NORDICROAD AND TRANSPORT RESEARCH | NO.1 | 2010 WWW.NORDICROADS.COM

EU projects:

Persuade andRe-Road

Road Surface

– Durability, Economy andEnvironmental Impact

2 | NORDIC NO. 1 2010 NORDIC NO. 1 2010 | 3www.nordicroads.com

News from Contents

Swedish National Road andTransport Research Institute (VTI)

VTI is an independent, internationally establishedresearch institute which is engaged in the transportsector. Our work covers all modes, and our core com-petence is in the fields of safety, economy, environ-ment, traffic and transport analysis, public transport,behaviour and the man-vehicle-transport system inte-raction, and in road design, operation and maintenan-ce. VTI is a world leader in several areas, for instancein simulator technology.

Danish Road Directorate (DRD)Danish Road Institute (DRI)

The Road Directorate, which is a part of TheMinistry of Transport, Denmark, is responsible fordevelopment and management of the nationalhighways and for servicing and facilitating traffic onthe network. As part of this responsibility, theDirectorate conducts R&D, the aim of which is tocontribute to efficient road management and to thesafe use of the network. The materials researchcomponent is carried out by the Danish RoadInstitute.

Technical Research Centreof Finland (VTT)

VTT Technical Research Centre of Finland is a con-tract research organisation with a staff of 2,800. Inthis joint publication, the VTT expertise areas coverresearch and development of transportation, logis-tics and road structures. The work is carried out infive research groups employing a staff of 60.

Icelandic RoadAdministration (ICERA)The ICERA's mission is to provide the

Icelandic society with a road system in accordancewith its needs and to provide a service with the aimof smooth and safe traffic. The number of employe-es is about 340. Applied research and developmentand to some extent also basic research concerningroad construction, maintenance, traffic and safety isperformed or directed by the ICERA. Developmentdivision is responsible for road research in Iceland.

Norwegian Public Roads Administration (NPRA)

The Norwegian Public Roads Administration is oneof the administrative agencies under the Ministry ofTransport and Communications in Norway. TheNPRA is responsible for the development and mana-gement of public roads and road traffic, as well as theVehicle Department. This responsibility includesresearch and development of all areas related to roadtransport and the implementation of R&D results.

Institute of Transport Economics (TØI),

NorwayThe Institute of Transport Economics

is the national institution for transport researchand development in Norway. The main objectives ofthe Institute are to carry out applied research andpromote the application and use of results throughconsultative assistance to public authorities, thetransport industry and others. The Institute is anindependent research foundation employing aboutone hundred persons.

Editorial notesNordic Road & Transport Research is a joint publi-cation of six public road and transport researchorganisations in the Nordic countries, Denmark,Finland, Iceland, Norway, and Sweden. The mainobjective of the publication is to disseminate re-search results and news from the institutions, espe-cially to researchers and decision makers. Each insti-tution is responsible for the selection and presenta-tion of the material from its own scope of activities.

Nordic Road & Transport Research is publishedthree times a year. It is regularly sent out, free ofcharge, to recipients selected by the six jointpublishers. Free sample copies are also sent out onspecial request.

Reproduction and quotation of the texts are allow-ed if reference is made to the author and source.However, legislation regulates and restricts the rightto reproduce the illustrations. Please contact therespective publishing institution for information.

Advertising is not accepted.Correspondence about the contents of the publi-

cation:

Please write to the author or to the respectivepublishing organisation.

Requests for back issues, and notification of add-ress changes:

Readers outside the Nordic countries: please writeto the Editor-in-chief at the VTI in Sweden.

Readers in the Nordic countries: please contactthe publishing institution of your country.

Addresses: see back cover.

The Editorial Board consists of the following representatives of the publishing institutions

Editor-in-Chief, SwedenMagdalena Green, VTInordic@vti.se

DenmarkHelen Hasz-Singh, DRIhhz@vd.dk

FinlandKari Mäkelä, VTTkari.makela@vtt.fi

IcelandG. Pétur Matthiasson, ICERAgpm@vegagerdin.is

NorwayThorbjørn Chr. Risan, NPRAthorbjorn.risan@vegvesen.noHarald Aas, TØI ha@toi.no

Graphic DesignJohnny Dahlgren Grafisk produktion AB,

Linköping, Sweden

Issue 3,900

ISSN 1101-5179

CoverPhotos.com

Determining the Spreading Accuracy of Equipment for Winter Maintenance Services | p4

Which Parement Lasts Longest? | p6

Environmentally Friendly Pavements in Norway | p7

Persuade – a New EU Noise Project | p8

A New Approach in Research on Bituminous Mixtures | p10

Road Surface Measurement – a Journey over Many Years | p12

Re-Road – Optimizing the Potential in Recycling of Asphalt | p14

Road User Requirements and Experiences Regarding Road Surface Conditions | p16

Extreme Weather Impact on European Transport Systems | p18

Self-adapting Traffic Prediction Model Learns While Working | p19

E6 Trondheim–Stjørdal, Mid-Norway: A Pilot Project Using Competitive Dialogue | p20

Environmental Damage Caused by Road Salting – a Literature Review | p22

2 | NORDIC NO. 1 2010 NORDIC NO. 1 2010 | 3www.nordicroads.com

News from Contents

Swedish National Road andTransport Research Institute (VTI)

VTI is an independent, internationally establishedresearch institute which is engaged in the transportsector. Our work covers all modes, and our core com-petence is in the fields of safety, economy, environ-ment, traffic and transport analysis, public transport,behaviour and the man-vehicle-transport system inte-raction, and in road design, operation and maintenan-ce. VTI is a world leader in several areas, for instancein simulator technology.

Danish Road Directorate (DRD)Danish Road Institute (DRI)

The Road Directorate, which is a part of TheMinistry of Transport, Denmark, is responsible fordevelopment and management of the nationalhighways and for servicing and facilitating traffic onthe network. As part of this responsibility, theDirectorate conducts R&D, the aim of which is tocontribute to efficient road management and to thesafe use of the network. The materials researchcomponent is carried out by the Danish RoadInstitute.

Technical Research Centreof Finland (VTT)

VTT Technical Research Centre of Finland is a con-tract research organisation with a staff of 2,800. Inthis joint publication, the VTT expertise areas coverresearch and development of transportation, logis-tics and road structures. The work is carried out infive research groups employing a staff of 60.

Icelandic RoadAdministration (ICERA)The ICERA's mission is to provide the

Icelandic society with a road system in accordancewith its needs and to provide a service with the aimof smooth and safe traffic. The number of employe-es is about 340. Applied research and developmentand to some extent also basic research concerningroad construction, maintenance, traffic and safety isperformed or directed by the ICERA. Developmentdivision is responsible for road research in Iceland.

Norwegian Public Roads Administration (NPRA)

The Norwegian Public Roads Administration is oneof the administrative agencies under the Ministry ofTransport and Communications in Norway. TheNPRA is responsible for the development and mana-gement of public roads and road traffic, as well as theVehicle Department. This responsibility includesresearch and development of all areas related to roadtransport and the implementation of R&D results.

Institute of Transport Economics (TØI),

NorwayThe Institute of Transport Economics

is the national institution for transport researchand development in Norway. The main objectives ofthe Institute are to carry out applied research andpromote the application and use of results throughconsultative assistance to public authorities, thetransport industry and others. The Institute is anindependent research foundation employing aboutone hundred persons.

Editorial notesNordic Road & Transport Research is a joint publi-cation of six public road and transport researchorganisations in the Nordic countries, Denmark,Finland, Iceland, Norway, and Sweden. The mainobjective of the publication is to disseminate re-search results and news from the institutions, espe-cially to researchers and decision makers. Each insti-tution is responsible for the selection and presenta-tion of the material from its own scope of activities.

Nordic Road & Transport Research is publishedthree times a year. It is regularly sent out, free ofcharge, to recipients selected by the six jointpublishers. Free sample copies are also sent out onspecial request.

Reproduction and quotation of the texts are allow-ed if reference is made to the author and source.However, legislation regulates and restricts the rightto reproduce the illustrations. Please contact therespective publishing institution for information.

Advertising is not accepted.Correspondence about the contents of the publi-

cation:

Please write to the author or to the respectivepublishing organisation.

Requests for back issues, and notification of add-ress changes:

Readers outside the Nordic countries: please writeto the Editor-in-chief at the VTI in Sweden.

Readers in the Nordic countries: please contactthe publishing institution of your country.

Addresses: see back cover.

The Editorial Board consists of the following representatives of the publishing institutions

Editor-in-Chief, SwedenMagdalena Green, VTInordic@vti.se

DenmarkHelen Hasz-Singh, DRIhhz@vd.dk

FinlandKari Mäkelä, VTTkari.makela@vtt.fi

IcelandG. Pétur Matthiasson, ICERAgpm@vegagerdin.is

NorwayThorbjørn Chr. Risan, NPRAthorbjorn.risan@vegvesen.noHarald Aas, TØI ha@toi.no

Graphic DesignJohnny Dahlgren Grafisk produktion AB,

Linköping, Sweden

Issue 3,900

ISSN 1101-5179

CoverPhotos.com

Determining the Spreading Accuracy of Equipment for Winter Maintenance Services | p4

Which Parement Lasts Longest? | p6

Environmentally Friendly Pavements in Norway | p7

Persuade – a New EU Noise Project | p8

A New Approach in Research on Bituminous Mixtures | p10

Road Surface Measurement – a Journey over Many Years | p12

Re-Road – Optimizing the Potential in Recycling of Asphalt | p14

Road User Requirements and Experiences Regarding Road Surface Conditions | p16

Extreme Weather Impact on European Transport Systems | p18

Self-adapting Traffic Prediction Model Learns While Working | p19

E6 Trondheim–Stjørdal, Mid-Norway: A Pilot Project Using Competitive Dialogue | p20

Environmental Damage Caused by Road Salting – a Literature Review | p22

NORDIC NO. 1 2010 | 54 | NORDIC NO. 1 2010 www.nordicroads.com

Determining the Spreading Accuracy of Equipment for Winter MaintenanceServices

The objective is to develop a method to document the ability of agiven salt spreader to achieve accurate dosage and distributionacross the road – for the sake of road safety, the environmentand the economy.

In the period from 2006 to 2009, the SaltSpreader Development Group of the

Danish Road Directorate worked on thedevelopment of methods to assess the useof spreading materials to maintain roadpassability in snow and ice conditions.

The SUG works in the context of the so-called Winter Committee, and consists of abroad range of representatives from theDanish Road Directorate, the local authori-ties and the Sund&Baelt Partner Ltd, withoccasional participants from the DanishAssociation of Consulting Engineers andthe private sector. The group’s objective isto make recommendations for require-ments for spreading equipment.

Besides establishing standards for dosa-ge and distribution accuracy, the groupaimed to develop methods to assess suchparameters. This was done in cooperationwith the University of Aarhus’ EngineeringCentre Bygholm (ECB) in Horsens. TheECB has Europe’s largest spreading labora-tory, and is built to meet the existing stan-dards for the test of commercial fertilizerspreaders used in agriculture.

Distribution and spreadingDistribution and spreading tests are car-ried out by collecting spread material infunnels situated across the path. When thematerial is dry salt, the amount spread isregistered by an electronic scale placed

lecting the salt, moistened salt or brinedirectly from the spreader, without anyspreading actually taking place. After beingcollected, the material has been registeredby an electronic scale. The results are mostaccurate when the spreading disc is notused, as this produces considerable vibra-tions that can be perceived as noise.Dosage tests are used to provide documen-tation of dosage precision and of theresponse time elapsed when changingfrom a dosage level to another. It is expec-ted that the actual dosage does not varymore than 6% in relation to the desiredamount.

The tests have been carried out with thematerials most commonly used in Denmark,i.e. vacuum salt, sea salt and mineral salt.

Criteria for test resultsThe criteria used to assess test results wereestablished with the purpose of ensuringmaximum coverage of the road surface andwere set up to reduce salt consumption ingeneral, and to reduce the amount of saltbeing spread outside the road, which is anunnecessary hazard to the environment. Thecriteria are still being discussed, but the gene-ral objective is to achieve an even distributionacross the whole width of the road with theleast possible loss to the surroundings.

A positive development in spreadingequipment has been noticed during thetest period. It is important, however, that afinal decision is made regarding these cri-teria so that all involved parties, such asequipment producers, have a goal for theirdevelopment work.

Determining the Spreading Accuracy of Equipment for Winter MaintenanceServices

After more than 40 years as one of the lea-ding experts in Norwegian transport plan-ning, Tore Knudsen has now retired and iswrapping up his professional career.Having earned a PhD in transportationplanning from the University of California,Berkley, he was a professor at theNorwegian Institute of Technology (NTH)from 1966-1980 and 1995-1996. Duringthe 1980s Knudsen was head of and lea-ding consultant for transport planning inthe consulting company Asplan. In 1996 hewas appointed head of the TransportResearch division at SINTEF.

His main professional interest has beenin transport modelling and cost-benefitanalysis. Many Norwegian transport plan-ners have had the privilege of experien-cing Tore Knudsen as an enthusiastic and

inspiring lecturer. He has now retired fromhis position at SINTEF, but is still activelyadvising others on transport study issues.On 15 April SINTEF and NTNU hosted anhonorary seminar to mark Tore Knudsen’sretirement.

DearSubscriberof the NordicRoad &TransportResearch

Retired after more than 40 years

Dr. Tore Knudsen (Photo: SINTEF)

A salt spreader runs over the measuring field with plates.

Collecting container on weight cell.

Tine Damkjaer, DRD, Denmark, Krister Persson, Engineering CentreBygholm, Denmark

Contact: Tine Damkjaer, Engineer

The Danish Road Directorate, Ministry of Transport,

Copenhagen, Denmark, tida@vd.dk

Krister Persson, Cand agro.

Engineering Centre Bygholm Horsens, Denmark

krister.persson@agrsci.dk

under each funnel. When the materialbeing spread is moistened salt or brine, thequantity is determined by a conductibilitymeasurement, which has proven to be suf-ficiently accurate, and will be recommen-ded in order to achieve quick results.

The tests show that the distributionimage of a given spreader is narrower whenthe material is collected in the funnels atthe testing facility than it is in real life con-ditions. This is due to the fact that on a realroad, salt bounces towards the edge afterhitting the surface. To ensure as realisticconditions as possible, plates with a tarmac-like surface have been laid before and afterthe measurement field, so the materialbeing spread can bounce outwards. Theuse of such plates gave satisfactory results.

The spreading tests were conducted at dif-ferent speeds. In the beginning, the speed wasbetween 40 and 60 km/h, which correspondsto real life conditions. It has been decidedthat future tests will be conducted at 10 km/h,as this will ensure conditions that are easy toreproduce, and at the same time minimisethe risk of accidents during the tests.

Dosage testsDosage tests have been carried out by col-

Current status of the project is that thebasic aspects of test and measurement met-hods seem to be ready. These are some issu-es to be taken care of in the near future:• Establishing final requirements for

equipment/certification criteria• Preparing test protocols for certification

procedures.• Reviewing instruction manuals in order

to ensure that they are intelligible to thestaff using the equipment

• Developing procedures for testing GPS-guided spreaders.The first steps towards cooperation with

the other Nordic countries have beentaken. The aim is to develop common met-hods, as well as conducting common testsof equipment.

Through the magazine we wish continuously to supply you withthe latest results of the Nordic transport research. Now wewould greatly appreciate if you could help us to define the bestcurrent way to do it by filling this Reader Survey.

This year it is exactly twenty years since Nordic Road &Transport Research was published for the first time. A lot ofresearch done in the Nordic countries in the field of transportduring these years has, through the magazine, reached out toreaders all over the world.

As you know, the magazine is published as a paper issue aswell as on the website nordicroads.com. We now wish that youcould let us know which way of publishing you value most byanswering the reader survey you will find on the website

nordicroads.com.

Please, take some minute or two and let us know your opinion!Thank you!

The editorial board of the Nordic Road & Transport Research

NORDIC NO. 1 2010 | 54 | NORDIC NO. 1 2010 www.nordicroads.com

Determining the Spreading Accuracy of Equipment for Winter MaintenanceServices

The objective is to develop a method to document the ability of agiven salt spreader to achieve accurate dosage and distributionacross the road – for the sake of road safety, the environmentand the economy.

In the period from 2006 to 2009, the SaltSpreader Development Group of the

Danish Road Directorate worked on thedevelopment of methods to assess the useof spreading materials to maintain roadpassability in snow and ice conditions.

The SUG works in the context of the so-called Winter Committee, and consists of abroad range of representatives from theDanish Road Directorate, the local authori-ties and the Sund&Baelt Partner Ltd, withoccasional participants from the DanishAssociation of Consulting Engineers andthe private sector. The group’s objective isto make recommendations for require-ments for spreading equipment.

Besides establishing standards for dosa-ge and distribution accuracy, the groupaimed to develop methods to assess suchparameters. This was done in cooperationwith the University of Aarhus’ EngineeringCentre Bygholm (ECB) in Horsens. TheECB has Europe’s largest spreading labora-tory, and is built to meet the existing stan-dards for the test of commercial fertilizerspreaders used in agriculture.

Distribution and spreadingDistribution and spreading tests are car-ried out by collecting spread material infunnels situated across the path. When thematerial is dry salt, the amount spread isregistered by an electronic scale placed

lecting the salt, moistened salt or brinedirectly from the spreader, without anyspreading actually taking place. After beingcollected, the material has been registeredby an electronic scale. The results are mostaccurate when the spreading disc is notused, as this produces considerable vibra-tions that can be perceived as noise.Dosage tests are used to provide documen-tation of dosage precision and of theresponse time elapsed when changingfrom a dosage level to another. It is expec-ted that the actual dosage does not varymore than 6% in relation to the desiredamount.

The tests have been carried out with thematerials most commonly used in Denmark,i.e. vacuum salt, sea salt and mineral salt.

Criteria for test resultsThe criteria used to assess test results wereestablished with the purpose of ensuringmaximum coverage of the road surface andwere set up to reduce salt consumption ingeneral, and to reduce the amount of saltbeing spread outside the road, which is anunnecessary hazard to the environment. Thecriteria are still being discussed, but the gene-ral objective is to achieve an even distributionacross the whole width of the road with theleast possible loss to the surroundings.

A positive development in spreadingequipment has been noticed during thetest period. It is important, however, that afinal decision is made regarding these cri-teria so that all involved parties, such asequipment producers, have a goal for theirdevelopment work.

Determining the Spreading Accuracy of Equipment for Winter MaintenanceServices

After more than 40 years as one of the lea-ding experts in Norwegian transport plan-ning, Tore Knudsen has now retired and iswrapping up his professional career.Having earned a PhD in transportationplanning from the University of California,Berkley, he was a professor at theNorwegian Institute of Technology (NTH)from 1966-1980 and 1995-1996. Duringthe 1980s Knudsen was head of and lea-ding consultant for transport planning inthe consulting company Asplan. In 1996 hewas appointed head of the TransportResearch division at SINTEF.

His main professional interest has beenin transport modelling and cost-benefitanalysis. Many Norwegian transport plan-ners have had the privilege of experien-cing Tore Knudsen as an enthusiastic and

inspiring lecturer. He has now retired fromhis position at SINTEF, but is still activelyadvising others on transport study issues.On 15 April SINTEF and NTNU hosted anhonorary seminar to mark Tore Knudsen’sretirement.

DearSubscriberof the NordicRoad &TransportResearch

Retired after more than 40 years

Dr. Tore Knudsen (Photo: SINTEF)

A salt spreader runs over the measuring field with plates.

Collecting container on weight cell.

Tine Damkjaer, DRD, Denmark, Krister Persson, Engineering CentreBygholm, Denmark

Contact: Tine Damkjaer, Engineer

The Danish Road Directorate, Ministry of Transport,

Copenhagen, Denmark, tida@vd.dk

Krister Persson, Cand agro.

Engineering Centre Bygholm Horsens, Denmark

krister.persson@agrsci.dk

under each funnel. When the materialbeing spread is moistened salt or brine, thequantity is determined by a conductibilitymeasurement, which has proven to be suf-ficiently accurate, and will be recommen-ded in order to achieve quick results.

The tests show that the distributionimage of a given spreader is narrower whenthe material is collected in the funnels atthe testing facility than it is in real life con-ditions. This is due to the fact that on a realroad, salt bounces towards the edge afterhitting the surface. To ensure as realisticconditions as possible, plates with a tarmac-like surface have been laid before and afterthe measurement field, so the materialbeing spread can bounce outwards. Theuse of such plates gave satisfactory results.

The spreading tests were conducted at dif-ferent speeds. In the beginning, the speed wasbetween 40 and 60 km/h, which correspondsto real life conditions. It has been decidedthat future tests will be conducted at 10 km/h,as this will ensure conditions that are easy toreproduce, and at the same time minimisethe risk of accidents during the tests.

Dosage testsDosage tests have been carried out by col-

Current status of the project is that thebasic aspects of test and measurement met-hods seem to be ready. These are some issu-es to be taken care of in the near future:• Establishing final requirements for

equipment/certification criteria• Preparing test protocols for certification

procedures.• Reviewing instruction manuals in order

to ensure that they are intelligible to thestaff using the equipment

• Developing procedures for testing GPS-guided spreaders.The first steps towards cooperation with

the other Nordic countries have beentaken. The aim is to develop common met-hods, as well as conducting common testsof equipment.

Through the magazine we wish continuously to supply you withthe latest results of the Nordic transport research. Now wewould greatly appreciate if you could help us to define the bestcurrent way to do it by filling this Reader Survey.

This year it is exactly twenty years since Nordic Road &Transport Research was published for the first time. A lot ofresearch done in the Nordic countries in the field of transportduring these years has, through the magazine, reached out toreaders all over the world.

As you know, the magazine is published as a paper issue aswell as on the website nordicroads.com. We now wish that youcould let us know which way of publishing you value most byanswering the reader survey you will find on the website

nordicroads.com.

Please, take some minute or two and let us know your opinion!Thank you!

The editorial board of the Nordic Road & Transport Research

6 | NORDIC NO. 1 2010 www.nordicroads.com NORDIC NO. 1 2010 | 7

facing owing to fatigue, and a lower risk ofdeformations.

The sections are also inspected visuallywith respect to cracking and other damagesuch as loose aggregates.

Laboratory experimentsParallel with the measurements made on thedifferent observation sections, in the form of

measurements of different surface proper-ties, laboratory analyses have also been per-formed on cores drilled on various occa-sions. It was mainly functional propertiesthat were analysed, but the thickness of cour-ses and voids ratios have also been determi-ned on all cores to provide background data.On bitumen recovered from the cores, rela-tively comprehensive studies of both traditio-

nal and functional properties have also beenmade. Some preliminary tests were alsomade initially, inter alia in the VTI circularroad simulator with respect to wear resistan-ce, in order to verify that the surfacings satis-fy the requirements.

The Swedish road network has graduallybeen subjected to increasing loads. Most

newly constructed roads in Sweden havebitumen pavements but some also haveconcrete pavements. For a comparison ofthe different constructions in a long-termperspective, European route E6 to the northof Halmstad was constructed as a test roadwhen it was upgraded to motorway standard.

Test roadWhen E6 was converted into a motorway,the Fastarp-Heberg setion was constructedas a test road with pavements of differentstructural design. VTI was commissionedby the Swedish Road Administration todocument the construction and to monitorthe changes in condition on the 19 diffe-rent observation sections. The test roadwhich has a total length of 21 km, one thirdof which has a bituminous surfacing andtwo thirds a cement concrete surfacing, wasopened to traffic in the autumn of 1996.

Apart from rutting, longitudinal evennessand the properties of the different wearingcourses were studied, with the intention tohighlight the differences between the diffe-rent pavements with regard to stability, rutwear, deformation resistance, maintenancecosts, friction and noise.

High traffic load over 10 yearsOver a period of ten years, 1996–2006, VTIhas monitored the condition of the differentpavement types which are designed to stand

Which Pavement Lasts Longest?

up to what is a high traffic load for Swedishconditions. The evaluation shows, inter alia,that pavements with concrete surfacing havegood wear resistance and thus good resistan-ce to rutting. As regards friction and noise,there is little difference between bitumenand concrete surfacings.

Changes have been monitored by acomprehensive measurement programmewith the emphasis on measuring the trans-verse profile of the road. Other surfaceproperties which have been measured arefriction, surface evenness and noise. Thestructural condition of the observation sec-tions has been monitored by falling weightmeasurements and visual inspection of thecondition of the sections with regard todamage. Other parameters which havebeen measured are temperature, trafficand the use of studded tyres.

Transverse profile measurementsThe transverse profile has been measuredusing two different equipments, the laserprofilometer Primal and a RST (RoadSurface Tester) vehicle.

The laser profilometer Primal measuresthe profile of the surface by means of a wheelmounted on a self propelled carriage whichmeasures the distance between the measu-ring wheel and a laser plane. Measurementswith Primal were made both in spring andautumn, a total of 20 measurements.

The most recent transverse profile measu-rement showed that, after ten years’ traffic,there is still little rutting on the concrete sec-tions. The rutting found on the concrete sec-tions has been caused by studded tyre wear.

Rut depth measurements have also been

made with Laser RST on eight occasions.RST measures surface regularity both lon-gitudinally and transversely, roughness ofthe surface and road gradient at the speedof traffic.

Stud wear is measured with a special laserprofilometer, Primal, developed by VTI,which measures the transverse profile of theroad over one metre long sections. The laserprofilometer is fixed to the wearing courseby fixtures installed in the metre sectionconcerned. The surface is measured in theautumn and spring with high precision, andthe difference between the profile measu-red in the autumn and spring correspondsto the amount of surfacing abrasion wornaway by studded traffic in the winter.

FrictionFriction has been measured on all observa-tion sections with the VTI Saab FrictionTester. Measurements have been made in thespring and autumn at a speed of 70 km/h onan irrigated surface. On all sections exceptone, friction improved during the first winter.

The pavementThe structural condition of the test sec-tions has been documented through loadtests with a Falling Weight Deflectometerand visual inspections.

For measurements in and between theruts, the VTI falling weight deflectometerhas applied a load of 50 kN . The valuesgive an indication of the deflectometerstiffness of the pavement and of the elasticproperties of the subsoil. Generally spea-king, lower values indicate better condi-tions, i.e. a lower risk of cracking in the sur-

There is a large number of different road pavements today, allwith different capacities to stand up to rutting due to abrasion bystudded tyres and deformation caused by heavy traffic. For futureplanning and investments in technical solutions that are correctfor the purpose, the different pavements must be evaluated. Tomake measurements on a road and evaluate its qualities, it isnecessary to have recourse to a large number of different met-hods, an area where VTI has made a lot of progress.

Contact: Leif Viman, leif.viman@vti.se

Bengt-Åke Hultqvist, bengt-ake.hultqvist@vti.se

Facts: The R&D programme “Environmentally

Friendly Pavements” of the Norwegian Public

Roads Administration (NPRA) was conducted by

the Road technology section of the Technology

Department in Trondheim during the period 2004-

2009 in close collaboration with other units within

the NPRA and external partners.

This article is based on the final programme

report: Statens vegvesen, Teknologirapport nr.

2578

Contact person: Jostein Aksnes. E-mail:

jostein.aksnes@vegvesen.no

Read more: www.vegvesen.no/Miljovegdekke

(Download English report under <Sluttrapporter fra

prosjektet>)

Magdalena Green,VTI, Sweden

PHOTO: VTI

Environmentally Friendly Pavementsin Norway

Results from five years of research and development in Norwayon how to reduce tyre noise and dust emissions from road trafficare now available in the final report from the EnvironmentallyFriendly Pavements programme.

The Environmentally Friendly Pavementsprogramme was conducted by the

Norwegian Public Roads Administration(NPRA) during the period 2004–2009 inclose collaboration with research institu-tions and the road industry. The mainfocus of the programme was to optimisethe environmental properties of road sur-faces with respect to low road tyre noiseand road dust emissions. The researchresults show that:• The noise level of new low noise asphalt

pavements is 3–9 dB(A) lower than thereference (SMA11, older than oneyear).

• The noise reducing effect decreasesrelatively rapidly for all types of pave-ments that have been investigated. Theannual increase in noise levels measu-red on Norwegian pavements is conside-rably higher than what is reported froma number of other countries. Thisincrease is particularly great during thefirst winter. Natural explanations for thisphenomenon are the wear from stud-ded tires and their influence on thepavement surface texture.

• The friction levels of environmentallyfriendly pavements do not differ from

traditional asphalt types and do notrequire special attention with respect towinter operations. Porous asphalt pave-ments most likely have better frictionproperties than traditional asphalts.

• It is difficult to develop pavements withconsiderably higher wear resistancethan those we have today without com-promising other important propertiessuch as stability and friction. However,through adjusted requirements formaterial quality and mix design, it ispossible to maintain the durability oflow noise pavement alternatives.Thin asphalt layers yielded the most

promising results in the cost-benefit analy-sis. Experience from other countries indi-cates that there is a potential for develo-ping more durable thin layers with longerlasting noise reducing properties than whathas been achieved in the field tests in thisprogramme. Those types of low noise pave-ments should be regarded as a good alter-native where the conditions are favourable.

Traditional asphalt pavements (SMAand AC) with reduced aggregate uppersieve size (8 mm or less) also have favou-rable properties with respect to noise. Thecost-benefit ratio is not quite as good as forthe thin asphalt layers because of the limi-ted wear resistance and the generation ofdust. However, with more focus on optimi-sing the wear resistance of this type ofmixes (better quality of fine aggregates,

polymer modified binder, optimum mixcomposition) the applicability of thesepavements may be increased, in particularin areas with a low percentage of cars withstudded tyres in the winter.

Restricted use of porous pavements isrecommended. Experience with their useunder Norwegian climate and traffic con-ditions is still very limited. Clogging of thepores is still considered to be a problem.The cleaning of porous surfaces with theequipment that is currently available is notvery efficient. Another negative factor forporous pavements is the limitations in theirapplicability. The volume of porous pave-ments is likely to be quite small for manyyears, making it difficult for contractors todevelop the special workmanship that isrequired to ensure a porous asphalt ofgood quality.

Jostein Aksnes, NPRA, NorwayRagnar Evensen, ViaNova Plan og Trafikk AS

6 | NORDIC NO. 1 2010 www.nordicroads.com NORDIC NO. 1 2010 | 7

facing owing to fatigue, and a lower risk ofdeformations.

The sections are also inspected visuallywith respect to cracking and other damagesuch as loose aggregates.

Laboratory experimentsParallel with the measurements made on thedifferent observation sections, in the form of

measurements of different surface proper-ties, laboratory analyses have also been per-formed on cores drilled on various occa-sions. It was mainly functional propertiesthat were analysed, but the thickness of cour-ses and voids ratios have also been determi-ned on all cores to provide background data.On bitumen recovered from the cores, rela-tively comprehensive studies of both traditio-

nal and functional properties have also beenmade. Some preliminary tests were alsomade initially, inter alia in the VTI circularroad simulator with respect to wear resistan-ce, in order to verify that the surfacings satis-fy the requirements.

The Swedish road network has graduallybeen subjected to increasing loads. Most

newly constructed roads in Sweden havebitumen pavements but some also haveconcrete pavements. For a comparison ofthe different constructions in a long-termperspective, European route E6 to the northof Halmstad was constructed as a test roadwhen it was upgraded to motorway standard.

Test roadWhen E6 was converted into a motorway,the Fastarp-Heberg setion was constructedas a test road with pavements of differentstructural design. VTI was commissionedby the Swedish Road Administration todocument the construction and to monitorthe changes in condition on the 19 diffe-rent observation sections. The test roadwhich has a total length of 21 km, one thirdof which has a bituminous surfacing andtwo thirds a cement concrete surfacing, wasopened to traffic in the autumn of 1996.

Apart from rutting, longitudinal evennessand the properties of the different wearingcourses were studied, with the intention tohighlight the differences between the diffe-rent pavements with regard to stability, rutwear, deformation resistance, maintenancecosts, friction and noise.

High traffic load over 10 yearsOver a period of ten years, 1996–2006, VTIhas monitored the condition of the differentpavement types which are designed to stand

Which Pavement Lasts Longest?

up to what is a high traffic load for Swedishconditions. The evaluation shows, inter alia,that pavements with concrete surfacing havegood wear resistance and thus good resistan-ce to rutting. As regards friction and noise,there is little difference between bitumenand concrete surfacings.

Changes have been monitored by acomprehensive measurement programmewith the emphasis on measuring the trans-verse profile of the road. Other surfaceproperties which have been measured arefriction, surface evenness and noise. Thestructural condition of the observation sec-tions has been monitored by falling weightmeasurements and visual inspection of thecondition of the sections with regard todamage. Other parameters which havebeen measured are temperature, trafficand the use of studded tyres.

Transverse profile measurementsThe transverse profile has been measuredusing two different equipments, the laserprofilometer Primal and a RST (RoadSurface Tester) vehicle.

The laser profilometer Primal measuresthe profile of the surface by means of a wheelmounted on a self propelled carriage whichmeasures the distance between the measu-ring wheel and a laser plane. Measurementswith Primal were made both in spring andautumn, a total of 20 measurements.

The most recent transverse profile measu-rement showed that, after ten years’ traffic,there is still little rutting on the concrete sec-tions. The rutting found on the concrete sec-tions has been caused by studded tyre wear.

Rut depth measurements have also been

made with Laser RST on eight occasions.RST measures surface regularity both lon-gitudinally and transversely, roughness ofthe surface and road gradient at the speedof traffic.

Stud wear is measured with a special laserprofilometer, Primal, developed by VTI,which measures the transverse profile of theroad over one metre long sections. The laserprofilometer is fixed to the wearing courseby fixtures installed in the metre sectionconcerned. The surface is measured in theautumn and spring with high precision, andthe difference between the profile measu-red in the autumn and spring correspondsto the amount of surfacing abrasion wornaway by studded traffic in the winter.

FrictionFriction has been measured on all observa-tion sections with the VTI Saab FrictionTester. Measurements have been made in thespring and autumn at a speed of 70 km/h onan irrigated surface. On all sections exceptone, friction improved during the first winter.

The pavementThe structural condition of the test sec-tions has been documented through loadtests with a Falling Weight Deflectometerand visual inspections.

For measurements in and between theruts, the VTI falling weight deflectometerhas applied a load of 50 kN . The valuesgive an indication of the deflectometerstiffness of the pavement and of the elasticproperties of the subsoil. Generally spea-king, lower values indicate better condi-tions, i.e. a lower risk of cracking in the sur-

There is a large number of different road pavements today, allwith different capacities to stand up to rutting due to abrasion bystudded tyres and deformation caused by heavy traffic. For futureplanning and investments in technical solutions that are correctfor the purpose, the different pavements must be evaluated. Tomake measurements on a road and evaluate its qualities, it isnecessary to have recourse to a large number of different met-hods, an area where VTI has made a lot of progress.

Contact: Leif Viman, leif.viman@vti.se

Bengt-Åke Hultqvist, bengt-ake.hultqvist@vti.se

Facts: The R&D programme “Environmentally

Friendly Pavements” of the Norwegian Public

Roads Administration (NPRA) was conducted by

the Road technology section of the Technology

Department in Trondheim during the period 2004-

2009 in close collaboration with other units within

the NPRA and external partners.

This article is based on the final programme

report: Statens vegvesen, Teknologirapport nr.

2578

Contact person: Jostein Aksnes. E-mail:

jostein.aksnes@vegvesen.no

Read more: www.vegvesen.no/Miljovegdekke

(Download English report under <Sluttrapporter fra

prosjektet>)

Magdalena Green,VTI, Sweden

PHOTO: VTI

Environmentally Friendly Pavementsin Norway

Results from five years of research and development in Norwayon how to reduce tyre noise and dust emissions from road trafficare now available in the final report from the EnvironmentallyFriendly Pavements programme.

The Environmentally Friendly Pavementsprogramme was conducted by the

Norwegian Public Roads Administration(NPRA) during the period 2004–2009 inclose collaboration with research institu-tions and the road industry. The mainfocus of the programme was to optimisethe environmental properties of road sur-faces with respect to low road tyre noiseand road dust emissions. The researchresults show that:• The noise level of new low noise asphalt

pavements is 3–9 dB(A) lower than thereference (SMA11, older than oneyear).

• The noise reducing effect decreasesrelatively rapidly for all types of pave-ments that have been investigated. Theannual increase in noise levels measu-red on Norwegian pavements is conside-rably higher than what is reported froma number of other countries. Thisincrease is particularly great during thefirst winter. Natural explanations for thisphenomenon are the wear from stud-ded tires and their influence on thepavement surface texture.

• The friction levels of environmentallyfriendly pavements do not differ from

traditional asphalt types and do notrequire special attention with respect towinter operations. Porous asphalt pave-ments most likely have better frictionproperties than traditional asphalts.

• It is difficult to develop pavements withconsiderably higher wear resistancethan those we have today without com-promising other important propertiessuch as stability and friction. However,through adjusted requirements formaterial quality and mix design, it ispossible to maintain the durability oflow noise pavement alternatives.Thin asphalt layers yielded the most

promising results in the cost-benefit analy-sis. Experience from other countries indi-cates that there is a potential for develo-ping more durable thin layers with longerlasting noise reducing properties than whathas been achieved in the field tests in thisprogramme. Those types of low noise pave-ments should be regarded as a good alter-native where the conditions are favourable.

Traditional asphalt pavements (SMAand AC) with reduced aggregate uppersieve size (8 mm or less) also have favou-rable properties with respect to noise. Thecost-benefit ratio is not quite as good as forthe thin asphalt layers because of the limi-ted wear resistance and the generation ofdust. However, with more focus on optimi-sing the wear resistance of this type ofmixes (better quality of fine aggregates,

polymer modified binder, optimum mixcomposition) the applicability of thesepavements may be increased, in particularin areas with a low percentage of cars withstudded tyres in the winter.

Restricted use of porous pavements isrecommended. Experience with their useunder Norwegian climate and traffic con-ditions is still very limited. Clogging of thepores is still considered to be a problem.The cleaning of porous surfaces with theequipment that is currently available is notvery efficient. Another negative factor forporous pavements is the limitations in theirapplicability. The volume of porous pave-ments is likely to be quite small for manyyears, making it difficult for contractors todevelop the special workmanship that isrequired to ensure a porous asphalt ofgood quality.

Jostein Aksnes, NPRA, NorwayRagnar Evensen, ViaNova Plan og Trafikk AS

NORDIC NO. 1 2010 | 98 | NORDIC NO. 1 2010 www.nordicroads.com

ROAD SURFACE

Persuade – a New EU Noise Project

In September 2009 a new EU project oninnovative noise reducing road pave-

ments started. Representatives from twelveEuropean research institutes and compa-nies met for a kickoff meeting at theBelgian Road Research Laboratory(BRRC). BRRC has the role to coordinatethis new project which has been namedPERSUADE, an abbreviation for”Poroelastic Road Surface: an innovationto avoid damages to the environment”.

Concept and purposeThe main purpose of PERSUADE is todevelop and test new road pavements withvery high noise-reducing effect. The pave-ments will be based on an aggregate of rub-ber material instead of the traditionalstone aggregates; they will also be designedwith a high proportion of air voids. The airvoids will make the pavement porous,which in combination with the elastic rub-ber granules will make it flexible, both ofwhich contribute to reduce noise from thetyre/road contact. By using rubber granu-late from used vehicle tyres, the environ-mental aim of the project is two-fold: toreduce noise from road traffic and at thesame time to give a considerable amount of

used tyres in Europe a second lifecycle.The final mixtures produced in PERSUA-DE might include also a certain amount ofsand or stone aggregate; mainly to increasefriction. The EU Commission and its pro-ject reviewers found this so interesting thata support of 3.4 million euros was obtainedfor this project in hard competition withother project proposals.

The poroelastic road surface is original-ly a Swedish invention from the 1970swhich was tried in Sweden in the 1980s, butwithout success. The Japanese adopted theconcept in the 1990s and started compre-hensive research which still goes on afterabout 15 years. In 2000–2005 VTI conduc-ted a project, sponsored mainly byVinnova, which was similar to PERSUADEbut was of a much smaller scale [1]. Thisproject ended with a test of three poroelas-tic materials on a street in Stockholm,which failed due to break-up of the tooweak asphalt under the rubber surface.Before this happened, people were enthu-siastic about the dramatic noise reductionexperienced on the street. The experiencefrom the VTI and the Japanese projectsnow constitute the basic level from whichPERSUADE starts. When the Swedish andJapanese activities were most intensive, in2000–2005, several common workshopswere organized and one or two study tripswere made each year; these continuedannually after 2005. In 2005 also peoplefrom the Danish Road Institute took partin a study tour to Japan [2].

The purpose of the PERSUADE projectis to develop and test poroelastic materials,first in the laboratories, later on roadsunder traffic. The pavements shall providesubstantial noise reduction and acceptableoperation over a reasonable lifetime, whileat the same time, meet requirements onfriction and other traffic safety issues.Some might suspect that a flexible pave-ment might cause much higher rolling resi-stance and thus energy consumption andCO2 emissions but, in fact, it is hoped thatlow losses in the material will provide simi-lar rolling resistance as conventionalasphalt, and in the best case even reducethe rolling resistance.

In the first instance, the poroelasticroad surfaces will primarily be consideredfor use on ”black spots”, which is the termused for limited areas where noise exposu-re is very high, and where it is not possibleor desirable to use noise barriers etc.

Performing the projectThe project will run for six years. This isunusually long for an EU project but makesit possible in the first years to work on deve-lopment and testing of new materials in thelaboratory after which full-scale tests of thenew pavements will be carried out. It is theintention to test pavements in fiveEuropean countries, including Denmarkand Sweden. The materials and the layingprocesses might vary between the countriesand in Sweden special concerns apply forsevere winter conditions. A comprehensive

measuring programme will be set up whichwill include noise, friction, rolling resistan-ce, etc. Furthermore, cost-benefit analyseswill be carried out where poroelastic roadsurfaces will be compared to other ”tradi-tional” types of noise reduction measures,such as façade insulation and ”conventio-nal” noise-reducing pavements. Life cycleanalyses will also be included.

From Denmark, the Road Directorate,Danish Road Institute and NCC Roads willtake part in the PERSUADE project andfrom Sweden the partner is VTI. Recently,a state-of-the-art report was prepared byVTI and BRRC [3], which can be downloa-ded from the project website. The PER-SUADE website [4] will present the resultsfrom the project and some other relevantinformation and will be updated frequent-ly during the entire project.

References1. Sandberg, Ulf; Kalman, Björn (2005): "The

Poroelastic Road Surface – Results of an Ex-peri-

ment in Stockholm". Proceedings of the Forum

Acusticum 2005 conference in Budapest,

Hungary, August 2005.

2. "Noise reducing pavements in Japan. Study Tour

Report". Notat 31, 2005. Road Directorate,

Danish Road Institute. See www.vd.dk

Figure 1: Overview of poroelastic road surface testsections laid in Stockholm in 2004, which gavetyre/road noise reductions of 10 dB(A) [1]. In the win-ter, the old asphalt pavement onto which the rubberpavement was glued separated from a lower asphaltlayer, forcing the experiment to finish.

Figure 2: Overview of poroelastic road surface laid in Mie in Japan in 2004. This experiment had to be interrup-ted when, a few months later, wet friction failed to meet the Japanese standard.

"Development and testing of poroelastic road pavements withhigh noise reductions without sacrificing safety and durability arethe challenges in the EU project PERSUADE"

Tine Damkjær, Danish Road Directorate,DenmarkHans Bendtsen, Danish RoadDirectorate, Danish Road Institute DRI,Ulf Sanberg, VTI, Sweden

3. Sandberg, Ulf; Goubert, Luc; Biligiri, Krishna;

Kalman, Björn (2010): "State-of-the-art regar-

ding poroelastic road surfaces". Deliverable

D8.1, available for download on the PERSUADE

website; see [4].

4. The PERSUADE website; see

http://persuade.eu.com or http://persuade-

project.eu (both addresses work equally well).

Contact:Hans Bendtsen, hbe@vd.dk

Read more:http://persuade.fehrl.org/

NORDIC NO. 1 2010 | 98 | NORDIC NO. 1 2010 www.nordicroads.com

ROAD SURFACE

Persuade – a New EU Noise Project

In September 2009 a new EU project oninnovative noise reducing road pave-

ments started. Representatives from twelveEuropean research institutes and compa-nies met for a kickoff meeting at theBelgian Road Research Laboratory(BRRC). BRRC has the role to coordinatethis new project which has been namedPERSUADE, an abbreviation for”Poroelastic Road Surface: an innovationto avoid damages to the environment”.

Concept and purposeThe main purpose of PERSUADE is todevelop and test new road pavements withvery high noise-reducing effect. The pave-ments will be based on an aggregate of rub-ber material instead of the traditionalstone aggregates; they will also be designedwith a high proportion of air voids. The airvoids will make the pavement porous,which in combination with the elastic rub-ber granules will make it flexible, both ofwhich contribute to reduce noise from thetyre/road contact. By using rubber granu-late from used vehicle tyres, the environ-mental aim of the project is two-fold: toreduce noise from road traffic and at thesame time to give a considerable amount of

used tyres in Europe a second lifecycle.The final mixtures produced in PERSUA-DE might include also a certain amount ofsand or stone aggregate; mainly to increasefriction. The EU Commission and its pro-ject reviewers found this so interesting thata support of 3.4 million euros was obtainedfor this project in hard competition withother project proposals.

The poroelastic road surface is original-ly a Swedish invention from the 1970swhich was tried in Sweden in the 1980s, butwithout success. The Japanese adopted theconcept in the 1990s and started compre-hensive research which still goes on afterabout 15 years. In 2000–2005 VTI conduc-ted a project, sponsored mainly byVinnova, which was similar to PERSUADEbut was of a much smaller scale [1]. Thisproject ended with a test of three poroelas-tic materials on a street in Stockholm,which failed due to break-up of the tooweak asphalt under the rubber surface.Before this happened, people were enthu-siastic about the dramatic noise reductionexperienced on the street. The experiencefrom the VTI and the Japanese projectsnow constitute the basic level from whichPERSUADE starts. When the Swedish andJapanese activities were most intensive, in2000–2005, several common workshopswere organized and one or two study tripswere made each year; these continuedannually after 2005. In 2005 also peoplefrom the Danish Road Institute took partin a study tour to Japan [2].

The purpose of the PERSUADE projectis to develop and test poroelastic materials,first in the laboratories, later on roadsunder traffic. The pavements shall providesubstantial noise reduction and acceptableoperation over a reasonable lifetime, whileat the same time, meet requirements onfriction and other traffic safety issues.Some might suspect that a flexible pave-ment might cause much higher rolling resi-stance and thus energy consumption andCO2 emissions but, in fact, it is hoped thatlow losses in the material will provide simi-lar rolling resistance as conventionalasphalt, and in the best case even reducethe rolling resistance.

In the first instance, the poroelasticroad surfaces will primarily be consideredfor use on ”black spots”, which is the termused for limited areas where noise exposu-re is very high, and where it is not possibleor desirable to use noise barriers etc.

Performing the projectThe project will run for six years. This isunusually long for an EU project but makesit possible in the first years to work on deve-lopment and testing of new materials in thelaboratory after which full-scale tests of thenew pavements will be carried out. It is theintention to test pavements in fiveEuropean countries, including Denmarkand Sweden. The materials and the layingprocesses might vary between the countriesand in Sweden special concerns apply forsevere winter conditions. A comprehensive

measuring programme will be set up whichwill include noise, friction, rolling resistan-ce, etc. Furthermore, cost-benefit analyseswill be carried out where poroelastic roadsurfaces will be compared to other ”tradi-tional” types of noise reduction measures,such as façade insulation and ”conventio-nal” noise-reducing pavements. Life cycleanalyses will also be included.

From Denmark, the Road Directorate,Danish Road Institute and NCC Roads willtake part in the PERSUADE project andfrom Sweden the partner is VTI. Recently,a state-of-the-art report was prepared byVTI and BRRC [3], which can be downloa-ded from the project website. The PER-SUADE website [4] will present the resultsfrom the project and some other relevantinformation and will be updated frequent-ly during the entire project.

References1. Sandberg, Ulf; Kalman, Björn (2005): "The

Poroelastic Road Surface – Results of an Ex-peri-

ment in Stockholm". Proceedings of the Forum

Acusticum 2005 conference in Budapest,

Hungary, August 2005.

2. "Noise reducing pavements in Japan. Study Tour

Report". Notat 31, 2005. Road Directorate,

Danish Road Institute. See www.vd.dk

Figure 1: Overview of poroelastic road surface testsections laid in Stockholm in 2004, which gavetyre/road noise reductions of 10 dB(A) [1]. In the win-ter, the old asphalt pavement onto which the rubberpavement was glued separated from a lower asphaltlayer, forcing the experiment to finish.

Figure 2: Overview of poroelastic road surface laid in Mie in Japan in 2004. This experiment had to be interrup-ted when, a few months later, wet friction failed to meet the Japanese standard.

"Development and testing of poroelastic road pavements withhigh noise reductions without sacrificing safety and durability arethe challenges in the EU project PERSUADE"

Tine Damkjær, Danish Road Directorate,DenmarkHans Bendtsen, Danish RoadDirectorate, Danish Road Institute DRI,Ulf Sanberg, VTI, Sweden

3. Sandberg, Ulf; Goubert, Luc; Biligiri, Krishna;

Kalman, Björn (2010): "State-of-the-art regar-

ding poroelastic road surfaces". Deliverable

D8.1, available for download on the PERSUADE

website; see [4].

4. The PERSUADE website; see

http://persuade.eu.com or http://persuade-

project.eu (both addresses work equally well).

Contact:Hans Bendtsen, hbe@vd.dk

Read more:http://persuade.fehrl.org/

NORDIC NO. 1 2010 | 1110 | NORDIC NO. 1 2010 www.nordicroads.com

ROAD SURFACE

The production and laying of hot bitumi-nous mixtures is an expensive and pre-

cise process that demands that great care istaken at all stages. It is therefore importantto have knowledge of the raw materials andthe predicted ability of the mixtures toendure external forces on the surface ofthe road.

The Icelandic Innovation Center hasrecently received new equipment to mea-sure properties of bituminous mixtures.This includes a new roller compactor tomake sample plates, a wheel track machine(small device) to measure deformation,and a Prall machine to measure abrasionfrom studded tires. Testing of bituminousmixtures has in the past been mostly limi-ted to the much debated Marshall stabilitymethod and the Icelandic asphalt industryhas relied on traditional receipts, develo-ped in the past or imported from otherNordic countries.

Now, after the implementation of theEuropean Standards for bituminous mixtu-res, the Icelandic Road Administration(ICERA) will switch over to the new testmethods in their road guidelines, as well asreplace old requirements with new ones

for different asphalt types. It is thereforeimportant to gain experience with the newtest methods by testing the traditional mix-tures as well as designing and testing newand improved mixtures.

New test methods – new requirementsThe Innovation Center is working on seve-ral research projects concerning hot mixasphalt. Deformation and abrasion proper-ties of traditional mixtures have been mea-sured, both on laboratory compacted sam-ples and on sample plates from the roadsurface. Also, mixtures that have not beenin use in Iceland can be tested and develo-ped, i.e. mixtures with different aggregategrading and filler types, different pavinggrade (PG) of bitumen, new additives suchas polymer modification, wax, etc. Theresults in the long run will be reflected inlonger lasting pavements with all theadvantages involved; less maintenance andrehabilitation, less pollution, less use of rawmaterial and more comfort for the driversand passengers.

The Icelandic Road Administration,Municipality of Reykjavik and two asphaltplants have supported the purchase ofnecessary machinery and the researchfund of the Icelandic Road Administrationsupports the present research projects.

Is dust from bituminous surfacingsoverestimated?The airborne dust in urban areas with hightraffic rate is of increasing concern. It hasbeen rightfully stated that abrasion fromstudded tires is the major cause for the pro-duction of harmful airborne dust. On theother hand, when estimating the quantityof dust from various sources, the total rutdepth of wheel tracks has been consideredto be entirely caused by abrasion. This ishowever not always the case and it has beendemonstrated that deformation on hotsummer days does occur. Harmful dustestimations should therefore take summerdeformation into account, but wheel tracktesting indicates that deformation of tradi-tional Icelandic asphalt mixtures couldprove to be considerable.

External changes and new materialsWith time, many parameters affectingasphalt pavement behavior and durabilityhave changed. The total traffic load isincreasing and heavy vehicle loads and airpressure in tires have also increased. Thetype of studs in studded tires and propor-tional use of such tires has also changedwith time. Moreover, there are indicationsof changes in the weather, including hightemperature records on warm summerdays, which may add to the deformation of

Pétur Pétursson,Innovation Center Iceland

Research opportunities with new European test methods and tes-ting equipment.

Contact:Pétur Pétursson

E-mail: petur.p@nmi.is

Arnpór Óli Arason

E-mail: arnthor.a@nmi.is

Read more: Two interim reports (in Icelandic) have

been published, see

http://www.nmi.is/files/NMIS0905_188551803.pdf

and

http://www.nmi.is/files/NMÍS1002_972470607.pdf

A New Approach in Research on Bituminous Mixtures

traditional asphalt mixtures in asphalt sur-facings. Additionally, the identification ofharmful airborne dust from pavements isrelatively recent and was not of much con-cern some decades ago. In fact, it can bereasoned that in the old days, when asphal-tic surfacings took over and dusty gravelstreets disappeared, everyone was veryhappy to get rid of the dust.

It is normal that changes occur withtime in our environment, such as trafficrelated factors and climatic changes, butalso new technology, development and newmaterials are being introduced. All thesechanges call for development and re-eva-luation of receipts for bituminous mixtu-

res, where both resistance to deformationand abrasion will be optimized.

It should not be forgotten that some 30years ago, the results from extensive andsuccessful research projects were used toset up the traditional receipts for asphaltconcrete in Iceland. Later stone masticasphalt was introduced to the market, alsoin a successful way. Those receipts have ser-ved well in the Reykjavik area, at least whilethe traffic rate and volume were less thantoday.

Research and implementationIceland, as well as many other Europeancountries, is currently in the process of

implementing harmonized European testmethods and product standards for bitumi-nous mixtures. The Innovation Center isnow well prepared to take part in interna-tional research projects on the propertiesof bituminous mixtures. An informalNordic technical mirror group forEuropean standards in the field of bitumi-nous mixtures does exist, and may proof tobe a good scientific platform for ideas con-cerning research needs and areas.

The author with the new wheel trackingmachine (left) and roller compactor (right).

Sawn section through sample plates which have beentested in the wheel tracking machine.

A close-up of the Prall abrasion machine.

l

NORDIC NO. 1 2010 | 1110 | NORDIC NO. 1 2010 www.nordicroads.com

ROAD SURFACE

The production and laying of hot bitumi-nous mixtures is an expensive and pre-

cise process that demands that great care istaken at all stages. It is therefore importantto have knowledge of the raw materials andthe predicted ability of the mixtures toendure external forces on the surface ofthe road.

The Icelandic Innovation Center hasrecently received new equipment to mea-sure properties of bituminous mixtures.This includes a new roller compactor tomake sample plates, a wheel track machine(small device) to measure deformation,and a Prall machine to measure abrasionfrom studded tires. Testing of bituminousmixtures has in the past been mostly limi-ted to the much debated Marshall stabilitymethod and the Icelandic asphalt industryhas relied on traditional receipts, develo-ped in the past or imported from otherNordic countries.

Now, after the implementation of theEuropean Standards for bituminous mixtu-res, the Icelandic Road Administration(ICERA) will switch over to the new testmethods in their road guidelines, as well asreplace old requirements with new ones

for different asphalt types. It is thereforeimportant to gain experience with the newtest methods by testing the traditional mix-tures as well as designing and testing newand improved mixtures.

New test methods – new requirementsThe Innovation Center is working on seve-ral research projects concerning hot mixasphalt. Deformation and abrasion proper-ties of traditional mixtures have been mea-sured, both on laboratory compacted sam-ples and on sample plates from the roadsurface. Also, mixtures that have not beenin use in Iceland can be tested and develo-ped, i.e. mixtures with different aggregategrading and filler types, different pavinggrade (PG) of bitumen, new additives suchas polymer modification, wax, etc. Theresults in the long run will be reflected inlonger lasting pavements with all theadvantages involved; less maintenance andrehabilitation, less pollution, less use of rawmaterial and more comfort for the driversand passengers.

The Icelandic Road Administration,Municipality of Reykjavik and two asphaltplants have supported the purchase ofnecessary machinery and the researchfund of the Icelandic Road Administrationsupports the present research projects.

Is dust from bituminous surfacingsoverestimated?The airborne dust in urban areas with hightraffic rate is of increasing concern. It hasbeen rightfully stated that abrasion fromstudded tires is the major cause for the pro-duction of harmful airborne dust. On theother hand, when estimating the quantityof dust from various sources, the total rutdepth of wheel tracks has been consideredto be entirely caused by abrasion. This ishowever not always the case and it has beendemonstrated that deformation on hotsummer days does occur. Harmful dustestimations should therefore take summerdeformation into account, but wheel tracktesting indicates that deformation of tradi-tional Icelandic asphalt mixtures couldprove to be considerable.

External changes and new materialsWith time, many parameters affectingasphalt pavement behavior and durabilityhave changed. The total traffic load isincreasing and heavy vehicle loads and airpressure in tires have also increased. Thetype of studs in studded tires and propor-tional use of such tires has also changedwith time. Moreover, there are indicationsof changes in the weather, including hightemperature records on warm summerdays, which may add to the deformation of

Pétur Pétursson,Innovation Center Iceland

Research opportunities with new European test methods and tes-ting equipment.

Contact:Pétur Pétursson

E-mail: petur.p@nmi.is

Arnpór Óli Arason

E-mail: arnthor.a@nmi.is

Read more: Two interim reports (in Icelandic) have

been published, see

http://www.nmi.is/files/NMIS0905_188551803.pdf

and

http://www.nmi.is/files/NMÍS1002_972470607.pdf

A New Approach in Research on Bituminous Mixtures

traditional asphalt mixtures in asphalt sur-facings. Additionally, the identification ofharmful airborne dust from pavements isrelatively recent and was not of much con-cern some decades ago. In fact, it can bereasoned that in the old days, when asphal-tic surfacings took over and dusty gravelstreets disappeared, everyone was veryhappy to get rid of the dust.

It is normal that changes occur withtime in our environment, such as trafficrelated factors and climatic changes, butalso new technology, development and newmaterials are being introduced. All thesechanges call for development and re-eva-luation of receipts for bituminous mixtu-

res, where both resistance to deformationand abrasion will be optimized.

It should not be forgotten that some 30years ago, the results from extensive andsuccessful research projects were used toset up the traditional receipts for asphaltconcrete in Iceland. Later stone masticasphalt was introduced to the market, alsoin a successful way. Those receipts have ser-ved well in the Reykjavik area, at least whilethe traffic rate and volume were less thantoday.

Research and implementationIceland, as well as many other Europeancountries, is currently in the process of

implementing harmonized European testmethods and product standards for bitumi-nous mixtures. The Innovation Center isnow well prepared to take part in interna-tional research projects on the propertiesof bituminous mixtures. An informalNordic technical mirror group forEuropean standards in the field of bitumi-nous mixtures does exist, and may proof tobe a good scientific platform for ideas con-cerning research needs and areas.

The author with the new wheel trackingmachine (left) and roller compactor (right).

Sawn section through sample plates which have beentested in the wheel tracking machine.

A close-up of the Prall abrasion machine.

l

NORDIC NO. 1 2010 | 1312 | NORDIC NO. 1 2010 www.nordicroads.com

ROAD SURFACE

Road Surface Measurement – a Journey over Many Years

Every year, the road surface condition in Sweden is monitored.Tens of thousands of kilometres are surveyed to collect data thatprovides an up-to-date, detailed, complex, and almost completelyobjective picture of the condition and change in condition. Thisdata is one of many parameters used when determining the needfor road maintenance.

Monitoring of the road condition hasbeen carried out for many years. As

early as 1975, road surface condition mea-surement technology became an importantpart of VTI’s work. Development of thistechnology has been going on for morethan 30 years.

Friction and surface evennessIn the 1970s, VTI, in collaboration withSaab, began the development of a road sur-face friction tester - the Saab FrictionTester. Further developments included thefitting of road wear measurement sensors,25 small wheels and an accelerometer formeasurement of surface evenness. Thiswas, in fact, the beginning of the develop-ment of VTI’s Road Surface Tester (RST)equipment.

Mechanical wear and the need for fre-quent calibration caused a major problemwith the measuring wheels – a problemthat was solved with laser sensors. Intensivedevelopment work began with the use oflaser sensors – sensors that were world lea-ding in terms of technology for a long timeand still remain among the best perfor-

ming in this field. The first RST with laserswas ready in 1980. Laser RST consisted of abeam, mounted at the front of a Chevroletvehicle, equipped with eleven laser sensorsthat could, at normal traffic speed, remote-ly measure a 3.1 m transverse profile andsimultaneously calculate rut depth andride comfort index. At this time, invest-ment and efforts, driven by the SwedishRoad Administration, were at the fore frontof world research.

VTI has so far been involved in the con-struction and delivery of around 30 RSTvehicles to countries such as Saudi Arabia,USA, Australia, UK, Hungary, Spain andSweden.

Data acquisitionInformation collected from road surfacemeasurements provides a basis for mana-ging the maintenance of paved roads.

At the beginning of the 1980s, the per-sonal computer and Microsoft concept hadnot yet been introduced, however, intensi-ve technological research was in progressto develop a data collection computer sys-tem. Since memory capacity was minimalcompared with that of today, it was essenti-al that programs should be extremely effec-tive and make the best possible use of avai-lable memory. The VTI hive off company,

Primal Data AB, soon delivered a data col-lection computer system, highly competentfor that time, which was installed in theLaser RST vehicle.

Knowledge of road surface condition isan important part of data provision for thePavement Management System (PMS) usedby the Swedish Road Administration. A PMSis a tool and support system used to reach anoptimal level of road maintenance, and isbased on national economic assessments. APMS performs systematic planning of main-tenance and operations, and also acts as atool for the determination of where, whenand how certain treatments should be car-ried out. For a PMS to function, informationis needed on: traffic load, construction/structural condition, road type, climate, geo-logy, drainage system condition, relatedcosts, and data on road surface condition.

Bearing capacity and crackingTo achieve effective road maintenanceplanning and be able to determine diffe-rent treatment strategies, it is necessary tohave a good knowledge of the road net-work condition and its required standards.Planning ensures the correct treatment, atthe right location and at the right time. Toachieve this, it is essential to have a correctand sufficiently comprehensive descriptionof, not only the roads surface condition,but also of the structural condition.Therefore, to complement and add furtherinformation, the development of road con-dition measurement systems continued.

Around 1990 the activity reached itspeak and a real effort was made to developfurther measuring systems that were nee-ded to complement Laser RST. Hive offcompanies were formed and measuringequipment was developed; the Laser RoadDeflection Tester (RDT) measures, at nor-mal traffic speed, pavement strength andbearing capacity, and PAVUE measures thepresence of cracks in the road surface.Both these systems were designed to assessthe structural state of the road. For variousreasons, the Swedish Road Administrationdecided to terminate investment, andequipment and associated patents weresold off.

Foundation for specifications and requirementsToday, VTI’s role in this field has changed.There is only minor technical develop-

located with DGPS (satellite support) andcomplemented with digital photographs ofthe road environment. VTI’s Laser RST isprimarily used for research but also forconsultancy tasks. A bright future liesahead for the technology that started atVTI 30 years ago, and with further concen-tration on focus, attitude and discipline(FAD) it is likely to become a competitiveand successful activity in achieveing theobjectives of road maintenance.

FAD was formulated by a prominentAmerican researcher; it is an abbreviation for• Focus – concentration on the intended

goal• Attitude - motive and determination to

reach the goal • Discipline – make considered efforts

and monitor these.

Magdalena Green,VTI, Sweden

ment, and VTI instead provides supportand expertise to the Swedish RoadAdministration on specifications and requi-rements for condition measurement withsurvey vehicles. Thanks to the investmentsin technical development, a market hasbeen established where several companiescarry on commercial activity. Conditionmeasurements carried out at present areprocured through competitive tenderingby the Swedish Road Administration, withVTI as an important partner for specifyingrequirements and selecting the contractor.

VTI has at its disposal advanced roadsurface monitoring equipment based onthe Laser RST concept. The equipmentcomprises of sensors and technology whichenable the properties required by theSwedish Road Administration to be measu-red such as rut depth, IRI (InternationalRoughness Index), and macrotexture,MPD (Mean Profile Depth). Measurementsare carried out at normal traffic speed,

Contact: Leif Sjögren, leif.sjogren@vti.se

PHOTO: VTI/HEJDLÖSA BILDER

NORDIC NO. 1 2010 | 1312 | NORDIC NO. 1 2010 www.nordicroads.com

ROAD SURFACE

Road Surface Measurement – a Journey over Many Years

Every year, the road surface condition in Sweden is monitored.Tens of thousands of kilometres are surveyed to collect data thatprovides an up-to-date, detailed, complex, and almost completelyobjective picture of the condition and change in condition. Thisdata is one of many parameters used when determining the needfor road maintenance.

Monitoring of the road condition hasbeen carried out for many years. As

early as 1975, road surface condition mea-surement technology became an importantpart of VTI’s work. Development of thistechnology has been going on for morethan 30 years.

Friction and surface evennessIn the 1970s, VTI, in collaboration withSaab, began the development of a road sur-face friction tester - the Saab FrictionTester. Further developments included thefitting of road wear measurement sensors,25 small wheels and an accelerometer formeasurement of surface evenness. Thiswas, in fact, the beginning of the develop-ment of VTI’s Road Surface Tester (RST)equipment.

Mechanical wear and the need for fre-quent calibration caused a major problemwith the measuring wheels – a problemthat was solved with laser sensors. Intensivedevelopment work began with the use oflaser sensors – sensors that were world lea-ding in terms of technology for a long timeand still remain among the best perfor-

ming in this field. The first RST with laserswas ready in 1980. Laser RST consisted of abeam, mounted at the front of a Chevroletvehicle, equipped with eleven laser sensorsthat could, at normal traffic speed, remote-ly measure a 3.1 m transverse profile andsimultaneously calculate rut depth andride comfort index. At this time, invest-ment and efforts, driven by the SwedishRoad Administration, were at the fore frontof world research.

VTI has so far been involved in the con-struction and delivery of around 30 RSTvehicles to countries such as Saudi Arabia,USA, Australia, UK, Hungary, Spain andSweden.

Data acquisitionInformation collected from road surfacemeasurements provides a basis for mana-ging the maintenance of paved roads.

At the beginning of the 1980s, the per-sonal computer and Microsoft concept hadnot yet been introduced, however, intensi-ve technological research was in progressto develop a data collection computer sys-tem. Since memory capacity was minimalcompared with that of today, it was essenti-al that programs should be extremely effec-tive and make the best possible use of avai-lable memory. The VTI hive off company,

Primal Data AB, soon delivered a data col-lection computer system, highly competentfor that time, which was installed in theLaser RST vehicle.

Knowledge of road surface condition isan important part of data provision for thePavement Management System (PMS) usedby the Swedish Road Administration. A PMSis a tool and support system used to reach anoptimal level of road maintenance, and isbased on national economic assessments. APMS performs systematic planning of main-tenance and operations, and also acts as atool for the determination of where, whenand how certain treatments should be car-ried out. For a PMS to function, informationis needed on: traffic load, construction/structural condition, road type, climate, geo-logy, drainage system condition, relatedcosts, and data on road surface condition.

Bearing capacity and crackingTo achieve effective road maintenanceplanning and be able to determine diffe-rent treatment strategies, it is necessary tohave a good knowledge of the road net-work condition and its required standards.Planning ensures the correct treatment, atthe right location and at the right time. Toachieve this, it is essential to have a correctand sufficiently comprehensive descriptionof, not only the roads surface condition,but also of the structural condition.Therefore, to complement and add furtherinformation, the development of road con-dition measurement systems continued.

Around 1990 the activity reached itspeak and a real effort was made to developfurther measuring systems that were nee-ded to complement Laser RST. Hive offcompanies were formed and measuringequipment was developed; the Laser RoadDeflection Tester (RDT) measures, at nor-mal traffic speed, pavement strength andbearing capacity, and PAVUE measures thepresence of cracks in the road surface.Both these systems were designed to assessthe structural state of the road. For variousreasons, the Swedish Road Administrationdecided to terminate investment, andequipment and associated patents weresold off.

Foundation for specifications and requirementsToday, VTI’s role in this field has changed.There is only minor technical develop-

located with DGPS (satellite support) andcomplemented with digital photographs ofthe road environment. VTI’s Laser RST isprimarily used for research but also forconsultancy tasks. A bright future liesahead for the technology that started atVTI 30 years ago, and with further concen-tration on focus, attitude and discipline(FAD) it is likely to become a competitiveand successful activity in achieveing theobjectives of road maintenance.

FAD was formulated by a prominentAmerican researcher; it is an abbreviation for• Focus – concentration on the intended

goal• Attitude - motive and determination to

reach the goal • Discipline – make considered efforts

and monitor these.

Magdalena Green,VTI, Sweden

ment, and VTI instead provides supportand expertise to the Swedish RoadAdministration on specifications and requi-rements for condition measurement withsurvey vehicles. Thanks to the investmentsin technical development, a market hasbeen established where several companiescarry on commercial activity. Conditionmeasurements carried out at present areprocured through competitive tenderingby the Swedish Road Administration, withVTI as an important partner for specifyingrequirements and selecting the contractor.

VTI has at its disposal advanced roadsurface monitoring equipment based onthe Laser RST concept. The equipmentcomprises of sensors and technology whichenable the properties required by theSwedish Road Administration to be measu-red such as rut depth, IRI (InternationalRoughness Index), and macrotexture,MPD (Mean Profile Depth). Measurementsare carried out at normal traffic speed,

Contact: Leif Sjögren, leif.sjogren@vti.se

PHOTO: VTI/HEJDLÖSA BILDER

NORDIC NO. 1 2010 | 1514 | NORDIC NO. 1 2010 www.nordicroads.com

ROAD SURFACE

The technical part of the project is divi-ded into five work packages:

• WP1 Sampling and Characterization ofReclaimed Asphalt (RA)

• WP2 Impact of RA quality and charac-teristics on mix design and performanceof asphalt containing RA

• WP3 Environmental performance ofRA

• WP4 RA processing and RA manage-ment at the mixing plant

• WP5 Performance modelling of RA.In the initial reference to Re-Road in

this magazine we had just passed the "kick-off" meeting, but now the first interimreports to support the further activities ofthe project are in the tube for review andthe last quality check before publicationoutside the consortium. As work packageleader of WP4, I will here mention specifi-cally an interim report in the format of asmall survey which WP4 performed to pro-

Re-Road – Optimizing the Potential inRecycling of Asphalt

In a former number of this magazine (Nordic No. 1, 2009) therewas an appetizer concerning the start of a European project "Re-Road – End of Life Strategies of Asphalt Pavements" runningfrom 2009–2012. The project consortium involves eighteen part-ners of which four originates from the Nordic countries. Apartfrom the VTI, which also holds the role of project coordinatorthrough Björn Kalman, the Swedish Geotechnical Institute, PeabAsfalt AB and Danish Road Institute participate in the researchproject which is funded by the EU Commission under the 7thframework programme.

vide background information of WP2.The tasks for WP4 are closely related to

practical application in the road sector,and the partners of that work package havegood connections to asphalt producers andcontractors. WP2 was involved in develo-ping an optimum laboratory mixing proce-dure to obtain the best possible characteri-zation of impact of reclaimed asphalt onmix design. As an initial starting point –apart from the European standard for labo-ratory mixing EN 12697-35 – WP2 was inte-rested in the present experience for per-forming laboratory mixing – especiallywhen reclaimed asphalt was introduced. Bydrawing on the industry contacts of thepartners of WP4, a small survey was puttogether for practise of laboratory mixingto establish an appropriate mix design formaterials including reclaimed asphalt. Thedeadline was rather tight as an initial sam-pling of practise was to be presented toWP2 12 May 2009 though the sampling wascontinued until October 2009 to harvestadditional contributions.

The report contains more than 22

responses from six countries (Belgium,Denmark, Germany, Slovenia, Sweden andUnited Kingdom). The number of responsesdoes not on the surface reveal the coveragein each country, but in general a major, ifnot a total market share, is represented bythe responses, so the report gives a reaso-nable trend of the present state of the art.

The responses cannot be taken andsummarized over the total range as somepoints are dependent on type of plant(batch plant or drum mixer and how thereclaimed asphalt is introduced), the mar-ket situation in which the company opera-tes, availability to RA and local acceptanceof RA in mixes – especially surface layers.But certain lessons can be learnt from thesurvey and 13 statements are highlightedin the report. A few of them will be mentio-ned here, yet it will be necessary to gothrough the responses to the questionnairefor a more thorough examination of theindividual items.• Marshall mix design is still the predomi-

nant method of performing mix optimi-zation.

• Almost all companies use heated andpredried reclaimed asphalt in laborato-ry mixing irrespective if they use coldfeed addition of RA in the asphalt plant.

• Almost all companies aim for a homoge-neous mixed asphalt material in thelaboratory even though it means longermixing times in the laboratory than inthe asphalt plant.

• A few companies do not use laboratorymixing for mix design at all, but optimi-ze mix design through full scale produc-tion based on experience and knowledgeof the characteristics of the constituents.

• Only a very few responses claim thattheir laboratory mixing procedure is lin-ked closely to the conditions of the localasphalt plant.

• In general, mixing temperatures – bothin laboratory and in the plant – areselected based on binder viscosity orpreselected from experience dependingof the grade of binder.

Erik Nielsen, DRD,Denmark

Reclaimed asphalt – slabs from utility works ready tobe processed and re-used.

Asphalt plant equipped for recycling.

NORDIC NO. 1 2010 | 1514 | NORDIC NO. 1 2010 www.nordicroads.com

ROAD SURFACE

The technical part of the project is divi-ded into five work packages:

• WP1 Sampling and Characterization ofReclaimed Asphalt (RA)

• WP2 Impact of RA quality and charac-teristics on mix design and performanceof asphalt containing RA

• WP3 Environmental performance ofRA

• WP4 RA processing and RA manage-ment at the mixing plant

• WP5 Performance modelling of RA.In the initial reference to Re-Road in

this magazine we had just passed the "kick-off" meeting, but now the first interimreports to support the further activities ofthe project are in the tube for review andthe last quality check before publicationoutside the consortium. As work packageleader of WP4, I will here mention specifi-cally an interim report in the format of asmall survey which WP4 performed to pro-

Re-Road – Optimizing the Potential inRecycling of Asphalt

In a former number of this magazine (Nordic No. 1, 2009) therewas an appetizer concerning the start of a European project "Re-Road – End of Life Strategies of Asphalt Pavements" runningfrom 2009–2012. The project consortium involves eighteen part-ners of which four originates from the Nordic countries. Apartfrom the VTI, which also holds the role of project coordinatorthrough Björn Kalman, the Swedish Geotechnical Institute, PeabAsfalt AB and Danish Road Institute participate in the researchproject which is funded by the EU Commission under the 7thframework programme.

vide background information of WP2.The tasks for WP4 are closely related to

practical application in the road sector,and the partners of that work package havegood connections to asphalt producers andcontractors. WP2 was involved in develo-ping an optimum laboratory mixing proce-dure to obtain the best possible characteri-zation of impact of reclaimed asphalt onmix design. As an initial starting point –apart from the European standard for labo-ratory mixing EN 12697-35 – WP2 was inte-rested in the present experience for per-forming laboratory mixing – especiallywhen reclaimed asphalt was introduced. Bydrawing on the industry contacts of thepartners of WP4, a small survey was puttogether for practise of laboratory mixingto establish an appropriate mix design formaterials including reclaimed asphalt. Thedeadline was rather tight as an initial sam-pling of practise was to be presented toWP2 12 May 2009 though the sampling wascontinued until October 2009 to harvestadditional contributions.

The report contains more than 22

responses from six countries (Belgium,Denmark, Germany, Slovenia, Sweden andUnited Kingdom). The number of responsesdoes not on the surface reveal the coveragein each country, but in general a major, ifnot a total market share, is represented bythe responses, so the report gives a reaso-nable trend of the present state of the art.

The responses cannot be taken andsummarized over the total range as somepoints are dependent on type of plant(batch plant or drum mixer and how thereclaimed asphalt is introduced), the mar-ket situation in which the company opera-tes, availability to RA and local acceptanceof RA in mixes – especially surface layers.But certain lessons can be learnt from thesurvey and 13 statements are highlightedin the report. A few of them will be mentio-ned here, yet it will be necessary to gothrough the responses to the questionnairefor a more thorough examination of theindividual items.• Marshall mix design is still the predomi-

nant method of performing mix optimi-zation.

• Almost all companies use heated andpredried reclaimed asphalt in laborato-ry mixing irrespective if they use coldfeed addition of RA in the asphalt plant.

• Almost all companies aim for a homoge-neous mixed asphalt material in thelaboratory even though it means longermixing times in the laboratory than inthe asphalt plant.

• A few companies do not use laboratorymixing for mix design at all, but optimi-ze mix design through full scale produc-tion based on experience and knowledgeof the characteristics of the constituents.

• Only a very few responses claim thattheir laboratory mixing procedure is lin-ked closely to the conditions of the localasphalt plant.

• In general, mixing temperatures – bothin laboratory and in the plant – areselected based on binder viscosity orpreselected from experience dependingof the grade of binder.

Erik Nielsen, DRD,Denmark

Reclaimed asphalt – slabs from utility works ready tobe processed and re-used.

Asphalt plant equipped for recycling.

NORDIC NO. 1 2010 | 1716 | NORDIC NO. 1 2010 www.nordicroads.com

ROAD SURFACE

Road User Requirements and ExperiencesRegarding Road Surface Conditions

The condition of our state-maintained roads is regularly monito-red by the Swedish Road Administration, both by objective roadsurface measurements and by collecting the views of those whodrive on state roads through questionnaire surveys. The agree-ment between the objective measurements and the views expres-sed by road users is not particularly good. In order to understandthe disagreement between the two methods of assessment it isnecessary to review the indices and the methods employed incollecting data.

Contact: Anita Ihs, anita.ihs@vti.se

Jan Andersson, jan.andersson@vti.se

The primary objective of the project“The demand of road users regarding

road conditions” is to find out a) how toask questions regarding road conditions inorder to receive valid and reliable subjecti-ve data, and b) to find out what objectivedata that should be collected in the futurein order to obtain a better agreement bet-ween subjective and objective data.

Regular monitoringAt present, the Swedish Road Administrationroutinely assess the condition of state-main-tained roads by means of road surface con-dition measurements. It is mainly rut depthand surface roughness, expressed in termsof IRI (International Roughness Index)that forms the basis for road conditionassessments. These objective measure-ments show that the condition of roads hasneither improved nor deteriorated overthe years.

At the same time, the staff of theSwedish Road Administration annuallyinterview private and professional driversto find out how pleased or displeased theyare with the maintenance of the state-main-tained roads. Road users are asked what

ceived to the greatest extent to result inharmful consequences for driving, and itwas considered that there was an increasedrisk of an accident or that the driver had toconcentrate more on driving. However, theresults also indicate clear differences bet-ween different road categories, betweendifferent groups of drivers and betweendrivers in different regions.

Simulator studyIn the third stage of the project, the VTIdriving simulator was used to study how theroad surface affects road users’ perceptionof comfort and safety.

In a driving simulator, the environmentunder study can be gradually altered inorder to pinpoint which changes give riseto an effect such as changed driver beha-viour. Since there are many factors apartfrom the condition of the road surfacewhich affect road user comfort and a fee-ling of safety, it is necessary to have stret-ches of roads that are homogeneous in allrespects apart from the road surface pro-perties, whose effect is to be studied. This issomething that can only be achieved in adriving simulator. The fact that the appea-rance of the road surface is coupled withrealistic sounds and realistic vibrations atthe level of detail employed in this study ishowever unique and has required extensi-ve development.

In the first part of the simulator study,tests were made to find out how impressionssuch as visual impression, sound and vibra-tions from the road surface affect road userperceptions regarding comfort and safety.

On the basis of driving data such as speedand lateral position, together with the testsubjects’ estimates of how comfortable andsafe the road surface was to drive on, theconclusion could be drawn that the visualimpression, on its own, does not affectspeed, but has an effect on lateral position.Sound affects variance in speed, and vibra-tions affect variance in lateral position.Finally, vibration and sound also have aneffect on speed in interaction with the visu-al impression. Hence, all three impressionsaffected different measures of driver beha-viour on its own or in combination.

In order to elicit the drivers’ subjectiveperceptions of different road surfaces, simu-

lator driving was combined with a semi-dynamic questionnaire that the drivers hadto respond to while driving. Estimates ofcomfort and safety reveal a clear pattern ofhow different impressions affect the drivers’perception of the road surface. This impliesthat visual impression, sound and vibrations,both individually and in combination, affectthe subjective perception of safety and com-fort. Hence, in order to affect road user’sexperience of the road surface all threeimpressions (one by one or in combination)can increase road user’s satisfaction, or dis-satisfaction, with the road surface (in termsof comfort and safety).

The second simulator experiment com-prised eight road surfaces with differentproperties such as patches, ruts with and wit-hout water, and rough surface. On the basisof participants estimates the different typesof damage/ properties were ranked. Roadsurfaces with ruts full of water stand out andwere perceived to be least safe. The roughsurface was considered as one of the leastcomfortable in addition to ruts full of water,but it was not perceived to be as unsafe. Theestimates were completed before the drivingsession in the simulator, during the drivingsession and after the driving session.Participant estimates were very reliable andindicate that participant estimates can beused when the participant knows andunderstands the surfaces discussed.

There was a strong relation between per-ceived comfort and perceived safety, i.e. aroad surface that is perceived to be safe isalso perceived as comfortable. However, thisrelation is not so strong that it provides anexpression for the same thing, i.e., there isan obvious and strong relation betweenexperienced comfort and safety but, never-theless, they do not explain the same thing.

Visual impression, sound and vibrationsVisual impression, sound and vibrations allcontribute, both individually and in combi-nation, to a reduced perception of comfortand safety. It is however not possible tostate clearly which impression has the grea-test impact; this varies depending on thetype of damage to the road surface.

The experiments also reveal that thereare great and clear differences between dif-ferent types of road surface. For example,road surfaces with ruts full of water are per-ceived to be both less comfortable and lesssafe to drive on compared to road surfaceswith dry ruts. This implies, in turn, that thecondition index "rut" that is used today isinsufficient to obtain the perceptions ofroad users regarding the road surface. Acondition index that describes where watercollects after rain is even more important.

Sound was found to be an importantfactor for road user perception of comfortand speed, i.e., sound could be captured infuture by a condition index such as texture,for example.

One evident example of what creates aperception of a poor road is the patchedroad. Even the visual impression of a pat-ched road reduces drivers’ perception ofcomfort. If the noise generated by the textu-re and roughness of the patches is added,the perception of comfort deterioratesmore. If, finally, the vibrations caused bypoorly laid patches, with protruding jointsand other roughness, are added, comfort isfurther reduced. One interpretation of thisis that it is possible to minimise the negativeeffect of patching on driver perception pro-vided that protruding joints and roughareas are avoided and that the texture andcolour of the patch are as similar to the restof the surfacing as possible.

Generally, the conclusion that can bedrawn is that the greatest effort should bemade to ensure that the road surface has auniform colour, generates little noise andhas a uniform noise level, and that it is assmooth as possible, in order to obtain thatthe road users should perceive it as comfor-table and safe.

they think of the maintenance of roads ingeneral, and also more specifically abouttheir views regarding rutting and surfaceroughness, i.e. the factors that are monito-red. The results show that professional dri-vers are less pleased than private drivers.The general tendency, with the exceptionof the latest year, is that the proportion ofpleased road users is decreasing.

The agreement between the measure-ments of road condition and the views ofroad users, according to the surveys, is thusnot very good. It is therefore necessary toinvestigate the reason for this discrepancyto understand which objective measure-ments are needed to be developed in orderto also gain insight about road users’ expe-riences of road surface conditions.

Increased understandingThe project which is financed by theSwedish Road Administration has been car-ried out in the form of three independentstages, 1) a study of the literature, 2) focusgroups and a subsequent questionnairestudy, and 3) a driving simulator study.

The aim of the project was to enhancethe understanding of what requirements,needs and expectations road users expressin the relation to the surface condition ofroads, and to formulate questions that will

elicit valid and reliable subjective data. Byunderstanding the demands of the roadusers, it will be possible to find out theobjective indices needed to describe roadconditions from the perspective of roadusers. This will result in better utilisation ofthe data collected at present and indicatewhat the measures are for tomorrow.

The study of the literature reveal that anincreasing number of road managementauthorities wish to find out how well theymanage to satisfy the wishes of road usersregarding various aspects of the road net-work. The results from the focus groupinterviews indicate that the wish of all theparticipants was to have a road surface thatwas smooth, quiet and preferably recentlysurfaced, as well as wide without any unex-pected narrow portions.

Damage types included in the question-naire study such as, patching and repairs,as well as rutting, were perceived to be themost common while uneven/weak roadedges and large rough areas were seen tooccur less often. Generally, acceptance ofdamage was low, and it was lowest for pot-holes, followed by large areas of rough sur-face and uneven/weak road edges. Drivershad the highest degree of acceptance forpatches and repairs. It was rutting in wetconditions and potholes which were per-

PHO

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Magdalena Green,VTI, Sweden

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NORDIC NO. 1 2010 | 1716 | NORDIC NO. 1 2010 www.nordicroads.com

ROAD SURFACE

Road User Requirements and ExperiencesRegarding Road Surface Conditions

The condition of our state-maintained roads is regularly monito-red by the Swedish Road Administration, both by objective roadsurface measurements and by collecting the views of those whodrive on state roads through questionnaire surveys. The agree-ment between the objective measurements and the views expres-sed by road users is not particularly good. In order to understandthe disagreement between the two methods of assessment it isnecessary to review the indices and the methods employed incollecting data.

Contact: Anita Ihs, anita.ihs@vti.se

Jan Andersson, jan.andersson@vti.se

The primary objective of the project“The demand of road users regarding

road conditions” is to find out a) how toask questions regarding road conditions inorder to receive valid and reliable subjecti-ve data, and b) to find out what objectivedata that should be collected in the futurein order to obtain a better agreement bet-ween subjective and objective data.

Regular monitoringAt present, the Swedish Road Administrationroutinely assess the condition of state-main-tained roads by means of road surface con-dition measurements. It is mainly rut depthand surface roughness, expressed in termsof IRI (International Roughness Index)that forms the basis for road conditionassessments. These objective measure-ments show that the condition of roads hasneither improved nor deteriorated overthe years.

At the same time, the staff of theSwedish Road Administration annuallyinterview private and professional driversto find out how pleased or displeased theyare with the maintenance of the state-main-tained roads. Road users are asked what

ceived to the greatest extent to result inharmful consequences for driving, and itwas considered that there was an increasedrisk of an accident or that the driver had toconcentrate more on driving. However, theresults also indicate clear differences bet-ween different road categories, betweendifferent groups of drivers and betweendrivers in different regions.

Simulator studyIn the third stage of the project, the VTIdriving simulator was used to study how theroad surface affects road users’ perceptionof comfort and safety.

In a driving simulator, the environmentunder study can be gradually altered inorder to pinpoint which changes give riseto an effect such as changed driver beha-viour. Since there are many factors apartfrom the condition of the road surfacewhich affect road user comfort and a fee-ling of safety, it is necessary to have stret-ches of roads that are homogeneous in allrespects apart from the road surface pro-perties, whose effect is to be studied. This issomething that can only be achieved in adriving simulator. The fact that the appea-rance of the road surface is coupled withrealistic sounds and realistic vibrations atthe level of detail employed in this study ishowever unique and has required extensi-ve development.

In the first part of the simulator study,tests were made to find out how impressionssuch as visual impression, sound and vibra-tions from the road surface affect road userperceptions regarding comfort and safety.

On the basis of driving data such as speedand lateral position, together with the testsubjects’ estimates of how comfortable andsafe the road surface was to drive on, theconclusion could be drawn that the visualimpression, on its own, does not affectspeed, but has an effect on lateral position.Sound affects variance in speed, and vibra-tions affect variance in lateral position.Finally, vibration and sound also have aneffect on speed in interaction with the visu-al impression. Hence, all three impressionsaffected different measures of driver beha-viour on its own or in combination.

In order to elicit the drivers’ subjectiveperceptions of different road surfaces, simu-

lator driving was combined with a semi-dynamic questionnaire that the drivers hadto respond to while driving. Estimates ofcomfort and safety reveal a clear pattern ofhow different impressions affect the drivers’perception of the road surface. This impliesthat visual impression, sound and vibrations,both individually and in combination, affectthe subjective perception of safety and com-fort. Hence, in order to affect road user’sexperience of the road surface all threeimpressions (one by one or in combination)can increase road user’s satisfaction, or dis-satisfaction, with the road surface (in termsof comfort and safety).

The second simulator experiment com-prised eight road surfaces with differentproperties such as patches, ruts with and wit-hout water, and rough surface. On the basisof participants estimates the different typesof damage/ properties were ranked. Roadsurfaces with ruts full of water stand out andwere perceived to be least safe. The roughsurface was considered as one of the leastcomfortable in addition to ruts full of water,but it was not perceived to be as unsafe. Theestimates were completed before the drivingsession in the simulator, during the drivingsession and after the driving session.Participant estimates were very reliable andindicate that participant estimates can beused when the participant knows andunderstands the surfaces discussed.

There was a strong relation between per-ceived comfort and perceived safety, i.e. aroad surface that is perceived to be safe isalso perceived as comfortable. However, thisrelation is not so strong that it provides anexpression for the same thing, i.e., there isan obvious and strong relation betweenexperienced comfort and safety but, never-theless, they do not explain the same thing.

Visual impression, sound and vibrationsVisual impression, sound and vibrations allcontribute, both individually and in combi-nation, to a reduced perception of comfortand safety. It is however not possible tostate clearly which impression has the grea-test impact; this varies depending on thetype of damage to the road surface.

The experiments also reveal that thereare great and clear differences between dif-ferent types of road surface. For example,road surfaces with ruts full of water are per-ceived to be both less comfortable and lesssafe to drive on compared to road surfaceswith dry ruts. This implies, in turn, that thecondition index "rut" that is used today isinsufficient to obtain the perceptions ofroad users regarding the road surface. Acondition index that describes where watercollects after rain is even more important.

Sound was found to be an importantfactor for road user perception of comfortand speed, i.e., sound could be captured infuture by a condition index such as texture,for example.

One evident example of what creates aperception of a poor road is the patchedroad. Even the visual impression of a pat-ched road reduces drivers’ perception ofcomfort. If the noise generated by the textu-re and roughness of the patches is added,the perception of comfort deterioratesmore. If, finally, the vibrations caused bypoorly laid patches, with protruding jointsand other roughness, are added, comfort isfurther reduced. One interpretation of thisis that it is possible to minimise the negativeeffect of patching on driver perception pro-vided that protruding joints and roughareas are avoided and that the texture andcolour of the patch are as similar to the restof the surfacing as possible.

Generally, the conclusion that can bedrawn is that the greatest effort should bemade to ensure that the road surface has auniform colour, generates little noise andhas a uniform noise level, and that it is assmooth as possible, in order to obtain thatthe road users should perceive it as comfor-table and safe.

they think of the maintenance of roads ingeneral, and also more specifically abouttheir views regarding rutting and surfaceroughness, i.e. the factors that are monito-red. The results show that professional dri-vers are less pleased than private drivers.The general tendency, with the exceptionof the latest year, is that the proportion ofpleased road users is decreasing.

The agreement between the measure-ments of road condition and the views ofroad users, according to the surveys, is thusnot very good. It is therefore necessary toinvestigate the reason for this discrepancyto understand which objective measure-ments are needed to be developed in orderto also gain insight about road users’ expe-riences of road surface conditions.

Increased understandingThe project which is financed by theSwedish Road Administration has been car-ried out in the form of three independentstages, 1) a study of the literature, 2) focusgroups and a subsequent questionnairestudy, and 3) a driving simulator study.

The aim of the project was to enhancethe understanding of what requirements,needs and expectations road users expressin the relation to the surface condition ofroads, and to formulate questions that will

elicit valid and reliable subjective data. Byunderstanding the demands of the roadusers, it will be possible to find out theobjective indices needed to describe roadconditions from the perspective of roadusers. This will result in better utilisation ofthe data collected at present and indicatewhat the measures are for tomorrow.

The study of the literature reveal that anincreasing number of road managementauthorities wish to find out how well theymanage to satisfy the wishes of road usersregarding various aspects of the road net-work. The results from the focus groupinterviews indicate that the wish of all theparticipants was to have a road surface thatwas smooth, quiet and preferably recentlysurfaced, as well as wide without any unex-pected narrow portions.

Damage types included in the question-naire study such as, patching and repairs,as well as rutting, were perceived to be themost common while uneven/weak roadedges and large rough areas were seen tooccur less often. Generally, acceptance ofdamage was low, and it was lowest for pot-holes, followed by large areas of rough sur-face and uneven/weak road edges. Drivershad the highest degree of acceptance forpatches and repairs. It was rutting in wetconditions and potholes which were per-

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NORDIC NO. 1 2010 | 1918 | NORDIC NO. 1 2010 www.nordicroads.com

ROAD SURFACE

PHOTO: FINNISH TRANSPORT AGENCY

Self-adapting Traffic Prediction ModelLearns While WorkingSelf-adapting Traffic Prediction ModelLearns While Working

There is often too little time to collect data for creating trafficmodels, leading to a small number of samples that representrandom incidents and consequently poor ability to predict theirconsequences. The ability to learn while working online couldimprove this. The purpose of this doctoral dissertation was todevelop a method for making a self-adapting short-term predic-tion model for the flow status that would also be practical forlong-term online use.

Satu Innamaa, VTTFinland

Road users benefit more from accuratetravel time information when there is

great variability in travel times. However,without short-term prediction, real-timeinformation on travel time cannot be given.Much research has been done over the past15 years in the field of travel time predic-tion. However, most of the models develo-ped so far have been static and cannot dealwith new types of situations, regularly requi-ring new man-made calibration and freshdata. Unfortunately, there is often too littletime to collect data for creating such amodel, leading to a small number of sam-ples that represent random incidents andconsequently poor ability to predict theirconsequences. The ability to learn whileworking online could improve this but thereis a lack of knowledge on how to develop apractical, self-adapting prediction model.

The purpose of the study was to develop amethod for making a self-adapting short-term prediction model for the flow status(i.e. a five-step travel speed-based classifica-tion). Specifically, the objective was to find amethod that (1) could predict the flow statuson a satisfactory level, (2) would learn byitself during online operation, and (3)would also be practical for long-term onlineuse. The model was based on field-measuredtravel time data and self-organising maps.The test site was Ring Road I in the Helsinkimetropolitan area. The road was regularlycongested. Models were based on travel timeand road weather data. Travel time data was

collected by a license platerecognition system. Modelswere based on data collectedduring an 8-month period.The prediction performanceof the models was testedduring a separate 8-monthperiod.

The forecasts were based onthe outcomes of previous occa-sions when the traffic situationwas similar to the present(Figure 1). The forecast was setto the most common outcomein the cluster of these similarsamples. Forecasts were madefor vehicles entering the roadsections within the next 15 minutes on thebasis of weather and road condition and tra-vel time information. The forecast was givenat 5-minute intervals for 5-minute periods.To make the model learn while working onli-ne from the traffic situations it encountered,the distribution of outcome classes was upda-ted in the cluster used for making the fore-cast as soon as the “correct” answer was mea-sured in the field. Consequently, there wasno need to restore the samples to a database;rather, all that was needed was to increasethe number of matches in an outcome distri-bution table. This table was as big as thenumber of clusters times the number of out-come classes.

The model was allowed to work onlineand its performance was studied as afunction of time for a 250-day period. Theproportion of correct forecasts was 93.8%over the entire trial period and 80.9% incongested conditions for the first test sec-

tion (A) in normal weather and road con-ditions. Corresponding proportions were96.3% and 82.3% for the second test sec-tion (B). The average daily change in theproportion of correct forecasts was positiveover the whole trial period: +0.4% for roadsection A and +0.3% for road section B.Two naïve comparison models were made.The first one based the forecast on averagetravel time for the 5-minute period and dayof the week in question for each road sec-tion. The second one used the latest mea-surements directly as forecasts. Both com-parison models performed considerablyworse than the self-adapting model.

Figure 1. Principles of the prediction model.

Contact: Satu Innamaa, VTT

E-mail: satu.innamaatt@vtt.fi

Read more: Innamaa S (2009). Short-term predic-

tion of traffic flow status for online driver informa-

tion. Doctoral dissertation, VTT Publications: 708.

VTT, Espoo. 79 p. + app. 90 p.

http://www.vtt.fi/inf/pdf/publications/2009/P708.pdf

It is possible to both predict and mitigate disruptions in thetransportation of people and goods. EU has launched a researchproject which studies the effects of extreme weather events onthe safety and reliability of traffic systems. The EWENT project,which is coordinated by VTT Technical Research Centre ofFinland, will also estimate the cost effects of weather-related dis-ruptions. The project is motivated by the concern over the increa-se in extreme weather events caused by climate change.

Extreme Weather Impact onEuropean Transport Systems

Pekka Leviäkangas, VTT,Finland

The EWENT project supports ways ofmitigating the effects of extreme weat-

her events on the transport of people andgoods. The study will focus on the safetyand reliability of air, ground and watertransport as well as on the cost effects oftraffic disruptions.

The project will identify dangerousextreme weather events and estimate theirprobability and effects. It will also estimatethe cost effects of traffic disruptions, suchas costs associated with human casualties,material damages and discontinued supplychains. A lot of information exists aboutthe effects of weather events, but this is thefirst project which intends to estimate theircost effects methodically.

The main purpose of the project is tosupport adaptation to climate change. Inaddition to the authorities, the projectresults may be useful for businesses, projectfinancers and insurers. The results can beleveraged in various ways, such as in crea-ting sizing criteria of infrastructures, poin-ting out needs for enhanced maintenancecapabilities, development of cooperationbetween authorities and preparedness forexceptional conditions. The pre-enginee-

ring of co-European and national riskmanagement methods and processes is oneof the project’s key tasks.

The project will be carried out between2010 and 2012. The total project budget isapproximately 2 million euros. The partici-pants of the EWENT project coordinatedby VTT are: German Aerospace Center(Germany), Institute of TransportEconomics (Norway), Foreca ConsultingLtd (Finland), Finnish MeteorologicalInstitute (Finland), Meteorological Servicein Cyprus (Cyprus), Österreichische

Wasserstrassen GmbH (Austria), EuropeanSevere Storms Laboratory (Germany) andWorld Meteorological Organisation (UN).

The Consultative Board of the projectconsists of representatives from the FinnishMinistry of Transport and Communica-tions, the European Investment Bank,OECD, insurance company Allianz and thePolytechnic University of Turin.

Contact: Pekka Leviäkangas

E-mail: pekka.leviakangas@vtt.fi

NORDIC NO. 1 2010 | 1918 | NORDIC NO. 1 2010 www.nordicroads.com

ROAD SURFACE

PHOTO: FINNISH TRANSPORT AGENCY

Self-adapting Traffic Prediction ModelLearns While WorkingSelf-adapting Traffic Prediction ModelLearns While Working

There is often too little time to collect data for creating trafficmodels, leading to a small number of samples that representrandom incidents and consequently poor ability to predict theirconsequences. The ability to learn while working online couldimprove this. The purpose of this doctoral dissertation was todevelop a method for making a self-adapting short-term predic-tion model for the flow status that would also be practical forlong-term online use.

Satu Innamaa, VTTFinland

Road users benefit more from accuratetravel time information when there is

great variability in travel times. However,without short-term prediction, real-timeinformation on travel time cannot be given.Much research has been done over the past15 years in the field of travel time predic-tion. However, most of the models develo-ped so far have been static and cannot dealwith new types of situations, regularly requi-ring new man-made calibration and freshdata. Unfortunately, there is often too littletime to collect data for creating such amodel, leading to a small number of sam-ples that represent random incidents andconsequently poor ability to predict theirconsequences. The ability to learn whileworking online could improve this but thereis a lack of knowledge on how to develop apractical, self-adapting prediction model.

The purpose of the study was to develop amethod for making a self-adapting short-term prediction model for the flow status(i.e. a five-step travel speed-based classifica-tion). Specifically, the objective was to find amethod that (1) could predict the flow statuson a satisfactory level, (2) would learn byitself during online operation, and (3)would also be practical for long-term onlineuse. The model was based on field-measuredtravel time data and self-organising maps.The test site was Ring Road I in the Helsinkimetropolitan area. The road was regularlycongested. Models were based on travel timeand road weather data. Travel time data was

collected by a license platerecognition system. Modelswere based on data collectedduring an 8-month period.The prediction performanceof the models was testedduring a separate 8-monthperiod.

The forecasts were based onthe outcomes of previous occa-sions when the traffic situationwas similar to the present(Figure 1). The forecast was setto the most common outcomein the cluster of these similarsamples. Forecasts were madefor vehicles entering the roadsections within the next 15 minutes on thebasis of weather and road condition and tra-vel time information. The forecast was givenat 5-minute intervals for 5-minute periods.To make the model learn while working onli-ne from the traffic situations it encountered,the distribution of outcome classes was upda-ted in the cluster used for making the fore-cast as soon as the “correct” answer was mea-sured in the field. Consequently, there wasno need to restore the samples to a database;rather, all that was needed was to increasethe number of matches in an outcome distri-bution table. This table was as big as thenumber of clusters times the number of out-come classes.

The model was allowed to work onlineand its performance was studied as afunction of time for a 250-day period. Theproportion of correct forecasts was 93.8%over the entire trial period and 80.9% incongested conditions for the first test sec-

tion (A) in normal weather and road con-ditions. Corresponding proportions were96.3% and 82.3% for the second test sec-tion (B). The average daily change in theproportion of correct forecasts was positiveover the whole trial period: +0.4% for roadsection A and +0.3% for road section B.Two naïve comparison models were made.The first one based the forecast on averagetravel time for the 5-minute period and dayof the week in question for each road sec-tion. The second one used the latest mea-surements directly as forecasts. Both com-parison models performed considerablyworse than the self-adapting model.

Figure 1. Principles of the prediction model.

Contact: Satu Innamaa, VTT

E-mail: satu.innamaatt@vtt.fi

Read more: Innamaa S (2009). Short-term predic-

tion of traffic flow status for online driver informa-

tion. Doctoral dissertation, VTT Publications: 708.

VTT, Espoo. 79 p. + app. 90 p.

http://www.vtt.fi/inf/pdf/publications/2009/P708.pdf

It is possible to both predict and mitigate disruptions in thetransportation of people and goods. EU has launched a researchproject which studies the effects of extreme weather events onthe safety and reliability of traffic systems. The EWENT project,which is coordinated by VTT Technical Research Centre ofFinland, will also estimate the cost effects of weather-related dis-ruptions. The project is motivated by the concern over the increa-se in extreme weather events caused by climate change.

Extreme Weather Impact onEuropean Transport Systems

Pekka Leviäkangas, VTT,Finland

The EWENT project supports ways ofmitigating the effects of extreme weat-

her events on the transport of people andgoods. The study will focus on the safetyand reliability of air, ground and watertransport as well as on the cost effects oftraffic disruptions.

The project will identify dangerousextreme weather events and estimate theirprobability and effects. It will also estimatethe cost effects of traffic disruptions, suchas costs associated with human casualties,material damages and discontinued supplychains. A lot of information exists aboutthe effects of weather events, but this is thefirst project which intends to estimate theircost effects methodically.

The main purpose of the project is tosupport adaptation to climate change. Inaddition to the authorities, the projectresults may be useful for businesses, projectfinancers and insurers. The results can beleveraged in various ways, such as in crea-ting sizing criteria of infrastructures, poin-ting out needs for enhanced maintenancecapabilities, development of cooperationbetween authorities and preparedness forexceptional conditions. The pre-enginee-

ring of co-European and national riskmanagement methods and processes is oneof the project’s key tasks.

The project will be carried out between2010 and 2012. The total project budget isapproximately 2 million euros. The partici-pants of the EWENT project coordinatedby VTT are: German Aerospace Center(Germany), Institute of TransportEconomics (Norway), Foreca ConsultingLtd (Finland), Finnish MeteorologicalInstitute (Finland), Meteorological Servicein Cyprus (Cyprus), Österreichische

Wasserstrassen GmbH (Austria), EuropeanSevere Storms Laboratory (Germany) andWorld Meteorological Organisation (UN).

The Consultative Board of the projectconsists of representatives from the FinnishMinistry of Transport and Communica-tions, the European Investment Bank,OECD, insurance company Allianz and thePolytechnic University of Turin.

Contact: Pekka Leviäkangas

E-mail: pekka.leviakangas@vtt.fi

NORDIC NO. 1 2010 | 2120 | NORDIC NO. 1 2010 www.nordicroads.com

E6 Trondheim–Stjørdal, Mid-Norway:

A Pilot Project Using Competitive Dialogue

For the first time the Norwegian Public Roads Administration(NPRA) has chosen a contractor using the procurement procedu-re "competitive dialogue". The project chosen to pilot this proce-dure is the construction of a complicated tunnel in quick clayunderneath buildings in the Møllenberg district in Trondheim. Thisproject is part of the E6 Trondheim-Stjørdal highway project.

“Competitive dialogue", a procure-ment procedure governed by the

Regulations relating to public acquisitions,may be useful when awarding particularlycomplex projects. The objective of this pilotproject is to develop guidelines for the useof this procurement procedure, as well as tocarry out the construction work.

The processIn October 2008 the E6 Trondheim-Stjørdal highway project held an informa-

Article based on different information from NPRA.

Contact: Project Manager Harald Inge Johnsen.

E-mail: harald.johnsen@vegvesen.no

More information on:www.vegvesen.no/Vegprosjekter/

e6ost/For+the+industry

cipating companies, NCC Construction andAF Group/Züblins, chose to submit a bidpackage for this part of the E6 Trondheim-Stjørdal highway project.

Both offers were better than the originalplan sketch. The offer from AF Group/Züblins was considered more professional,but the cost was almost double comparedwith the bid from NCC. As this vast pricedifferential outweighed the other conside-rations, the NPRA and NCC Constructionsigned the 70 million euro contract inNovember 2009.

The challengesThe contract is for the construction ofapproximately 500 metres of new four-lanehighway between Pirbrua (the Pier Bridge)and the district of Møllenberg, of whichabout 300 metres is a concrete tunnelthrough uncompacted material prior totransition to tunnel in rock. A 120-metrestretch of the tunnel passes through quickclay. The quick clay is basically quite weak,with firmness like wet clay before agitating(Su 30–50) and like motor oil (0.5 kPa)after it has been agitated. This is 10 percen-tage points above the floating limit for clay,which means that it must be disturbed aslittle as possible.

The building pit will be below sea leveland will reach solid bedrock 20 metresbelow the ground. Its biggest building pitwill be 20 metres deep and about 24 metreswide.

tion seminar about the project itself, theupcoming contracts and the procurementprocedure known as "competitive dialo-gue". As competitive dialogue is a relativelynew procedure, there are few projectswhere it has been implemented in theEuropean Economic Area.

Due to little response from the construc-tion industry early in the process, the NPRAfelt a need to give the contractors a greaterunderstanding of the procedure, its possibi-lities and responsibilities. Three contractorsparticipated in the dialogue phase. Theywere asked to use the summer of 2009 todraw up their offers, but at the opening oftenders in September, only two of the parti-

The tunnel will be built along a mainroad which is heavily trafficked. The districtof Møllenberg has many historical and pro-tected wooden buildings which are close toand above the tunnel. In the original plan 12buildings were to be moved to a parking areanearby for storage during the three-year buil-ding period, but with the solution of theNCC only six buildings need to be moved.

In addition, a new railroad underpasswill be built, which involves removal of themain railway line (Nordland Line) duringpart of the building period.

The building methodNCC Construction has chosen a traditional

solution for constructing the tunnel. Thequick clay will be stabilised with lime andconcrete piling to make it resistant tomovement. Then steel sheet pile will beused to stiffen the walls of the building pitand to prevent the clay from moving.Throughout the construction period thegroundwater level will be maintained. Thebuilding pit will go all the way to the colla-ring, where the rock will be separated by acut and slip operation.

By reducing the distance between the twolines towards the tunnel opening, the met-hod of NCC Construction will save 6 of the 12buildings which were scheduled to be moved.

This winter NCC has been busy doing

sampling, rigging up and carrying outdetailed planning. In the middle of Marchthe Nordland Line was moved temporarilybeyond the local station at Lademoen inorder to build the new railroad underpass.

Construction work will be in full swingafter Easter 2010. The entire project isscheduled to be completed in June 2013.

The NPRA has signed a contract with NCC Construction for 500 metres of new four-lane highway through thedistrict of Møllenberg in Trondheim, including a 300-metre tunnel to be built through uncompacted material.Using NCC’s solution, six of the twelve buildings inside the blue area will not be affected. (Photo: NPRA)

The construction work will go through and under the district of Møllenberg along the northern main road out ofthe city of Trondheim. Large residential buildings in Møllenberg must be relocated temporarily and some, inclu-ding a church (white building), must be demolished and rebuild when the tunnel construction work is finished.(Photo: NPRA)

Thorbjørn Chr. Risan,NPRA, Norway

NORDIC NO. 1 2010 | 2120 | NORDIC NO. 1 2010 www.nordicroads.com

E6 Trondheim–Stjørdal, Mid-Norway:

A Pilot Project Using Competitive Dialogue

For the first time the Norwegian Public Roads Administration(NPRA) has chosen a contractor using the procurement procedu-re "competitive dialogue". The project chosen to pilot this proce-dure is the construction of a complicated tunnel in quick clayunderneath buildings in the Møllenberg district in Trondheim. Thisproject is part of the E6 Trondheim-Stjørdal highway project.

“Competitive dialogue", a procure-ment procedure governed by the

Regulations relating to public acquisitions,may be useful when awarding particularlycomplex projects. The objective of this pilotproject is to develop guidelines for the useof this procurement procedure, as well as tocarry out the construction work.

The processIn October 2008 the E6 Trondheim-Stjørdal highway project held an informa-

Article based on different information from NPRA.

Contact: Project Manager Harald Inge Johnsen.

E-mail: harald.johnsen@vegvesen.no

More information on:www.vegvesen.no/Vegprosjekter/

e6ost/For+the+industry

cipating companies, NCC Construction andAF Group/Züblins, chose to submit a bidpackage for this part of the E6 Trondheim-Stjørdal highway project.

Both offers were better than the originalplan sketch. The offer from AF Group/Züblins was considered more professional,but the cost was almost double comparedwith the bid from NCC. As this vast pricedifferential outweighed the other conside-rations, the NPRA and NCC Constructionsigned the 70 million euro contract inNovember 2009.

The challengesThe contract is for the construction ofapproximately 500 metres of new four-lanehighway between Pirbrua (the Pier Bridge)and the district of Møllenberg, of whichabout 300 metres is a concrete tunnelthrough uncompacted material prior totransition to tunnel in rock. A 120-metrestretch of the tunnel passes through quickclay. The quick clay is basically quite weak,with firmness like wet clay before agitating(Su 30–50) and like motor oil (0.5 kPa)after it has been agitated. This is 10 percen-tage points above the floating limit for clay,which means that it must be disturbed aslittle as possible.

The building pit will be below sea leveland will reach solid bedrock 20 metresbelow the ground. Its biggest building pitwill be 20 metres deep and about 24 metreswide.

tion seminar about the project itself, theupcoming contracts and the procurementprocedure known as "competitive dialo-gue". As competitive dialogue is a relativelynew procedure, there are few projectswhere it has been implemented in theEuropean Economic Area.

Due to little response from the construc-tion industry early in the process, the NPRAfelt a need to give the contractors a greaterunderstanding of the procedure, its possibi-lities and responsibilities. Three contractorsparticipated in the dialogue phase. Theywere asked to use the summer of 2009 todraw up their offers, but at the opening oftenders in September, only two of the parti-

The tunnel will be built along a mainroad which is heavily trafficked. The districtof Møllenberg has many historical and pro-tected wooden buildings which are close toand above the tunnel. In the original plan 12buildings were to be moved to a parking areanearby for storage during the three-year buil-ding period, but with the solution of theNCC only six buildings need to be moved.

In addition, a new railroad underpasswill be built, which involves removal of themain railway line (Nordland Line) duringpart of the building period.

The building methodNCC Construction has chosen a traditional

solution for constructing the tunnel. Thequick clay will be stabilised with lime andconcrete piling to make it resistant tomovement. Then steel sheet pile will beused to stiffen the walls of the building pitand to prevent the clay from moving.Throughout the construction period thegroundwater level will be maintained. Thebuilding pit will go all the way to the colla-ring, where the rock will be separated by acut and slip operation.

By reducing the distance between the twolines towards the tunnel opening, the met-hod of NCC Construction will save 6 of the 12buildings which were scheduled to be moved.

This winter NCC has been busy doing

sampling, rigging up and carrying outdetailed planning. In the middle of Marchthe Nordland Line was moved temporarilybeyond the local station at Lademoen inorder to build the new railroad underpass.

Construction work will be in full swingafter Easter 2010. The entire project isscheduled to be completed in June 2013.

The NPRA has signed a contract with NCC Construction for 500 metres of new four-lane highway through thedistrict of Møllenberg in Trondheim, including a 300-metre tunnel to be built through uncompacted material.Using NCC’s solution, six of the twelve buildings inside the blue area will not be affected. (Photo: NPRA)

The construction work will go through and under the district of Møllenberg along the northern main road out ofthe city of Trondheim. Large residential buildings in Møllenberg must be relocated temporarily and some, inclu-ding a church (white building), must be demolished and rebuild when the tunnel construction work is finished.(Photo: NPRA)

Thorbjørn Chr. Risan,NPRA, Norway

NORDIC NO. 1 2010 | 2322 | NORDIC NO. 1 2010 www.nordicroads.com

Environmental Damage Caused byRoad Salting– a Literature Review

Salt SMART is a four-year research and development project ini-tiated by the Norwegian Public Roads Administration. The motiva-tion for the project is an increasing focus on the environmentalconsequences related to the use of salt (sodium chloride) onroads in wintertime. A key objective is to document the environ-mental damage caused by road salt and other relevant alternati-ve de-icing chemicals. This article summarises the main resultsof a literature review.

There have been numerous investiga-tions into the use of road salts and their

environmental impact. A literature reviewhas been conducted which surveys bothnational and international literature focu-sing on the effects road salting has on sur-face water (flora and fauna), groundwater,terrestrial plants and soil. Two main groupsof de-icing chemicals are considered in thisreport: chloride-based and organic-based.An assessment is given for estimations ofcritical load for species and natural envi-ronments. Bioforsk performed the SaltSMART-financed literature review in coo-peration with UMB (University of LifeSciences), with researchers from Denmark,Sweden and Finland as a Nordic referencegroup.

Microorganisms and fauna in soilSodium chloride alters the soil structureand the composition of cations during ionexchange in soils. The washing out of cal-cium and magnesium from the soil as aresult of sodium chloride use leads to

increased potential for colloidal transportin soil, with a possibility of reducedhydraulic conductivity if pores becomeblocked with particles. Increased mobilityof organic and inorganic colloids results inthe increased mobility and wash out ofheavy metals such as lead and copper, whilethe addition of chloride will increase themobility of substances such as cadmiumand zinc due to the release of chloridecomplexes.

Calcium magnesium acetate containscalcium and magnesium, both of which sta-bilise clay particles and improve drainageand aeration of the soil. Degradation ofacetate and other organic-based de-icingagents can result in a lack of oxygen in soilbecause oxygen is used during degrada-tion. This can mean an increase in thetransport of iron, manganese and othermetals because a precipitated oxidised bin-ding of iron and manganese is reduced,released and becomes more mobile.

Microorganisms in soil near heavily traf-ficked roads can be harmed by sodiumchloride. Chronic effects on soil springtails(Collembola) are proven at concentrationsof 280 mg Cl/l. As for aquatic organisms,both chronic and sub-lethal effects occur

when salt concentrations are considerablylower than the concentrations where acuteeffects occur. Microorganisms, flora andfauna are dependent on each other in thesoil ecosystem, and it is unclear how thisecosystem is affected by different de-icingagents.

PlantsSalt can cause damage to plants as a resultof uptake through soil and by spray.Numerous studies have shown that thedeposition of airborne sodium chloridedeclines exponentially with increasing dis-tance from the road. The greatest spraydamage is usually found within a zone ofapproximately 10 metres from the road.Local soil variation, roadside forests andclimate determine the magnitude of saltdamage to vegetation.

Salt damage as a result of uptakethrough soil is a serious problem. It cantake a long time before symptoms of saltdamage disappear. Changes in speciescomposition and losing out areas to otherspecies along roads are a natural conse-quence of the use of road salt.

Determining critical loads that areapplicable in a field situation is difficult,

Kjersti J. Wike, NPRA,Norway

Contact: Kjerst J. Wike, kjersti.wike@vegvesen.no

References: Salt SMART. Environmental damages

caused by road salting

- a literature review. Report from the Technology

department no. 2587 (in press). Also available in

Norwegian (2535).

Read more:http://www.vegvesen.no/en/Professional/Research

+and+development/SaltSMART

because the extent of damage is dependenton a number of factors. Sodium chloridedamages plants both by uptake throughthe roots and directly through spray; thereis not necessarily a link between toleranceto uptake through the roots and toleranceto direct spray.

Alternative de-icing agents also affectplants, but a number of studies indicatethat the effects are less than when usingsodium chloride.

Surface waterLakes in Norway which are affected by theuse of sodium chloride during winter main-tenance have developed salt gradients (dif-ference between water in the upper leveland bottom level > 10mg C/l). In the bot-tom levels of salt affected lakes, oxygendepletion gives higher concentrations ofiron and manganese in the water. Use ofchloride salts can also lead to an increasein the concentration of heavy metals andbase cations (such as Ca and Mg) in thesurface water.

Natural chloride concentrations inNorwegian lakes are usually between 1-10mg/l. Acute effects of exposure < 4 days,acute effects of exposure for 1 week andchronic effects arise at Cl-concentrations ofrespectively (ca.) 6000 mg/l, 1100 mg/land 560 mg/l if we allow effects on 50% oforganisms (EC50) (fish, shellfish, algae).If effects are based on only 5% of the orga-nisms, then chronic effects can arise at con-centrations of ca 200 mg/l. Changes inspecies composition and physiologicalchanges in certain species (chronic effects)arise at much lower concentrations thanacute effects. The general trend in a num-ber of studies shows that the chloride-basedde-icing agents are less toxic to aquaticorganisms (fish, shellfish, and algae) thanthose based on acetate.

GroundwaterSince chloride is difficult to remove, themost important way to avoid an unfortuna-te influence on groundwater is dilution.

Decomposition of organic de-icing

agents increases with temperature and nut-rient contribution (N and P). It is impor-tant to ensure enough residence time inthe unsaturated zone to ensure that chemi-cals are broken down before reachinggroundwater. Organic de-icing agents havedifferent oxygen consumption, but ingeneral, decomposition of these oftenresults in increased iron and manganeseconcentrations in groundwater and someti-mes also poisonous mercaptan.

PHOTO: KNUT OPEIDE, NPRA

NORDIC NO. 1 2010 | 2322 | NORDIC NO. 1 2010 www.nordicroads.com

Environmental Damage Caused byRoad Salting– a Literature Review

Salt SMART is a four-year research and development project ini-tiated by the Norwegian Public Roads Administration. The motiva-tion for the project is an increasing focus on the environmentalconsequences related to the use of salt (sodium chloride) onroads in wintertime. A key objective is to document the environ-mental damage caused by road salt and other relevant alternati-ve de-icing chemicals. This article summarises the main resultsof a literature review.

There have been numerous investiga-tions into the use of road salts and their

environmental impact. A literature reviewhas been conducted which surveys bothnational and international literature focu-sing on the effects road salting has on sur-face water (flora and fauna), groundwater,terrestrial plants and soil. Two main groupsof de-icing chemicals are considered in thisreport: chloride-based and organic-based.An assessment is given for estimations ofcritical load for species and natural envi-ronments. Bioforsk performed the SaltSMART-financed literature review in coo-peration with UMB (University of LifeSciences), with researchers from Denmark,Sweden and Finland as a Nordic referencegroup.

Microorganisms and fauna in soilSodium chloride alters the soil structureand the composition of cations during ionexchange in soils. The washing out of cal-cium and magnesium from the soil as aresult of sodium chloride use leads to

increased potential for colloidal transportin soil, with a possibility of reducedhydraulic conductivity if pores becomeblocked with particles. Increased mobilityof organic and inorganic colloids results inthe increased mobility and wash out ofheavy metals such as lead and copper, whilethe addition of chloride will increase themobility of substances such as cadmiumand zinc due to the release of chloridecomplexes.

Calcium magnesium acetate containscalcium and magnesium, both of which sta-bilise clay particles and improve drainageand aeration of the soil. Degradation ofacetate and other organic-based de-icingagents can result in a lack of oxygen in soilbecause oxygen is used during degrada-tion. This can mean an increase in thetransport of iron, manganese and othermetals because a precipitated oxidised bin-ding of iron and manganese is reduced,released and becomes more mobile.

Microorganisms in soil near heavily traf-ficked roads can be harmed by sodiumchloride. Chronic effects on soil springtails(Collembola) are proven at concentrationsof 280 mg Cl/l. As for aquatic organisms,both chronic and sub-lethal effects occur

when salt concentrations are considerablylower than the concentrations where acuteeffects occur. Microorganisms, flora andfauna are dependent on each other in thesoil ecosystem, and it is unclear how thisecosystem is affected by different de-icingagents.

PlantsSalt can cause damage to plants as a resultof uptake through soil and by spray.Numerous studies have shown that thedeposition of airborne sodium chloridedeclines exponentially with increasing dis-tance from the road. The greatest spraydamage is usually found within a zone ofapproximately 10 metres from the road.Local soil variation, roadside forests andclimate determine the magnitude of saltdamage to vegetation.

Salt damage as a result of uptakethrough soil is a serious problem. It cantake a long time before symptoms of saltdamage disappear. Changes in speciescomposition and losing out areas to otherspecies along roads are a natural conse-quence of the use of road salt.

Determining critical loads that areapplicable in a field situation is difficult,

Kjersti J. Wike, NPRA,Norway

Contact: Kjerst J. Wike, kjersti.wike@vegvesen.no

References: Salt SMART. Environmental damages

caused by road salting

- a literature review. Report from the Technology

department no. 2587 (in press). Also available in

Norwegian (2535).

Read more:http://www.vegvesen.no/en/Professional/Research

+and+development/SaltSMART

because the extent of damage is dependenton a number of factors. Sodium chloridedamages plants both by uptake throughthe roots and directly through spray; thereis not necessarily a link between toleranceto uptake through the roots and toleranceto direct spray.

Alternative de-icing agents also affectplants, but a number of studies indicatethat the effects are less than when usingsodium chloride.

Surface waterLakes in Norway which are affected by theuse of sodium chloride during winter main-tenance have developed salt gradients (dif-ference between water in the upper leveland bottom level > 10mg C/l). In the bot-tom levels of salt affected lakes, oxygendepletion gives higher concentrations ofiron and manganese in the water. Use ofchloride salts can also lead to an increasein the concentration of heavy metals andbase cations (such as Ca and Mg) in thesurface water.

Natural chloride concentrations inNorwegian lakes are usually between 1-10mg/l. Acute effects of exposure < 4 days,acute effects of exposure for 1 week andchronic effects arise at Cl-concentrations ofrespectively (ca.) 6000 mg/l, 1100 mg/land 560 mg/l if we allow effects on 50% oforganisms (EC50) (fish, shellfish, algae).If effects are based on only 5% of the orga-nisms, then chronic effects can arise at con-centrations of ca 200 mg/l. Changes inspecies composition and physiologicalchanges in certain species (chronic effects)arise at much lower concentrations thanacute effects. The general trend in a num-ber of studies shows that the chloride-basedde-icing agents are less toxic to aquaticorganisms (fish, shellfish, and algae) thanthose based on acetate.

GroundwaterSince chloride is difficult to remove, themost important way to avoid an unfortuna-te influence on groundwater is dilution.

Decomposition of organic de-icing

agents increases with temperature and nut-rient contribution (N and P). It is impor-tant to ensure enough residence time inthe unsaturated zone to ensure that chemi-cals are broken down before reachinggroundwater. Organic de-icing agents havedifferent oxygen consumption, but ingeneral, decomposition of these oftenresults in increased iron and manganeseconcentrations in groundwater and someti-mes also poisonous mercaptan.

PHOTO: KNUT OPEIDE, NPRA

Danish Road Institute Helen Hasz-SinghGuldalderen 12DK-2640 HedehusenePhone +45 72 44 70 00Email hhz@vd.dkWeb www.roaddirectorate.dk

NORDICDENMARK

VTT Technical Research Centreof FinlandKari MäkeläP.O.Box 1000FI-02044 VTTPhone +358 20 722 4586Email kari.makela@vtt.fiWeb www.vtt.fi

FINLAND

Icelandic Road AdministrationG. Pétur MatthiassonBorgartún 7IS-105 ReykjavikPhone +354 522 1000Email gpm@vegagerdin.isWeb www.vegagerdin.is

ICELANDInstitute of Transport EconomicsHarald AasGaustadalléen 21NO-0349 OsloPhone +47 22 57 38 00Email ha@toi.noWeb www.toi.no

NORWAYNorwegian Public RoadsAdministrationThorbjørn Chr. RisanP.O. Box 8142 DepNO-0033 OsloPhone +47 915 02030Email thorbjorn.risan@vegvesen.noWeb www.vegvesen.no

NORWAY

VTIMagdalena GreenSE-581 95 LinköpingPhone +46 13 20 42 26Orderphone +46 13 20 42 69Email nordic@vti.seWeb www.vti.se

SWEDEN

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Requestsfor back issues, and notifica-tion of address changes.Readers outside the Nordiccountries: see Swedish add-ress. Readers in the Nordiccountries: see adressesabove.

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