Engelhardt, & Bernhardt, 2014)

Fatal Serious Slight

Agr

icul

tura

lVeh

icle

s

Casualties 63 631 1,679

Goods moved (Billion tkm) 5

Casualty rate per billion tkm 12.6 126.2 335.8

HG

Vs

Casualties 564 3850 14499

Goods moved (Billion tkm) 398

Casualty rate per billion tkm 1.4 9.7 36.4

Ratio of casualty rates (agricultural/HGV) 8.9 13.0 9.2

It can be seen that based on this measure, agricultural vehicles cause casualties andbetween around 9 and 13 times the rate per unit of goods moved than is the case innormal road freight using HGVs. Many factors will contribute to this, including the fact


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that agricultural vehicles get used on the road for tasks other than freight movement,HGVs travel longer distances, at higher speeds but with a higher proportion of traffic onsafer roads such as motorways. However, the relative like for like risk presented by eachvehicle will also form part of the net result.

4.3.3 Collisions by road class

Agricultural vehicles fulfil a specialist role and are typically banned from using the highestspeed highways (motorways in the UK). As such, their exposure to risks will be differentto that of other vehicle types. The influence of speed on collision risk (see Section 4.1)and the effectiveness of ABS on heavy goods vehicles (see Section 5.2.3) have both beenshown to vary on different classes of road so this variation may be an importantconsideration.

Analysing the EU accident data shows that the distribution of agricultural vehiclecollisions by road class is, as expected, different to that of all vehicles as a whole (seeFigure 4.8 on the following page).

The definition of road types3 used in the Figure is summarised below:

· Principal arterial: Motorways or Expressways mainly serving long distance andinter-urban movements.

· Secondary arterial road: Connected to principal arterials and serving middledistance movements but not crossing through neighbourhoods.

· Collector: A collector crosses urban areas and collects or distributes trafficto/from local roads and/or to and from arterial roads.

· Local: A road used for direct access to various land uses (property, commercialareas etc.) at low service speeds not designed to serve interstate or suburbanmovements.

It can be seen that more than half of agricultural vehicle fatalities occur on secondaryarterial roads, compared with 44% for all collisions. As would be expected few occur onprimary arterials because there will be very little agricultural traffic on such roads. It ispossibly more surprising that there is not much difference between agricultural collisionsand all traffic collisions when local roads are considered. However, this may be becausethere is no split in the definition between urban and rural.

It can be seen that the severity of collisions also tends to vary by road class, thoughmuch less for agricultural vehicles than for all vehicles. That is, collisions on secondaryarterial roads are more likely to prove fatal, representing 24% of all casualties but 44%of all fatalities (46% and 51% when only those involving an agricultural vehicle areconsidered). This may possibly be linked to the fact that the speed of agriculturalvehicles remains relatively low even on more major roads whereas the speed of othervehicles will increase in line with the speed limit on major roads. These complexities arelikely to correlate with different usage of agricultural vehicles and highlight thecomplexity of trying to map findings from other vehicle types to agricultural vehicles.

3 It should be noted that these definitions do not necessarily match those used in contributingmember states and the time at which individual member states have been able to supply data inthis form has varied. This has meant that for some countries there has been a step change indistribution at a fixed point in time and also that the proportion of ‘unknowns’ is relatively high.


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Slightly injured casualties FatalitiesAll

colli

sion

sCol

lisio

nsin

volv

ing

agricu

ltura

l tra

ctor

s

Figure 4.8: Distribution of EU collisions by road classSource: Analysis of CARE database

Similar analyses have been undertaken based on GB data with national road classdefinitions and the story is very similar (Figure 4.9). Motorways and A(M) roads areapproximately equivalent to ‘Primary Arterials’ and ‘A’ roads will approximate tosecondary arterials. It can be seen that 54% of GB fatalities involving an agriculturalvehicle occur on ‘A’ roads.


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Figure 4.9: Distribution of GB collisions by road classSource: Analysis of Stats19 database, average for years 2005-15

When collisions of lower severity were considered, a slightly smaller proportion occurredon ‘A’ roads. The trend over time was examined to see if the changes in the nature offarming, agricultural vehicle design and use had influenced the distribution of collisionsby types of road. The number of fatalities was strongly affected by low number variationand so the results were grouped into killed and seriously injured (KSI) and into major (M,A(M), A) roads and minor (B, C, and U) roads in order to increase statistical power. Theresults are shown in Figure 4.10 and it can be seen that there is no evidence to suggest asystematic change in pattern, with correlation factors approaching zero.


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Figure 4.10: Distribution of GB KSI casualties from accidents involving one agriculturalvehicle by major and minor road over time

Source: Analysis of Stats 19 data

4.3.4 Speed capability and collision speeds

Neither the maximum speed capability of an agricultural vehicle, nor the actual speed ofvehicles at the moment of collision are recorded in the CARE or GB Stats19 databases.Thus, collisions cannot be divided by either measure to specifically identify the number ofcollisions sustained by agricultural vehicles capable of in excess of 40 km/h or to assesswhether the speed was a factor in the collision.

It is possible to link GB Stats19 data to registration data containing the make, model andmaximum permitted mass of a vehicle. It was thought that this might allow speedcapability to be inferred from this proxy information. However, when the analysis wasattempted it was found that the data for agricultural vehicles was very poorly recorded.Registration data only appeared to be available for 39% of cases (normally around two-thirds) and although vehicle make was routinely recorded in those linked cases, vehiclemodel was only rarely completed.

A literature search has also revealed no studies that contained such information in anunambiguous form. (Bende & Kuhn, 2011) did contain information on the speed theagricultural vehicle was travelling at before impact. They found that 53% of collisionsinvolved an agricultural vehicle travelling at 20 km/h or less while only 4% involved atractor travelling at in excess of 40 km/h. However, the study did not provide anyinformation on the speed capability of the tractors involved, which is critical to thecorrect understanding of the risks.

The authors of the study were contacted directly to ask if they had any additionalinformation that could be useful. They responded that there was no direct evidence of thespeed capability of the vehicles but that 20% of the agricultural tractors involved in theaccident data sample, had an engine power in excess of 74 kW. Engine power can form apartial proxy for speed capability because only higher-powered vehicles will be offeredwith high speed capability. This could also be seen by the fact that 86% of the 4% ofvehicles that were travelling at between 41 and 60 km/h had an engine power in excessof 74 kW.


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The data used by (Bende & Kuhn, 2011) related to collisions in the year 2008. Data onthe stock of tractors in Germany was identified for 2012 but not earlier. This data showedthat around 22% of tractors had an engine power in excess of 70kW and 4.8% had amax speed capability of 41 to 60 km/h. Given the slightly rising trend over time, ittherefore appears that the collision involvement is broadly in line with the exposure interms of the number of vehicles with the relevant capabilities.

This relationship with exposure also applies across different countries. For example, theproject team were provided with an analysis of road accident data in Italy4 that aimed toevaluate the statistical relevance of ABS on Agricultural tractors with a maximum speedin excess of 40 km/h. A range of collision data was analysed, examining for example, theproportion of all collisions that involved an agricultural vehicle, age of the vehicle andpolice reported causation factors in relation to brakes and driver error. They concludedthat ABS fitment would be irrelevant to reduce road accidents in Italy. However,currently tractors capable of exceeding 40 km/h are not permitted in Italy so, bydefinition, none of the accidents studied would have occurred with a tractor speedexceeding 40 km/h and therefore cannot provide direct insight into whether ABS wouldprovide a safety benefit or not. The conclusion of the work stands true only for as long asItaly does not permit high speeds.

4.3.5 Age of tractors involved in collision

Analysis by (CEMA, 2015) concluded that the main problem with road accidents withtractors was older machinery. They analysed CARE data for seven EU states that hadtractor age available5. They found that 56% of all road accidents with tractors resulting ininjury (and 69% of fatal accidents with tractors) involved tractors that had been in usefor more than 12 years.

They combined this data with separate data relating vehicle age to average hours of useto show that the risk of an accident per hour of use dramatically increases when thetractor age exceeds 12 as reproduced in Figure 4.11.

Figure 4.11: Risk per operating hour of a road accident involving a tractor by age oftractor involved

Source: (CEMA, 2015)

4 PowerPoint slides provided by FederUnacoma, titled ‘Accidents with AG machinery & tractors inItaly’.5 Austria, Finland, France, Germany, Italy, Spain, UK


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It can be seen that the biggest increases in risk are for tractors aged 21+ at the time ofthe collision.

An analysis of collisions in Great Britain has been undertaken using collision data fromthe years 2005 to 2015. This has been divided by the age of the tractor at the time ofcollision, thus a 5-year-old tractor in Figure 4.12 may have been 5 years old in 2005 or in2015, such that it could have been manufactured at any time between 2000 and 2010.

Figure 4.12: Cumulative proportion of GB casualties, by severity, from collisionsinvolving an agricultural vehicle by age of agricultural vehicle involved

Source: Analysis of Stats19 data

The results here are in stark contrast to those identified by (CEMA, 2015). In GreatBritain over the most recent 11-year period available, less than 20% of casualtiesinvolving agricultural vehicles involved one that was more than 12 years old and therewas little difference for different collision severities. In fact, this data strongly suggeststhat young vehicles are involved in most collisions with 60% of all casualties andfatalities occurring in collisions involving agricultural vehicles aged 5 years old or less atthe time of the collision.

(CEMA, 2015) measured exposure to risk in terms of operating hours and equivalent datawas not available for Great Britain. Thus, identical collision rates could not be calculated.The number of registered vehicles is often used as a proxy for exposure and the averageage distribution of the fleet is shown as a cumulative frequency plot in Figure 4.13.

It can be seen that during a very similar time frame, less than 30% of registeredagricultural vehicles were less than 5 years old but these were responsible for around60% of casualties. Although we have no national data available regarding the on-roaddistances driven by agricultural vehicles, anecdotal evidence suggests that it is likely tobe the explanation. That is, the newest vehicles travel much larger distances on the roadthan older vehicles. This behaviour can be observed to be true in other forms of roadtransport, including both passenger and goods vehicles.

This hypothesis is supported by the results of a survey of agricultural contractors in theUK (NAAC, 2017). Although only one part of the market, and the part most likely to usetractors very intensively, the results showed that the majority of road use was


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undertaken with more powerful tractors and that these would be used for up to around1,500 hours per year and would be replaced around every 5 years.

Figure 4.13; Cumulative frequency of number of agricultural vehicle registrations in theUK by age of vehicle

Source: DfT vehicle licensing statistics

It is possible to calculate a casualty rate per 100,000 registered vehicles for eachcasualty severity and for each age of vehicle. In order to quickly view how this casualtyrate changes with age of vehicle, this has been plotted as an indexed casualty rate. Thatis, one year old vehicles have been selected as the reference point and separately foreach casualty severity, other ages have been referenced to 1 year old vehicles such thata value of 2 would suggest the rate for that age of vehicle is double that of a 1 year oldvehicle and a value of 0.5 would show a rate half that of a 1 year old vehicle. The resultsare shown in Figure 4.14.

It can be seen that collision rates are much lower for vehicles of less than 1 year old thanthey are for 1 year old vehicles. This is an artefact of the data. The number of vehiclesregistered is measured on the last day of the year. Vehicles less than 1 year old at thattime might have been registered on the 1st day of the year but may equally have onlybeen registered the very same day. Thus, on average, they will have been on the roadfor much less time than 1 year old vehicles and the expectation would be that theaverage would be around half a year each.

Although data on fatalities is subject to large annual variations as a consequence of lownumbers, it can clearly be seen that the collision rate per registered vehicle is highest fornew vehicles and becomes very low for old vehicles. Based on anecdotal evidence aroundroad use, it is highly likely that this is strongly related to declining road travel as vehiclesage. It should also be noted that when comparing to the (CEMA, 2015) profile that ifusage (operating hours or kilometres driven) declines with age faster than the number ofcollisions do, then the rate per unit of use may still increase for older vehicles.


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Figure 4.14: Index of casualty rate per 100,000 registered vehicles by severity and ageof vehicle (1 year old vehicle = index of 1)

However, it is clear, based on GB data at least that newer vehicles will be involved in themajority of on-road collisions. In all other comparisons, the GB data has followed verysimilar patterns and trends to that of the EU suggesting that GB is broadly representativeof the EU when it comes to agricultural vehicle collisions. However, the basic inputnumbers that (CEMA, 2015) is likely to have been based on have been independentlychecked and the difference does seem to be genuine, as shown in Table 4.4.

Table 4.4: Proportion of collisions involving 1 agricultural vehicle by age category of theagricultural vehicle, excluding unknowns. Source: (European Commission, 2017)

CountryAge category of agricultural vehicle

<=12 years >12 years

Austria 31% 69%

Germany 52% 48%

Spain 33% 67%

Finland 64% 36%

France 36% 64%

Italy 40% 60%

United Kingdom 88% 13%

EU-7 49% 51%

The reason for the differences in this particular field is not known.

-0.20

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

0 5 10 15 20 25 30

Inde

x of c

asua

lty ri

sk p

er 1

,000

regi

ster

ed ve

hicl

es(1

year

old

=1)

Age of vehicle at time of collision (years)

Serious Slight Fatal


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4.3.6 Vehicle Mass

The Gross Vehicle Weight (GVW) of agricultural vehicles is also understood to haveincreased over recent times and to be correlated in recent years with an increase inmaximum speed capability. The GVW of a vehicle involved in a collision can be obtainedby linking Stats19 to vehicle registration databases. This link was found to be effective inonly around 75% of cases. For those cases that did successfully link, the GVW wasunknown in 82% of cases. Thus, the results from the small number of remaining caseshave the potential to be significantly inaccurate if there is even a small systematic biasbetween known and unknown cases.

Where known, the distribution of fatalities by mass of tractor was as shown in Table 4.5,below.

Table 4.5: Distribution of GB casualties from collisions involving agricultural vehicle byGVW of agricultural vehicle (2005-15). Source: Analysis of enhanced Stats19 data

Gross vehicle weight(tonnes)

Proportion of casualties

Fatal All severities

<5t 19% 13%

5 – 10t 56% 69%

10 – 15t 17% 15%

>15t 8% 3%

It can be seen that tractors in the range of 5 to 10 tonnes are most frequently involvedin all casualties and fatalities, though vehicles of other sizes (lighter and heavier) have abigger share of fatalities than all casualties suggesting collisions involving those vehiclesmay be more severe. However, it is worth re-emphasising the large potential for bias asa consequence of many unknowns and the numbers involved were clearly too small forany meaningful analysis of trends over time.

4.3.7 Collision type

Increasing average speed and decreasing differential speeds between vehicles has beenshown to have the potential to change the type of collisions seen (see Section 4.1). ABSin other vehicle types has also been shown to affect the type of collisions seen. It hasbeen estimated that high speed tractors will have penetrated the market to a significantdegree but that ABS will remain at negligible market penetration for the yearsconsidered.

A high level indication of the type of collisions sustained by agricultural vehicles can beobtained by considering the road user categories injured in those collisions. Thedistribution of fatality types is considered in Figure 4.15, below for the EU and in Figure4.16, below for Great Britain.

It can be seen that the distribution of fatality types from collisions involving agriculturalvehicles is substantially different in the GB data to the EU data. Across the EU as awhole, tractor occupants are the most commonly killed road users in collisions involvingagricultural vehicles, despite the mass ratio advantage that they would enjoy over mostother road users and the relative hostility of the agricultural vehicle structures that wouldcontact other road users. Car occupants and moped and motorcycle riders as a group arejointly next most important but still less in combination than the tractor occupants.

This pattern is reversed in the GB data where agricultural vehicle occupants representonly 12% of those killed in collisions involving agricultural vehicles. When allmotorcycles, regardless of engine size, are considered as one group they are mostimportant with a combined 40% of fatalities, closely followed by passenger cars at 36%.


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Figure 4.15: Distribution of EU fatalities from collisions involving agricultural vehicles byclass of road user

Source: Analysis of CARE database

Figure 4.16 Distribution of GB fatalities from collisions involving agricultural vehicles byclass of road user

Source: Analysis of Stats 19 database

The reason for this fundamental difference was unknown and so investigated in moredetail. The CARE data was examined in more detail to look for differences between the 8different Member States representing the largest contribution to the overall EUagricultural vehicle collision population6. In this case, it was found that while the GBpattern was different to the majority of Member States it was broadly similar to Germany

6 Germany, Greece, Spain, France, Italy, Poland, Portugal and the UK


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and France. Thus, there seems to be a divide between UK, Germany and France and theother 5 major contributors to EU agricultural vehicle collisions. The reason for thedifferences is unknown but could potentially relate to the extent to which agriculturaltraffic mixes with other forms of traffic.

Stats19 records in one field whether the vehicle in question skidded, overturned, and/orjack-knifed. The number of casualties from accidents involving an agricultural vehicle areshown below, divided by whether or not the agricultural vehicle suffered on of thesebraking instabilities.

Table 4.6: The number of casualties from collisions involving an agricultural vehicle byagricultural vehicle instability type and year. Source: Analysis of Stats 19 accidents

YearInstability Type

None Skidded Skidded andoverturned Jack-knifed Jack-knifed

& overturned Overturned

2005 918 39 16 4 5 52

2006 823 49 19 10 5 34

2007 876 49 11 6 2 28

2008 732 39 10 10 10 42

2009 681 40 6 1 7 35

2010 684 47 12 19 3 30

2011 613 39 10 4 12 31

2012 728 35 8 13 14 30

2013 613 31 7 14 7 39

2014 658 34 6 8 6 24

2015 561 33 5 3 9 26

Total 7887 435 110 92 80 371

Distribution 88% 5% 1% 1% 1% 4%

Figure 4.17: Trend in the proportion of casualties (all severities) from collisions involvingan agricultural vehicle that skidded and/or jack-knifed

Source: Analysis of Stats 19 data


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When considering the possible influence of ABS alone on collisions above, then the maincategories will be skidded, skidded and overturned, jack-knifed, and jack-knifed andoverturned. It is unlikely that ABS will influence collisions where the agricultural vehiclepurely overturned without skidding. ABS may influence some of those collisions wherethere were no instabilities, if it improved the stopping performance of the brakes.However, these have been ignored for the purposes of this analysis. Thus, it can be saidthat a maximum of around 8% of all collisions might be in scope of the ability of ABS toreduce braking instabilities, with additional unidentified casualties in scope of any abilityto reduce stopping distance. The trends over time in these ‘in-scope’ skidding and jack-knifing collisions are unclear because there is considerable year on year fluctuation, asshown in Figure 4.17.

It can be seen that there is some suggestion of a changing trend first increasing thendecreasing but the correlation is extremely weak and it is not likely to differ significantlyfrom what might occur by random chance.

While ABS fitment in agricultural tractors will have remained low throughout this period,market penetration of high speed tractors will have been increasing substantially. Itmight, therefore, have been reasonably expected that the relative frequency of jack-knifemight have increased. However, during this period some important changes were madeto tractor-trailer braking practice in the UK and Ireland. As 50 km/h tractors started topenetrate these markets tractor manufacturers began to experience abnormally highlevels of tractor brake failure under warranty, to the extent that at the peak the majorityof warranty claims for tractor brake failure were originating from the UK and Ireland.

Investigations by manufacturers and independent bodies (Scarlett, 2009) revealed thatthe problem could usually be traced to sub-standard trailer braking system performanceand, as such, manufacturers began rejecting tractor warranty claims, charging farmersfor the brake repairs and publicising both the nature of the problem and potentialsolutions to it (Scarlett, Harding, & Wyatt, 2010). This prompted a substantial voluntaryimprovement in the standard of trailer brakes from around 2010/11 with a fairlypronounced move, both on the part of trailer manufacturers & purchasers, towardshigher performance pneumatic braking systems for trailers. It was then found that stifftrailer suspension and poor load sensing led to problems with excessive tyre wear as aconsequence of frequent wheel lock when braking whilst unladen or lightly-loaded (seeSection 6.3), which has also acted to promote an increase in voluntary fitment of trailerABS.

Thus, while increased speed capability would be expected to increase the incidence ofjack-knife, the improvement in trailer brakes would be expected to have decreased it. Itis possible that these trends have cancelled out to result in the actual observed trend.

4.3.8 Contributory factors

The GB accident data also includes an assessment of the factors that contributed to thecollision. This is completed by the reporting police officer within a short time of thecollision and it is not therefore an expert assessment of causation after extensiveinvestigation. It is also only recorded in cases where the officer attended the scene. Aselection of contributory factors that were considered potentially relevant to tractorspeed and/or braking instability were examined for the years 2005-15. The proportion ofcasualties where each of the selected factors were recorded is shown in Table 4.7.

The factors were selected for their relevance to ABS and high speed tractors. However,data from a small sample of collisions in Switzerland (CEMA, 2017) suggested thatbroadly speaking the top 5 ‘causes’ of collisions were rollover (24%, arguably this is acollision mechanism not a cause, i.e. the rollover is an event caused by driver error,excess speed, vehicle defect, etc.), behaviour of other road users (20%), operatorvisibility (15%), machine maintenance (13%) and vehicle driver behaviour (11%). Thishas been summed to say together these factors are responsible for 80% of on-roadcollisions, though this is highly unlikely to be the case because collision data almost


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always allows more than one contributory cause to be coded per collision such that manycollisions might have had more than one of these factors involved.

Table 4.7: The frequency with which selected contributory factors were applied to theagricultural vehicle involved in the collision. Source: analysis of Stats 19 data

Contributory factor Proportion of all casualties Proportion of fatalities

Loss of control 3.4% 6.0%

Travelling too slow for conditions 2.9% 4.8%

Defective brakes 0.9% 2.4%

Slippery Road 3.1% 2.0%

Exceeding speed limit or travellingtoo fast for conditions 2.7% 2.0%

Sudden braking 1.6% 1.2%

The incidence of rollover can be seen to be very high compared with the GB data(rollover involved in 10% of casualties). In-depth data from GB (Knight I. , 2001),though historic, also shows both some difference and some commonality. In a detailedstudy of 41 fatal collisions involving agricultural vehicles it was found that 39% ofagricultural vehicle drivers at least contributed to the cause of the collision, while 81% ofother vehicle drivers contributed. Thirty nine percent of the agricultural vehicles involvedwere suffering some form of mechanical defect but in most of these the defect did notcontribute to the cause of the collision. Approximately 12% had defects that wereconsidered contributory and these were most often lighting defects or defects in thecoupling between tractor and trailer.

Accidents involving SbS and ATVs4.4All-terrain vehicles (ATVs) and Side-by-Side vehicles (SbS) are not recorded as aseparate category in any of the collision data available. In Great Britain, for a proportionof collisions, it is possible to link the collision data to registration data such that the makeand model of vehicle can be identified. An analysis was undertaken for collisions in theyears 2011 to 2015 that sought to identify known ATVs or SBS vehicles by their makeand model. In total, 135 vehicles were identified and they were involved in collisions ofthe following severity.

Table 4.8: Number of collision-involved vehicles by year and collision severity

Year Fatal Serious Slight Total

2011 4 4

2012 2 9 11

2013 3 10 26 39

2014 21 26 47

2015 2 11 21 34

Total 5 44 86 135

These vehicles were classified as many different Stats19 vehicle types, mainly ‘other’ butalso ‘car’ and ‘powered two wheeler’ (PTW). It can be seen that the overlap with theanalysis of agricultural vehicles in the preceding section will be very small.


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Table 4.9: Number of collision-involved vehicles by Stats19 vehicle type and collisionseverity

Vehicle type Fatal Serious Slight Total

PTW 2 18 20

Car 2 10 12

Agricultural 1 2 3

Other 5 39 55 99

unknown 1 1

Total 5 44 86 135

The type of road user injured in collision with these vehicles is almost always the driveror rider of the vehicle (84%) or a passenger on the vehicle (15%). Less than 1% (1case) involved a pedestrian.

Overall, there were 141 casualties identified from collisions involving these vehicles,compared with a total for agricultural vehicles (mainly tractors and trailers) of 3,667 inthe same time period. Thus, the scale of the problem involving SBS and ATVs isapproximately one 26th of that of other agricultural vehicles.


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Overview of anti-lock braking systems (ABS)5

Current use of ABS on agricultural vehicles5.1The primary purpose of a vehicle anti-lock braking system (ABS) is to minimise / preventloss of tyre - ground surface adhesion during braking, thereby avoiding wheellocking / skidding and permitting steerability of the vehicle to be maintained (see Figure5.1 and Section 5.2). However, vehicle stopping distances are also reduced, particularlyon low-adhesion surfaces, and vehicle stability improved, particularly in the case oftractor-trailer combinations (see Section 5.2). Indeed, notes to the German NationalBraking Regulations (as cited by (Moore, 2015)) apparently state that:

“the main benefit of ABS is not just a potentially shorter stopping distance, butrather the fact that, in emergency stops, the vehicle’s steering and ride stability ismaintained such that obstacles can be negotiated and any gaps between themcan be utilised to prevent collisions.”

Figure 5.1: Maintaining tractor steerability during braking through use of ABS(Copyright CNH Industrial)

During ABS operation, sensors monitor the rotational speed of the vehicle’s wheels and(if during braking) the speed of one or more wheels reduces significantly relative to theothers, vehicle braking effort is automatically modulated by rapid release and thensubsequent re-application of the brakes; this is normally achieved by reducing and thenincreasing braking system actuation pressure.

ABS is far from a new concept: having originally been developed to improve aircraftstability whilst braking during landing, the technology was transferred to trucks andbuses in the 1970s, becoming a mandatory fitment by the late-1980s. The technologyhas then since been transferred and today is in widespread use upon both passenger carsand motor cycles. ABS first became available on more specialised, transport-orientatedtractors in the early-2000s: they have since been offered by certain manufacturers asoptional equipment on a very limited number of ‘conventional’ Category T1 tractormodels since 2010 (see Section 5.1.1).

As discussed in Section 2.3, the Relevant Agricultural Vehicle (RAV) grouping consideredby this study comprises the following vehicle categories / types in the40 < Vmax ≤ 60 km/h speed range:


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· T1b: ‘Conventional’ agricultural tractors.

· T2b: Narrow-track agricultural tractors.

· T4.3b:Low-clearance, low centre-of-gravity (CoG) transporter-type tractors.

· ATV: All-Terrain Vehicles type approved as Category T1.

· SbS: Side-by-Side utility-type vehicles type approved as Category T1 or T3.

· R3b: Agricultural trailers of 3500 < MPMaxles ≤ 21000 kg.

· R4b: Agricultural trailers of MPMaxles > 21000 kg.

· S2b: Interchangeable towed equipment of MPMaxles > 3500 kg.

The generic ABS systems which are (currently) technically-available for use uponagricultural vehicles may be categorised according to the following characteristics:

· The medium used within the ABS control / modulating valve(s), e.g. air,automotive-type brake fluid or mineral hydraulic oil.

· The medium used to actuate the vehicle’s (foundation) brakes, again eitherair, automotive-type brake fluid or mineral hydraulic oil.

Automotive (on-road vehicle) ABS systems frequently utilise the same medium for bothbrake control / modulation and subsequent brake application, but the specific demands ofoff-road / agricultural vehicles and their braking systems often requires a more flexibleapproach. This is primarily dictated by the brake application method / medium used onthe vehicle, but other factors, including the construction of the vehicle, the availablespace for ABS component installation and the availability of a compressed air brakingsystem (either for the target vehicle or trailers / equipment towed by it), also caninfluence the practicality and cost of ABS installation. The generic ABS systems which, inthe view of this investigation, are potentially suitable for use upon agricultural vehiclesare summarised by Table 5.1.

Information gathering by the investigation, by means of manufacturer and stakeholdersurveys, face-to-face meetings and review of relevant literature (see Section 1.2)returned the following insight into the current availability of ABS on agricultural tractorsand vehicles type-approved as agricultural tractors.

Of the 10 manufacturers of Category T1 or T1 and T2 tractors who responded to thesurvey:

· One manufacturer offers ABS as standard (although the number of models iscurrently unknown) on all T1 models irrespective of whether the maximum designspeed is Vmax < 40 km/h, 40 < Vmax ≤ 60 km/h or Vmax > 60 km/h.

· Two manufacturers offer ABS as an optional extra (on 6 model ranges and1 model range respectively). It is noted that neither manufacturer producesVmax > 60 km/h vehicles.

· Seven manufacturers do not offer ABS as standard or as an option on any of theirmodels. It is noted that none of these manufacturers produces Vmax > 60 km/htractors.

· Seven manufacturers produce T2a Narrow-Track tractors (Vmax ≤ 40 km/h), butnone currently offer T2b (Vmax > 40 km/h) models. Consequently, at least atpresent, ABS provision does not appear to be an issue for such (narrow-track)tractors.


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No manufacturers of Category T4.3 (Low-clearance, low-centre of gravity, transporter-type tractors (see Section 2.3.3)) were found to currently offer ABS on their vehicles,despite the availability of T4.3b (Vmax ≤ 50 km/h) versions. However, given that suchvehicles’ service braking systems are largely of conventional, automotive-type design, itis understood that they may accept off-the-shelf hydraulically-actuated ABS systemsfrom the light-duty truck sector with minimum modification, assuming the functionality ofsuch systems is deemed adequate for the application.

It is understood that no manufacturers of Side-by-Side (SbS) vehicle or All-TerrainVehicles (ATV) currently offer vehicles with ABS. However, the investigation has beeninformed that this situation is due to change in the near future, albeit details of the ABSsystem (believed to be for an ATV) have not yet been provided.

This change in system provision has apparently resulted from the fact that the Vmaxcapability of both vehicle types can be up to 65 – 80 km/h, but it is usually limited (byelectronic engine management system) to Vmax ≤ 40 or ≤ 60 km/h when models aretype-approved as agricultural tractors. It is understood that a manufacturer wishes totype-approve a Vmax > 60 km/h ATV as an agricultural tractor and so, in order to complywith the current requirements of (EU) 2015/68 (European Union, 2015), intends to installABS on the vehicle. It is assumed this will be an automotive-type system, but precisedetails are not known.

Table 5.1: Generic ABS systems potentially suitable for use on agricultural vehicles

ABS Type(System Modulating/ Control Medium)

BrakeActuationMedium

System Availability forOff-Road / AgriculturalVehicles

Comments

(1) Pneumatic Pneumatic Yes – MatureTruck ABS-derived system. Requirescompressor & air reservoir(s) onvehicle

(2) Pneumatic Hydraulic –Brake Fluid Yes - Mature

Adaptation of (1). Only suitable forvehicles with limited brakeapplication fluid displacements (e.g.external disc brakes)

(3) Pneumatic Hydraulic –Mineral Oil Yes - Mature

Adaptation of (1). Suitable forhydraulically-applied (internal)tractor disc brakes (very common)

(4) Hydraulic –Brake Fluid

Hydraulic –Brake Fluid

Yes/No – Some Maturesystems / some Proof-of-Concept – Each onlysuited for certain(lower mass) vehicleapplications

Derived from Automotive (LightTruck or Car) systems. Lowinstallation space requirements. Onlysuitable for vehicles with limitedbrake application fluid displacements(e.g. external disc brakes)

(5) Hydraulic –Mineral Oil

Hydraulic –Mineral Oil

Yes/No – Systemsunder Development

Particularly suited to hydraulic oil-applied braking systems (e.g. manytractors). Lower installation spacerequirements

Note: Where systems are stated as ‘Under Development’ or ‘Proof of Concept’, we have been informed thatthat the estimated time to market readiness / series production will be within the timescale of the currently-proposed legislative deadline for mandatory ABS introduction on 40 < Vmax ≤ 60 km/h agricultural tractors.


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5.1.1 Current Category T1 tractor ABS systems

As previously discussed, current ABS systems used on agricultural tractors may becategorised according to the medium used within the ABS control / modulating valves(e.g. air, automotive-type brake fluid or mineral hydraulic oil) and the medium used toactuate the vehicle’s (foundation) brakes (again either air, automotive-type brake fluid ormineral hydraulic oil).

Of the three T1 tractor manufacturers who currently offer ABS on some / all of theirproducts (i.e. Fendt, CNH Industrial and JCB (see Table 5.2)), the particular systemschosen and their methods of implementation highlight the diversity of tractordesign / construction and the requirement to develop somewhat bespoke solutions toachieve the same objective.

Table 5.2: Agricultural vehicles which currently offer ABS systems

VehicleType Vehicle Make / Model

Vehicle BrakeActuationMedium

ABS Modulating /Control Medium Comments

T1b

Fendt 900 Varioseries Pneumatic Pneumatic ABS offered as option

(~€5k)

New Holland T7 LWB& T7 HD series plusassociated Case-IH &Steyr models

Hydraulic(mineral oil) Pneumatic

ABS offered as option withBasic (~€4k) orEnhanced (~€5k)functionality

JCB Fastrac (allmodels)

Hydraulic(brake fluid) Pneumatic ABS standard fitment

across entire vehicle range

T2b - - - T2b vehicles are currentlynot produced

T4.3b - - - ABS not offered

ATV - - -

ABS currently not offeredbut is expected in the nearfuture from onemanufacturer – costunknown

SbS - - - ABS not offered but may beavailable in the near future

R3b /R4b

Various – widelyavailable as option onlarger trailers(MPMaxles ≥ 12000 kg)

Pneumatic Pneumatic

ABS offered either as abasic system (~€500 –1000) or as part of an EBS(Electronic Braking System)(~€3.5 – 5k)

- Hydraulic - ABS not available

S2bVarious Pneumatic Pneumatic

Typically only offered onlarge / heavy vehicleswhich (due to mass ratio)are classified asCategory R. Same systemsas used on Category R.

- Hydraulic - ABS not available


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The optional ABS systems offered on the 180 – 240 hp (134 – 180 kW) New Holland T7LWB series and the 270 – 300 hp (200 – 224 kW) T7 Heavy-Duty series tractors (Figure5.2) provide a good illustration of the typical problems which are likely to challenge theinstallation of ABS on T1 tractors (Figure 5.3). In common with the majority ofconventional T1 tractors (see Table 6.1), the front and rear axle service brakes of thesetractors are internally-housed, oil-immersed units, actuated hydraulically by a servo-assisted system utilising mineral hydraulic oil. However, at the time of systemdevelopment, no ABS system utilising this medium was commercially-available.

Figure 5.2: New Holland T7 LWB tractor (left) and T7 Heavy-Duty tractor (right)(Copyright CNH Industrial)

Figure 5.3: Air-over-hydraulic ABS installation on New Holland T7 LWB series (180-240 hp) tractors and comparable Case-IH & Steyr models


CNH Industrial therefore choose to employ a readily-available pneumatically-operatedABS system, to convert the operator’s foot brake control to a pneumatic system, andthen to convert the pneumatic output of the ABS module back to hydraulic pressure (via


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three dedicated Air-over-Hydraulic converter units) to enable actuation of the front andrear axle brakes. Three converter / actuators are required because, in common with mosttractor braking systems and, indeed all current tractor ABS systems, whilst the front axlehas individual brake units for each wheel, they are controlled as a pair. However, therear axle wheels each have individual brakes which are controlled separately. Thispermits the ABS system to provide enhanced vehicle control when braking with the leftand right wheels on surfaces of different adhesion (split-μ). It also permits independentrear wheel brake application to permit tighter turning at low speeds in-field.

Sensors are installed within the front and rear axle housings to monitor the rotationalspeed of each wheel (Figure 5.3). Consequently the ABS system senses wheel speed ateach wheel, but only modulates braking effort across (effectively) three wheels (frontpair and each rear wheel). Such configurations are known as 4-sense / 3-modulate(4S / 3M) systems.

However, ABS installation was found to be far from a trivial task: compared with thestandard (non-ABS) model, the vehicle required a larger air (braking) reservoir capacity,a water cooled air compressor, a dedicated brake circuit and air brake circuit, anElectronic Control Unit to control the service brakes and provide ABS functionality, anABS distribution valve, three pneumatic-over-hydraulic actuators and speed sensors foreach wheel.

Figure 5.4: Schematic layout of Fendt 900 Vario braking system (standard model)(Copyright AGCO GmbH)

The challenges to ABS installation on the 275 – 395 hp Fendt 900 Vario vehicle models(Figure 3.7) were marginally fewer in number because, whilst they also utilise internally-housed, oil-immersed brakes on the front and rear axles, unlike the CNH / New Hollandtractors, the service brakes of the Fendt tractor are operated by pneumatic actuators.Theoretically this permitted a pneumatic based ABS system to directly interface with theexisting vehicle service braking system (Figure 5.4). However, other challenges remainedin terms of wheel speed sensor installation and configuration of the ABS system tointeract and operate effectively with the vehicle’s four-wheel drive (4wd) driveline andcontinuously-variable transmission (CVT). Unlike the New Holland installation, Fendtchose to install wheel speed sensors externally at the axle ends but, in common with theNew Holland system, a 4-sense / 3-modulate 4S / 3M ABS configuration is employed.


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JCB were one of the first manufacturers to provide ABS on an agricultural tractor,introducing a system on their Fastrac vehicles in 2001. There are currently three modelranges of Fastrac vehicle (Figure 3.7), covering the 160 – 350 hp (120 – 260 kW) powerrange. They are specifically-designed to deliver superior performance in transportapplications, compared with conventional tractors. This is reflected in the provision ofboth front and rear axle suspension and Vmax = 70 km/h capability. However, the Fastracis type-approved as a Category T1b vehicle.

The ABS installation on the Fastrac was probably the most convenient of the threeexamples presented here (i.e. New Holland, Fendt and JCB) because the vehicle utilises apneumatically-controlled and hydraulically-actuated (air-over-oil) service braking system.Automotive-type dry-disc and caliper-type brake units are mounted externally at the axleends (Figure 5.5) and are actuated hydraulically using automotive-type brake fluid.Whilst this type of foundation brake is found on some tractor 4wd front axle installations,it is a relatively uncommon solution for both the front and rear axles of a vehicle.

Figure 5.5: Vehicle chassis configurations of JCB Fastrac 3000 series (left) and8000 series (right)

(Copyright JCB)

The benefit in terms of ABS installation is that, as subsequently found by New Holland, itis possible to utilise pneumatic ABS control hardware derived from on-road (truck)applications. The pneumatic-to-hydraulic converters required to enable brake actuationwere already fitted to the Fastrac vehicle. However, this is not to underestimate theconsiderable effort required to develop appropriate ABS operating / control strategies foreffective system operation in on-road and off-road conditions, in different loadingconditions (e.g. with / without front and/or rear mounted implements) and when towingtrailers with / without mass transfer characteristics (e.g. balanced / unbalanced).

5.1.2 Current Category R3 / R4 trailer ABS systems

As far as this investigation has been able to determine, at present there are nocommercially-available ABS systems for agricultural trailers or interchangeable towedequipment equipped with either inertia or hydraulically-actuated service braking systems.The absence of inertia-based ABS systems is not a restriction because inertia-operatedbrakes are not permitted on R3b, R4b or S2b vehicles (Table 2.1).

The current absence of ABS systems for high-pressure hydraulically-actuated ‘trailer’braking systems is an undoubted disadvantage. However, at this present time, hydraulictrailer braking systems are very rarely (if ever) used on agricultural trailers ofVmax > 40 km/h. The current national regulations of EU Member States which do permitthe use of agricultural trailers at > 40 km/h (Section 3.4) require braking systemfunctionality which cannot be met by simple single-line hydraulic braking systems. Thishas resulted in the widespread use of dual-line pneumatic systems for agricultural trailers


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and related towed equipment of Vmax > 40 km/h. Given the common use of this brakinghardware on trucks and buses, the cost-effectiveness of such systems (~€600 / vehicle)is now so great that it is unlikely a hydraulic braking system with equivalent functionalitycould be economically-competitive. In combination these factors make the futurecommercial development of ABS systems for hydraulically-braked Vmax > 40 km/hagricultural trailers / towed equipment very unlikely.

A dual-line pneumatic braking system is therefore currently a prerequisite for ABSinstallation upon agricultural trailers or interchangeable towed equipment but, generally,such systems are only found on trailers of larger mass / carrying capacity. Twocontrasting (but nonetheless related) approaches appear to be employed for theprovision of ABS functionality in such instances:

· Numerous UK manufacturers of larger (payload ≥ 14,000 kg, MPMaxles> 16000 kg)agricultural trailers offer ABS as optional equipment on their vehicles, if they arefitted with conventional, dual-line pneumatic braking systems (Figure 5.6). TheABS systems employed are direct derivatives of truck-trailer systems and, due toautomotive volumes, are seemingly very cost-effective. UK trailer manufacturerscurrently offer such systems for ~€500 – 1000 retail and have done so for manyyears. The systems are also available for retro-fit installation to existingpneumatically-braked trailers / towed equipment.

· Certain German and Austrian trailer and/or towed equipment manufacturersprovide ABS functionality by installing truck-type electro-pneumaticEBS (Electronic Braking System) technology (Figure 5.7). This high-end,intelligent system can provide many features in addition to ABS (e.g. activevehicle stability control), but it is more costly than a basic pneumatic trailer ABS(€3500 – 5000 cited). Additionally, in the view of certain survey respondents, thepresence of EBS (a relatively new technology in agricultural applications) maymake a second-hand vehicle less attractive to secondary or tertiary users.

Figure 5.6: Agricultural trailer dual-line pneumatic braking system incorporating ABS(N.B. Single-line hydraulic braking system installed in parallel)

(1) pneumatic control line, (2) pneumatic Supply line, (3) hydraulic supply / control line,(4) trailer ABS power & warning light lead, (5) pneumatic brake actuators,

(6) wheel speed sensors, (9) Relay/Emergency/Load-Sensing Valve,(10) ABS ECU & modulator valves, (11) hydraulic brake actuators

(Copyright J H Milnes Ltd)

55

5 5

6

6


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Figure 5.7: Schematic layout of a (truck-type) centre-axle trailer with EBS and ABS(N.B.: Certain features (e.g. pneumatic axle suspension) may not be present on

agricultural vehicles)(Copyright Knorr-Bremse GmbH)

The effectiveness of ABS5.2Braking systems at the most basic level are required to stop a vehicle quickly and in asafe and stable manner. Braking so hard that the wheels stop turning can have effects onboth of these properties. The effect of locked wheels will vary with a range of otherparameters including vehicle speed, surface friction properties, tyre slip characteristics,and driver steering activity. Thus, systems such as ABS that act to prevent wheel lockwill affect only a certain subset of collisions.

5.2.1 Stability and steerability during braking

One of the basic properties of road vehicles is that their tyres can only generate sidewaysforces when they are rolling. Once fully locked tyre side force drops to zero. The effect ofthis varies depending on which wheels lock, as illustrated in Figure 5.8, where lockedwheels are shaded red.

The graphic was produced in relation to HGVs but the principles are directly applicable toagricultural vehicles. If the wheels on the front axle lock and can no longer generate sideforce, then there is a loss of steering control. That is, the vehicle will continue in astraight line tangential to the path it was following at the moment the wheels locked,regardless of driver input at the steering wheel. This is the case regardless of whether ornot the vehicle is towing a trailer. The rigid truck shown is directly equivalent in this caseto a solo tractor, ATV or a side by side vehicle. If the wheels on the rear axle lock whilethe front wheels remain rolling then the vehicle will tend to spin. If the vehicle is towinga trailer and the rear wheels of the towing vehicle lock then the towing vehicle begins tospin while the trailer remains stable. This is called jack-knife. If the rear wheels of thetrailer lock while the tractor remains stable then the trailer begins to rotate around thecoupling and this is called trailer swing.


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Figure 5.8: Illustration of the effect of locked wheels on braking stability

It can be seen that only two of the four possible instability mechanisms identified, areapplicable to rigid vehicles. The remaining two can occur only with tractor trailercombinations or articulated vehicles.

The effects of these braking instabilities are highly dependent on speed. Significantdepartures from the intended path and/or heading of the vehicle take time to develop. Atlow speeds, provided the vehicle has brakes of basic good efficiency, the vehicle will stopin a very short distance and time. This distance or time is usually insufficient forsignificant instability to develop before the vehicle comes to rest. The exception is in verylow friction conditions, for example road surfaces contaminated with wet mud or diesel orcovered in snow or ice.

(Dodd, Bartlett, & Knight, 2006) undertook extensive braking tests with agriculturaltractors towing trailers. A measure of tractor stability is shown in Figure 5.9 duringbraking tests from 40 km/h with balances of braking across the vehicle combination. NoABS was active on either tractor or trailer during any of these tests.

Figure 5.9: Tractor stability during straight line braking from 40 km/h with differenttractor trailer brake balances and no ABS

Source: (Dodd, Bartlett, & Knight, 2006)


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It can be seen that only in the situations representing inadequate or defective trailerbrakes was there any significant instability in the tractor. Measures to control the brakingcompatibility of combinations were included in the resultant revisions to the agriculturalvehicle braking regulations. These measures would be expected to substantially reducethe chances of such brake imbalances in service, such that jack-knife instabilities instraight line braking should only occur at less than 40 km/h where either an old trailerpre-dating new standards is towed, trailer brakes are defective (e.g. poor maintenance)and/or where the tyre road friction is substantially reduced by ice, snow and/orcontamination by mud or diesel.

Additional straight line braking was undertaken at higher speed using a JCB Fastracequipped with ABS to tow the same trailer, with and without the ABS active. The resultsare shown in Figure 5.10.

This data confirms that 40 km/h is the speed at which instability commences foragricultural vehicles towing trailers with good brake balance across the combination, on agood clean asphalt surface wetted with water. It can be seen that ABS was sufficient tocompletely control this instability, even though it was only available on the tractor andnot the trailer.

At 60 km/h, the result without ABS was actually more severe than indicated by the graphabove, the point plotted actually reflecting the moment the driver chose to abort the testdue to concern over the possibility of collision between tractor and trailer and/or rollover.The brakes had to be released less than 2.5 seconds after first application. This isindicated by Figure 5.11.

Figure 5.10: Tractor stability during straight line braking from higher speeds withbalanced braking across the combination on a good condition asphalt surface in wet

conditionsSource: (Dodd, Bartlett, & Knight, 2006)


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Figure 5.11: Instability reached at the point a 60 km/h wet test without ABS wasaborted for safety reasons


It should be noted that these results were obtained with a balanced trailer that imposedno vertical load on the tractor. In tests with an unbalanced trailer, it was found thatduring straight line braking the trailer imposed sufficient additional vertical load on thetractor that even at full pedal application the rear wheels of the tractor did not lock. Inthis situation, ABS was not necessary to prevent instability. However, failing to reach thepoint of wheel lock means that the stopping distance will not be as short as it could be inthis situation and manufacturers would not be prevented by regulation from increasingthe power of the brakes such that they could reach the point of wheel lock even whentowing an unbalanced trailer.

The earlier research also compared a JCB Fastrac and a traditional tractor design fromFendt, both without ABS (Figure 5.12). The behaviour was found to be very similar andso the conclusions appeared equally applicable to both traditional and new designs.

Figure 5.12: Straight line braking, wet conditions, balanced trailer, comparison betweenJCB and Fendt without ABS



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(Dodd, Bartlett, & Knight, 2006) also undertook braking in a turn tests. In this case,there was a difference in performance both with and without ABS function and betweenthe different tractors and trailers tested.

The JCB Fastrac without ABS had brakes sufficiently powerful to lock both front wheels.In this case, the yaw rate (shown in Figure 5.13) drops very quickly to zero, indicatingthat the vehicle quickly stops negotiating the turn and commences travelling in a straightline. In an on-road situation, this is equivalent to a tractor coming around a bend, seeinga hazard ahead, applying emergency braking and then travelling in a straight line suchthat the vehicle either crosses into the oncoming traffic lane and/or leaves the road.

The behaviour of the Fendt tractor is different from the JCB when braking in a turn.Initially, the yaw rate increases significantly before dropping steadily to zero. The Fendttractor locked only the wheels on the inside of the curve (which would be lightly loadedbecause of the load transfer to the outer wheels while cornering). Thus, significantcornering forces remain. The increase in yaw rate indicates a momentary tightening ofthe line through the corner. That is, if the driver does not adjust the steering, then thevehicle will follow a tighter bend. If severe enough, this could cause a vehicle to leavethe road to the inside of the bend. In some cases, with passenger cars, this type ofbehaviour is severe enough to cause a full vehicle spin. However, in this case, thetightening of the line was relatively small and should be easily compensated by thedriver.

It can be seen from Figure 5.13 that activating ABS on the JCB prevents the front wheellock such that the vehicle continues to follow the bend with the yaw rate droppingsteadily as the vehicle comes to rest. It does this without the tightening of the line seenin the Fendt. ABS has therefore done an excellent job of stabilising the tractor.

Figure 5.13: Yaw rate time history during braking in a turn with an unbalanced trailerSource: (Dodd, Bartlett, & Knight, 2006)

However, tests were repeated with the balanced trailer (not equipped with ABS). In thesetests severe instability was identified (Figure 5.14).

It can be seen that in the absence of ABS, the tractor suffered a sharp increase and thenlarge reversal of yaw rate in response to the brake application. The comparator run withABS enable would suggest stabilisation but yaw rate was measured on the tractor only.Thus, the tractor was indeed stabilised. However, trailer swing still occurred as shown inFigure 5.15.


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Figure 5.14: Tractor yaw rate, brake in a turn in wet conditions JCB Fastrac with/withoutABS


Figure 5.15: Illustration of trailer swing during 50 km/h brake in a turn, JCB Fastrac withABS active


This behaviour was not confined only to the JCB. The Fendt traditional tractor showedsimilar behaviour as illustrated in Figure 5.16. This culminated in a full rollover of thetrailer.


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Figure 5.16: Jack-knife, trailer swing and wheel lift during brake in a turn in a Fendt withbalanced trailer


This track testing has proven that ABS is effective at enabling steerability undercombined braking and turning and this will apply to both solo tractors and tractor trailercombinations. Although not explicitly tested, the results suggest that stability will also bemaintained for a solo tractor while braking and turning. There is clear evidence thatabove 40 km/h jack-knife can occur in straight line braking when tractors are towingtrailers. With the vehicles tested here this was much more evident with balanced thanunbalanced trailers but vehicles with greater brake power would behave differently. ABSstabilises combinations well in straight line braking, even when fitted only to the tractorand not the trailer. While ABS can improve tractor stability when braking in a turn, thereis clear evidence that trailer swing can still occur when the trailer is not equipped withABS. Thus, ABS is required on the full combination to fully stabilise the combination.

All of these conclusions were reached on a test surface of high quality, well texturedasphalt in normal wet conditions. Stability and steerability problems would be reduced indry conditions such that the effect of ABS would be expected to be less. However, inlower friction conditions (e.g. worn asphalt wet, contamination with mud/oil etc. and/orice or snow) then stability problems and the effect of ABS would be expected to be muchgreater.

5.2.2 Stopping distance

Vehicles that are not equipped by ABS are generally required by braking regulations tofulfil criteria relating to ‘adhesion utilisation’. Essentially these requirements are intendedto ensure that the front axle locks before the rear axle. This helps to minimise theseverity of instability arising from locked wheels. The logic of this is that if the frontwheels lock first, the vehicle will be travelling in a straight line at the moment the rearwheels lock. Thus, the chances of the vehicle spinning are reduced.

In older passenger cars, this was often achieved by means of a simple pressure limitingvalve on the rear brake circuit. This would mean that in high friction conditions, the rearwheel could end up being under-braked, increasing the stopping distance. When a vehicleis fitted with ABS, it does not have to comply with this requirement and so, in somecases, ABS can appear to substantially improve stopping distance. This is an indirecteffect of the improved stability making it technically easier to design to the limit forstopping distance, rather than a direct effect of the mechanism itself.

The requirement for passenger cars applies to all decelerations between 0.15 and 0.8g.For agricultural tractors, the restriction is only applied at decelerations between 0.15 and0.3g. It is not known how the different implementation of this requirement foragricultural vehicles will affect any similar indirect improvement of stopping distance.


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The direct effect of ABS on stopping distance is in relation to the tyre road frictioncharacteristics, in particular the relationship between tyre slip and friction. An example ofthis relationship is shown in Figure 5.17.

Figure 5.17: Example of tyre longitudinal slip vs friction relationship

In order for forces to develop between the tyre and the road then there has to be someslip between the two. The relationship after that point varies considerably depending onthe properties of both tyre and road surface and any contaminant (e.g. water) betweenthe two. Typically the peak friction will be developed at a relatively low level of slip.

Most drivers do not have sufficient skill and refinement on the brake pedal to be able tomaintain wheel slip within tight margins. Thus, there is an opportunity for ABS toimprove on driver performance if it can keep the wheel slip within a tight corridor (e.g.the ‘sweet spot’ identified in Figure 5.17, which is close to the peak for typical dry andwet asphalt). Typically, vehicles where the components have low inertia and the mediumthrough which the brakes are applied is incompressible (i.e. passenger cars) can achievevery rapid and precise modulation of the brakes. This means that they can keep utilisingvery close to peak friction in many common conditions and reduce stopping distancecompared to locked wheel braking and even skilled driver modulated braking. However,even on very good systems, surfaces with unusual characteristics can result in increasedstopping distances if their slip characteristics are significantly different to those assumedin the programming of the ABS.

Heavy vehicles tend to have large heavy wheels and large heavy brake components.Many of them also actuate the brakes using air, a highly compressible fluid. Thisintroduces considerable additional inertia and hysteresis into the system and makes rapidprecise modulation of brake pressure more difficult. In addition to this, tyres aredesigned differently and their slip characteristics might be different. This can lead to abraking characteristic more like that illustrated by Figure 5.18.

This shows that although the ABS does prevent all but momentary wheel lock (which ispermitted under ABS regulations), it allows wide variation in the slip experienced by thewheel (sometimes known as deep cycling of the pressure or wheel speed). This can meanthat the average deceleration is considerably lower than implied by the peak availablefriction. Thus, increases in stopping distance relative to locked wheel braking are morelikely. It should be noted that this characteristic is based on the performance of oldtechnology from Heavy Goods Vehicles (HGVs). Technology has been improvingconsistently for many years and it is quite possible that it has evolved to the point thatmore refined slip control can improve stopping distances on a wider range of surfaces.


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Figure 5.18: Illustration of potential tyre slip characteristics and ABS actuation on heavyvehicles with high component inertia and hysteresis.

This variation of ABS stopping performance on different surfaces can be graphicallyillustrated in certain ‘off-road’ conditions. It has long been established in studies ofpassenger car ABS that greater deceleration can be achieved by a locked wheel than byan ABS controlled wheel. This is because a locked tyre will dig into the gravel and createa wedge of material ahead of the tyre, known as the wedge effect. This is demonstratedin passenger car tests undertaken by (Forkenbrock, Flick, & Garrot, 1999). Results fromtests of a variety of cars on a deep gravel surface showed that on average the stoppingdistance of 9 cars was between 24% and 30% longer with ABS activated compared withlocked wheel braking. However, when 8 vehicles were tested on grass, the stoppingdistance was on average 4% shorter when ABS was active. One vehicle was tested onvery wet grass with standing water patches and it was found that in these conditions, thestopping distance under locked wheel braking was 30% longer than under ABS braking.This is consistent with views expressed by some agricultural vehicle manufacturersduring the stakeholder consultation but others simply state that off-road performance isworse. The test results and theory would suggest the type of off road surface will have asignificant effect as to whether ABS offers benefits or disadvantages. The extent to whichthose different surfaces are prevalent at each manufacturers test facilities may havesome bearing on their views and the prevalence of different surfaces on real farms acrossdifferent times of year could reasonably be expected to be a strong determinant ofwhether the net effect of ‘off-road’ ABS would be beneficial or not.

As stated previously, braking technology has advanced significantly in recent years.Some braking systems manufacturers have proposed technical solutions to off-roadperformance as illustrated in Figure 5.19.

time (seconds)


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Figure 5.19: Example of possible modifications to ABS control to improve off-roadperformance

(Copyright Knorr-Bremse)

This proposal appears to be predicated on the basis that the vehicle will not be used athigh speed in off-road conditions where the ‘wedge effect’ is likely to be significant (e.g.gravel or deep mud). At high speed it modulates the pressure to a shallow depth,meaning it will control slip in a tight corridor well suited to optimising stability andstopping distance on asphalt surfaces. At lower speeds 15-40 km/h, the pressure ismodulated in deep cycles that allow the vehicle to lock momentarily. This allows some ofthe advantage of the ‘wedge effect’ to be taken to improve off-road stopping distance atthe expense of on road stopping distance but while maintaining stability in both cases.Below 15 km/h, the system is deactivated entirely. Thus, at low speed the system isoptimised for off-road performance. At high speed it is optimised for on-roadperformance. No information has been found actually quantifying the performance of thistype of system on different surfaces.

The agricultural vehicle braking regulation requires that ABS can be switched off andwould permit, but not require, this type of dual mode control.

5.2.3 Real world effectiveness of ABS

The evidence in the preceding section shows that in physical tests, ABS is highly effectiveat stabilising agricultural vehicles under emergency braking. However, its effectiveness interms of preventing collisions in real world service will depend on how often suchcircumstances occur on the public road, the interaction with the driver, and if there areany unforeseen consequences of fitting ABS. That is, track tests might show that ABS ishighly effective at stabilising brake in a turn manoeuvres but if, in real service, tractordrivers very rarely brake in a turn then the number of instances where performance isimproved will be small. Similarly, track tests can show that an ABS maintains steerabilityunder braking but if drivers do not make rapid and appropriate steering inputs in suchemergency situations the benefit will be small. If in addition, there is an unintendedconsequence that drivers do not like the feel of ABS modulation and release the brakes,the benefits seen on the track would be further undermined. Thus, a system that ishighly effective on the test track may not be so effective in service.

At a high level, there are two different ways of quantifying the likely effect of a measure:

· Predictive studies: Study accidents that have occurred where the safety featurewas not present and apply engineering analysis to assess what effect fitting thefeature would be expected to have.


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· Retrospective studies: Comparing the accident involvement of vehiclesequipped with the feature with the involvement of those that are not equipped.

There are significant advantages and disadvantages to both approaches (see for example(Knight & Broughton, 2010) for a detailed consideration). Predictive studies can focus onprecise system characteristics and be very specific but rely heavily on theory and cannotfully account for any behavioural adaptation or unintended consequences. Retrospectivestudies in theory directly measure the real change including any effect of behaviouraladaptation or unintended consequences so in theory are more robust. However, it isharder to precisely isolate the variable you are trying to measure (e.g. the effect of ABSin this case) from other changes affecting crash risk that will have occurred in the sametime period. As such, they can suffer from a range of confounding factors. While this canbe mitigated with high quality accident and exposure data and sophisticated analytics, itis not always possible to overcome the data limitations. Results must be interpreted verycarefully as a consequence.

There are relatively few studies of the effect of ABS on agricultural vehicles and there areno retrospective studies. (Bende & Kuhn, 2011) studied data from insurance claims inGermany and predicted that 1% of killed or seriously injured casualties from accidentsinvolving agricultural vehicle could be prevented by ABS and 4% of all accidents.However, correspondence with the authors reveal that this was based only on a simpleassumption that all rear end collisions where the tractor driver braked would have beenrelevant to ABS and does not consider the level of effectiveness or the relevance of othercollision types such as those involving jack-knife.

In a position paper on the subject of ABS (CEMA, 2013), the association of EuropeanAgricultural machinery manufacturers cited the study by (Bende & Kuhn, 2011) asevidence of their estimate that agricultural vehicle ABS would prevent 1% of fatalitiesand 4% of all collision involving an agricultural vehicle. In their conclusions, they stated:

“No statistically significant reduction of accidents can be expected from theintroduction of ABS on tractors. On the contrary, based on the experience fromroad vehicles, there is a significant risk that the introduction of ABS in tractorsmay lead to an increase of fatal run-off-road accidents and accidents involving thehitting of animals, pedestrians or cyclists.”

There have been extensive retrospective studies of the influence of ABS when fitted toother road vehicle types, particularly in the USA. (CEMA, 2013) cites (Kahane & Dang,2009) and (Allen, 2010) and it is the information from these studies that appears to bereferred to in the conclusion. (Kahane & Dang, 2009) provided the most recent reviewand update of this research as it relates to passenger cars. (Allen, 2010) provides one ofthe only studies specifically examining the effectiveness of ABS on heavy goods vehiclesbased on retrospective techniques. Both studies used sound retrospective analysistechniques and were funded by US government.

(Kahane & Dang, 2009) reported on the long-standing history of analysis of the influenceof ABS on accidents involving passenger cars, where the findings have fairly consistentlybeen that ABS produces substantially beneficial reductions in some crash types but thatthese were offset by substantial increases in other types of crash such that the netoverall effect was small. Depending on severity of collision, country of data and studytechniques the net effect could be a slight improvement or worsening of the situation asattributable to ABS. Individual studies and authors often tried to explain these resultswith theories that might possibly explain them and these theories can sometimes besubsequently cited as facts. (Kahane & Dang, 2009) provide an excellent summary of thepossible explanations put forward for the counter-intuitive results observed in studies ofreal world ABS on passenger cars, which is reinterpreted below:

· Lack of driver knowledge of ABS: for example, a driver might take their foot ofthe brake when they feel the pedal vibration associated with ABS action.

· Misperception of risk and/or risk compensation: Drivers may drive moreaggressively because they perceive ABS will offer more benefit than it really can.


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· Longer stopping distances: for example, on loose surfaces once a vehicle hasalready left the road.

· Drivers not sufficiently skilled to exploit the additional capabilitiesprovided by ABS: for example, if a driver fails to see a stationary vehicle aheaduntil very late they might simultaneously brake and steer. Without ABS, thesteering does nothing and they collide with the stationary vehicle. With ABS, thecar swerves and avoids the collision but the driver does not modify the steering toa good avoidance course and leaves the road. This simultaneously reduces thefrequency of a two-vehicle collision by one but increases run-off road collisions byone.

· Flaws in the performance of early ABS technologies.

· Confounding factors: All retrospective studies of this type measure associationbetween variables and do not prove causation. Thus, it is possible that theobserved increase in run-off-road collisions was not a consequence of ABS but ofsome other vehicle feature that was correlated with the fitment of ABS but wasnot accounted for in the analysis. For example, if vehicles equipped with ABS wereon average more powerful, or attracted a riskier demographic of driver (e.g.‘sportier’).

(Kahane & Dang, 2009) reported that there had been comprehensive research into thesetheories and that little evidence was found to support any of them except the lack ofdriver knowledge of ABS. They report that NHTSA undertook several initiatives toimprove driver knowledge and a second round of retrospective analyses showed that theincrease in fatal run-off road collisions had halved. However, there were methodologicallimitations to those studies and the main purpose of the 2009 study was to assess thelong term effect once all of these variables had steadied and larger data samples wereavailable. (CEMA, 2013) cited the results of (Kahane & Dang, 2009) as follows:

· ABS has close to a zero net effect on avoiding fatal crash involvements.

· ABS is relatively effective in helping to avoid nonfatal crashes, by reducing theoverall crash involvement rate by 6 %.

· However, at the same time, ABS can be causally linked to the rise of fatal run-off-road crashes of passenger cars which increased by a statistically significant 9 %.This figure increased to a statistically significant 34% on wet, snowy, or icy roads,where ABS is most likely to be activated. On these roads, all three types of fatalrun-off-road accidents (side-impact with fixed objects, first event roll-over and allother run-off road crashes) increased significantly. For one type of accidents(side-impact with fixed objects) the observed increase was actually as high as85%.

The main results of (Kahane & Dang, 2009) are directly reproduced in Table 5.3.

It can be seen that the figures (CEMA, 2013) cited are broadly correct but more detail isavailable. In particular, (Kahane & Dang, 2009) were still unable to explain the increasesin run-off road collisions. However, since the introduction of ABS, the passenger carindustry had built on the functionality offered by ABS to develop electronic stabilitycontrol (ESC). This adds lateral acceleration, yaw rate and steering wheel angle sensorsto an ABS system and when the sensors detect that the vehicle is not heading in thedirection demanded by the driver input, it applies selective braking at individual wheels inorder to help the driver achieve the desired path. So, (Kahane & Dang, 2009) analysedthe effect of ABS and ESC in combination. The results are shown in Table 5.4.


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Table 5.3: Main results of long term study of passenger car ABS effect in the USA.Source: (Kahane & Dang, 2009)

Positive estimate denotes a reduction in crash involvements with ABS; Yellow cells: Statisticallysignificant estimates (at the one-sided 0.05 level)

All roads Wet, snowy or icyroads

Cars LTVs Cars LTVs

Fata

l Cra

sh I

nvol

vem

ents All fatal involvements 1 -1 -1 -6

All run-off-road crashes -9 -6 -34 -10

Side impacts with fixed objects -30 None -85 -4

First-event rollovers -11 -10 -52 -31

All other run-off-road crashes -3 -5 -17 -3

Pedestrian/bicyclist/animal 13 14 None -14

Culpable involvements with other vehicles 4 -1 12 -6

All

Cra

sh I

nvol

vem

ents All fatal involvements 6 8 16 14

All run-off-road crashes -1 11 -13 3

Side impacts with fixed objects -20 -9 -43 -15

First-event rollovers 3 17 -12 6

All other run-off-road crashes 5 15 -3 9

Pedestrian/bicyclist/animal -8 -42 -8 -10

Culpable involvements with other vehicles 17 20 37 36

Table 5.4: Effect of ABS and ESC in combination on passenger car fatal accidents (top)and all accidents (bottom). Source: (Kahane & Dang, 2009)

Percent reduction of fatal involvements

Four-wheel ABS ESC Combined

Pass

enge

r ca

r fa

tal a

ccid

ents Passenger cars

All fatal involvements 1 14 15

All run-off-road crashes -9 36 30

Culpable involvements with other vehicles 4 19 22

LTVs

All fatal involvements -1 28 27


Culpable involvements with other vehicles -1 34 33

All

Acc

iden

ts

Passenger cars




LTVs


All run-off-road crashes 11 72 75



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It can be seen that in combination, ABS and ESC offer substantial positive benefits in allcategories of collision, fatal or otherwise, such that the combined total benefit would begreater than for ESC alone. ABS function is very closely associated with ESC. As aminimum, an ABS function must be incorporated when ESC applies selective brakingbecause the ESC does not know the friction of the surface it is on and has no other wayof ensuring the automatically applied braking does not lock a wheel thus worseninginstability. ABS requires no additional hardware to ESC and does not, therefore, addsignificant cost compared with ESC alone. However, it should be noted that this analysisdoes not say whether the addition of ESC means that the specific accidents that ABSmade worse would no longer be made worse, or merely whether the adverse effect ofABS remained but was outweighed by the benefit of ESC on separate crashes of thesame category.

In addition to these results, (Kahane & Dang, 2009) undertook a preliminary cost benefitanalysis, for ABS alone, based on the simplifying assumption that ABS had zero effectnot just on fatalities but also serious injuries (based on the theory that crashes withserious injury might share more characteristics with fatal crashes than with slight injuryor damage only crashes). They found that the benefits of ABS on damage only and slightinjury collisions was at least equivalent to the costs of mandating ABS on all passengervehicles.

The extent of research on HGV ABS is much less and so, (Allen, 2010) presents theresults of a single analysis rather than a synthesis and update of many years of study.(CEMA, 2013) reports the results as follows:

· A statistically significant reduction of 6% was observed for crashes in which ABS isassumed to be potentially influential (relative to a control group).

· Concerning involvement in fatal crashes, only a statistically insignificant 2%reduction effect was observed.

· Among the types of crashes that ABS addresses, there was a reduction in jack-knife incidents and off-road overturns.

· By contrast, an increase was observed in the number of accident involvementsthat would include the hitting of animals, pedestrians, or bicycles and – only infatal crashes – rear-ending lead vehicles in two-vehicle crashes.

Again, this is broadly accurate but omits some important details:

· The estimate of 6 % reduction in crashes (all severities) where ABS was expectedto offer a potential benefit translates to a 3% reduction in all crashes. Both ofthese results were statistically significant.

· For fatal crashes, the estimates were 4% of ABS sensitive crashes, translating to2% of all crashes, neither result being statistically significant.

· Within these ‘net’ overall effects for fatal crashes, there was a:

o Reduction in run-off-road overturn of 22.5% (statistically significant).

o Reduction in jack-knife of 18% (statistically significant).

o Reduction in ‘at-fault’ multi-vehicle collisions of 9% (statistically significant).

o Increase in collisions with pedestrians, cyclists or animals of 9% (notstatistically significant).

o Increase in collisions where the HGV was the impacting vehicle in front to rearshunt collisions of 10% (not statistically significant).

· ABS was found to be much more effective on wet roads than on dry roads. In the7 US states analysed, crashes on wet roads represented 20% of the total.

· The effectiveness of HGV ABS varied substantially by road type. It was much moreeffective on low speed roads (those with a speed limit <55 mile/h, or 88 km/h)


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than it was on high speed roads. In particular, ABS was less effective on trueinterstate routes (equivalent to Motorways in EU) compared with other high speedrural routes.

· The report clearly highlights two methodological limitations that will result in theanalysis under-estimating the effect of ABS. It analysed data from before andafter the mandatory introduction of ABS and assumed ABS fitment was 0% in thebefore period and 100% in the after period. In reality, some vehicles will havebeen optionally equipped with ABS before the deadline and some will have haddefective ABS after the deadline, reducing the difference in number of vehiclesequipped. If 10% of vehicles were equipped voluntarily before the deadline and4% were defective after, it would increase the estimate of effectiveness (allcrashes) from 6% to 11%.

In contrast to other vehicle types, ABS on motorcycles has generally been found to behighly effective in terms of real world crash reduction. (CEMA, 2013) cited an InsuranceInstitute for Highway Safety (IIHS) study showing a 37% reduction in risk of fatalcrashes with motorcycle ABS and, as a European example, (Rizzi, Strandroth, Kullgren,Tingvall, & Fildes, 2015) showed a reduction in risk of fatal of 34% in Spain and 42% inSweden.

(CEMA, 2013) point to different characteristics of motorcycle braking and accidents aspossible explanations for the difference, with strong justification. Effectively, theconsequences of wheel lock on a motorcycle can be more severe than for 4-wheelvehicles. If a front wheel is locked it is very hard for the rider not to fall off the bike.Thus, riders tend to under-use the front brake in order to avoid stability problems. Givenrelatively high load shift from rear to front under braking on a motorcycle, this can meanthat the stopping distance is increased substantially from the optimum. ABS can giveriders the confidence to fully exploit the brakes such that stopping performance can besubstantially improved while also avoiding the instances of instability where riders dolock the wheels.

5.2.4 Extrapolating effectiveness estimates to EU collisions involving agriculturalvehicles

In their conclusions in relation to the effectiveness of ABS (CEMA, 2013) conclude thatthere will be no statistically significant reduction in accidents from the introduction ofABS on tractors. This has been shown to be correct for fatal accidents involving cars andtrucks but not correct for fatal accidents involving motorcycles or non-fatal crashesinvolving cars trucks or motorcycles. (CEMA, 2013) also conclude that there is asignificant risk that the introduction of ABS in tractors may increase fatal run-off roadcollisions and collisions with pedestrians, cyclists and animals. The evidence shows that:

· Passenger car ABS reduces fatal collisions with pedestrians etc. but increases fatalrun-off road collisions.

· HGV ABS decreases fatal run-off road collisions but increases fatal collisions withpedestrians etc.

Thus, the two different vehicle types studied have opposing results in this respect,suggesting something in the vehicle performance or its usage characteristics aresignificantly different between passenger cars (CEMA, 2013) acknowledge the differencesbetween motorcycles and passenger cars but not the difference between passenger carsand trucks or between agricultural vehicles and any of the other three road vehicle types.

There are many factors that need to be considered when assessing the applicability offindings for the three road vehicle types to agricultural vehicles, including but not limitedto:

· Motorcycles and, in most cases, passenger car accidents do not involve towing oftrailers. As such, only half of the 4 identified braking instabilities caused by lockedwheels are applicable. On-road accidents involving agricultural vehicles often


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involve tractors towing trailers. As such, ABS can benefit all 4 identified brakinginstabilities and, in this sense, agricultural vehicles would be expected to behavemore like the HGVs, where strong reductions in the incidence of jack-knifeincidents were observed.

· The research on HGVs found that there was a substantial difference in theeffectiveness of ABS on high speed and low speed roads. Accidents involvingagricultural vehicles more frequently occur on low speed roads.

· Maximum speeds of road vehicles are all in excess of 110 km/h (bearing in mindUS trucks are not subject to speed limiters as in Europe), the agricultural vehiclesin the scope of this proposal have a maximum speed of just 60 km/h. This mayinfluence consideration of the effectiveness on high speed roads.

· The speed capability of cars trucks and buses has been well in excess of speedlimits for a long period and can be considered constant over time. The sale of‘high speed’ tractors has been increasing substantially in the last 10 years inseveral member states such that the speed capability of the agricultural vehiclefleet will have been increasing slowly over recent year and that increase will beexpected to accelerate in future as sales continue to increase. Thus, predictions ofthe future benefit of mandating ABS on high speed tractors cannot be solely basedon past data dominated by the accident patterns experienced by a fleet dominatedby lower speed tractors.

· The net casualty savings of ABS can be considered a product of the differingeffects in specific crash types, for example, for trucks the savings in jack-knifeaccidents versus the increase in pedestrian accidents. So, the net benefit dependson the fundamental distribution of different crash types in the absence of ABS. Ifaccidents involving jack-knife were very rare and pedestrian crashes verycommon then you would expect ABS to give a substantial net increase incasualties. If the reverse were true you would expect a substantial net decrease incasualties. Agricultural vehicle accidents differ in the distribution of crash typescompared with trucks, cars or motorcycles. Thus, exactly the same effects inspecific crash types could produce a quite different net effect.

· Geography – most of the studies referred to come from the USA and in the case ofthe truck study much data came from only 7 of the 50 States. Road geometries,traffic mixes, weather and a wide range of other parameters may differsignificantly compared to the EU and, in fact, between different EU MemberStates.

Thus, at worst the assumption that ABS in agricultural vehicles will have a zero neteffect, the worst effect observed for passenger cars combined with the worst effectobserved for HGVs and none of the beneficial effects observed for non-fatal collisions andmotorcycles, is technically invalid. At best, it is just one of a range of possible outcomes,several of which may be considerably more beneficial.

Perception of benefits and impacts of implementing ABS on agricultural5.3vehicles

As part of the survey of stakeholders (see Section 1.2), information was sought on:

· The perceived benefits of implementing ABS on agricultural vehicles.

· The perception of accidents involving agricultural vehicles, with respect to possiblecauses and whether the impact, if any, that the implementation of ABS onagricultural vehicles might have on accident levels.

· Alternative safety measures that might offer similar or greater safety benefitsthan the fitment of ABS to agricultural vehicles.

It is recognised that any findings are based purely on subjective opinion; however it wasconsidered that the results would still be of benefit/interest.


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5.3.1 Perceived benefits of ABS fitment

Stakeholders were presented with a list of potential benefits and asked to identify thosewhich they thought were applicable to the fitment of ABS. Figure 5.20 summarises theresults.

Figure 5.20: Perceived benefits of ABS fitment on agricultural vehicles

There were 39 responses in total. Improved vehicle stability was perceived to be mostlikely benefit, being selected by 27 respondents. Thirteen respondents considered thatother benefits might result, including

· Improvements in operation through the ability to include features such as hillhold/hill descent control, emergency brake assistance, coupling force control, androll-over protection (by active braking of selected wheels).

· Improved steerability.

· Reduced tyre wear.

Four respondents considered that there were no benefits to be gained from the fitment ofABS. Three respondents considered that there could be negative benefits associated withthe fitment of ABS, namely that agricultural vehicle drivers might drive with less care andtake greater risks, based on the perception that having ABS fitted made the vehicle saferto use.

5.3.2 Perceived impact of ABS fitment on accidents

Stakeholders were asked to consider the possible causes of accidents involvingagricultural vehicles by ranking the pre-defined causes listed below in terms of orderof significance/importance (from 1 (most important) to 6 (least important)). Thosepossible causes listed under ‘other’ are those suggested directly by the surveyrespondents themselves.

· Low agricultural vehicle speeds relative to other traffic on the road.

· Poor conspicuity of agricultural vehicles, irrespective of the time of day.

· Tractors turning across the carriageway to access side roads, field entrances,etc. and thereby turning across the paths of oncoming or overtaking vehicles.

· Poor awareness of the size, speed and/or possible behaviour of agriculturalvehicles and road layout, by other road users.

0

5

10

15

20

25

30

Improveddriveability

Improvedstability

Accidentavoidance

Other None Negativebenefits

Num

ber o

f res

pond

ents


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· Poor braking performance of agricultural vehicles when preparing to turn orreacting to the movements of other vehicles.

· Other, including but not limited to:

o Agricultural vehicle use, e.g. high variance of tractor and trailer loads, poortractor/trailer compatibility, or overloading.

o Agricultural vehicle design, e.g. poor visibility within the immediate vicinityof the vehicle (front, side and rear), and (for SbSs and ATVs) corneringstability with respect to speed.

o Agricultural vehicle condition, e.g. poor maintenance or lack ofmaintenance.

o Human factors, e.g. driver age, general human error, poor judgement ofspeed differences between vehicles, tired (inattentive) agricultural vehicledrivers (due to long working hours), lack of concentration/experience byagricultural vehicle drivers (in comparison to drivers of heavy goods vehicles),lack of appropriate training for agricultural vehicle drivers, and (for SbSs only)a lack of knowledge of the vehicles.

The responses received did not indicate a consistent or common rank ordering. However,based upon the average ranked importance (from 1 (most important) to 6 (leastimportant)) the highest ranked possible causes were considered to be tractors turningacross the carriageway (2.52) and poor conspicuity (2.64). Table 5.5 summarises theaverage rankings.

Table 5.5: Assessment of the perceived ranking of possible causes of accidents involvingagricultural vehicles (1 = most important, 6 = least important)

Low speed Poorconspicuity

Tractorsturning

Poorawareness

Poorbraking Other

Total number ofresponses 39 36 37 41 32 27

Total number ofunranked responses 5 3 4 7 4 8

Total number ofranked responses 34 33 33 34 28 19

Average rankedimportance 3.18 2.64 2.52 2.88 4.18 5.00

Stakeholders were then asked to consider a number of criteria with regard to theimplementation of ABS on agricultural vehicles, giving their opinion in terms of a scorefrom 1-5 (None – Considerable) or ‘Unknown’. The criteria were as follows:

· The extent to which ABS would reduce the likelihood of accidents whenfitted to (a) agricultural tractors, (b) SbSs and ATVs, or (c) agricultural trailersand interchangeable towed equipment.

The majority of respondents suggested that there would be no impact on thelikelihood of accidents if agricultural tractors, agricultural trailers or towedequipment were fitted with ABS. In the case of SbSs and ATVs, the majorityconsidered the impact to be unknown; where respondents did score the impact,this was ranked by the majority to be moderate for SbSs and none/moderate forATVs. The full results are presented in Table 5.6.

· The extent to which ABS would reduce the severity of accidents whenfitted to (a) agricultural tractors, (b) SbSs and ATVs, or (c) agricultural trailersand interchangeable towed equipment.


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The majority of respondents suggested that there would be no impact on theseverity of accidents if agricultural tractors, agricultural trailers or interchangeabletowed equipment were fitted with ABS. The majority considered the likely impactupon SbS and ATV accident severity to be unknown; where respondents did scorethe impact, this was ranked by the majority to be moderate for both SbSs andATVs. The full results are presented in Table 5.7.

· The extent to which ABS would be beneficial to the safety of other roadusers when fitted to (a) agricultural tractors, (b) SbSs and ATVs, or(c) agricultural trailers and interchangeable towed equipment.

The majority of respondents suggested that there would be no benefit to thesafety of other road users if agricultural tractors, agricultural trailers orinterchangeable towed equipment were fitted with ABS; for SbSs and ATVs, themajority considered the potential benefit to be unknown; where respondents didscore the potential benefit, this was ranked by the majority to be moderate forboth SbSs and none/moderate for ATVs. The full results are presented in Table5.8.

Table 5.6: Assessment of the perceived extent to which fitment of ABS would reduce thelikelihood of accidents (figure denote the percentage of respondents selecting a given

scale of impact)

Vehicle type towhich ABS is fitted

No ofrespondents

Scale of impact

Unknown 1(None) 2 3

(Moderate) 4 5(Considerable)

Agricultural tractors 46 10.9% 28.3% 23.9% 15.2% 15.2% 6.5%

Side-by-Sidevehicles (SbSs)

(T3/T1)36 52.8% 16.7% 5.6% 19.4% 5.6% 0.0%

All-terrain vehicles(ATVs) (T3) 35 54.3% 17.1% 2.9% 17.1% 8.6% 0.0%

Agricultural trailers 46 13.0% 26.1% 21.7% 13.0% 10.9% 15.2%

Interchangeabletowed equipment 47 10.6% 29.8% 25.5% 23.4% 8.5% 2.1%

Table 5.7: Assessment of the perceived extent to which fitment of ABS would reduce theseverity of accidents (figure denote the percentage of respondents selecting a given

scale of impact)


No ofrespondents

Scale of impact

Unknown 1(None) 2 3




(T3/T1)34 50.0% 14.7% 11.8% 17.6% 2.9% 2.9%





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Table 5.8: Assessment of the perceived extent to which fitment of ABS would bebeneficial with respect to the safety of other road users (figure denote the percentage

of respondents selecting a given scale of impact)


No ofrespondents

Scale of impact

Unknown 1(None) 2 3




(T3/T1)32 53.1% 12.5% 9.4% 18.8% 6.3% 0.0%




5.3.3 Alternative safety measures

Stakeholders were also asked what alternative measures they considered might offerequivalent or greater safety benefits compared to the fitment of ABS. The responses aresummarised in Table 5.9. Whilst these alternative measures will not be included in thecost benefit analysis (see Section 8), Annex 1 discusses some of these measures in moredetail and includes comments on potential costs.

Table 5.9: Alternative measures perceived to offer equivalent or greater safety benefitscompared to the fitment of ABS, as suggested by stakeholders

Category Description

Braking Technologies described in Regulation (EU) No 167/2013 andsupplementing regulationsIntroduction of tractor-trailer braking compatibility corridors fromRegulations (EU) 2015/68 and (EU) 2016/1788Control of trailer braking system via drive-stick input (CVT transmission/ vehicle travel speed control)EBS for trailers and ESC for towing vehicles

Other vehicle controls V2V communicationsImproved recognisability of slow-moving or turning agricultural vehiclesVehicle distance controlHorizontal acceleration sensing/vehicle stability control

Other vehicle measures Seatbelts and roll-over protective structures (ROPS)

Vehicle maintenance Improved maintenance & roadworthiness checks

Vehicle conspicuity Improved lighting and signalling (Possibly also improved markings)

Driver field of vision Improved field of vision for tractor driver (e.g. mirrors, cameras, blindspot proximity alarms)Camera systems for identifying OTHER road users when entering /crossing the carriagewayDriver assist systems that actively warn or actuate to avoid a crashSurround sensing systems with autonomous vehicle interventions


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Category Description

Driver training Improved driver training for tractor driversMinimum driver age and/or licensingImproved driver training for OTHER ROAD USERS

Safety of other roadusers

Minimum requirements for pedestrian protectionMandatory helmets for T-category ATV users

Enforcement measures Limiting allowed towed mass in relation to tractor massImproved accident reportingBetter police checking of on-road speeds


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Issues affecting the wider implementation of ABS systems6on agricultural vehicles

Technical availability6.1As discussed in Section 5.1, the generic ABS systems which are (currently) technically-available for use upon agricultural vehicles may be categorised according to the followingcharacteristics:

· The medium used within the ABS control / modulating valve(s), (e.g. air,automotive-type brake fluid or mineral hydraulic oil).

· The medium used to actuate the vehicle’s (foundation) brakes, (againeither air, automotive-type brake fluid or mineral hydraulic oil).

The range of brake actuation systems / media typically employed on the agriculturalvehicles considered by this investigation and the technical availability of suitable ABSsystems for these applications are summarised in Table 6.1. The inherent characteristicsof the generic ABS systems which are potentially suitable for interfacing with theseagricultural vehicle brake actuation systems (see Table 5.1) may be summarised asfollows:

· Pneumatic ABS: A mature, truck-derived technology, which is readily-availableand well-developed to suit the specific operational needs of agricultural tractorsand associated (towed) vehicles. Installation requires certain pneumatic brakingsystem components to be present on the vehicle (e.g. air compressor, storagereservoir(s), operator brake control valve). Some of these are often present onCategory Tb vehicles, particularly if they are equipped to energise and controlpneumatic braking systems on towed trailers and equipment (Figure 6.1).

Pneumatic ABS is particularly suited to vehicles with pneumatic brake actuation,but can interface with hydraulically-actuated braking systems via Air-over-Hydraulic (AoH) converter units (see Section 5.1.1 and Figure 6.1). It can beparticularly convenient if the vehicle utilises different brake actuation media onthe front and rear axles (e.g. hydraulically-braked front axle / pneumatically-braked rear axle (Figure 6.2)). Unfortunately, current truck-derived AoH converterunits are bulky and require considerable installation space (typically 3 requiredper vehicle – see Figure 5.3), but it is understood that considerably more compactdesigns are under development.

· Hydraulic (automotive-type brake fluid) ABS: These are believed to bederivations of automotive (e.g. car or light-medium truck) ABS systems.Unfortunately their limited fluid displacement capability restricts their brakeactuation capability and potentially limits the maximum vehicle mass range towhich they may be applied. This limits their suitability for larger (T1b) agriculturaltractor applications. Nonetheless, these systems may well be suitable for otheragricultural tractor categories (e.g. T4.3b, ATVs, SbS).

· Hydraulic (mineral oil) ABS: These systems are believed to have beenspecifically-developed for agricultural vehicle (tractor) applications, but they arecurrently understood to be at ‘Functional Prototype - High Level of Maturity’ or‘Proof of Concept’ stages of product development (see Table 6.2). These ABSsystems are specifically intended to interface directly with the hydraulic (mineraloil)-actuated service braking systems fitted to many tractors and self-propelledagricultural vehicles. However, they are not intended to operate in conjunctionwith hydraulically-actuated trailer or towed equipment braking systems. Fortractor applications, such hydraulic ABS systems potentially require significantly


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less (total) system installation space, although certain components are believed tobe of similar size to those of pneumatic ABS systems.

Table 6.1: Brake actuation systems typically used on agricultural vehicles and currenttechnical availability of ABS systems for those vehicles

VehicleType

Brake ActuationSystem / Medium

Comments re. Actuation System ABS technical availability?

T1b

Hydraulic (mineraloil)

System used on majority of T1btractors

Yes – Systems exist butdevelopment ongoing

Pneumatic +Hydraulic (mineraloil)

Found on certain vehicles – Rear axlebraked pneumatically – Front axlebraked hydraulically

Yes – Mature – Incommercial use

Pneumatic +Hydraulic (brakefluid)

Usually only on higher-speed vehicleswhich utilise external ‘dry’ disc brakes


Pneumatic only Found on a minority of (mainly larger)tractors


T2b Hydraulic (mineraloil)

T2b tractors do not yet appear to beavailable. Installation space constraintslikely to preclude use of other brakeactuation mediums

Yes – Systems exist butdevelopment ongoing

T4.3bHydraulic (brakefluid) – Servo-assisted

Vehicle fitted with enhancedautomotive-type ‘dry’ disc brakingsystem on front & rear axles

Yes – Mature – Vehicle canaccept Light/ MediumTruck system

ATV Hydraulic (brakefluid)

External ‘dry’ disc and/or internalmulti-plate ‘wet’ disc brakes –Hydraulically-actuated

Yes – Proof-of-Conceptexists but is believed torequire furtherdevelopment. Furthercommercial system due tobe released in near future

SbS Hydraulic (brakefluid)

Mainly hydraulically-actuated external‘dry’ disc brakes. Would acceptautomotive (car) type ABS solution

Yes – Proof-of-Conceptexists but is believed torequire furtherdevelopment

R3b /R4b

PneumaticMost common system for Vmax > 40km/h, particularly on larger trailers(MPMaxles ≥ 12000 kg)

Yes – Mature –Truck-trailer-derived systemreadily-available

HydraulicUsually found on Vmax ≤ 40 km/hand/or smaller trailers(MPMaxles < 12000 kg)

No – Small potentialmarket unlikely tostimulate systemdevelopment

S2b

Pneumatic

Popularity dependent upon nationalmarket preferences. Also found onlarge / heavy vehicles which (bydefinition) become Cat R

Yes – Mature –Truck-trailer-derived systemreadily-available

HydraulicMore common system for trailedimplements, but less-suited to use atVmax > 40 km/h

No – Small potentialmarket unlikely tostimulate systemdevelopment


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Figure 6.1: Agricultural tractor pneumatic ABS system with hydraulic brake actuation viaair-over-hydraulic (AoH) converter units. Pneumatic trailer braking control system also

incorporated(Copyright Knorr-Bremse)

Figure 6.2: Similar agricultural tractor pneumatic ABS installation, but with hydraulic(AoH) actuation of front axle brakes and pneumatic actuation of rear axle brakes

(Copyright Knorr-Bremse)

AoH Converter forFront Axle Brakes

AoH Converters forRear Axle Brakes

Pneumatic Trailer Brake Valve & Couplings

AoH Converter forFront Axle Brakes

Pneumatic Actuatorsfor Rear Axle Brakes


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Practical issues associated with ABS installation / implementation6.2

6.2.1 Wheel speed sensor installation

For ABS to operate effectively it must receive accurate data regarding the speed of thevehicle’s wheels, so that the sudden deceleration during braking of one or more wheels(impending wheel lock) may be detected and the appropriate reduction in braking effortinstigated by the ABS control unit. On trucks, truck trailers and other on-road automotivevehicles, this is usually achieved by installation of electronic inductive-type sensors at theaxle ends, which detect the rate of movement of a toothed exciter ring mounted insidethe wheel hub (Figure 6.3). This type of installation works well for on-road vehicles and iswidely-used with success on larger agricultural trailers / interchangeable towedequipment, which tends to be fitted with commercial vehicle-type axles.

Figure 6.3: Inductive wheel speed sensor installation on a truck and/or agriculturaltrailer axle

(Copyright Erentek Ltd)

Figure 6.4: Typical tractor stressed, cast chassis and axle configuration, with suspendedfront axle (Claas Axion 800 series)

(Copyright Claas)


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However agricultural tractor axles are usually very different to those found on on-roadvehicles. Rear axle assemblies normally comprise a rotating driveshaft supported by apart-oil-filled structural casting; these are attached to either side of the rear centraltransmission casting / assembly (Figure 6.4). Front axles are also usually rigid, casthousings with enclosed drive-shafts to each wheel end, where ‘king-pin’ swivel joints areprovided to permit steering of the vehicle (see Figure 6.5 (left)). Front axle suspension isprovided on limited number of tractor models by independent wheel-type systems(Figure 6.5 (right)), but suspended rigid-beam designs are by far the most numerous. Asdiscussed previously, virtually without exception, Vmax > 40 km/h tractors feature bothfour-wheel drive (4wd) and front axle suspension, the latter being a mandatoryrequirement in certain EU Member States (see Section 3.4).

Regarding ABS wheel speed sensor installation, the dilemma facing the tractormanufacturer is whether to install sensor exciter rings:

a) On the axle drive-shafts inside the part-oil-filled axle casings?

b) Externally at the axle / wheel ends within additional protective housings?

Approach (a) has much to recommend it, as the sensing components faces are protectedfrom external (e.g. mud, water) contamination, but it requires initially-costly machining/ modification of the axle casing to accept the sensors, the sensor entry point into thecasing must be adequately sealed, and the external parts of the sensor body and thecable exit must be adequately protected. This approach has been used with success bythe New Holland ABS system (see Figure 5.3 and Figure 6.6). Some tractormanufacturers have raised concerns regarding the reliable operating temperature rangeand effective (oil) sealing of the inductive sensors in such installations, but currentevidence does not appear to support these concerns.

Figure 6.5: Alternative designs of suspended front axle for agricultural tractors. Rigidbeam (left) and independent wheel suspension (right)

(Copyright Scarlett Research & Dana-Spicer)

Approach (b) requires the design and installation of bespoke housings / mountings at theaxle ends of the tractor, both to support and to protect the sensors and associatedexciter rings. Such installations undoubtedly face greater challenges in terms ofcontamination in off-road conditions but, realistically, are mechanical engineeringchallenges and they avoid the need to modify the axle housings of the vehicle: a possiblydesirable scenario if ABS is an optional feature on a given vehicle model range. Currentlyboth Fendt and JCB utilise this approach (see Section 5.1.1).

It is worth noting that the majority of tractor manufacturers source 4wd front axles froma relatively small number of dedicated axle manufacturers (e.g. Carraro, Dana-Spicer,ZF). It would seem that, if ABS were to be mandatory, in order to reduce system cost(through volume manufacture), such axles could be supplied with wheel-speed sensorspre-installed.


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Figure 6.6: Wheel speed sensor installations on New Holland tractors fitted with ABS:front axle (left & centre) and rear axle (right)


Regarding wheel speed sensor installation on agricultural trailers and towed equipment,as previously mentioned, the exciter ring component of such sensing systems (Figure6.3) is already commonly installed on the commercial-vehicle axle designs frequentlyused on higher mass and Vmax > 40 km/h equipment. Due to higher production volumesworldwide, supported by the on-road sector, in many cases the purchase cost of suchaxles is lower than lower-specification versions intended for agricultural applications.

However, whilst the exciter ring may be present on (commercial-type) axle, it is usuallynecessary to install the (relatively cheap) inductive-type sensors and associated cables:this reportedly adds ~€50 to the overall axle cost. Also, it should be noted that,irrespective of the number of axles on the trailer / towed equipment, it is normal practiceto only sense the wheel speed of one axle, reducing the overall cost of sensor installationyet further.

In the case of lower mass trailers / towed equipment which may currently use lowerspecification axles without the provision to readily-accept wheel speed sensors, ABSinstallation would potentially require the installation of higher-specification axles. Suchaxles are readily available on the market (with wheel speed sensors installed), but it isaccepted that this would increase the overall cost of ABS installation on such lower massvehicles. These factors have been considered by the Cost Benefit Analysis (seeSection 8.3).

6.2.2 Vehicle braking system actuation

In many respects this aspect determines the potential level of complexity of ABS systeminstallation on agricultural tractors or trailers. As discussed in Section 6.1 (see also Table5.1), the brake actuation system(s) present on the vehicle may influence the preferredchoice of ABS type(s) for ease of installation, but this choice may be limited by currentsystem availability / maturity (Table 6.2). Frequently alternative generic ABS systemsmay be fitted to a given vehicle model, but the installation complexity and overall systemcost (system purchase cost + installation cost) may differ between system types.

The current product maturity of pneumatic ABS systems has made them a popular choiceamongst tractor and trailer manufacturers who offer ABS (see Table 5.2 and Table 6.1).If a tractor or trailer’s braking system is already configured for pneumatic actuation, thedifficultly of installing a pneumatic ABS system is relatively limited. However, ashighlighted in Section 6.1, the majority of current tractors employ hydraulic brakeactuation systems and so, in the current absence of commercially-mature hydraulic ABSsystems for agricultural tractors, or if both pneumatic and hydraulic brake actuationsystems are present on the same vehicle, it is necessary to employ Air-over-Hydraulic


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(AoH) converter units to interface between the ABS and hydraulic brake actuation system(see Figure 6.1).

Unfortunately current AoH converter designs are derived from the truck components andare bulky (Figure 6.7). Additionally, for a typical 4S / 3M tractor ABS system, three AoHunits are required which, in total, can represent quite a packaging challenge on a moderntractor (Figure 6.8). It may seem difficult to believe but, particularly on larger, morecomplex tractors, component packaging space is at a premium. Engine exhaustemissions requirements have required the installation of both exhaust gas after-treatment equipment and additional tanks for diesel exhaust fluid storage. Theserequirements, together with the need to maximise diesel fuel storage capacity, so as notto restrict tractor daily working hours between refuelling, pose an ongoing challenge tothe tractor designer. The prospect of having to accommodate three bulky AoH units,possibly at the expense of a reduction in fuel tank capacity, is understandably not afavoured option. Fortunately it is understood that more compact AoH converter designsare under development and, subject to market demand, are likely to be made availablecommercially.

Figure 6.7: Current design of Air-over-Hydraulic (AoH) converter unit: maincomponents (left) and installed on an agricultural tractor (right)


Theoretically, the commercial availability of mature ABS systems, with the ability tointerface directly with tractor service braking systems actuated hydraulically usingmineral-based oil, would be a major advantage. However, the challenges these systemshave to overcome, in comparison with hydraulically-actuated braking systems onautomotive vehicles, which employ automotive-type brake fluid, are numerous:

· Fluid displacement for brake actuation: Automotive-type hydraulically-actuated braking systems (e.g. dry disc & caliper or dry drum systems) generallyrequire limited fluid displacement volumes to apply the vehicle brakes. However,with certain exceptions (e.g. JCB Fastrac), hydraulically-actuated tractor brakesnormally are of the single or multi-plate, oil-immersed type, applied by an annularpiston. Brake application by this method requires a much greater volume of fluidto be displaced by the actuation system, effectively making the task of the ABSsystem more difficult. Consequently it has not been possible simply to transferhydraulically-based ABS designs from the automotive sector, due to their limitedfluid displacement capability. Rather it has been necessary to develop new ABSsystems specifically to accommodate the larger fluid displacement requirements ofhydraulically-actuated tractor braking systems.

· Speed of response in cold temperatures: Currently the majority ofhydraulically-actuated tractor service braking systems utilise the same hydraulicfluid as the other hydraulic services on the vehicle. This is usually also thetransmission / rear axle lubricating oil: consequently it is usually of higher


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viscosity than automotive-type brake fluid and is also more subject to viscosityincreases at lower temperatures. ABS inherently needs the brake actuationsystem to respond rapidly to modulation signals generated by the ABS controlmodule in order to operate effectively. This is a recognised issue and the hydraulic(mineral oil) ABS systems currently under development are understood to beaddressing it.

Figure 6.8: Braking system installation (featuring Air-over-Hydraulic (AoH) ABS) on NewHolland T7 Heavy Duty tractors: system components shown in yellow

(1) air compressor, (2) air processing unit, (3) air reservoirs, (4) pneumatic foot brake valve,(5) ABS control module, (6) air-hydraulic converter units, (7) pneumatic trailer brake control valve,

(8) pneumatic trailer braking system couplings


6.2.3 ABS control strategy development and implementation

It has often been said that “tractors are not trucks” and few would question the logicbehind this statement. However, as highlighted by this report, agricultural tractor-trailercombinations do perform on-road transport operations at total / gross vehicle massesequivalent to large truck-trailer combinations. The logic behind the application of truck-type ABS technology to agricultural tractors and trailers is therefore also valid. However,whilst ABS hardware may be transferred to agricultural vehicles, with certainadaptations, truck-type ABS control strategies (software) could not be transferred withsimilar ease. The specific nature of agricultural tractors, their multiple loadingconfigurations, the split between on-road and in-field operation and the frequentpresence of intelligent driveline control systems on the vehicle, required the developmentand refinement of ABS control software and systems to provide acceptable and reliablelevels of performance. This has required considerable effort and investment; both on thepart of braking equipment suppliers and also the small number of tractor manufacturerswho have chosen to implement ABS technology (see Section 5.1.1). Whilsttrailer / trailed equipment manufacturers have been, in the majority of instances, able toutilise off-the-shelf ABS systems derived from truck-based products (operating on 12 voltas opposed to 24 volt power supply), tractor manufacturers found that a range of issuesrequired addressing. These included the following:

7

1

8

3

5

3

2

6

4


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· Effective sensing of vehicle speed: This is a pre-requisite for effective ABSoperation. However, despite the provision of speed sensors on all wheels, thepioneering implementers of agricultural tractor ABS have apparently encountereddifficulties in ensuring reliable vehicle speed data is obtained at all times. Factorssuch as the larger rolling circumference of tractor tyres (compared with those oftrucks) and also the normal practice to engage the vehicle’s four wheel drive(4wd) system during braking, have possibly contributed to this issue. The problemappears to have been largely addressed by the incorporation of a vehicleacceleration sensor (accelerometer) within the ABS control module. Moderndesigns of ABS control modules for on-road truck-trailer installations apparentlyincorporate this feature to enable the roll stability of the vehicle to be controlledby active braking of certain of the vehicle’s wheels. The utilisation of this type ofABS module on agricultural tractors, together with further bespoke controlsoftware development, seems to have overcome the problem.

· Interaction with vehicle driveline / transmission control systems: Asmentioned above, as a distinct departure from on-road vehicle control methods, itis normal practice for the 4wd system of a tractor to be engaged during vehiclebraking. Originally this was done to provide braking effort (via the 4wd driveline)on the otherwise unbraked tractor front axle. Today most Vmax > 40 km/h tractorsfit brakes on their front axles, but generally these are of lower capacity than thosefitted to the rear axle; consequently the practice of 4wd engagement on braking isretained. As can be imagined, this poses intriguing control issues for the ABScontrol software, but appears to have been addressed with considerable success.

Additionally, the majority of current agricultural tractor models offered with ABSare fitted with continuously-variable transmissions (CVTs); indeed, suchtransmissions are present on an increasing proportion of > 200 hp (> 150 kW)tractors, which themselves are most likely to have Vmax > 40 km/h capability. CVTtransmissions are controlled by intelligent vehicle software, usually in conjunctionwith engine speed and power output. Consequently, tractor manufacturers foundit necessary for the ABS system to control both the vehicle’s brakes and thetransmission (and engine) during ABS operation, to ensure one system was notfighting against the other in an undesirable manner. To achieve this it wasnecessary for the tractor engine-transmission control system to communicate withthe ABS control system and vice-versa. Again, an issue which has been addressedsuccessfully, but by no means a small task.

· Off-road vehicle braking behaviour: The issues surrounding the potentiallyundesirable effects of ABS on vehicle off-road stopping distances have beendiscussed in Section 5.2.2. Whilst it is widely accepted that ABS potentiallyimproves the on-road braking performance of a vehicle, it can in certain instancesdetract from off-road braking performance and result in longer stopping distancesin such conditions. When operating off-road on loose soil or gravel-type tracks,shorter stopping distances can result from disabling / switching-off the ABSsystem and permitting the wheels to lock during braking, whereby a ‘wedge’ ofmaterial builds up in front of the locked wheels, helping to decelerate the vehicle.Directional control of the vehicle is of course lost during such ‘wedge braking’, butit is claimed that a shorter stopping distance is a worthwhile trade-off.

This is a familiar issue for ABS manufacturers as is applies to vehicles (mainlyconstruction trucks) used in both on and off-road conditions. Consequently currenttractor ABS systems have been configured to provide a range of differentoperating characteristics to best-suit the prevailing operating conditions. Thespecific solutions are as follows:-

o ‘On-Road’ ABS operating mode: When stopping from speed (V > 40 km/h),vehicle brake application pressure is modulated to prevent wheel-locking andto maintain vehicle directional control. However, even when operating in this‘on-road’ mode, the ABS modulation is de-activated when the vehicle speed


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reduces below a pre-determined (customer-selected) threshold (e.g. 5, 8 or12 km/h), below which wheel-locking (and wedge-braking) are permitted.

o ‘Off Road’ ABS operating mode: An in-cab switch enables the driver toselect ‘off-road’ ABS mode (Figure 6.9). Above ~40 km/h ABS behaviour isidentical to the ‘on-road’ mode, but as speed reduces into the40 > V > 15 km/h range, the ABS software permits a more aggressive,selective-wheel-lock, ‘deep-cycle’ brake control mode. Finally, whenV < 15 km/h, wheel locking is permitted to maximise any ‘wedge braking’benefits. Should the operator attempt to drive above 40 km/h in ‘off-road’mode, the vehicle is either prevented from exceeding 40 km/h or the ABSautomatically defaults to ‘on-road’ mode. This threshold could, of course, beset at an alternative value during system programming.

Figure 6.9: ABS system switchable ‘Off-Road’ operating mode(Copyright Knorr-Bremse)

It therefore appears that braking system manufacturers have gone to some lengths todevelop a range of speed-dependent ABS operating strategies to address concernsregarding off-road braking behaviour of ABS-equipped vehicles, with the objective ofsatisfying the dual objectives of maximising vehicle braking performance and retainingvehicle directional control. Two of the three agricultural tractor manufacturers whichcurrently offer ABS (see Section 5.1.1) provide an operator’s switch to disable the systemfor off-road operation, if so desired. However, the system is automatically re-enabledabove a certain threshold forward speed.

Potential benefits of ABS installation / implementation on agricultural6.3vehicles

This investigation has primarily focussed upon the potential improvements in vehiclebraking performance and the associated cost and manufacturing complexity issues whichmay result from ABS installation upon agricultural vehicles. However, there are a rangeof additional benefits which can potentially be realised once a vehicle (tractor) is fittedwith ABS. Essentially a modern, multi-facetted ABS system permits control of thevehicle’s braking system to be effected via vehicle control software. Given the wide rangeof vehicle sub-systems already controlled by intelligent software on larger agriculturaltractors, this potentially enables integrated control of the vehicle’s driveline to achievegreater functionality. Some of the options explored (and in certain cases realised) to-dateinclude:

· Automatic brake application (Hill-Holding): To assist vehicle hill starts. Thetractor’s brakes continue to be applied, automatically, when the driver’s foot isremoved from the brake pedal, until the clutch pedal is released sufficiently for


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the engine-transmission to prevent the vehicle rolling backwards. However, thisfeature is only of real benefit on tractors equipped with stepped-ratio (Powershift)transmissions, because those fitted with CVT transmissions automatically providethis functionality via the engine-transmission control system.

· Intelligent tractor steering brake control: (Figure 6.10) Marketed by NewHolland as the ‘ABS SuperSteer’ system. Conventional tractor braking systemsrequire the driver to press the ‘independent’ left or right brake pedals to operatethe rear wheel brakes individually to assist tight-radius turning at field headlands.The ABS SuperSteerTM system either (a) operates the inner rear wheel brakeautomatically as the steering wheel is turned (in response to front wheel steeringangle), or (b) conventionally by operator control via the independent brakepedals. However, in both instances the speed of the inner wheel is monitored bythe ABS system and brake pressure is controlled to ensure the wheel is not over-braked, does not skid and so does not damage the field surface: a particularlyimportant issue on grassland.

Figure 6.10: New Holland ABS SuperSteerTM system. Traditional in-field headlandturning by use of independent rear wheel brake pedals (left) and automatic ABS-

controlled independent rear wheel brake operation (right)


· Traction control: On certain on-road vehicles, independent, intelligent control ofthe wheel brakes is employed to maintain / enhance vehicle traction in conditionsof poor tyre-ground surface adhesion. However, agricultural tractors have beendesigned from a very early stage to operate effectively in conditions of poor oruneven traction. To achieve this they are fitted with 4wd systems and differentiallocks on both the front and rear axles. It is common practice on medium / largetractors (>125 hp / 93 kW) to engage / disengage either or both of these systemsautomatically and/or intelligently, depending upon vehicle steering angle, forwardspeed and even wheelslip level. Consequently, with such functionality alreadypresent on the vehicle, the additional traction control features which may beprovided by an ABS system at anything other than higher on-road operatingspeeds, are likely to be limited.

· Intelligent trailer braking control: When operating an agricultural tractor andtrailer combination, it is desirable that the braking systems of each vehiclegenerate sufficient braking effort to bring the combination to a controlled stopwhilst under complete control. In order to do this, each vehicle must generatebraking effort proportional to the loads being carried by its axles but,unfortunately, the magnitudes of these loads change regularly, many times duringthe working day, depending upon whether the trailer is laden or unladen. As(common) rigid drawbar / unbalanced trailers also transfer a proportion of theirloading onto the tractor (see Section 2.3.6), the tractor’s braking system is alsorequired to deliver varying levels of performance. This is a widely-recognised issue


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and various approaches have been implemented to address it, the most commonbeing the installation of a load sensing valve on the trailer’s suspension system(Figure 5.6), to vary the vehicle’s braking effort in relation to the load beingcarried. However, the characteristics of the robust mechanical suspension systemsfrequently fitted to agricultural trailers / towed equipment often cause theeffectiveness of such devices to be compromised.

For the first time in EU legislation, Regulation (EU) 2015 / 68 (European Union,2015) introduced mandatory ‘compatibility corridors’ for agricultural vehiclebraking performance, to try and improve the balance of braking between thetowing and the towed vehicle. This is undoubtedly a good move, but the ultimatelevel of improvement gained will be dependent upon the capabilities of the brakinghardware employed.

Intelligent trailer braking control systems permit the braking effort of the trailer tobe varied in relation to that of the tractor, by use of an electronically-controlledtractor-trailer brake control valve mounted on the tractor. This provides a greaterrange of system operating characteristics, which can be configured to operatemore closely in relation to the tractor’s braking behaviour, in response to datainput from vehicle-mounted accelerometers and wheel-speed sensors. Potentialbenefits include:

i) Trailer brake control in response to tractor engine braking / CVT drivelinebraking or use of the tractor’s exhaust brake (if fitted);

ii) Improved tractor-trailer coupling force control during braking, therebyreducing the risk of jack-knifing.

It may be questioned how these functions are related to ABS. Simply that if ABSis already installed upon the tractor and an EBS (Electronic Braking System) isfitted to the trailer (to provide ABS functionality), the wheel speed sensors,vehicle accelerometers, communication and control hardware will already bepresent to support an intelligent trailer braking control system.

· Vehicle stability control: This is also primarily of benefit to tractor-trailercombinations, particularly those vehicles with higher Centre-of-Gravity (CoG)locations (e.g. forage wagons, high-sided trailers) and/or those frequently used onsteeply sloping ground. Automatic application of one or more individual wheelbrakes, in response to vehicle acceleration and speed input data, can be used tostabilise the vehicle whilst cornering and undertaking other manoeuvres. Again,the intelligent vehicle braking system control capability present in an ABS canprovide a platform for such enhanced functionality on the vehicle.

· Tyre wear reduction: As commented previously, the performance of loadsensing systems on agricultural trailer / towed equipment fitted with mechanicalsuspension systems is frequently sub-optimal. This can result in ‘over-braking’ ofthe vehicle whilst unladen or part-loaded, causing wheel-locking / skidding andexcessive trailer tyre wear. It is common practice for large trailers and towedequipment to be fitted with large and expensive (~€500 each) ‘flotation’-typetyres to minimise in-field soil compaction. Whilst not a substitute for a load-sensing braking system (which is in any case a mandatory requirement onVmax > 40 km/h trailers and towed equipment), ABS can reduce the likelihood oftrailer wheel locking during braking and thereby extend tyre life. With four or sixtyres on a tandem or tri-axle trailer, the saving in tyre replacement costs alonecan potentially justify the investment in ABS technology.


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Practical availability and economic availability6.4

Given the apparent ready-availability of pneumatically-based ABS systems for use onagricultural tractors and trailers / towed equipment, the practicality and economicfeasibility of their installation is, in practice, determined by a range of factors, including:

· The brake application method / medium used on the vehicle.

· The available space for ABS component installation.

· To a lesser extent, the availability of a pneumatic braking system on the vehicle(tractor), either for the target vehicle or for trailers / interchangeable equipmenttowed by it. Such systems are highly likely to be present upon Tb(Vmax > 40 km/h) tractors which, as previously discussed (see Section 3.3.1), arealmost certainly to be of ≥ 130 hp (≥ 97 kW) rated engine power.

The situation regarding ABS installation on agricultural trailers and interchangeabletowed equipment (Category R and S) is relatively clear-cut. ABS installation onpneumatically-braked vehicles presents few challenges, given the presence of (orfeasibility of installing) suitable wheel speed sensors. If the vehicle is designed from theoutset for Vmax > 40 km/h use, this is unlikely to be an issue (see Section 6.2.1). Maturepneumatic ABS systems are readily-available at reasonable cost (~€500 OEM cost for abasic system (Figure 5.6)) and they may be installed without difficulty. More complex(and capable) EBS systems are also available (Figure 5.7), but at greater cost. However,ABS systems are not currently available for hydraulically-braked trailers (Table 6.1 andTable 6.2) but, as discussed previously (see Section 5.1.2), hydraulic braking systemsare unlikely to be fitted to Vmax > 40 km/h trailers / towed equipment.

Pneumatically-based ABS technology is readily available for use on agricultural tractors(e.g. T1b) but, due to the bespoke nature of the target vehicle, it may well be necessaryto approach ABS installation on a model-range by model-range basis. The systemconfiguration and/or installation approach which may be suitable for one model rangemay be entirely unsuited to another. Whilst this does not necessarily increase the base-cost of the ABS hardware to the vehicle manufacturer, it may substantially increase theinstallation and bespoke development costs which must be incurred in order to provideABS, thereby potentially increasing system cost to the vehicle user.

The factors highlighted at the beginning of this section are likely to influence thepreferred choice of ABS system for ease of installation on agricultural tractors, which inturn may be limited by current system availability / maturity (see Table 6.1 and Table6.2). Frequently, alternative generic types of ABS system may be fitted to a given vehiclemodel, but the installation complexity and overall system cost (system cost to the OEM +installation cost + development cost) may differ between the ABS types. It has not beenpossible for this investigation to quantify and report the potential overall system costs forreasons of commercial confidentiality, but ABS suppliers have commented that,depending upon production volumes, system costs to OEMs may be in the region ~€1000– 1300. Where offered as optional equipment, tractor manufacturers currently retail ABSat ~€4000 – 5000.

Installation of pneumatic ABS systems may be more challenging on smaller / lower-power vehicles, due to space and other engineering constraints. Also, ABS cost remainslargely the same although the retail price of smaller vehicles is substantially lower.Fortunately, such vehicles are not typically offered with 40 < Vmax ≤ 60 km/h capability.Study of the current European agricultural tractor designs (Scarlett, 2013) suggests thatrated engine power and vehicle size (Max Permissible Mass (MPM)) can provide relativelyclear threshold levels below which T1 tractors with 40 < Vmax ≤ 60 km/h capability arenot offered (see Section 8.2).

The pioneering tractor manufacturers who already offer ABS (see Section 5.1.1) have,without doubt, incurred substantial system development costs, but have undertakenthese activities as a commercially-orientated activity, no doubt in conjunction with


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braking equipment suppliers. Other tractor manufacturers approaching the introductionof ABS for the first time will undoubtedly benefit from the experience gained in this areaand this is likely to be reflected in reduced system development costs for their specificvehicle applications. Nonetheless, the likely magnitudes these costs should not beunderestimated and, where possible, have been taken into consideration in the Cost-Benefit Analysis (Section 8).

On the basis of the above information and further engagement with the agriculturalvehicle industry, a range of feasible increases in vehicle costs likely to result from ABSprovision, have been estimated and are presented in Section 8.3.

Concerns had been raised by some agricultural vehicle manufacturers that the number ofABS braking equipment manufacturers / suppliers is limited and therefore may restrictfree-market competition. It is perfectly true that the market is dominated by a smallnumber of manufacturers and, due to the level of investment required for productdevelopment, the specialised nature of agricultural vehicle applications and relativelysmall vehicle production volumes (in automotive terms), it is unlikely to attract newentrants. Most ABS technology currently offered (or under development) for agriculturalvehicle applications originates from manufacturers who offer similar products to the on-road truck and/or truck-trailer markets (e.g. Knorr-Bremse, WABCO and Haldex).However, other manufacturers supply braking equipment to agricultural tractor andtrailer / trailed equipment manufacturers and may choose to enter the market if there isperceived to be sufficient demand for product. Unfortunately, the still pending decisionregarding the mandatory installation of ABS within the EU for agricultural vehicles of40 < Vmax ≤ 60 km/h capability (as evidenced by current publicity originating fromcertain stakeholders) has created uncertainty and this has done little to encourage newentrants. Conversely, other vehicles type-approved as agricultural tractors (e.g. ATVsand SbSs) could potentially utilise ABS technology derived from other automotive sectorsand hence those manufacturers which supply product to them. Consequently, the issue ofABS technology supply to the agricultural vehicle market would (at present) appear to befar from monopolistic or restrictive.

In many respects the situation regarding the future development / production / supply ofABS technology to the agricultural vehicle market is reminiscent of previous situationswhere the technological content of such vehicles has made a step change. During thelate-1980s / early-1990s most tractor manufacturers choose to install electro-hydraulic3pt implement hitch control systems upon their vehicles. At that time the market wasdominated by the Bosch ‘Hitchtronic’ EHR product and many tractor manufacturerschoose to purchase and install the complete Bosch system. Some larger tractormanufacturers elected to develop their own systems ‘in-house’, but even certain of thesechoose to purchase certain elements of the Bosch system to interface with their owndesigns. The project team are unaware that such a monopolistic product supply situationwas reported to be detrimental to the agricultural tractor industry of the time, but thenthe introduction of ‘EHR' was a market-led development as opposed to a requirementimposed by legislation.

The agricultural vehicle industry has a long and successful track record of adapting andutilising technology originating from the on-road sector. Inevitably, in the early stages ofsuch initiatives, product costs to (tractor) OEMs may be higher, but usually bespokeadaptations are made within the agricultural sector and cost-reduction measures areimplemented to improve the economic balance of the situation. Third-party suppliers areonly too aware of this and therefore tend to price product accordingly and/or offerongoing system improvements in order to retain future business. Such economic issuesdo not appear to represent an undue restriction to the installation of (pneumatic) ABStechnology upon agricultural trailers, where potential reductions in tyrewear / replacement costs appear to justify investment in ABS technology.


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Summary6.5Based on the information presented in the previous Sections, Table 6.2 summarises thecurrent availability of ABS systems for agricultural vehicles in terms of a TechnologyReadiness Stage (TRS) based approach, whereby the different stages are as follows:

· TRS01: Concept ABS technology

· TRS02: Functional prototype ABS technology with low degree of maturity

· TRS03: Functional prototype ABS technology with high degree of maturity

· TRS04: Market ready ABS technology – ready for/in early stages of introduction to market

· TRS05: Readily available ABS technology, proven in the market

Whilst it was originally proposed to consider the practical applicability and economicfeasibility of the systems using a similar approach, the assessment has highlighted thatthis will vary, particularly in the case of agricultural tractors, on a model-to-model basis,due largely to the brake application method / medium used on the vehicle and theavailable space for ABS component installation. As such, a useful categorisation byvehicle category cannot be achieved.

Table 6.2: Generic ABS systems potentially suitable for use on agricultural vehicles

VehicleType

Vehicle Brake ActuationMedium

ABS Type (SystemModulating / Control

Medium)

Current TechnologyReadiness Stage (TRS)

T1b / T2b

Pneumatic Pneumatic TRS05

Hydraulic (mineral oil) Pneumatic TRS05

Hydraulic (mineral oil) Hydraulic (mineral oil) TRS02 or 03 dependingon system

Hydraulic (brake fluid) Pneumatic TRS05

T4.3b Hydraulic (brake fluid) Hydraulic (brake fluid) TRS04 or 05 dependingon system

ATV Hydraulic (brake fluid) Hydraulic (brake fluid) TRS01 or 04 dependingon system

SbS Hydraulic (brake fluid) Hydraulic (brake fluid) TRS01 or 04 dependingon system

R3b / R4bPneumatic Pneumatic TRS05

Hydraulic Hydraulic ABS not available

S2bPneumatic Pneumatic TRS05

Hydraulic Hydraulic ABS not available


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Possible alternative criteria for ABS implementation7The current text of Regulation (EU) 2015/68 (European Union, 2015) uses agriculturalvehicle maximum design speed (Vmax) as threshold criteria for the mandatoryimplementation of ABS. As discussed in Section 1.1, vehicles of Categories Tb, R3b, R4band S2b of Vmax > 60 km/h are required to be fitted with ABS. Additionally, unless thetext of the regulation is amended, ABS will also become mandatory on Category Tbtractors of 40 < Vmax ≤ 60 km/h from 1st January 2020 or 1st January 2021 onwards (newtypes or new vehicles, respectively).

Vmax is in many respects an appropriate criterion for ABS implementation, being directlyrelated to the likely Kinetic Energy (K.E.) of a vehicle in motion and the consequentloading placed on the vehicle’s braking system during deceleration. However, asdiscussed in Section 2, Categories Tb, Rb and Sb potentially encompass a very widerange of vehicles, some of which may not necessarily readily-accept or indeed require theimplementation of ABS technology.

Vehicle mass is another promising criterion, combining as it does with velocity todetermine vehicle Kinetic Energy and braking system load. Historically, vehicle(maximum / gross) mass has been employed in the national legislation of certain EUMember States to target the implementation of ABS upon on-road vehicles. Regulation(EU) 167/ 2013 states that agricultural vehicles of Vmax > 40 km/h shall meet anequivalent level of functional safety, with regard to brake performance and, whereappropriate, anti-lock braking systems, as motor vehicles and their trailers.Consequently, the possibility of employing vehicle mass as an additional criterion,alongside Vmax, is perhaps worthy of further investigation, in order to ensure that ABStechnologies are indeed targeted towards agricultural vehicles “where appropriate”.

There is possibly considerable merit in restricting the imposition of ABS to larger, morepowerful vehicles which are likely to undertake the majority of agricultural transportoperations. As discussed in Section 3.2, the availability and usage Vmax > 40 km/h is verymuch restricted to vehicles of > 130 hp (97 kW) rated engine power and tractors in the151-230 hp and 231-320 hp categories were found to perform the majority of ‘MaterialTransport’ operations (Figure 3.11), working in conjunction with agricultural trailers of10-14 tonnes and 14.1-17 tonnes carrying capacity (~11,000-13,900 kg MPMaxles).

Trailer carrying capacity and consequent Total (Gross) Mass effectively dictates thepower rating and consequent size of tractor required for effective tractor-trailer transportoperation at V > 40 km/h. The power:mass ratio of the combination, particularly inrelation to the higher levels of on-road rolling resistance generated by tractor and trailertyres, essentially dictates if higher speeds are achievable when laden.

Figure 7.1 presents the likely variation in the operating / gross mass of V > 40 km/htractor and trailer combinations (N.B. rigid drawbar / unbalanced trailer) with tractorengine power. Study of vehicle data has shown that, when attached to an appropriately-sized (laden) rigid drawbar-type trailer, the tractor’s operating mass (sum of axlemasses) is likely to equal / approach the vehicle’s Maximum Permissible Mass (MPM).Consequently the Total (Gross) Mass of a 200 hp tractor + trailer combination is likely tobe approximately 30,000 kg.

Vehicle specification data shows that the maximum permissible mass (MPM) ofCategory T1 tractors correlates strongly with vehicle rated engine power (Figure 7.2).This is of little surprise as larger, more powerful tractors are required to operate larger,heavier attached (mounted) implements and so need greater payload capability. Thisquantity, in conjunction with vehicle unladen mass, effectively determines the vehicle’smaximum permissible mass.


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Figure 7.1: Likely variation of tractor-trailer combination gross mass with tractor enginepower

Figure 7.2: Relationship between T1 tractor maximum permissible mass and ratedengine power

Source: (Scarlett, 2015) & (Scarlett, 2016)


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A direct correlation also exists between the sum of technically-permissible mass peraxle (MPMaxles) of an agricultural trailer and its carrying capacity (Figure 3.19 and Figure7.6). Both the R3b and S2b categories embrace an extremely wide range of vehicle sizesand build-complexity; in some cases greatly increasing the cost, difficulty and even thefeasibility of ABS installation (see Section 6). However, agricultural trailers / towedequipment do not operate in isolation, but rather only when used in combination with atractor. Consequently, when assessing likely risk to other road users, the ‘worst-case’vehicle configurations are:

i) Solo-Tractor with mounted implement(s), operating at a mass close to maxpermissible mass.

ii) Tractor + fully-laden Trailer combination.

Figure 7.3 illustrates the variation in kinetic energy of these vehicle configurations withtractor rated engine power (equivalent to vehicle size) over the 40 < Vmax ≤ 60 km/hspeed range currently under consideration for mandatory ABS installation.

Figure 7.3: Variation of tractor and tractor + trailer kinetic energy with tractorsize (rated engine power) and forward speed

Figure 7.4 presents the same agricultural vehicle data, but also illustrates the kineticenergy levels of trucks of a range of different masses (7.5, 12, 20 and 40 tonnes), eachtravelling at a nominal speed of 60 km/h. It will be noted that the K.E. of a solo tractorof > 175 hp potentially equates or even exceeds that of a 12,000 kg gross mass truck:virtually all Vmax > 40 km/h tractor-trailer combinations would also exceed this K.E. level,irrespective of their actual speed of travel above 40 km/h.


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Figure 7.4: Comparison of kinetic energy levels of agricultural tractors andtractor + trailer combinations with those of trucks travelling at 60 km/h

If travelling at V ≥ 50 km/h, most tractor-trailer combinations of > 175 hp (> 130 kW)tractor size (i.e. Lower Middleweight 6 cylinder vehicle and larger (Figure 7.2)) wouldexceed the K.E. of a 20,000 kg truck travelling at 60 km/h; whereas a ~300 hp (225 kW)tractor plus R4 trailer combination would effectively be equivalent to a 40,000 kg(articulated truck & trailer) vehicle at comparable travel speeds.

Figure 7.5 presents an entirely theoretical concept of implementing a (tractor) maxpermissible mass threshold of MPM ≥ 11,500 kg. Vehicles of this size and larger would berequired to fit ABS if their Vmax > 40 km/h, whereas those of lower mass would notrequire ABS unless their Vmax capability exceeded 60 km/h. This potentially generates thefollowing benefits:

· ABS would only be required on larger, more powerful tractors (typically > 175 hp(130 kW)) in the 40 < Vmax ≤ 60 km/h range. These higher-powered vehicles arethose most likely to be capable of towing heavier trailers / towed equipment atspeed. They also are more expensive and more complex and so could support theundoubted additional cost of ABS more readily.

· Smaller / lighter / cheaper T1 tractors and also (possible future) T2b modelswould not have to be subjected to the possible burden of mandatory ABS.

· Implementation in this manner would ensure an equivalent level of agriculturaltractor (braking system) performance and safety to that of ≥ 12,000 kg trucks.

Figure 7.6 presents a similar concept for agricultural trailers and interchangeable towedequipment. The proposed threshold would result in ABS being mandated only on R3b andS2b vehicles of 40 < Vmax ≤ 60 km/h and MPMaxles ≥ 12,000 kg, whereas lower massexamples would not require ABS unless Vmax exceeded 60 km/h. Category R4 vehicleswould of course require ABS if Vmax > 40 km/h.


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Figure 7.5: Possible maximum permissible mass (MPM) threshold value (≥ 11,500 kg)for the introduction of ABS on 40 < Vmax ≤ 60 km/h Category T1 tractors

Figure 7.6: Possible maximum permissible mass (MPMaxles) threshold value(≥ 12,000 kg) for the introduction of ABS on 40 < Vmax ≤ 60 km/h Category R3 and S2

vehicles


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The possible benefits of this approach are that ABS would only be required on larger,more expensive trailers (typically >10,500 kg carrying capacity (rigid drawbar-type))which are more likely to be fitted with higher-specification (pneumatic) braking systemsand axles which will readily accept wheel speed sensors. Consequently, the cost andcomplexity of ABS installation would be significantly lower (see Section 8.3). Smaller(3500 < MPMaxles < 12,000 kg) R3b trailers and numerous S2b towed equipment wouldavoid the burden of mandatory ABS and thereby avoid the imposition of greater costs onusers.

It should be noted that the aforementioned alternative implementation criteria are onlyconcepts, but they are evaluated fully, alongside other possible policy options, by theCost Benefit Analysis (see Table 8.1).


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Cost benefit analysis8

Overview of CBA methodology8.1The cost benefit analysis is intended to be suitable to inform a European CommissionImpact Assessment, should this be carried out, in accordance with the guidelines laiddown for these (European Commission, 2009)7. The aim has been to define the mostpromising policy options and to study their effects over a defined evaluation period, inthis case for a period of 15 years from the date the measure would be expected to comeinto force. As far as possible, the costs will be identified for each year of the study, interms of the increase in retail cost of an agricultural vehicle as paid by the end consumer(the farmer). Similarly, the benefits for each year of the evaluation period will beestimated and, wherever possible, monetised. A cost benefit ratio has been calculatedfrom the total benefits over the evaluation period, divided by the total costs. This hasbeen repeated for each policy option.

The agricultural vehicle market is relatively diverse across Europe and data recording isnon-uniform. Thus, there is much that remains unknown that has to be estimated orexcluded from consideration. The study has used the best information that can bederived, bearing in mind the need for proportionality in the time and cost required toundertake the assessment.

Development of CBA scenarios8.2Guidelines suggest that Impact Assessments should identify a ‘do nothing’ option whichdocuments what would happen if the Commission did not intervene in the market. Atleast one ‘do something’ option should then be defined and the impact of doingsomething is measured as the difference between the two options. It is usual that the‘do-nothing’ option is effectively equivalent to ‘business as usual’. That is, the freemarket evolves in accordance with market forces. The baseline condition therefore,typically involves simple forecasting of recent trends, with consideration for other policiesalready implemented but excluding the effects of other new policies not yet implemented.The ‘do something’ option usually represents a regulatory intervention that might, forexample, involve making some form of minimum standard mandatory. This involvesintroducing step changes in the market.

The case specifically assessed in this report is unusual in this respect because, if theCommission now choose to implement the ‘do nothing’ option, then an existing timedclause in an existing Regulation will enter into force and require mandatory fitment ofABS to agricultural tractors with a maximum speed capability between 40 and 60 km/h.Thus, doing nothing will see a substantial change compared with business as usual. Thefirst ‘do something’ option would revoke this new requirement such that ABS did notbecome mandatory on those tractors. Effectively, this would be the only option thatwould see the market evolve freely in a ‘business as usual’ manner. Thus, this is theoption that forms the baseline for the purposes of forecasting and care is required in theinterpretation of costs and benefits. For example, when considering option 1 relative tooption zero, the ‘benefit’ of the option would be a reduction in costs and the ‘cost’ wouldbe a reduction in the economic benefit of casualty reduction expected. Again, this is theopposite to normal expectation and indeed some other options within this study.Standard terminology has been modified where possible to try to avoid confusion.

The options identified are reproduced in full in Table 8.1.

7 Available from http://ec.europa.eu/smart-regulation/impact/commission_guidelines/docs/iag_2009_en.pdf

Study on the availability of anti-lock braking systems for agricultural and forestry vehicles with a maximum design speed between 40 km/h and 60 km/h

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Table 8.1: Proposed policy options for assessment

Option Scenario type Outcome (Tractors) Outcome (Trailers)

0 Do nothing(Tractor ABS only)

ABS on all Category Tb tractors,40 < Vmax≤ 60 km/h No ABS on trailers, 40 < Vmax ≤ 60 km/h

1 No ABS No ABS on any Category Tb tractors,40 < Vmax≤ 60 km/h No ABS on trailers, 40 < Vmax ≤ 60 km/h

2 Partial ABS(Trailer only)

No ABS on any Category Tb tractors,40 < Vmax≤ 60 km/h

ABS on Category R3b / R4b trailers,40 < Vmax ≤ 60 km/h

3 Partial ABS(Larger Trailer only)

No ABS on any Category Tb tractors,40 < Vmax≤ 60 km/h

ABS on Category R3b trailers, MPMaxles ≥12,000 kg and R4b trailers, 40 < Vmax ≤ 60 km/h

4 Full ABS(Tractor + Trailer)

ABS on any Category T1b tractors,40 < Vmax≤ 60 km/h

ABS on Category R3b/R4b trailers,40 < Vmax ≤ 60 km/h

5 Partial ABS(Tractor + Larger Trailer)

ABS on any Category T1b tractors,40 < Vmax≤ 60 km/h


6 Partial ABS(Larger Tractor + Trailer)

ABS on any Category T1b tractors, MPM ≥11,500 kg, 40 < Vmax≤ 60 km/h

ABS on Category R3b / R4b trailers,40 < Vmax ≤ 60 km/h

7 Partial ABS(Larger Tractor + Larger Trailer)

ABS on any Category T1b tractors, MPM ≥11,500 kg, 40 < Vmax≤ 60 km/h


8 Partial ABS(Faster Tractor + Trailer) ABS on any Cat T1b tractor, Vmax >50 km/h ABS on Category R3b / R4b trailers,

40 < Vmax ≤ 60 km/h

9 Partial ABS(Faster Tractor + Larger Trailer) ABS on any Cat T1b tractor, Vmax >50 km/h ABS on Category R3b / R4b trailers, MPMaxles ≥

12,000 kg, 40 < Vmax ≤ 60 km/h


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Thus, the options considered removing all requirements for ABS (Option 1) or,alternatively, increasing the requirements to include tractor and trailers, as well as avariety of alternative permutations of partial ABS requirements:

· Trailer ABS instead of tractor ABS.

· Restricting ABS only to larger, more powerful vehicles likely to be undertakingsubstantial on-road transport work (see Section 7).

· Restricting ABS only to higher speed vehicles within the 40 < Vmax ≤ 60 km/hrange, targeting only higher risk vehicles.

The options have considered only a limited range of vehicle categories (T1, R3 and R4).This is because:

· Evidence showed that ATVs and SBS vehicles were involved in only a very smallfraction of agricultural vehicle collisions. In addition to this, their use in on-roadtransport was considered to be very low due to inherently low carrying capacityand their mass is more comparable with on-road ‘car like’ quadricycles whichdespite 100% road use, do not require ABS.

· The majority of on-road agricultural transport activities are likely to be undertakenby Category T1 and R3 or R4 vehicle combinations (see Sections 2.3 and 3.3). S2vehicles performing load-carrying functions will also fall under Category R3 or R4.No T2b vehicles are currently available and transport activities form a smallproportion of their normal usage (Nathanson, Scarlett, & Barlow, 2014). T4.3bvehicles are produced in small numbers and, by definition, are of relatively lowmass (MPM ≤ 10,000 kg).

However, it should be noted that if the option is to remove the mandatory requirementfor ABS on tractors of T1b, it would be removed from all categories of tractor with amaximum design speed of between 40 and 60 km/h.

Costs of ABS when fitted to a new vehicle8.3Engagement with the agricultural vehicle industry has led to the definition of a range offeasible additional costs that would be expected to result in the following marginalincreases in the price of a new vehicle:

· Tractor: €3,000 to €5,000.

· Small trailer: €1,300 to €1,900 (reflecting likely absence of pneumatic brakingsystem & axle(s) to readily accept wheel speed sensors).

· Large Trailer: €500 to €1,000.

These are based on a variety of information sources:

· Collective industry estimates (e.g. CEMA, CLEPA).

· Detailed information from individual manufacturers and tier one supplierson component and R&D costs.

· Published information on the actual existing system price where ABS is alreadyspecified as an optional extra.

The estimates are, therefore, relatively soundly sourced. However, it is not justimportant to consider what the price is now but also in the future. A range of factorscould influence that going forward:

· Optional or standard fit: Where a customer chooses an option because they seevalue in it, it is a premium, discretionary purchase. Where a feature is standard fiton every vehicle, then there is no premium benefit for the customer and itbecomes a commodity. Thus, the price charged for mandatory standard fit itemsis at the, typically low, margin for the overall vehicle while optional extras areoften priced higher, allowing an increased margin. Thus, the change to mandatory


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fit may decrease both the price to the farmer but also any margin made on thefeature by the manufacturer.

· Designed in from the start: When a feature is added into an existing product, itrequires a range of modifications to make it fit and work correctly. When anentirely new model is designed, it is often possible to accommodate the newfeature more efficiently at lower cost. Thus, the marginal price of ABS may reduceas brand new models are designed with it from scratch.

· Economies from scale: Agricultural ABS is currently sold in very low volumes.Volumes will increase very substantially if made mandatory and this is likely todecrease the price.

Thus, the prices above have been included as those for the year 2020. No rigorousevidence on the scale of the above reductions was identified so an arbitrary assumptionwas made that over the period 2020 to 2030, the price would reduce by between 1% and4% per year before stabilising at the lower level for the remainder of the evaluationperiod (2030-2035).

Proper consideration of the 'affordability' of systems to farmers would require assessmentof the effect of the increase in price on the sales volume of new tractors, effectively thefrequency with which they are replaced. Economists use the concept of ‘price elasticity’as a simple measure of this effect and it is defined as a ratio that says, for example, thata 10% increase in price will result in a 1% fall in sales. This information should bederived empirically in a market that is relevant to the measure being assessed. Noinformation on such elasticities could be readily found in the literature relating toagricultural tractors. (Jorgensen & Persson, 2013) report a low price elasticity in relationto brand choice (that is customers would often stick with a given brand despite priceincreases relative to competitors) but not in relation to replacement time. A detailedsurvey to develop new empirical data was beyond the scope of this study. Thus, properconclusions about affordability cannot be drawn. However, it is possible to state that lowvoluntary uptake of ABS where it is available as an option suggests that the end-userfeels it may cost more than it is worth. However, whether that would be sufficient toaffect the likelihood of buying a new vehicle with ABS instead of keeping an old onewithout ABS is a different question involving additional considerations around reliability,maintenance, capability and new features.

As noted, all consideration of the costs in the CBA have been the purchase price for thefarmer. In the widest economic sense, this additional cost on the farming industry, couldhave undesirable effects in terms of reducing profits increasing food prices or decreasingproduction or competition within farming if it resulted in reduced productivity. However,it will also represent a transfer to other industries. For example, the OEM, the tier 1supplier and all of the other actors in the supply chain would be expected to make aprofit on increased sales of ABS. The work would also increase employment in thatindustry and those employees would spend their money in other economic areas.Governments would tax the sale price of the vehicle, the corporate profits, individualincomes and the spending of individuals employed in the respective industries. Thus,losses in one area may be offset in other areas. Consideration of these wider economicimpacts and the balance between the farming, vehicle manufacture and vehicle supplychain industries has not been considered in this assessment. It is effectively from thepoint of view of the farming industry only.

The benefits of ABS8.4

The main benefit of ABS is a reduced risk of on-road collisions where instability as aconsequence of locked wheel braking was a contributory factor. However, it may alsohave a range of secondary benefits (see also Section 6.3):

· Improved control over brakes, resulting in opportunities for new functions withoutrequiring such a significant increase in hardware on the vehicle, for example:

o Hill hold assist.


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o Dynamic balancing of braking loads between tractor and trailer.

o Traction control.

o Brake Assist.

o Roll stability control.

· Reduced tyre wear during heavy braking.

· Off road collisions

o In some circumstances, such as loose gravel standard ABS may worsen brakeperformance

o In other circumstances, such as wet grass, it can improve off-road brakeperformance

o New control strategies have been proposed to minimise or eliminate any dis-benefits and maximise benefits off-road.

None of these secondary benefits of ABS have been explicitly monetised in this analysisbecause of a lack of available data. For example, no data was available quantifying thebenefits of additional systems or to document how many off-road collisions werecontributed to by braking instability.

Two distinct methods of quantifying the benefits were identified, each of which has theirown strengths and weaknesses:

1. Post-hoc statistical studies of the effectiveness of ABS: These attempt tomeasure actual in-service performance so are more realistic but can suffer fromconfounding factors because a wide variety of parameters influence collision risk.They are proof of association not causation and, in this particular case, they areonly available where ABS has been fitted to very different types of vehicle (cars,HGVs and motorcycles).

2. Predictive studies: These are based on dividing real world collisions into groupsthat it is considered the measure can benefit and estimating the effectivenesswithin that group by reference to experimental results. They avoid confoundingfactors but also cannot, by definition, account for unforeseen and unintendedconsequences. It has the advantage of being based on agricultural vehiclecollisions but suffers from a lack of detail in that data and low volumes ofcollisions reducing the ability to detect trends and accurately size the groups.

Thus, the cost benefit analysis has estimated the effectiveness of ABS by bothmethodologies. Within each methodology a range has also been applied to reflect theuncertainty in the results. As such, 4 baseline estimates of effectiveness have beenmade:

· Predictive studies: 25% to 50% reduction in the risk of collisions (any severity)involving skidding or jack-knifing.

· Retrospective studies:

o Lower effectiveness based on the study of passenger car ABS:

▪ 0% reduction in all fatalities from collisions involving agricultural vehicles.

▪ 3% reduction in serious collisions.

▪ 6% reduction in slight collisions.

o Upper effectiveness based on the study of HGV ABS:

▪ 2% reduction in all fatalities from collisions involving agricultural vehicles.

▪ 2.5% reduction in serious collisions.

▪ 3%% reduction in slight collisions.


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Studies of passenger car ABS (Kahane & Dang, 2009) have found that the performanceof ABS appears to improve over time, as drivers become more familiar with it. Therefore,the upper estimate based on retrospective studies (but not the lower estimate or eithermade on a predictive basis) includes an uplift in the effectiveness over the period 2020 to2030 such that in 2030 to 2035 it is 3.2% of all fatalities, 3.9% of all serious and 4.7%of all slight injuries from collision involving agricultural vehicles.

The predictive technique is based on the number of jack-knife collisions. Jack-knifecollisions can occur with well-balanced brakes where speeds are high. They can alsooccur at lower speeds when the brakes on tractor and trailer are not well balanced. Therelatively new braking requirements (Regulation (EU) 2015/68) for agricultural vehiclesincludes measures intended to improve the balance of braking between tractor andtrailer, in the form of compatibility corridors. These will act to reduce the chances of jack-knife that occur as a consequence of poor brake balance but not those as a consequenceof wheel lock at high speeds. Thus, it can be argued that this measure, which is alreadyimplemented but not yet strongly penetrating the market, will take some of the benefit ofABS.

The proportion of jack-knife collisions caused by each mechanism is not known so thiscannot be split precisely. In deriving an assumption that ABS, which can eliminate jack-knife entirely on a test track, would deliver 25% to 50% of the possible benefit, the factthat the compatibility corridors in the final version of the new braking regulations wereconsiderably wider than originally proposed so as to reduce the technical impact onvehicles, was considered. The fact that trailers can still be approved under very variablenational regulation, such that they may still in some cases not comply with compatibilitycorridors was also considered.

It should be noted that ABS can improve stopping distances in certain circumstances. Therequirements of the new braking Regulation (EU) 2015/68 will also improve stoppingdistances and other aspects of brake performance, such as failures caused by brake fade.These aspects of brake performance are not expected to directly affect the number ofjack-knife crashes and the estimated benefit of ABS does not include any reduction inany crashes other than those involving skidding or jack-knife. Thus, the estimate couldbe considered conservative and avoids much of the possible overlap with the benefits ofthe new braking regulation.

Some options consider application of mandatory ABS to only the tractor unit or only thetrailer. (Dodd, Bartlett, & Knight, 2006) showed that ABS on the tractor only couldachieve very significant improvements in stability even when the trailer was not fittedwith ABS. Thus, it has been estimated that all effectiveness figures should be reduced to75% of their value where only the tractor is equipped.

Similarly, where the trailer only is equipped, it has been estimated that the effectivenesswould reduce to 75% of the full combination. However, in this case, it is further reducedby the proportion of skidding or jack-knifing collisions that involved a tractor towing atrailer (72% of fatal, 61% of serious and 52% of slight based on GB statistics). In simpleterms some accidents involved a tractor without a trailer skidding and trailer ABS cannotinfluence such collisions. As a worked example, the lower retrospective effectiveness ofABS applied to trailer only in a slight casualty collision would be 6%*75%*52%=2.3%.

Forecasting the distribution of sales by vehicle type and how the fleet8.5changes as a consequence

Data regarding the sales of vehicles in the EU is required in order to quantify the industrywide cost of fitting ABS for each year of the evaluation period. This needs to be dividedinto the same categories as defined in the policy options

Data, categorised by the same vehicle types, is required about the total number ofvehicles registered for road use in the EU, for each year of the evaluation period. Thismust be combined with the new vehicle sales information and information about thefitment of ABS to those new vehicle sales to estimate the proportion of the tractor fleet


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that will be equipped with ABS in any given year of the evaluation period. This is requiredto help convert the change in collision risk associated with ABS to the actual number ofcasualties reduced. That is, the total expected benefit of ABS would only be fullyachieved when all agricultural road transport was undertaken by vehicles equipped withABS.

This data does not exist at any level in the EU. CEMA were only able to provide to theproject a single point estimate that in 2016 there were 170,000 tractors sold in Europe,of which around 17,000 were capable of in excess of 40 km/h. EuroStat does not providethe required information. The development of estimates has, therefore, necessitated theuse of a range of sample sets of data from a small number of individual Member Statesand national trade bodies combined with assumptions. This does introduce significantelements of uncertainty in the analysis.

(Jorgensen & Persson, 2013) reported an EU agricultural tractor market of 150,000 in2011. Stakeholders suggested that CEMA collected statistics on only 24 of the 28 EUMember States and that for the 24 collected, the total was 125k-135k. It was also notedthat CEMA collected statistics on several non-EU European countries, such as Turkey.

National data obtained for 6 EU countries (France, Germany, Italy, UK, Spain and theNetherlands) showed a declining trend in overall sales but an increasing trend in the saleof more powerful vehicles. Analysis of samples of data from regional dealerships, farmcontractors and two individual tractor manufacturers allowed estimates of the proportionof vehicles capable of Vmax > 40 km/h and due to the small numbers of vehicles capableof Vmax >60 km/h, it was assumed that all of these were capable of 40-60 km/h.

Forecasts were undertaken based on both correlation with recent trends and reaching anacceptable end point. These mostly involved logarithmic trend lines. For example, insome cases this was the best fit with past data, but in other cases the best fit was anexponential or polynomial trend which gave implausible (e.g. one category being inexcess of 100% of the fleet) results by the time the end of the evaluation period wasreached. In the first stage this forecasting was applied to new vehicle sales data. Wherepossible this was replicated for vehicle stock data. However, where appropriate thevalues for stock were calculated from an average scrappage rate derived from stock dataand adding the new sales generated from the forecast above. In effect, this was a partial‘churn’ model of the vehicle fleet.

For many of the subdivisions of vehicle category, this was based at a detailed level on UKdata as the main source of detailed information available. The data was scaled to an EUlevel using the best data available with respect to the national information for the abovementioned 6 EU countries and the overall fleet sizes estimated by CEMA, (Jorgensen &Persson, 2013) and other stakeholders. This therefore, accounted for the fact that the UKhas been a relatively advanced market for high speed tractors in the past, with manyother Member States not accepting them at all. Type Approval will now ensure that allMember States must permit high speed tractors to be sold. It has been assumed that by2035, all of the EU will be adopting them at similar rates to the UK. It should be notedthat this technique matches the single point estimate provided by CEMA for 2017.

The results for the main vehicle categories of interest are presented in Figure 8.1.


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Figure 8.1: Forecast Volume of EU sales of tractors of different types

With respect to fitment of ABS on tractors, it was assumed that a small proportion (1%)of 40-60 km/h tractors would voluntarily be equipped with ABS: Mainly JCB Fastracs butalso where traditional tractors such as Fendt and CNH see take up of their optionalsystems. For Option 1 where no vehicle sees mandatory ABS, it was assumed thisoptional fitment halves as companies move away from their investments in this area.Some stakeholders have indicated that they would consider this strategy. Where optionsmandate fitment in 2020, it was assumed that there would be a short ramp up from thatvalue ahead of the deadline with 5% in 2018, 30% in 2019 and 100% compliance in2020. This resulted in the following estimates of fleet penetration (total registrations) asshown in Figure 8.2 and Figure 8.3.

Figure 8.2: Forecast fleet penetration of ABS-equipped tractors in different policy options

It can be seen that the blue lines representing options where fitting ABS to T1 tractorswould be mandatory give the highest fleet penetration, options where there is no


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mandatory requirement (orange line) give the lowest. Between these limits, optionsinvolving only those T1 tractors above a mass threshold (grey line) results in a highermarket penetration than requiring ABS only for those whose Vmax exceeds 50 km/h(yellow line). Effectively, this means that more tractors are sold with a mass in excess ofthe threshold than with a speed capability exceeding 50 km/h.

Figure 8.3: Forecast fleet penetration of ABS-equipped trailers in different policy options

Developing the business as usual baseline (option 1- remove requirement8.6for ABS)

Two target populations are required to match the two different approaches for estimatingeffectiveness. One is the total number of casualties from collisions involving agriculturalvehicles in the EU, divided by casualty severity. This has been sourced directly from theCARE database. The other is the total number of casualties from collisions involvingskidding or jack-knifing in the EU, divided by casualty severity. This information is notrecorded in CARE. It was, therefore, derived by factoring the EU totals in the CAREdatabase by the proportion of the relevant collision types in GB (11% of fatalities, 9% ofserious and 8% of slight). Effectively this assumes that collisions in Great Britain arebroadly representative of those in the EU as a whole. Where comparisons were availablethis was generally found to be true except when considering the ages of vehicle involved.

In theory, the proportion of skidding and jack-knife collisions might be expected to bechanging significantly as a result of:

· Increasing speed capability of vehicles would be expected to increase risk.

· Fewer vehicles carrying more goods (higher mass) per vehicle for the sametransport task, potentially on different roads, has the potential to either increaseor decrease the frequency of jack-knife collisions.

· Improving fundamental brake performance, particularly improved trailer brakingand better tractor/trailer balance, at least partly as a consequence of Regulation(EU) 2015/68, would be expected to decrease risk.

It was not possible to separate speed capability or actual speed at the time of collision inthe accident data so the different mechanisms could not be analysed separately.Examination of the trends in skidding or jack-knifing, and indeed in relation to speedcauses, did not reveal significant changes in the patterns over time. However, the


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numbers involved were low and subject to considerable random scatter pattern. Thus, atthis time, no firm conclusion can be drawn on whether increasing speed capability oftractors without ABS presents an increasing risk of jack-knife, or whether the other brakeimprovements are reducing it. This must be considered an absence of evidence inrelation to both possible effects, rather than evidence of an absence of effect. For thisreason, the average proportion of skidding/jack-knife collisions was used and remainedconstant throughout the forecast period.

The target populations were forecast for future years. Over the long term, the number ofcasualties has been reducing strongly but this has slowed and, in many categories, comealmost to a stop in recent years. It is thought that the traffic reducing effect of recessionand the subsequent increase in the recovery period may be one influence in this but alsoincreases in collisions caused, for example, by distraction due to the use of moderntechnology such as smartphones while driving/walking etc. Thus, forecasts weregenerally based on a continued slow decrease levelling off as the effect of policies alreadyimplemented saturates the market (Figure 8.4).

Figure 8.4: Actual and forecast number of slightly injured casualties from collisionsinvolving agricultural tractors in the EU

Source: TRL analysis of CARE data (European Commission, 2017)

However, with respect to fatalities from agricultural vehicles there was evidence tosuggest a slightly different trend. Firstly, there was the theoretical evidence thatsuggests that increasing use of high speed tractors across Europe will generally increasecollision severity across different types of collision. This combines with the fact that bothin Great Britain and the EU a change in the relationship between fatalities and lowerinjury severities could be seen, suggesting an increase in the fatality rate per 100,000vehicles and that agricultural vehicle fatalities represent a growing proportion of all roadfatalities. As such, it was forecast that for fatalities from all types of collisions involvingagricultural vehicles (not just those where ABS is a relevant consideration), the slowdecline would in the future be replaced by a slow increase in the number, in the absenceof new policies to control these risks (see Figure 8.5).


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Figure 8.5: Actual and forecast number of fatalities from collisions involving agriculturaltractors in the EU

Source: TRL analysis of CARE data (European Commission, 2017)

As a baseline, it has been assumed that around 1% of new vehicle sales in the relevantcategories will be equipped with ABS as a consequence of standard fit across the rangefrom JCB and small numbers of optional take up from manufacturers such as Fendt andCNH. In scenario 1, this has been reduced to around 0.5% in future years, reflecting theexpression of some tractor OEMs that stated that they would consider walking away fromABS given a choice and the general lack of incentive for further investment that may besignalled by such a move.

Within each scenario, the fitment of ABS in each year as a percentage is multiplied by thenew vehicle sales figure for each year to produce a number of new vehicles equippedwith ABS. The partial vehicle churn model is used to sum these new sales, minusscrappage, into estimates of the number of such vehicles in the fleet. For the sake ofsimplicity it was assumed that the number in the fleet in 2005 was zero. This is notstrictly true because JCB had been producing vehicles with ABS for a few years beforethis but the overall number at that time would represent a negligible proportion of the EUparc.

Estimating and valuing casualty reductions8.7

The estimation of casualty reduction as a consequence of ABS in each scenario is asimple calculation:

∗ ∗

These terms have already been defined (see preceding sections) and the first two termsare straightforward. However, the linear use of the proportion of the fleet equipped canbe controversial. In normal road vehicle analyses, the assumption that if 10% of the fleetis equipped with the measure then 10% of the total expected benefit will be achieved isusually accepted. However, it is often debated because it may be argued, for example,that newer passenger cars tend to travel longer average distances than older cars,therefore they are more likely to become involved in a collision just due to exposure andso the benefits of the new measure will accrue faster than implied by the linear rate.However, the counter argument is that they can also be shown to travel more onmotorways which are safer roads and by the fact that in general people get wealthier as


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they get older, they tend to be bought by an older, safer demographic of driver. Thus,the influence of the measure will be felt more slowly than implied by the linearassumption.

When considering agricultural vehicles, the situation is different because they arepurchased as a capital investment intended purely to bring a financial return. There is astrong argument that newer vehicles will perform a disproportionate volume of the roadtransport task compared with older vehicles. There is also an unusually large ‘historic’fleet of very old tractors. For example, in 2016 in the UK, 40% of vehicles registeredwere in excess of 25 years old. These are relatively unlikely to be used intensively infrontline roles involving extensive road use. Thus, using the percent of vehicles equippedin a linear relationship to collision risk would appear to under-estimate the risk. UKcollision data would support this theory, showing that 60% of collisions involving tractorsinvolved one that was less than 5 years old. Based on this data, a linear relationshipbetween percentage of total fleet equipped and casualty reduction would grossly underestimate the effect.

However, (CEMA, 2015) argue not that newer vehicles are not more involved in transporttasks but that they are orders of magnitude safer than older vehicles such that it is oldervehicles that are involved in most collisions, with 69% of fatal collisions involving avehicle in excess of 12 years old. This position is also broadly supported by data for someother EU Member States with the relevant data available in CARE. Based on this data, alinear relationship between fitment rate and casualty reduction would slightly over-estimate the effect.

The reason for this stark difference in the distribution of collision risk by age of tractorbetween Great Britain and some other EU countries is not known. In the absence ofadditional data, a linear relationship has been retained.

The prevention of a casualty has been monetised at the following rates:

· Fatal: €1,564,503

· Serious: €231,278

· Slight: €17,753

These values were calculated by (Hynd, et al., 2015), and adopted by (Seidl, et al.,2017)

Results of the CBA8.8The overall results of the cost benefit analysis are summarised in Table 8.2.

As a reminder, the effect of the options presented in Table 8.2 are calculated relative tothe ‘do nothing’ option, that is, Option 0 where ABS becomes mandatory on tractors as itis currently written into the Regulation (EU) 2015/68.

The costs of fitting ABS and the total cost of casualties are summed for ‘do nothing’(Option 0) and for each ‘do something’ scenario (Options 1-9).

The costs of fitting ABS and the costs of casualties associated with the ‘do nothing’scenario are subtracted from each ‘do something’ scenario. Where total costs of fittingABS and casualties are less in a ‘do something’ scenario than they are in the ‘do nothing’scenario then the relative result is a negative number, a reduction in cost compared tomandating ABS on tractors. An overall reduction in cost is considered beneficial.

Summing those beneficial cost reductions over the years evaluated gives a total benefitof the policy. However, the values are discounted by 3.5% each year to reflect theeconomic norm that considers future money is worth less than the same amount ofmoney now. The revised total is normally referred to as the net present value.

The benefit to cost ratio is calculated by dividing the ‘benefit’ of reduced ABS fitmentcosts by the ‘cost’ of increased casualty cost.


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The policy option with the largest net monetary gains will not necessarily be the one withthe best benefit to cost ratio. If a policy options has very large benefits (e.g. €11 billion)and very large costs (e.g. €10 billion) it can have a very high net monetary gain(€1 billion) but the benefit to cost ratio could be fairly low (e.g. 1.1). A different optionwith lower benefits and cost (for example €2000 benefits and €1000 costs) would haveonly a small net monetary gain (€1000) but a much better benefit to cost ratio (2).Which measure, or combination of the two measures, an organisation should use todetermine the ‘best’ option depends on the objectives of the organisation generally, andthe policy under assessment specifically and their interpretation of the risk.

Selection of which policy is the ‘best’ to implement in this case will, therefore, be amatter for the European Commission and any impact assessment they choose toundertake. Such assessments should consider both the monetary affects should bebalanced alongside the non-monetised risks highlighted.

The sums in the table below represent the total for the evaluation period to 2035. Eithera reduction in the cost of fitting ABS or a reduction in the number of casualties, or themonetary value associated with those casualties, would be considered beneficial and ishighlighted in green. Increases in cost or casualties are highlighted in red.


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Table 8.2: Summary results from the cost benefit analysis

Option Option description Net Present Value (NPV) of change Benefit to Costratio (BCR)

Change infatalities

Change in seriouscasualties

Change inslight casualties

Upper Lower Upper Lower Upper Lower Upper Lower Upper Lower

1 No ABS -€ 3,037,294,695 -€ 1,375,623,885 308 20 46 - 125 54 349 169

2 Partial ABS(Trailer only) -€ 2,795,622,155 -€ 1,330,377,956 384 29 32 - 93 40 274 133

3 Partial ABS(Larger Trailer only) -€ 2,804,117,775 -€ 1,334,937,386 383 29 33 - 94 40 275 134

4 Full ABS(Tractor + Trailer) € 72,020,149 € 207,194,931 0.23 0.01 -14 - -34 -15 -81 -39

5 Partial ABS(Tractor + Larger Trailer) € 67,491,099 € 198,703,711 0.23 0.01 -14 - -33 -14 -80 -39

6 Partial ABS(Larger Tractor + Trailer) -€ 1,120,109,372 -€ 548,255,120 608 54 7 - 24 10 80 39

7 Partial ABS(Larger Tractor + Larger Trailer) -€ 1,128,603,424 -€ 552,803,618 596 52 7 - 24 11 82 40

8 Partial ABS(Faster Tractor + Trailer) -€ 2,075,868,849 -€ 999,154,174 407 31 22 - 65 28 195 95

9 Partial ABS(Faster Tractor + Larger Trailer) -€ 2,084,465,815 -€ 1,003,774,472 404 31 22 - 66 28 197 96


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Based on the net (benefits minus costs) present value figures, selecting policy option 1and removing the requirement to fit ABS to agricultural vehicles would result in thelargest monetary gain. The net present value associated with the option includes thebenefit of reduced costs of fitting and buying ABS and the cost associated with apredicted increase in the number of fatalities from collisions involving agriculturalvehicles. The prediction is that up to 46 more fatalities would be expected (across the EUup to 2035) under policy option 1 compared with doing nothing (policy option 0). Thelack of collision speed information and the lack of data around the market penetration of40-60km/h tractors contribute to substantial uncertainty in the analysis. This results in awide range of estimated effects. However, it can be seen that even at the extremes ofthe possible ranges, the overall effect of this option is always beneficial and the benefit tocost ratios are always substantially in excess of 1.

Mandating ABS on all 40 < Vmax ≤ 60 km/h Category T1b, R3b and R4b vehicles ormandating ABS on Category T1b and Categories R3b and R4b vehicles of MPMaxles≥ 12tonnes (Options 4 & 5), are the only two options with a BCR of less than 1 where thecosts of increased fitment of ABS outweigh the benefits of predicted casualty reductions.

In this case, the best BCR is achieved by mandating the fitment of ABS on T1b tractors ofMPM ≥ 11.5 tonnes and either all R3b and R4b trailers or just those ofMPMaxles≥ 12 tonnes (Options 6 and 7). Such options would lessen the overall net gain tobetween €0.55 billion and €1.1 billion. However, the improved BCR comes from the factthat the associated increase in casualties is lessened by proportionally more than the costof fitting the systems is increased.

Requiring ABS only on T1b tractors with a Vmax capability in excess of 50 km/h and ontrailers of R3b and R4b, or only those with a MPMaxles>12 tonnes (Options 8 and 9) fallsbetween the best monetary gain and best BCR on both measures. However, it wouldcomplicate the legislation by introducing a new speed threshold not used in any otherpart of the type-approval process.

The analysis above considers only the parameters that could be identified and monetised.For each of the options analysed there is also a range of non-monetised considerationsthat should be weighed alongside the numerical analysis.

8.8.1 Non-monetised considerations related to all options

The results for each option are obtained by measuring the difference between the costsand the casualty prevention values of the selected option and the equivalent values fromScenario 0, the ‘do nothing’ option. These results are shown in Table 8.3.

The range of uncertainty, a consequence of data limitations described previously, isalready significant but several important factors may still have further influence:

· The forecast of future casualty trends assumes only a very small effect ofincreasing tractor speed on collision severity, with no effect on collision frequency.If this effect proves larger or smaller in practice, then it will have a substantialeffect on the calculated benefits of ABS because a small change in absolutenumbers can be a large proportional change.

· The baseline estimates of the proportion of the agricultural vehicle fleet that fallinto each category is not well defined by existing data and has requiredconsiderable estimation based on extensive market knowledge. Variations thatapply equally to sales and total fleet will affect absolute numbers but not thedirection of the result. Variations that affect sales more than the vehicle parc orvice versa will affect benefit to cost ratios and, if sufficiently large, the direction ofresult.


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Table 8.3: Detailed Annual Results for policy option 1 – expressed as changes in costs and casualty prevention values relative to those predictedfor the ‘do nothing’ option of allowing ABS to become mandatory

Year

Policy Option 1 - Remove requirement for ABS

Costs (negative= benefit) Casualty value (negative = benefit) Net effects (negative beneficial, positive disbeneficial)

Upper Lower Upper Lower Upper-Lower Lower-upper Upper-Upper Lower-lower

2016 € - € - € - € - € - € - € - € -

2017 € - € - € - € - € - € - € - € -

2018 -€ 4,567,270.37 -€ 1,526,127.70 € 16,309.18 € 2,193.26 -€ 4,565,077 -€ 1,509,819 -€ 4,550,961 -€ 1,523,934

2019 -€ 36,949,239.68 -€ 16,998,650.34 € 144,592.55 € 19,468.82 -€ 36,929,771 -€ 16,854,058 -€ 36,804,647 -€ 16,979,182

2020 -€ 138,847,218.02 -€ 71,510,363.13 € 612,997.95 € 82,566.70 -€ 138,764,651 -€ 70,897,365 -€ 138,234,220 -€ 71,427,796

2021 -€ 149,370,322.70 -€ 76,307,829.49 € 1,084,391.69 € 151,686.23 -€ 149,218,636 -€ 75,223,438 -€ 148,285,931 -€ 76,156,143

2022 -€ 158,607,063.01 -€ 80,083,393.20 € 1,556,984.32 € 226,016.83 -€ 158,381,046 -€ 78,526,409 -€ 157,050,079 -€ 79,857,376

2023 -€ 166,943,820.22 -€ 83,012,133.42 € 2,030,665.23 € 305,666.21 -€ 166,638,154 -€ 80,981,468 -€ 164,913,155 -€ 82,706,467

2024 -€ 174,419,989.91 -€ 85,183,143.13 € 2,505,658.87 € 386,718.67 -€ 174,033,271 -€ 82,677,484 -€ 171,914,331 -€ 84,796,424

2025 -€ 181,076,563.80 -€ 86,679,368.72 € 2,982,473.72 € 457,918.14 -€ 180,618,646 -€ 83,696,895 -€ 178,094,090 -€ 86,221,451

2026 -€ 186,955,270.69 -€ 87,577,563.34 € 3,461,851.55 € 528,124.14 -€ 186,427,147 -€ 84,115,712 -€ 183,493,419 -€ 87,049,439

2027 -€ 192,097,937.58 -€ 87,948,390.31 € 3,944,717.82 € 597,214.33 -€ 191,500,723 -€ 84,003,672 -€ 188,153,220 -€ 87,351,176

2028 -€ 196,546,014.63 -€ 87,899,071.73 € 4,432,045.36 € 665,076.14 -€ 195,880,938 -€ 83,467,026 -€ 192,113,969 -€ 87,233,996

2029 -€ 203,084,609.83 -€ 88,682,361.64 € 4,934,888.54 € 733,100.63 -€ 202,351,509 -€ 83,747,473 -€ 198,149,721 -€ 87,949,261

2030 -€ 206,163,418.17 -€ 87,775,113.79 € 5,443,717.43 € 799,595.03 -€ 205,363,823 -€ 82,331,396 -€ 200,719,701 -€ 86,975,519

2031 -€ 208,206,865.91 -€ 89,036,944.21 € 5,950,120.88 € 863,105.41 -€ 207,343,760 -€ 83,086,823 -€ 202,256,745 -€ 88,173,839

2032 -€ 209,919,060.35 -€ 90,128,514.05 € 6,455,950.52 € 923,733.11 -€ 208,995,327 -€ 83,672,564 -€ 203,463,110 -€ 89,204,781

2033 -€ 208,888,509.08 -€ 89,987,695.19 € 6,953,570.88 € 980,254.30 -€ 207,908,255 -€ 83,034,124 -€ 201,934,938 -€ 89,007,441

2034 -€ 205,338,255.72 -€ 88,714,277.46 € 7,435,920.37 € 1,031,620.84 -€ 204,306,635 -€ 81,278,357 -€ 197,902,335 -€ 87,682,657

2035 -€ 199,482,262.34 -€ 86,403,947.14 € 7,896,378.31 € 1,076,944.16 -€ 198,405,318 -€ 78,507,569 -€ 191,585,884 -€ 85,327,003

Total -€ 3,027,463,692 -€ 1,385,454,888 € 67,843,235 € 9,831,003 -€ 3,037,294,695 -€ 1,453,298,123 -€ 2,959,620,457 -€ 1,375,623,885

BCR 308.0 20.4 44.6 140.9


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· The costs of ABS estimated for agricultural vehicles are high, at least an order ofmagnitude higher than for other vehicle types, and potentially two orders ofmagnitude compared with cars. These are consistent with prices charged by thosecurrently offering systems as options. Typically, prices are much lower when asystem is mandatory fitment on all vehicles, such that it has no discretionaryvalue to the customer. Fitment will be mandatory on agricultural vehicles capableof more than 60 km/h. The number of these is low but information from onemanufacturer does suggest an increase in cost at the low end of the range.

· The benefit of ABS is calculated as being directly proportional to the proportion ofthe total fleet equipped. The agricultural vehicle fleet contains an unusually highnumber of extremely old vehicles, such that the proportion of the total fleetreplaced with new vehicles each year is relatively small. However, evidencesuggests that the younger vehicles do the vast majority of the hard work offarming. If the benefit of ABS was linked to the proportion of this ‘hard working’fleet that was equipped then the benefit predicted would increase substantially.

· In the automotive market, ABS was a platform from which may other additionalsafety and convenience functions were evolved, including traction control, brakeassist, stability control etc. Given the higher costs of development relative to salesin the agricultural vehicle market, there is a risk that removing the strong marketsignal that mandatory ABS will provide will limit abilities to replicate the successof the automotive market in other areas of agricultural safety development (e.g.rollover prevention).

ABS also has the potential to influence the frequency or severity of off-road collisions,positively or negatively depending on the surface conditions and ABS specification.These collisions could not be quantified within the scope of this work.

· None of the analyses undertaken in this cost benefit study account for theeconomic value that the farming industry gain from an increase in the number ofvehicles with a speed capability of between 40 and 60 km/h or the amount thatthey are willing to pay to gain that capability.

8.8.2 Non-monetised considerations related to options that fully or partially remove therequirement for Tractor ABS (Options 1, 2, 3, 6, 7, 8, 9)

Many companies within the industry, particularly tier 1 suppliers such as WABCO, haveinvested considerable sums of money in developing ABS solutions that will work in theagricultural vehicle market, particularly in relation to hydraulic systems. If this option isselected, stakeholder feedback suggests that the voluntary take up of ABS in the marketwill remain very low and may even decrease compared with the preceding period. Thus,those sums invested to date by the industry will not be recovered from sales.

8.8.3 Non-monetised considerations related to options involving mandating ABS ontrailers (Options 2, 3, 4, 5, 6, 7, 8, 9)

Little difference was found between fitting trailer ABS to all R3b/R4b trailers and fitting itto just those of MPMaxles≥ 12 tonnes. This is because it was considered that very fewtrailers of less than 12 tonnes were used, or intended for use, in higher speed towing.However, it should be noted that the smaller trailers would typically use hydraulicbraking systems for which ABS is not readily available, thus forcing them to upgrade tocommercial standard air braked axles at additional unit cost. Such an upgrade may ormay not have other effects.

8.8.4 Non-monetised considerations relating to options involving mandatory ABS on T1btractors that were capable of more than 50 km/h only.

At present, most tractors capable of between 40 and 60 km/h are actually capable of amaximum design speed of 50 km/h. A significant proportion of those capable of higher


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speeds that currently exist will already have ABS (e.g. JCB Fastrac). However, as type-approval forces all EU countries to accept the sale of high speed tractors (though it doesnot force states to allow them to be used at higher speeds) it is likely that the proportionof vehicles capable of in excess of 50 km/h will grow.

In physical testing the risk of, for example, jack-knife was found even on a balancedcombination to increase almost exponentially from 40 to 60 km/h. Thus, the collision riskthat can be mitigated by ABS at 50 to 60 km/h is likely to be disproportionately largerthan the risk that can be mitigated at 40-50 km/h. It was not possible to account for thiswithin the model, which assumes the same risk at all speeds between 40 and 60 km/h.Properly accounting for this behaviour would mean the model would see greater benefitsof ABS without changing the costs. Thus, this option is, in reality, likely to be slightlymore beneficial than it appears in the monetised results.

8.8.5 Sensitivity to changes in the inputs

Despite the many uncertainties acknowledged within the model and the wide estimaterange resulting, the overall results remain very clear cut. None of the options have abenefit to cost ratio where the range of results, reflecting the uncertainty, spans 1(where costs = benefits). In most cases even the closest extreme is many times greaterthan (or smaller than) one. Thus, small changes in inputs are extremely unlikely toinfluence the overall result and only a limited sensitivity analysis has been undertakenconsidering the registration data, the cost of ABS and how the number of skidding andjack-knife collisions might change over time.

Changes to the estimates made in registration data can have a substantial effect in termsof the absolute net present values of the options and the casualty numbers. These canchange values by a factor of two. However, most changes affect both costs and benefitsin similar proportions such that it does not influence relative differences between costsand benefits. Changes that have a different effect on new vehicle sales compared withthe total population of vehicles equipped with ABS can affect costs and benefitsdifferently. However, the magnitude of those differences is generally smaller becausenew vehicle sales directly influence the vehicle population both with and without ABS.

Changes to consider the effect of ABS in proportion to how many of the ‘hard working’fleet of tractors and trailers on the road (assuming a lot of very old tractors (e.g. 25years or older) do very little work on the road) can vary the casualty effects by almost afactor of 2. However, this remains only a small value relative to the cost (< €100 millionagainst €1-3 billion). The effect of assuming a doubling of the proportion of casualtiesfrom agricultural vehicles where instability was involved is of a similar magnitude.

Thus, it can be concluded that the cost of the ABS itself is the dominant factor in theresult. Adjusting the cost shows that, depending on scenario and other settings, the‘lower’ case results would suggest an uncertain case (range of BCRs spanning 1) at anABS cost of the order of €150 to €250 per vehicle. In short, the model would only start tosuggest mandatory ABS on tractors might be cost-beneficial at costs of less than around€250 per vehicle.


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Analysis and discussion9Based on the information presented in the preceding Sections, the following statementssummarise the key findings and resulting views that will inform the final conclusions fromthe investigation, as presented in Section 10.

· There is clear evidence that the changing nature of agricultural businesses andfarming practices across the EU is increasing the exposure of agricultural vehiclesto the risk of road collisions. Business rationalisation and the consequent creationof larger farm units are resulting in the sale and use of fewer but larger (higher-powered) farm tractors. These vehicles are used by a smaller workforce toundertake operations over greater geographic areas (see Section 3.1).

· Evidence suggests that tractors in the 150 – 300 hp (112 – 224 kW) power rangemay spend up to 50% of their operating time engaged either in material transportor general travelling on-road. To maximise operational efficiency during suchactivities, faster (V max > 40 km/h) tractors are increasingly being used (wherenational legislation permits), towing heavier loads in order both to utilise availableengine power and to match crop harvesting machinery output (see Section 3.3).

· Most of these faster tractors have a maximum design speed in the range 40 to60 km/h. A small number of vehicles, dominated by one manufacturer, have amaximum speed capability in excess of 60 km/h and are already required bynational regulations (see Section 3.4) or EU type-approval, to be fitted with ABS.

· In the past agricultural tractors have, by virtue of their number and usage,represented only a very small proportion of vehicles involved in road collisions.However, the rate at which they occur per registered vehicle is considerablyhigher than might be expected compared with other vehicle types and the factthat they spend significant amounts of time (≥ 50%) operating off-road. Whenthey do become involved in collisions, they are much more likely than average toprove fatal (see Section 4).

· Vmax > 40 km/h agricultural tractors have been widely available from globalmanufacturers since 2003-06 and, in certain cases, during the preceding decade.At present only a limited number of EU Member States permit the sale and/or useof such vehicles, but from January 2018 it will no longer be possible to prohibitsuch sales. Member States may still choose to limit the speed at which they canbe used, but responsibility for complying with those limits will rest with the user(see Section 3.4). Evidence suggests that, unless severe penalties are imposed,tractors and associated towed vehicles will be driven at the maximum speedachievable: indeed, it is believed that, in certain circumstances, the smallerdifference in speed compared with other traffic can even reduce the frustrationand consequent risk-taking of other road users.

· Nonetheless, the body of generalised evidence concerning the effect of speed oncollisions clearly highlights a risk that the increasing market penetration of highspeed agricultural tractors could result in an increase in the frequency and/orseverity of road collisions. This is complicated by the effect of reducing the spreadof speeds around the average road speed and different patterns of usage ofdifferent road types compared with other vehicles (see Section 4). These factorsmay partially or even fully-offset the underlying increase in risk.

· A large body of engineering evidence is available to show that the risk of specifictypes of crashes, such as loss of control and jack-knife, increases with speed (seeSection 5.2).

· At present, there is little statistical evidence that these risks have so far caused asignificant change in the number or type of collisions involving agriculturalvehicles. This is despite an analysis suggesting that, taking the UK market as an


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example, tractors with high speed (Vmax > 40 km/h) capability might representaround 16% of the whole tractor fleet and 32% of the modern fleet (less than20 years old). There is some evidence to suggest that the number of fatalities isreducing by less than expected, such that the rate per registered vehicle isincreasing and fatal agricultural vehicle collisions are becoming a larger proportionof all road fatalities. This would be consistent with general evidence about theinfluence of speed. However, the data available on agricultural vehicle collisions isextremely limited and reliance on individual Member State data means thatsample sizes are small such that, when broken down to specific collision typessuch as jack-knife, random variation plays a significant role. Thus, at this stagethis should be considered an absence of evidence of any of the expected effects,NOT evidence of absence of those effects. Improving the ability to monitoragricultural vehicle road safety performance at the EU level would allow theserisks to be much better monitored over time (see Section 4).

· There is very clear engineering evidence that ABS is very effective at mitigatingthe risk of loss of control, jack-knife and trailer swing collisions. There is strongstatistical evidence of ABS working to reduce the frequency of this type ofcollisions when fitted to Heavy Goods Vehicles. However, there is also strongstatistical evidence to suggest that the risk of other collision types can increasewhen HGVs are fitted with ABS, such that the net benefits are smaller thanexpected. With passenger cars, this effect meant that the increases in risk insome collisions came very close to fully offsetting the reductions in other collisionssuch that the net effect on fatalities was almost zero, though there were stillbenefits in lower severity collisions (see Section 5.2)

· There is also strong evidence that, in other road vehicles, the inclusion of ABS hasacted as a development platform for a wide range of other advanced controlsystems operating through the braking system (see Section 5.2). In particular,the extension of ABS brake control technology to electronic stability control (ESC)systems in passenger cars has had a transformational effect, showing casualtyreduction effects second only to those of the seat belt.

· There is clear evidence that ABS systems will be technically feasible and availablefor nearly all relevant agricultural vehicle types (Categories T, R3, R4 & S2).However, the ease and economic feasibility of their installation is currentlydependent upon the brake application method / medium used on the vehicle andthe physical space available. Systems based on dedicated adaptations ofpneumatic truck / truck-trailer systems are already mature in the market andhave been utilised commercially on agricultural tractors and trailers. Hydraulic(mineral oil) ABS systems for agricultural tractors are mainly in late-stageprototype form and are expected to be in series production by 2019. Current ABSproduct development and market availability schedules indicate there is norequirement for (nor any likely market benefit likely to result from) delaying theimplementation date for mandatory ABS on 40 < Vmax ≤ 60 km/h tractors beyondthe proposed 2020 / 2021 dates.

· ABS systems are currently not available for trailers / towed equipment fitted withhydraulically-actuated braking systems and, given limited market demand andpossible high development costs, these may not be brought to the market.Consequently ABS installation would require the conversion of such (typicallylower-mass, less expensive) trailers / towed equipment to pneumatic brakingsystems. Perhaps fortunately, most trailers / towed equipment intended forV > 40 km/h use tend to feature pneumatic braking systems. Therefore, regardingtechnical / engineering criteria, in the majority of instances, there is everyjustification to fit ABS technology to agricultural vehicles, particularly those oflarger mass and/or higher speed capability (see Sections 5.1 and 6).

· Thus, there is strong evidence that the collision problem involving agriculturalvehicles is a small but possibly growing one, where the risk of fatality per unit of


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exposure is much greater than average. There is a risk that this problem mightincrease further in the future as higher speed capability further penetrates themarket. There is evidence to demonstrate that ABS will have a strong positiveeffect on specific types of collision directly related to speed and that it will have asmall net positive effect on crashes overall. It is clear that it is applicable andtechnically feasible on most relevant agricultural vehicle.

· However, the evidence identified suggests that the cost to farmers of purchasingABS on their new vehicle is one or two orders of magnitude greater than it is for aconsumer purchasing a car. It is, therefore, an expensive countermeasure whenapplied to agricultural vehicles. As such, the evidence suggests that the reductionin cost associated with removing the requirement for ABS will outweigh the dis-benefits of failing to achieve the anticipated casualty reduction associated withABS (see Section 8).

· Several options are available for the partial implementation of mandatory ABS inthe 40 < Vmax ≤ 60 km/h sector. For example, limiting mandatory ABS to tractorscapable of Vmax > 50 km/h and large trailers designed for V > 40 km/h operation,will achieve better benefit to cost ratios than simply removing the requirement forABS. However, overall, these will still have substantially higher net costs thansimply removing the requirement.

· The monetised benefits must be weighed against the non-monetised riskshighlighted, including but not limited to losses in the agricultural vehiclecomponent supply chain, the potential to reduce incentives for future investmentin new agricultural vehicle safety technology, particularly those that may usemore sophisticated brake control as part of their function, the incidence of off-road collisions and the uncertainty in the future influence of increasing on-roadspeeds and travel distances in agricultural operations (see Section 8).

· Further action to examine the functioning of the market would be required to fullyunderstand how, in the future, the costs of transferring important safetytechnologies to the agricultural vehicle sector could be minimised. Low productionvolume is one fundamental factor, but the EU sales volume of agricultural tractorsin 2016 was around 130,000. Over the same period, the sales volume of HGVs(trucks) in excess of 3.5 tonnes in the EU-15 was only 210,000 units. Given thatthe 13 Member States missing from the HGV data are typically the smallermarkets, it is likely that the HGV market is less than double the size of theagricultural tractor market. In the case of HGVs, ABS has worked successfully formany years and HGVs have in some way been the pioneers in more sophisticatedsafety technology such as automated emergency braking. However, the diversityof agricultural tractor size and build specifications undoubtedly presents additionalchallenges to the introduction of any new technology and this instance is noexception. Understanding the detailed reasons for these higher costs and takingmeasures where possible to reduce the differential, may prove critical to thesuccess of future safety measures.


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Conclusions10This investigation was undertaken to assess the current and future state-of-play in thedevelopment of technology to allow ABS to be installed on agricultural and forestryvehicles of 40 < Vmax ≤ 60 km/h. To ensure a comprehensive evaluation of the issue,ABS technology was assessed in terms of technical availability, applicability toagricultural and forestry vehicles and the likely costs and benefits of systemimplementation.

In terms of these three criteria, the conclusions of the investigation may be summarisedas:


· Applicability of ABS: Systems are applicable for use on relevantagricultural vehicles deemed likely to undertakeagricultural transport operations on-road.

· Cost Benefit Analysis: The likely costs of ABS implementation are highand are unlikely to be outweighed by monetisedsavings resulting from reduction in casualtynumbers during the 15 year evaluation period.

The findings of the investigation are as follows:

· Agricultural vehicle use: Changes in EU agriculture have resulted in the use offewer, larger (higher-powered) tractors which generally travel over greatergeographic areas to perform agricultural operations. Consequently greater on-roaddistances are travelled, both during material transport and general travel activities.

· Agricultural vehicle max speed capability has increased demonstrably.Vmax > 40 km/h tractors have been widely available for ~ 15 years and, where theiruse is permitted, have proven very popular in the marketplace. Where nationallegislation permits, they are increasingly used to tow heavier loads in order both toutilise available engine power and to match crop harvesting machinery output. It islikely that their market penetration will increase post-January 2018, following finalimplementation of EU type-approval legislation.

· Accidents involving agricultural vehicles form only a small proportion of the EUtotal. However, collisions involving agricultural vehicles are around 3 times morelikely to be fatal than the average for all collision types. Fatalities occur at a higherrate per registered vehicle than for other vehicle types, despite the limited roadusage. Also, the number of fatalities from such collisions appears to be reducingmore slowly than other vehicle types, such that they represent an increasingproportion of all fatalities. As higher speed tractors are likely to represent anincreasing proportion of the EU fleet in the future, there is a clear risk of anincrease in both collision frequency and severity, though the reduction in the speeddifferential with other road vehicles may counter this. The evidence to-date is verylimited but is consistent with an increase in collision severity but not frequency.

· Technical availability of ABS: ABS is technically feasible and available for nearlyall relevant agricultural vehicle types (Categories Tb, R3b, R4b & S2b). However,the ease and economic feasibility of their installation is currently dependent uponthe brake application method / medium used on the vehicle and the physical spaceavailable to accommodate system components. Mature pneumatically-based ABStechnology is readily-available for use on agricultural tractors (T1b) and also onagricultural trailers/towed equipment (R3b, R4b and S2b). Such ABS systems arealready in commercial use on a limited number of T1 tractor models, whilst


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hydraulic (mineral oil) ABS systems are at advanced stages of productdevelopment. Commercially-available hydraulic (brake fluid)-based light / mediumtruck systems are, based on our discussions with industry, understood to besuitable for installation on Category T4.3b vehicles. ABS systems for other tractorcategories are either at a proof-of-concept stage or in development (e.g. acommercial hydraulic system for ATVs is expected to be marketed in the very nearfuture).

Whilst ABS is readily-available for trailers / towed equipment fitted with pneumaticbraking systems, it is not currently available for such vehicles which employhydraulically-actuated braking systems and may not be brought to the market inthe foreseeable future. Such (typically lower-mass, less expensive) trailers / towedequipment would therefore require conversion to pneumatic braking systems topermit ABS installation. However, most trailers / towed equipment intended forV > 40 km/h use tends to feature pneumatic braking systems.

· Practical availability and applicability: Vehicle braking system actuationmethod and/or medium is significant in determining the complexity and associatedcost of ABS installation on agricultural vehicles, particularly as the majority oftractors employ hydraulic (mineral oil) brake actuation systems. The diverse natureof tractor design may well require ABS installation to be approached on a model-range by model-range basis. The space available for installation of some currentABS system components may also present a challenge. ABS implementation alsorequires installation of wheel speed sensors, but this appears to be a surmountableengineering challenge. For larger (pneumatically-braked) agricultural trailers andinterchangeable towed equipment, ABS systems may be installed without difficulty.Smaller vehicle applications are likely to be more costly. ABS technology iscurrently not available for hydraulically-braked trailers. Valid concerns regardingABS behaviour during off-road braking have been addressed by the provision ofmanual or automatic system disablement and/or alternative (slower speed)operating characteristics.

· Economic availability: The likely system diversity for ABS implementation onagricultural tractors will potentially increase system installation and developmentcosts, thereby increasing cost to the vehicle user. For reasons of commercialconfidentiality it has only been possible for this investigation to estimate potentialoverall system costs. ABS suppliers have commented that, depending uponproduction volumes, tractor system costs to OEMs may be in the region ~€1000 – 1300, to which installation and vehicle-based development costs must be added.Where offered as optional equipment, tractor manufacturers currently retail ABS at~€4000–5000. For agricultural trailers and interchangeable towed equipment,mature pneumatic ABS systems are readily available at reasonable cost (~€500OEM cost).

· Cost benefit analysis: Removing the requirement to fit ABS to agriculturalvehicles would result in the largest monetary gain (from between €1.3 billion - 3.0billion). This represents the cumulative savings in the cost of buying ABS minus thecasualty prevention value associated with the additional casualties that would beexpected to occur as a direct consequence. There is substantial uncertainty in theanalysis which results in a wide range of estimated effects. Benefit to cost ratios(BCRs) are calculated by dividing the savings in the cost of buying ABS by theprevention values associated with the increase in casualties. Even at the extremesof the possible ranges, the BCRs are always substantially in excess of 1.

Mandating ABS on all 40 < Vmax ≤ 60 km/h Category T1b, R3b and R4b vehicles ormandating ABS on Category T1b and Categories R3b and R4b vehicles ofMPMaxles≥ 12 tonnes, are the only two options with a BCR of less than 1.

The option with the largest monetary gain (benefits minus costs) can have arelatively low benefit to cost ratio, where both benefits and costs are large.Conversely where benefits and costs are small, high benefit to cost ratios can be


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achieved while total monetary gains remain small. Which measure, or combinationof the two measures, represents the ‘best’ option depends on the objectives ofthose setting the policy and their interpretation of the risk. Selection of which policyis the best to implement will, therefore, be a matter for the European Commissionand any impact assessment they choose to undertake and the monetary effectsshould be balanced alongside the non-monetised risks highlighted.

In this case, the best BCR is achieved by mandating the fitment of ABS on T1btractors of MPM ≥11.5 tonnes and either all R3b and R4b trailers or just those ofMPMaxles≥ 12tonnes. Such options would lessen the overall net gain to between€0.55 billion and 1.1 billion. However, the improved BCR comes from the fact thatthe associated increase in casualties is lessened by proportionally more than thecost of fitting the systems is increased.

Requiring ABS only on T1b tractors with a Vmax capability in excess of 50 km/h andon trailers of R3b and R4b (or only those of MPMaxles ≥ 12 tonnes) falls between thebest monetary gain and best BCR on both measures. However, it would complicatethe legislation by introducing a new speed threshold not used in any other part ofthe EU type-approval process.


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Possible options for amendment of Regulation (EU) 2015/6811

A comprehensive range of policy options have been identified and assessed(see Section 8). It is possible to summarise those detailed findings against the threecriteria upon which the investigation has focussed as follows:


· Applicability of ABS: Systems are applicable for use on relevantagricultural vehicles deemed likely to undertakeagricultural transport operations on-road.

· Cost Benefit Analysis: The likely costs of ABS implementation are highand are unlikely to be outweighed by monetisedsavings resulting from reduction in casualtynumbers during the 15 year evaluation period.

As demonstrated by the Cost-Benefit Analysis (Section 8), the European Commission hasa wide range of alternative policy options regarding the imposition of a mandatoryrequirement for ABS on agricultural vehicles of 40 < Vmax ≤ 60 km/h. The selection ofwhich, if any, of the identified policy options to implement (and related timescales) is amatter for the Commission and the relevant regulatory committees, informed by theanalysis presented in this report.

Thanks largely to the current content and structure of DelegatedRegulation (EU) 2015/68 (RVBR), the text of the regulation may be amended toaccommodate any of the proposed options (see Table 8.1). The regulation currentlyspecifies the vehicles to which ABS shall be fitted in Annex I / Section 2.2.1.21 (forCategory Tb) and Annex I / Section 2.2.2.16 (for Categories R3b, R4b & S2b).

Agricultural Tractors (Category Tb)11.1

The ABS introduction dates for Category Tb vehicles of 40 < Vmax ≤ 60 km/h arecurrently specified by Annex I / Section 2.2.1.21.2. The alternative policy options andassociated modifications required to the RVBR text are as follows:-

· Mandatory ABS on all 40 < Vmax ≤ 60 km/h Tb vehicles (Options 0, 4 or 5):

o No changes to text required.

· No ABS on any 40 < Vmax ≤ 60 km/h Tb vehicles (Options 1, 2 or 3):

o Delete Section 2.2.1.21.2 of Annex 1.

· Mandatory ABS on all 40 < Vmax ≤ 60 km/h Tb vehicles of MPM ≥ 11,500 kg(Options 6 or 7):

o Specify an additional tractor Max Permissible Mass threshold value inAnnex 1 / Section 2.2.1.21.2.

· Mandatory ABS on all Vmax > 50 km/h Tb vehicles (Options 8 or 9):

o Modify the vehicle Vmax criteria currently specified inAnnex 1 / Section 2.2.1.21.2 to 50 < Vmax ≤60 km/h


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Agricultural trailers and interchangeable towed equipment (Categories R3,11.2R4 & S2)

The RVBR currently does not contain any specific requirement for ABS implementation onCategory R3b, R4b or S2b vehicles of 40 < Vmax ≤ 60 km/h, as ABS is only mandatory forsuch vehicles of Vmax > 60 km/h (see RVBR Annex I / Section 2.2.2.16). However, if itwere deemed desirable to incorporate such a requirement for these vehicle types with40 < Vmax ≤ 60 km/h capability, this Section could be modified in one of the followingways to reflect the policy options assessed by the investigation.

· No ABS on 40 < Vmax ≤ 60 km/h R3b, R4b or S2b vehicles (Options 0 or 1):

o No changes to text required.

· Mandatory ABS on all 40 < Vmax ≤ 60 km/h R3b, R4b or S2b vehicles(Options 2, 4, 6 or 8):

o Modify the vehicle Vmax criteria currently specified inAnnex 1 / Section 2.2.2.16 from Vmax > 60 km/h to Vmax >40 km/h.

· Mandatory ABS on all 40 < Vmax ≤ 60 km/h R3b, R4b or S2b vehicles ofMPMaxles ≥ 12,000 kg (Options 3, 5, 7 or 9):

o Modify the vehicle Vmax criteria currently specified inAnnex 1 / Section 2.2.2.16 from Vmax > 60 km/h to Vmax >40 km/h and alsospecify an additional sum of technically permissible masses per axle (MPMaxles)threshold value. In practice this will only apply to R3 and some S2 vehicles as(by definition) R4 vehicles exceed the proposed mass threshold value.

N.B. It should be noted that the abovementioned policy options have been reviewedsolely on a basis of technical and economic feasibility: their potentialimplementation date(s) have not been considered. However, the project team areunaware of any technical restrictions which would prevent the installation and useof ABS on a Category R or S vehicle when towed by a Category T vehicle which isnot fitted with ABS. The trailer / towed equipment ABS requires an electricalpower supply from the tractor and it is desirable for a warning light to be installedwithin the tractor cab to indicate correct functioning of the trailer system, but allthese components may be retro-fitted to an existing / non-ABS tractor withoutdifficulty. Consequently there are no practical restrictions upon the introductorytimescale of ABS for Category R or S vehicles of 40 < Vmax ≤ 60 km/h.


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AcknowledgementsThe authors are grateful to the following:

· Richard Cuerden for carrying out the technical review of the report;

· Julie Austin for her assistance with project management;

· Robert Hunt and Ryan Robbins for assistance in the development andmanagement of the stakeholder surveys;

· Lynne Smith and Caroline Wallbank for their assistance in the accident dataanalysis.

· Those parties who responded to the stakeholder surveys

· The industry bodies and manufacturers who participated in the stakeholderdiscussions and/or provided information and data.

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Annex 1 REVIEW OF ALTERNATIVE MEASURES

In the questionnaires and meetings with industry, a range of other safety measures wereproposed as possible alternatives to anti-lock braking systems (ABS) for agriculturalvehicles (See Section 5.3.3). These numbered nineteen in total and are listed below:

· Braking measures already in Regulation (EU) 2015/68 (RVBR), e.g. compatibilitybands.

· Control of trailer braking system via drive stick input (Continuously-VariableTransmission - CVT)/vehicle travel speed control.

· Seat Belts.

· Roll-Over Protective Structures (ROPS).

· Electronic Braking Systems (EBS) for trailers.

· Vehicle to Vehicle Communication.

· Electronic Stability Control (ESC) for towing vehicles.

· Improved Lighting/Signalling.

· Improved conspicuity.

· Improved field of vision for tractor driver (e.g. mirrors, close proximity or junctioncameras, blind spot proximity alarms).

· Driver assist systems – collision warnings or avoidance systems.

· Improved maintenance & roadworthiness checks.

· Driver training/education (for drivers of both agricultural vehicles and othervehicles).

The main body of the report has shown the general relationships between increasedspeed and collision probability, consequences and types. It has also shown how accidentsinvolving loss of control (e.g. skidding and jack-knifing) collision risk increases withspeed and how this is particularly relevant for agricultural tractors (Section 4.3). Itshowed how ABS works and its effectiveness at helping to prevent skidding and jack-knife accidents at higher speeds (Section 5.2). The main body of the report also reviewedthe current accident data and exposure data, to quantify the occurrence of this type ofcollision (Section 4.3). The data showed that much of past accident data will bedominated by an agricultural vehicle fleet not capable of speeds in excess of 40 km/h,depending on year and country. Thus, the jack-knife collisions that have been occurringwill in many cases be caused not by high speed but by other problems, such as brakingimbalances between tractor and trailer. However, as a higher speed capability penetratesthe fleet, then the expectation would be that jack-knifes caused by locked wheels athigher speed and not by braking imbalances would occur in future unless ABS was fittedto control this risk. Thus, it can be considered that the aim of ABS is to limit the futureimpact of that specific increase in skidding and jack-knife that may be associated withthe increasing on-road use of tractors with a speed capability between 40km/h and 60km/h. Increase speed has been documented to have a range of other impacts on safetythat would not be influenced by ABS

Thus, when considering alternative measures to ABS, each can be categorised as follows:

· Direct alternative: A safety measure that aims to control the same safety risk asABS just using a different approach or mechanism.

· Indirect alternative: A measure that does not substantially affect the populationof collisions likely to be influenced by ABS, but which affects any other part of thecrash population.


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ABS is a well-known and understood technology that has been around in non-agriculturalmarkets for decades. Our analysis has suggested that mature production systems will beavailable to agricultural vehicles in almost all relevant categories by the time the RVBRrequires mandatory installation. The potential market maturity of each of the alternativemeasures will be considered wherever possible.

Accident data has identified the relevant target population of accidents that might beinfluenced by ABS and consideration has been given to how effective it might be withinthat target population. Published information is available concerning other populations ofagricultural vehicle collisions8, where possible the approximate size of the targetpopulation of each measure has been identified in comparison to ABS and, wherequantifiable in easily accessible published literature, its effectiveness within that targetpopulation. However, this is only a preliminary analysis and has not researched eachsubject exhaustively.

Annex 1.1 Braking measures already in the RVBRDetails of this measure were not provided by the respondents. However, it is assumedthat it relates to requirements in the revised RVBR to greatly improve the overall brakingperformance of both tractors and trailers and to add requirements to ensure substantialimprovements in the compatibility of the tractor and trailer in their brakingcharacteristics.

These measures are recent and, therefore, will not have been present in much of thepast accident data reviewed and they also affect collisions similarly, that is, improvingstopping distance and reducing the likelihood of jack-knife. However, these features havebeen directly assessed in the main cost benefit analysis, through the exclusion from thetarget population for ABS of jack-knife collisions that occurred as a result of brakesystem defects and imbalances where they involved tractor trailer combinations notcapable of speeds in excess of 40 km/h. This is because of the evidence (Dodd, Bartlett,& Knight, 2006) showing that in the absence of braking imbalances, jack-knife at speedsbelow 40 km/h did not develop significant angles because the vehicle stopped beforethere was time for it to occur. Even in the absence of such imbalances, jack-knife wouldstill occur at speeds greater than 40 km/h in the absence of ABS.

Thus, the measures already in the RVBR have been accounted for in the calculation ofbenefits and costs of ABS. Given that they are already a mandatory requirement, theycannot now be considered an alternatively to ABS.

Annex 1.2 Control of trailer braking system via drive stick input (CVTTransmission/vehicle travel speed control

Although details of the proposal were not received, it is expected that this measure isintended to provide improved matching of tractor and trailer braking levels to improvethe compatibility of towed combinations. As such it partially targets the same group ofcasualties as ABS and also the existing compatibility corridors in the RVBR. However, itrepresents a different approach. Better matching of tractor and trailer braking will help toreduce the chance of wheel lock by ensuring the braking required for a given decelerationis distributed appropriately between tractor and trailer. However, it cannot preventwheels locking when emergency braking is applied or when the road is very slippery.

Implementing such a system would be likely to require sensing of deceleration and/orsensing of the coupling forces applied between tractor and trailer to identify how hard thetrailer is braking and to control appropriately.

It will not be as effective as ABS at preventing jack-knife and trailer swing but it mayhelp in some circumstances. It will do nothing to aid steerability of the vehicle underbraking. The cost of the system is unknown.

8 See for example (Knight I. , 2001), (Dodd, Bartlett, & Knight, 2006), (Knight I. M., 2007)


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Annex 1.3 Seat beltsSeat belts are a proven benefit to safety in other road vehicles and have been mademandatory in agricultural vehicles within Reg. (EU) No 1322/2014. This Regulationrequires fitment of lap belts as a minimum standard but 3 point lap diagonal belts arealso permitted.

One of the primary benefits of seat belts in road accidents is the protection of occupantsin a severe frontal collision. (Knight I. , 2001) found that this was not a common crashtype resulting in the death of tractor occupants. Most tractor occupants were killed eitherwhen struck from the rear by another large vehicle such as a heavy goods vehicle (HGV),or where a tractor rolled over.

When heavy vehicles collide with the rear of an agricultural vehicle, it is common for theagricultural vehicle occupant to be ejected through the rear window, which is a significantcontributor to the severity of injuries received. The primary restraint in a rear impact isactually the seat back. Historically, most agricultural vehicles would have a low seat backto maximise occupant manoeuvrability within the cab. Such low seat backs offer littlerestraint in the event of a rear collision. Using a high seat back designed to perform wellin rear collision, similar to passenger car seats, would, therefore, have benefits.However, such seats will deform in the event of an impact and this can allow theoccupant to ramp-up the seat back which could potentially still allow partial ejection oreven simply a head collision with roof or rear structures. In this situation, the use of aseat belt would help prevent the ramping up action. A simple lap belt, well securedaround the hips would be adequate to achieve this action. This is already a requirementand may, therefore, act to improve the outcome for tractor drivers in this collision type,depending on the standard of the combined seat and restraint system.

(Smith, Couper, Donaldson, Neale, & Carroll, 2005) studied the effectiveness of seatbelts in quarry vehicle rollover incidents. This research found that a simple lap belthelped prevent ejection but allowed the occupant’s head to move around extensivelywithin the cab, thereby coming into contact with various cab structures which were oftennot designed with the prevention of head injury in mind. Thus, severe injury could stilloccur. The use of a 3-point seat belt improved the situation and a 4 point, 3 inertia reelharness designed specifically for use in off-road machines improved the restraint evenfurther. Although designed for quite different purposes the cab designs of the quarryvehicles and agricultural vehicles was not radically different and it is likely, therefore,that many of the results are transferrable. Thus, in this situation, the recentrequirements would be expected to improve the outcome in rollover collisions but furthergains may be possible with more sophisticated restraints.

Annex 1.4 Roll-Over Protective Structures (ROPS)As stated above, rollover is one of the leading causes of death for the occupants ofagricultural vehicles in road collisions and it is understood that more rollovers occur onthe farm. Maintaining a ‘survival space’ for the occupant is, therefore, an essential part ofprotecting those occupants and this is what ROPS are intended to do. However, asdiscussed above, ROPs will only be effective if the occupant stays within the structureand does not suffer heavy collision with the structure or with other hard objects withinthe structure. Thus, occupant restraint and seat belts are also an important part of theprotection.

ROPs have been mandatory on most new agricultural vehicles in most Member States for30 years or more and they are now a mandatory part of EU Type Approval. Unless thereis evidence that these are not working as intended, further requirements on new vehiclesmay have limited benefit. (CEMA, 2015) have suggested retrofitting ROPS to oldertractors not equipped with them. It is understood some Member States haveimplemented this sort of action in the past. Whether this is a cost effective measure forthose that haven’t already done so will depend strongly on how feasible it is to retrofiteffective structures (including consideration of occupant restraint) to old vehicles, how


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much it will cost per vehicle and how many vehicles not already equipped with theprotection remain in use.

Whilst a laudable and potentially effective safety initiative, it should be noted that thetarget population of such activities is existing ‘in-service’ vehicles, whereas therequirements of EU type-approval legislation apply only to new vehicles when first placedon the market. Thus, this solution cannot be implemented through the type approvalsystem.

Annex 1.5 Electronically controlled braking systems (EBS) for trailersElectronically controlled braking systems (EBS) have been available in the commercialHGV market for many years and are now the norm in that market. The basic concept ofthe system is that traditional truck brakes use air, which is a compressible fluid. HGVscan be long with as much as 15 m or more distance between the foot pedal and therearmost axle brake. The air pressure wave from a rapid application of the foot braketherefore takes a finite time to reach the brake chamber to the rear and this could meanthat full emergency braking would not be achieved for up to as much as 0.75 to 1 secondafter pedal application. In an EBS system the wheel brake is still applied by air pressurebut that air is stored locally. The air is controlled locally using an electro-pneumaticvalve. The signal to brake is still carried from the foot valve to the axles pneumaticallybut this is to provide a mechanical back-up only. In parallel to this, the signal is carriedelectronically to the near the wheel such that it is transmitted almost instantaneously,thus reducing brake reaction time and stopping distances.

A spin off benefit of this development was that the hardware now existed to fully controlthe brake pressure both in terms of reduction and increase in pressure. This has led to arange of additional brake control functions being incorporated within EBS systems. Forexample, all HGV EBS come equipped with ABS functions as standard. Some will havesome form of coupling force control, aimed at equalising braking between tractor andtrailer. Many also come with roll stability control functions, which requires only additionalsensing of lateral acceleration and additional software code.

Where trailers are air braked, similar brake reaction time and stopping distances may beexpected, perhaps slightly lower due to generally shorter lengths. The benefits ofadditional electronic control over the brakes could also be significant. However, thesystem will require many of the same components as standard ABS and possibly someadditional ones. It is, therefore, likely to be more beneficial than ABS but also morecostly.

Annex 1.6 Vehicle to Vehicle (V2V) CommunicationV2V communication is not, in and of itself, a safety system; it is merely an enablingtechnology. The information that you choose to communicate between vehicles and whataction the vehicle chooses to take based on that information is what determines theeffect on safety. Thus, there is a wide range of different safety applications, e.g. (NHTSA,2016), that aim at warning the driver or intervening in driving in order to stop a potentialcollision from occurring. These can include a variety of ‘junction assist’ systems aimed atpreventing collisions at intersections and it is thought that this is the type of system thatis intended by industry respondents referring to this as an alternative measure. It is,therefore, clearly an indirect alternative to ABS, aimed at preventing or mitigating adifferent crash population to ABS.

There is considerable overlap between active safety systems and assisted and automateddriving systems enabled by V2V communication and those enabled by on-board sensorssuch as radar, Lidar and cameras. The advantage of V2V is that it does not rely on line-ofsight and potentially has a longer range. Thus, it can ‘see’ hazards that the on-boardsensors cannot, giving earlier warning of potential crashes, enabling better levels ofavoidance. However, the disadvantage is that it will only work where the potentialcollision partner is also equipped with the same technology. Firstly, this requiresconsiderable standardisation effort across different sectors of industry (Original


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Equipment Manufacturers (OEMS), Tier 1 suppliers in agricultural vehicles, passengercars, goods vehicles, motorcycles, etc.). Secondly, the effectiveness of the technologydoes not increase linearly with fitment. If a vehicle is equipped with a crash avoidancesystem based on on-board sensors, then the driver immediately gets the full benefit ofthat safety system in all situations in which it is designed to function. However, when avehicle is equipped with a crash avoidance system based on V2V technology, it only getsthe benefit of that technology when it encounters another vehicle with that technology.Until fitment is common in the fleet, then other equipped vehicles may be encounteredonly rarely such that early adopters do not see the benefits. Mandatory fitment may berequired to overcome this barrier. The costs and benefits of such systems are not yetwell developed and will be highly variable based on the type of enabling technology usedand the use that is made within each vehicle and the market penetration rate.

The potential for junction assist systems, whichever technology is used to enable them,is high for agricultural vehicles. (Knight I. , 2001) showed that more than half of caroccupants and motorcyclists killed in collision with agricultural vehicles were killed whenthe agricultural vehicle was turning right (left for mainland Europe) either into, or out of,a side road. Two crash avoidance systems could conceivably help substantially in thesesituations:

· A system that prevents the vehicle pulling out from a T-junction if acollision is likely with an approaching vehicle. This could be implementedthrough the transmission by stopping acceleration, or through the brakes bystopping motion (or both). The former is possible because the vehicle would bestationary when the automated action was implemented.

· A system preventing the vehicle turning from the main road across thepath of an oncoming vehicle in the opposite lane and/or a vehicleovertaking from the rear. In this case, the vehicle is often already moving atthe point the turn commences so in this case, avoidance action through thebrakes would be necessary. At a minimum, this would require brake actuation andcontrol valves similar to ABS to automatically apply the brakes independent of thedriver. Where higher speeds are involved on larger roads, it is likely that ABSwould be necessary to ensure that the automated braking action did not haveadverse consequences in terms of braking stability, particularly in low frictionconditions. This is analogous to the situation for passenger cars. UNECERegulation 13-H (as amended) (United Nations, 2014) does not make ABSmandatory for passenger cars. However, the pedestrian protection regulation,Regulation (EC) No 78/2009 (European Community, 2009), makes it mandatoryfor passenger cars to be fitted with brake assist systems which boost braking overand above that demanded by the driver if it detects it as an emergency brakingapplication. UNECE Regulation 13-H governs the standard for brake assist systemsand requires that, if such systems are fitted, the vehicle must also be equippedwith ABS.

In terms of maturity, no current production vehicles (car, truck, or bus) use the form ofV2V communication envisaged, though rulemaking to introduce it is proposed in the USA.Volvo were first to market with a ‘turn across path’ collision avoidance system (based onforward looking radar and camera) on the 2015 XC90. Very few other vehicles areequipped with this sort of system. Some vehicles (e.g. Mercedes E class) are equippedwith automated braking systems that work when crossing a cross roads at speed. This isalso the scenario most commonly envisaged for V2V communication. However, this istypically an urban crash type and was not cited as a common agricultural type by (KnightI. , 2001). No current production systems will prevent a vehicle emerging from a T-Junction.

Thus, in summary, the potential for this type of system is strong within agriculturalvehicles but it does not directly mitigate the same group of accidents as ABS. It is not yetclear which of several competing technical ways of implementing the system will be best.The market maturity of systems is extremely low compared to ABS and, in some


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applications at least, ABS is likely to be a pre-requisite of a system. The effectiveness ofvehicle to vehicle communication will rely on widespread fitment across all other vehicletypes that agricultural vehicles encounter. At this stage, the proposal is too vague toallow cost benefit analysis.

Annex 1.7 Electronic Stability Control (ESC) for towing vehiclesESC is a mature system, mandatory for most road vehicles including passenger cars andHGVs. In road vehicles ESC controls two risks – that of directional instability (e.g.spinning) as a result of excessive steering, and rollover as a consequence of corneringtoo fast. In agricultural vehicle collisions, there are relatively few examples of spinning asa consequence of excessive steering (as opposed to locked wheel braking). Thus, themain focus would be on rollover.

In its implementation on heavy goods vehicles, EBS and therefore ABS are technical pre-requisites of fitting the system because the system must be able to activate the brakes,potentially each individual wheel brake separately, without driver intervention and veryrapidly. The system must be able to do this safe in the knowledge that these automatedbrake applications will not cause locked wheel braking instabilities, even if the roadsurface is slippery, which explains why ABS is a pre-requisite.

ESC is likely to be a substantial benefit in on-road rollovers which (Knight I. , 2001)found to represent about 10% of on-road agricultural vehicle fatalities but (CEMA, 2017)found to represent 24% of on road accidents, 39% of on-road fatalities and 51% of allaccidents when both road and field were considered. The reason for the difference inproportions identified is not known, however, the studies used different methodologies,in different countries and both involved relatively small sample sizes. It is also worthnoting that it is possible that many off-road rollovers occur not just because of a highcentre of gravity and cornering too fast but because of other factors such as traversingacross steep slopes or sliding sideways and then ‘tripping’ in mud. The system mayrequire significant development to be effective in this type of circumstance which is notprevalent in other road vehicles.

Unlike ABS alone, the engineering assessment that ESC will be effective is fully borne outin retrospective statistical studies in other road vehicles. In fact, the study of ABS(Kahane & Dang, 2009) which found it not very effective in passenger cars found thatadding ESC in a combined ABS/ESC transformed it from a system without a statisticallysignificant effect to one that was a major contributor to large scale fatality reduction.

Thus, it can be summarised that ESC in agricultural vehicles would be likely to come withABS by default and would extend the benefits of ABS significantly. It would be likely tocost more than ABS alone but the additional amount may not be that great becauserelatively little additional hardware would be required.

Although stakeholders specifically referred to this measure for towing vehicles, in somecases it may only be a trailer that overturns and it is perfectly technically feasible to fit itto a trailer independently of the towing vehicle.

Annex 1.8 Improved Lighting/Signalling(Knight I. , 2001) found that more than half of car occupant and motorcycle fatalitiesoccurring in collision with an agricultural tractor, involved the tractor making some formof right turn at the time (equivalent to a left turn in mainland Europe). This group wasdivided between those where the tractor was emerging from a side road or field onto themain road and those where they were leaving the main road and turning into a side roadof field. Improved signalling will mainly be relevant to those where the tractor wasturning off the road and it collided with road users overtaking it who failed to see thedirection indicators. This is a significant crash type but only a subset of the above,further reduced by the fact that the driver failed to use the direction indicators in some ofthose collisions.


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Similarly, a proportion of other road users were killed when they collided with the rear ofa slower moving vehicle and some of those were in dark conditions with poor or defectivelighting. Improving lighting as an aid to conspicuity in those cases also has potential,provided that it is maintained such that it remains effective in service including after usein dirty harsh conditions.

If it could be maintained 100% defect free then (Knight I. , 2001) estimated thatimproved lighting and signalling could potentially save the lives of around 20% of caroccupants and 15% of motorcyclists killed in collision with agricultural vehicles. Inprinciple, this is a greater casualty benefit that ABS offers. However, it should also benoted that (Knight I. , 2001) found that significant numbers of agricultural vehicles didsuffer from contributory defects and that a large proportion of these related to thelighting system. Thus, the potential benefit highlighted here may be substantially lessthan indicated unless complementary measures to ensure continued function in servicewere introduced.

Annex 1.9 Improved conspicuity (by means other than lighting)Improving conspicuity by means other than lighting would probably not have much effecton the turning accidents but may affect those where drivers collided with the rear of anagricultural vehicle because they failed to see it. It can also form a partial backup iflighting is poor as a consequence of inadequate maintenance. Typically, measures arebased on the use of retroflective tape. However, this does itself require maintenance. Ifcovered in thick mud it will not be effective.

Annex 1.10 Improved field of vision for tractor driver (e.g. mirrors,close proximity or junction cameras, blind spot proximityalarms)

(CEMA, 2017) found driver visibility to be a factor influencing the cause of 15% ofcollisions. By contrast (Knight I. , 2001) did not report any issues with respect toagricultural vehicle field of view in any of the 41 fatalities studied. However, improvedfield of vision can be considered in several different contexts. Two of the more importantare typically:

· Field of view in close proximity manoeuvring.

· Field of view when emerging from junctions.

HGVs suffer considerable difficulties in close proximity manoeuvring. They are large tallvehicles and tend to have blind spots around the vehicle such that pedestrians andcyclists can be hidden from view as the vehicle reverses, turns corners and pulls awayfrom rest. This results in a substantial number of fatalities. However, in studying thisproblem, it has been found that increasing the number of blind spot mirrors may nothave been as effective a solution as thought, possibly because of driver workload and thetime taken to look in each mirror and direct view during a complex manoeuvre andpossibly because the images of vulnerable road users in those mirrors could be small anddistorted. Research has found that vulnerable road users seen in direct vision through aglazed area were identified substantially quicker than those only visible through a mirror.Similar concerns can be applied to camera systems that add to the number of places thedriver needs to look or are complex or difficult for the driver to scan and detect thehazard.

(Knight I. , 2001) identified no collisions involving agricultural tractors on the road in thiskind of manoeuvring scenario. However, it may be much more of an issue in the farmenvironment, where the vehicle may, for example, be manoeuvring around a yard withpedestrians moving around it.

The driver of an agricultural vehicle can be seated a long way rearward of the front of thevehicle, particularly if ancillary equipment is mounted to the front at the time. Where thefield of view when emerging from a junction is restricted, this can make it difficult for thetractor driver to see traffic approaching on the main road. (Knight I. , 2001) did identify


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several collisions relevant to this situation and, therefore, there may be benefits incameras or mirrors specifically designed to help drivers see in this situation, subject toanalyses of workload etc. However, it should also be noted that field of view issues insuch cases can also relate to field exits or junctions sited close to bends such that it isthe bend that restricts the field of view and such devices would have no benefit.

In each of these cases, passive devices such as mirrors and cameras rely on drivers touse them properly and humans have been shown to be fallible in this respect. Camerasare now used in some applications more as a sensor than a field of view aid such thatpattern recognition software can identify collision threats and either warn the driver tobring it to their attention more directly, or to intervene automatically to reduce theprobability or severity of collision. These have strong potential to be more effective

Annex 1.11 Driver assist systems – collision warnings or avoidancesystems

In the passenger car, HGV and bus market, advanced driver assist systems are beingdeveloped at an exponential rate in order to warn drivers of collision risks or,increasingly, to intervene independent of the driver. Applications include, but are notlimited to:

· Forward collision warning.

· Automated emergency braking.

· Lane departure warning.

· Lane keep assist.

· Emergency lane keeping.

· Blind spot information system.

· City turn assist.

· Junction assist systems/start inhibit.

As discussed in the section relating to vehicle to vehicle communication (Annex 1.6),these systems have tremendous potential to improve safety. Those relating to assistanceat junctions to prevent agricultural vehicles turning across the path of other vehicleswould be particularly relevant. However, the systems are relatively new in the passengercar market, are more immature in the commercial vehicle market and do not exist at all,to the authors’ knowledge, in the agricultural vehicle market. At present, road goingversions are all based on sensors mounted on the vehicle, typically cameras, radar andor Lidar. The most sophisticated passenger cars, such as a Mercedes S class for example,may now be fitted with multiple cameras all around the vehicle, ultrasonic sensors frontand rear, two forward looking radars and four corner radars.

If the difference in cost between passenger car ABS and agricultural vehicle ABS isrepresentative of the difference in cost between Advanced Driver-Assistance System(ADAS) sensors in each market then the cost of such systems will be extremely high inthe agricultural vehicle market.

Annex 1.12 Improved maintenance & roadworthiness checks(Knight I. , 2001) found that 12% of agricultural vehicles involved in fatal collisions had acontributory defect. This is entirely consistent with the 13% found by (CEMA, 2017).Improved maintenance and roadworthiness checks do have significant potential toimprove safety. However, it must be borne in mind that even in industries where themaintenance of the vehicle is highly regulated with regular inspections, such as HGVsand buses, there is still a proportion of accidents where defects are a contributory factor.For example, in around 6% of HGVs involved in fatal accidents and around 3% of lightgoods vehicles, at least one contributory defect was found (Knight, Robinson, Neale, &Hulshof, 2009). In addition to this, researchers in North America have often questioned


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whether mandatory periodic inspection regimes are effective (see for example (Miedema,2003)).

Thus, while the potential for improvement is strong, it may not result in casualtyreduction as large as suggested by the base figures showing how often defective vehiclescontribute to collisions, particularly given the harsh environment that agricultural vehiclesoperate in and the practical difficulties that may be involved with a mandatory inspectionregime across a sparsely populated rural area.

It should also be noted that requirements to maintain vehicles and check theirroadworthiness cannot be implemented through the type approval system, whichspecifies only the requirements that new vehicles must meet before they can beregistered for use on the road. As such, they can be used to ensure systems aredesigned in a way that enables easier or more effective roadworthiness checks, forexample, requiring self-diagnostic tests and warning lamps if systems are not working.

Annex 1.13 Driver training/education (for drivers of both agriculturalvehicles and other vehicles)

Some form of human error is a contributory factor in most collisions and those involvingagricultural vehicles are no exception. Thus, driver training appears a very logical andpromising solution to the problem. However, while a huge amount of training isundertaken, there is little objective and rigorous analysis of the effectiveness of thattraining. Thus, at the very least, there is an absence of evidence of the effectiveness oftraining. Where studies have taken place, the results vary according to the type oftraining. With respect to most new driver training and to post license traininginterventions there is no evidence for an overall effect on the number of casualties, e.g.(Helman, 2013). While in some cases, effective training may simply lack robust evidenceof effect, in others there is direct evidence of no effect. Some promising techniques havebeen emerging in more recent years. For example, there is strong evidence thatgraduated driver licensing can reduce casualties and hazard perception training andtesting has evidence to suggest an 11% reduction in crashes whilst some fleet safetyinitiatives are backed by some evidence.

Thus, while training does have potential it is not necessarily an easy or cheap solutionand is much more complex than it may appear. In particular, training other vehicledrivers to respond correctly to encounters with agricultural vehicles, which for manydrivers will happen extremely rarely, may involve high costs in relation to the benefits.

It should also be noted that requirements to train drivers cannot be implementedthrough the type approval system, which specifies only the requirements that newvehicles must meet before they can be registered for use on the road.


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