wilton park, beaconsfieldnewwiltonpark.com/wp-content/uploads/pdf_downloads... · 3.4 summary...

Phil Jones Associates Ltd

The Aquarium

King Street

Reading

RG1 2AN

philjonesassociates.co.uk

Inland Ltd

Wilton Park, Beaconsfield

Transport Assessment

August 2017

Project Code: 02374


Inland Ltd Wilton Park, Beaconsfield

Version Control and Approval

Version Date Main Contributor Issued by Approved by

A – DRAFT 04 August 2017 JH/MF JH MF

B - FINAL 10 August 2017 JH/MF JH MF

Prepared for

Inland Ltd



Contents

Section Page

1 Introduction 6

1.1 Background 6

1.2 Development Proposals 6

1.3 Planning History 7

1.4 Scoping Discussions 8

1.5 Structure of the Report 9

2 Policy Review 10

2.1 National Planning Policy Framework (NPPF) 10

2.2 Planning Policy Guidance (PPG) 11

2.3 Buckinghamshire County Council Local Transport Plan 4 (2016 - 2036) 12

2.4 South Bucks LDF Core Strategy (Adopted 2011) 13

2.5 South Bucks District Council Wilton Park Development Brief SDP (2015) 14

2.6 Emerging Chiltern and South Bucks Local Plan (2014 - 2036) 16

2.7 Local Parking Standards 17

3 Existing Condition 18

3.1 The Site 18

3.2 Surrounding Highway Network 19

3.3 Sustainability of the Site 20

3.4 Summary Sustainability 29

3.5 Existing Traffic Flows 29

3.6 Highway Safety 29

4 Development Proposals 32

4.1 Development Mix and Layout 32

4.2 Access Arrangement 34

4.3 Parking Provision 35

4.4 Servicing 36

4.5 Sustainable Transport Strategy 36

5 Travel Demand 40

5.1 Introduction 40

5.2 Non-Residential Trip Generation 42

5.3 Wilton Park Total Trip Generation 47

5.4 Net Traffic Impact 47

6 Trip Distribution 49

6.1 Residential Trip Distribution 49

6.2 Commercial Trip Distribution 51

7 Assessment Parameters 53

7.1 Modelling Approach 53

7.2 Junctions to be Assessed 54

7.3 Assessment Horizons & Traffic Growth 54

8 Junction Capacity Modelling 56

8.1 London End Roundabout 56

8.2 Pyebush Roundabout 63

9 Mitigation Schemes 71

9.2 Signalised London End Junction - Preferred Option 71

9.3 Pyebush Roundabout Mitigation - Preferred Option 76

10 Summary and Conclusions 85



Appendices

Appendix A Scoping Correspondence

Appendix B Milton Heritage Cycle Route Map

Appendix C Traffic Survey Data

Appendix D Highway Safety Information

Appendix E Indicative Masterplan

Appendix F Trip Generation Surveys

Appendix G National Travel Survey (NTS) Data

Appendix H TRICS Outputs

Appendix I 2011 Census JtW Trip Distribution

Appendix J Community Hub Trip Distribution

Appendix K 2011 Census Office Trip Attraction & Distribution

Appendix L Assessed Traffic Flows

Appendix M London End Roundabout Modelling Results

Appendix N Phased Development Traffic Flows

Appendix O Pyebush Roundabout Modelling Results

Appendix P London End Roundabout – Preferred Mitigation Option

Appendix Q London End Signalised Junction – JCM Results

Appendix R Pyebush Roundabout – Preferred Mitigation Option

Appendix S Pyebush Roundabout Mitigation – JCM Results

Wilton Park, Beaconsfield 6 Inland Ltd


1 Introduction

1.1 Background

1.1.1 Phil Jones Associates (PJA) have been commissioned by Inland Ltd to prepare a Transport

Assessment (TA) to accompany an outline planning application for the residential led mixed-use

development at Wilton Park in Beaconsfield, Buckinghamshire.

1.1.2 The aim of this report, is to establish the transport implications of the proposed development as

set out by the criteria within the National Planning Policy Framework (NNPF) and the National

Planning Policy Guidance (NPPG) with specific reference to paragraph 32 of the NPPF that states:

"All developments that generate significant amounts of movement should be supported by a

Transport Statement or Transport Assessment. Plans and decisions should take account of whether

• the opportunities for sustainable transport modes have been taken up depending on the nature

and location of the site, to reduce the need for major transport infrastructure

• safe and suitable access to the site can be achieved for all people

• improvements can be undertaken within the transport network that cost effectively limit the

significant impacts of the development. Development should only be prevented or refused on

transport grounds where the residual cumulative impacts of development are severe."

1.2 Development Proposals

1.2.1 Outline planning permission is sought for:

Demolition of all existing buildings except those relating to sewage treatment works, site

maintenance building and 46 service family accommodation houses in southern area.

Comprehensive mixed-use redevelopment comprising: 304 residential properties (Class C3);

employment and community uses including new ATC facility (Classes A1, A3, B1, B2, D1 & D2);

formal and informal public open space, including local park and sports pitches with changing

facilities; new access road from A40 Pyebush Roundabout to form southern part of Beaconsfield

Relief Road; network of footpaths and cycleways including alterations to Minerva Way; car

parking; on-site access roads; and landscaping works (outline application with all matters

reserved except means of access and scale of development).

1.2.2 Details of the development mix and layout as well as the new access arrangements and likely

phasing are provided in Chapter 4 of this report.

Inland Ltd 7 Wilton Park, Beaconsfield


1.3 Planning History

Wilton Park Site Access / Eastern Relief Road Phase 1

1.3.1 The initial link off the Pyebush Roundabout into the Wilton Park scheme as consented by both South

Buckinghamshire District Council (SBDC) as Local Planning Authority and Buckinghamshire County

Council (BCC) as Highway Authority (Ref: 14/01467/FUL) is now constructed and operational. The

remaining alignment of Phase 1 of the relief road, as set out in Drawing '978-101 B' remains subject

to consent given October 2014.

1.3.2 A Transport Assessment has been prepared by PJA in July 2014 (hereafter referred to as 2014 TA)

which supported the application for the access road, tested the capacity of the access road and a

development of up to 350 dwellings, office space (4,375sq.m GFA) and a community hub

(2,200sq.m GFA) at Wilton Park. The report concluded that the proposed infrastructure, as designed

by Phil Jones Associates was appropriate as an access to the Wilton Park site and subsequent

development of this quantum of housing and employment. Although the assessment included the

traffic impact of the proposed redevelopment, the consent related only to the initial phase of the

Eastern Relief Road.

1.3.3 Detailed information and plans regarding the proposed site access arrangement at Wilton Park are

summarised in Chapter 4 of this report.

Jacobs A355 Improvements Eastern Relief Road Transport Assessment (2016)

1.3.4 Planning application 16/02283/CC submitted by Buckinghamshire County Council (BCC) in

November 2016 for a new relief road between A355 / Maxwell Road and Wilton Park on land to the

east of Beaconsfield was granted planning consent in July 2017. This section of the relief road marks

Phase 2 of the scheme and will link into the northern roundabout of the Wilton Park part of the

road (Phase 1) adjacent to Minerva Way approved under the 2014 consent. Details of the

pedestrian and cycle crossing point and short connecting link between the Phase 1 and Phase 2

road sections have still to be finalised.

1.3.5 The A355 Relief Road was anticipated in BCC's Core Strategy (see Chapter 2) and is recognised as

being necessary to reduce congestion on the A355 and enhance performance of the London End

Roundabout. To assess the impact of the relief road on the surrounding road network, a local

cordon model of the area was created using the Strategic Model for Buckinghamshire, the

assessment of which was done by Jacobs in August 2016. The modelling included an estimation of

the likely traffic generated by the Wilton Park scheme and therefore the results include the impact

of these vehicles.



1.3.6 The Transport Assessment report by Jacobs identifies that the introduction of the relief road will

lead to a reduction in traffic volume at the London End junction by 30%, with around 800 vehicles

travelling southbound diverting in the morning peak and 600 diverting northbound in the evening

peak. As such, it is concluded by Jacobs that the Relief Road provides "a significant net benefit for

the London End roundabout."

1.3.7 From a transport perspective, recent comments (Ref: CC/65/16) from Transport for

Buckinghamshire (TfB) dated 6th July 2017 states that Highways raised no objection to this

application, concluding:

• There are no specific highway safety issues within the study area that will be exacerbated as a

result of this proposal;

• Although the performance of some junctions may worsen as a result of the proposed relief road;

this is outweighed by the significant overall network benefits resulting from the relief road,

particularly at the London End roundabout;

• Remaining issues regarding the road layout can be addressed at the detailed design stage; and

• The application has demonstrated the strategic merits of the link road provision and that any

minor changes to existing junction operation are not considered severe.

1.3.8 As set out in the Jacobs assessment, the Relief Road presents a significant benefit in alleviating the

existing traffic conditions in the vicinity of the Wilton Park site, as well as further enhancing

connectivity to the Wilton Park development for both motorised and non-motorised road users

particularly for journeys to and from the north.

1.4 Scoping Discussions

1.4.1 An initial draft version of this Transport Assessment report was submitted to TfB in December 2016.

Comments were received via e-mail on 11th May 2017. PJA's response to these comments has been

incorporated into this updated report. In summary, the main comments are as follows:

• Further details are required to demonstrate the sustainable location of the development site.

This includes the provision of pedestrian infrastructure in the vicinity of the site and accessibility

to bus services;

• Manual Turning Count data from 2013 should be updated to reflect existing conditions;

• Detailed plans of Minerva Way as high quality, attractive and safe pedestrian/cycle route

between Beaconsfield and the site need to be provided;

• Design of pedestrian crossing at Minerva Roundabout junction to be explained in more detail;



• Existing dropped kerb crossing points over the London End roundabout will not offer a safe and

convenient means for pedestrians and cyclists to move from the site to the centre of

Beaconsfield and vice versa;

• Measures to improve public transport accessibility need to be considered, for the situations both

with or without the northern section of the relief road in place;

• The proposed usage and composition of the Community Hub should be clarified and resultant

vehicle trip generation should be considered in this assessment;

• Trip Distribution methodologies to be updated to include 2011 Census data;

• Details about traffic growth calculation and accompanying traffic flow diagrams to be provided;

and

• Modelling of London End roundabout to be updated to reflect observed queues and capacity

constraints on individual arms.

1.4.2 A summary of the scoping correspondence is attached in Appendix A.

1.5 Structure of the Report

1.5.1 The remainder of the report is structure as follows:

• Chapter 2 - Policy Review;

• Chapter 3 - Existing Conditions;

• Chapter 4 - Development Proposals;

• Chapter 5 - Travel Demand;

• Chapter 6 - Trip Distribution;

• Chapter 7 - Assessment Parameters;

• Chapter 8 - Junction Capacity Assessment;

• Chapter 9 - Mitigation Options; and

• Chapter 10 - Summary and Conclusions.



2 Policy Review

2.1 National Planning Policy Framework (NPPF)

2.1.1 The National Planning Policy Framework (NPPF) was published in March 2012 and sets out the

Government's planning policies for England and how these are expected to be applied to achieve

sustainable development. The NPPF replaces the previous policy guidance contained within PPS 3 -

Housing and PPG 13 - Transport.

2.1.2 Policies aimed at promoting sustainable development are covered by Paragraphs 29 to 41 of the

NPPF with Paragraph 32 stating that:

"All developments that generate significant amounts of movements should be supported by a

Transport Statement or Transport Assessment. Plans and decisions should take account of whether:

• The opportunities for sustainable modes have been taken up depending on the nature and

location of the site, to reduce the need for major transport infrastructure;

• Safe and suitable access to the site can be achieved for all people; and

• Improvements can be undertaken within the transport network that cost effectively limits the

significant impacts of the development. Development should only be prevented or refused on

transport grounds where the residual cumulative impacts of the development are severe."

2.1.3 Traffic congestion is an inherently difficult concept to define as it has both physical and relative

dimensions. The Department for Transport (DfT) define congestion in physical terms as:

"The way in which vehicles interact to impede each other's' progress. These interactions and their

influence on individual journeys usually increase as demand for the available road space

approaches capacity or when capacity itself is reduced through road works or closures for

example."

"However, this purely physical definition ignores the fact that congestion can mean very different

things to different people. For example, a person living in a rural area might regard an unusually

long queue of traffic experienced on their daily commute as severe congestion, while someone

living in an urban area might experience much longer hold-ups on a daily basis and regard the

same length queue as being almost totally uncongested. In relative terms, congestion can

therefore be defined in terms of the difference between users' expectations of the road network

and how it actually performs." (An introduction to the Department for Transport's Road

Congestion Statistics - DfT (2013))



2.1.4 For the purposes of the TA severity of impact has been defined as the point at which the increase

in journey time delay becomes unpredictable as set out in the 'Department for Transport's

'Introduction to Road Congestions Statistics'.

2.1.5 Paragraph 35 states:

"Plans should protect and exploit opportunities for the use of sustainable transport modes for the

movement of goods and people. Therefore, developments should be located and designed where

practical to:

• Accommodate the efficient delivery of goods

• Give priority to pedestrians and cycle movements, and have access to high quality public

transport facilities

• Create safe and secure layouts which minimise conflicts between traffic and cyclists and

pedestrians, avoiding street clutter and where appropriate establishing homes zones;

• Incorporate facilities for charging plug-in and other low emission vehicles; and

• Consider the needs of people with disabilities by all modes of transport."

2.1.6 This Transport Assessment reports on the impact the proposed development will have on the local

highway network and considers the accessibility and sustainability of the development site with

regards to the principles and guidance set out in the NPPF above. The objective of such assessment

is to ensure that the demand for travel is effectively managed, sustainable accessibility is maximised

and appropriate mitigation measures are identified to address any residual highways impact.

2.2 Planning Policy Guidance (PPG)

2.2.1 The National Planning Practice Guidance (NPPG) was published as a web-based resource in March

2014 and provides important information for any user of the planning system.

2.2.2 There is a specific section dedicated to transport entitled 'Travel Plans, Transport Assessments and

Statements in Decision Taking'. This section of the NPPG sets out the overarching principles of the

TA process and also more detailed consideration of the scope of assessments required.

• The key issues to be addressed in a Transport Assessment, as set out in the NPPG, are as follows:

• The planning context of the development proposal;

• Appropriate study parameters;

• An assessment of public transport capacity, walking / cycling capacity and road network

capacity;

• Road trip generation and trip distribution;



• Measures to promote sustainable travel;

• Safety implications of development; and

• Appropriate mitigation measures where applicable.

2.2.3 The above transport related policies and planning practice guidance have an important role to play

in facilitating sustainable development. The transport system needs to be balanced in favour of

sustainable modes of transport, giving people a real choice about how they travel. However, it is

also recognised that different policies and standards are required in different communities and

opportunities to maximise sustainable transport solutions will vary from urban to rural areas.

2.3 Buckinghamshire County Council Local Transport Plan 4 (2016 - 2036)

2.3.1 The Councils Local Transport Plan 4 covers all types of transport related issues and opportunities

within the County. To achieve the Council's objective of making Buckinghamshire a well-connected

and growing place to work and live, the document sets out a range of policies, the following of

which are of particular relevance for the current development proposals at Wilton Park.

2.3.2 Policy 2 - 'Travelling in Buckinghamshire and beyond: improving our connectivity' emphasises the

need for improvements on key transport links within the region, including the A355 corridor

between Aylesbury and Beaconsfield, to reduce congestion and improve journey times. Policy 2

states:

"We will work to improve the connectivity and reliability of Buckinghamshire's transport

network, stimulate economic growth and promote safer more sustainable travel."

2.3.3 Policy 3 - 'Managing the impacts of new developments' stresses the need to secure essential

infrastructure to meet the current and future needs of residents within the region. This includes

continuing to invest in the maintenance and improvement of the county's existing roads and

footpaths.

2.3.4 Policy 7 - 'Reliable Road Travel' addresses the need to provide a road network that ensure journey

time reliability and increased capacity by building new roads or expanding existing ones. To provide

a reliable road network the Council will encourage Highways England's investment programme to

develop and enhance strategic roads that help Buckinghamshire thrive. In addition, emphasis is put

on developing transport schemes that increase opportunities for sustainable travel to reduce

demand for car trips.

2.3.5 Policy 12 - 'Walking' and Policy 13 - 'Cycling' aim to build a high-quality network that encourages

the use of sustainable modes of transport, especially for shorter journeys. A case study of

Beaconsfield's cycle network informs Policy 13 which provides an example of locally led planning

and utilising local knowledge and resources to improve the cycle experience within Beaconsfield.



2.3.6 Policy 14 'Car Clubs, car sharing and taxis' stresses the opportunity of reducing the demand for

parking spaces and reduce the number of cars on the road network through securing of planning

agreements that enable the integration of car clubs into appropriate new developments. A helpful

tool is the implementation and monitoring of travel plans, which make the most of car club

opportunities within new developments.

2.3.7 Policy 16 'Total Transport' touches upon the importance of buses and community transport within

the region and highlights the need to ensure that developments are located near good public

transport or provide the right public transport.

2.4 South Bucks LDF Core Strategy (Adopted 2011)

2.4.1 The Core Strategy document prepared by South Bucks District Council is the most important

document of the South Bucks Local Development Framework (LDF) and establishes a long-term

strategy to manage development, provide services, deliver infrastructure and create sustainable

communities within the District. With regard to the proposed development at Wilton Park to which

this TA refers, three key objectives of the Core Strategy are of particular relevance:

• Focus new development in accessible locations, reducing the need to travel and increasing

opportunities for walking, cycling and public transport use.

• Encourage more sustainable forms of transport and increase travel choice to help reduce traffic

congestion and facilitate healthier, lower carbon lifestyles.

• Address traffic congestion (including on the A355/A40 to the east of Beaconsfield) and mitigate

the amenity impacts of HGV movements.

• realise these objectives, the Core Strategy comprises numerous Core Policies, the most relevant

of which are presented below.

2.4.2 The Core Strategy has identified Beaconsfield as having a 'Community Need' due to significant peak

time traffic problems, particularly at the junction of A355 with A40. A critical success factor of the

Strategy is to reduce congestion at this location. A range of measures will be needed to ease road

over-capacity, including mitigation measures as part of the redevelopment of Wilton Park. Section

3.2.58 of the Core Strategy argues:

"In the longer term, if traffic volumes increase as expected, an A355 Relief Road is likely to be

needed to reduce pressure on the London End roundabout, with the first part of this achieved by

the new access in to Wilton Park from Pyebush roundabout."

2.4.3 Regarding the wider transportation impact of the new developments within the District 'Core Policy

7 - Accessibility and Transport' states:



"The Council will seek to improve accessibility to services and ensure a safe and sustainable

transport network by supporting the rebalancing of the transport system in favour of more

sustainable modes of transport…. This rebalancing will be achieved by:

• Focusing new development that generates substantial transport movements in locations that

are accessible by public transport, walking and cycling.

• Working with the highway authority, Rights of Way Access Group, and others to improve

transport choices for local residents, especially in rural parts of the District.

• Encouraging safe and attractive improvements to pedestrian and cyclist routes and facilities.

• Supporting the greater use of rail services, including improvements to parking at train stations

and connecting bus services where viable.

• Ensuring that the impact of new development on the road network is minimised and mitigated

through the use of 'mobility management' measures such as Travel Plans."

2.4.4 The Core strategy identifies Wilton Park as an 'Opportunity Site', which will deliver much needed

housing and provide recreational facilities for the community. 'Core Policy 14 - Wilton Park

(Opportunity Site)' of the Core Strategy states that any development proposals should provide for

a sustainable mix of uses and be integrated with Beaconsfield through improved provision of

pedestrian and cycle infrastructure on the A40 and A355. In addition, the CP14 states:

"The redevelopment proposals should ensure an acceptable means of vehicular access. Any

access of Pyebush roundabout must be constructed so that it is capable of future upgrading and

extension to form an A355 Relief Road."

2.4.5 The following sections of this TA will take into consideration the objectives of the Core Strategy and

its Core Policies and assess the scope for mitigation measures that will help address localised traffic

congestion. As has been stated above, the new vehicular site access of Pyebush roundabout will

play an important role in mitigating against traffic impact on the local road network, a detailed

assessment of which has been provided in South Bucks DC's Wilton Park Development Brief SDP

(2015).

2.5 South Bucks District Council Wilton Park Development Brief SDP (2015)

2.5.1 This SPD has been prepared by South Bucks District Council to establish the principles that will guide

the future redevelopment of Wilton Park. As such, it deals with access for vehicles, cyclists,

pedestrians and public transport, including the mitigation of transport impacts on the strategic and

local road networks, and with other necessary infrastructure. The SPD does not include new policies

and does not form part of the Council's Development Plan. The SPD does however form a material

consideration in the determination of planning applications and will be considered alongside Core

Policy 14 and other local planning policies.



Access Road off Pyebush Roundabout

2.5.2 In relation to Core Policy 14 mentioned above, the Wilton Park Development Brief provides the

framework on which the new vehicle access road off Pyebush Roundabout has been consented.

2.5.3 Through consultation with local residents it was understood that there is considerable support for

the road to be a more integrated route, with a focus on pedestrians and cyclists rather than higher

vehicle speeds (69%) and set within a landscaped space which opens up views of the surrounding

area (81%).

2.5.4 The following statement have been made in the Adopted SPD:

"The access road should be constructed so that it is capable of being extended to form part of a

Relief Road but designed in a way that is sensitive to its context to facilitate safe and convenient

access between Beaconsfield and Wilton Park for pedestrians and cyclists as well as local vehicles

access…"

…and further:

"As the road enters the site and heads north towards Minerva Way, it should change character.

Designed as a 'street' it should be more than just a transport corridor. It should incorporate the

principles set out in the Department for Transport's 'Manual for Streets'. The Manual aims to change

street design for the better, reducing the impact of vehicles and giving a higher priority to the needs

of pedestrians and cyclists, with direct, attractive, safe, well connected, permeable street networks.

The route should be part of the first stage of a future A355 Relief Road. It must therefore be carefully

designed to perform an effective strategic function whilst also helping deliver a development that is

accessible and well-integrated with its surroundings."

Minerva Way

2.5.5 Furthermore, the Adopted SPD announced that the use of Minerva Way would be altered:

"Removing private vehicle traffic from Minerva Way (except for access to existing homes adjacent

to Park Lane and London Road), creates the opportunity for it to become a more attractive and safer

direct link between Wilton Park and Beaconsfield for pedestrians and cyclists."

2.5.6 Indeed, the SPD concludes that Minerva Way "will not be acceptable for general vehicle access"

though forms "a key part of the delivery of the scheme and provide a high quality, attractive and

safe pedestrian/cycle route between Beaconsfield and the site...it should provide linkages to the

new homes, community facilities and employment uses and connect with other routes in the

surrounding area."



2.5.7 Moreover, the SPD recognises that the western end of Minerva Way falls within the Beaconsfield

Conservation Area and, hence, any proposals for land inside the Conservation Area will be expected

"to preserve or enhance its character or appearance."

London End Roundabout

2.5.8 The London End Roundabout is a small four arm junction approximately 500m to the west of the

Pyebush Roundabout. The SPD acknowledges that "the layout of this junction is not sufficient to

cater for the traffic that uses it" and therefore there is a need to reduce congestion in the morning

and evening Peak Hours at this location. As such, the SPD concludes that the Transport Assessment

supporting the planning application for the Wilton Park scheme will need to demonstrate to the

Highway Authority's satisfaction "an acceptable level of traffic performance at London End

Roundabout and evidence that any residual cumulative impacts of the development on this junction

and elsewhere in Beaconsfield are acceptable."

2.5.9 The SPD also recognises that there is no formal crossing provision for pedestrians and cyclists at the

junction. Thus, the document sets out the importance to address the ease of safe movement across

this junction if Minerva Way is to be used as a pedestrian and cycle link between the Wilton Park

site and Beaconsfield.

2.6 Emerging Chiltern and South Bucks Local Plan (2014 - 2036)

2.6.1 Chiltern District Council and South Bucks District Council are preparing a new emerging joint Local

Plan for Chiltern and South Bucks Districts. Between 31st October 2016 until 12th December 2016

the Councils carried out public consultation on 'Preferred Green Belt Options' the Councils consider

should be taken forward in the Local Plan in order to help meet development needs. All comments

received within the consultation period are now being considered and will assist the Council in

producing a 'Draft Local Plan' document.

2.6.2 'Preferred Option 9: Area East of Beaconsfield' refers to an area that includes the Wilton Park site

and suggests that between 1,500 and 1,700 dwellings and 5ha of employment space could be

developed. The report notes that requirements as part of any development entail the provision of

community focal points as well as transport access points with emphasis on walking, cycling and

passenger transport. Reference is also made to the need to provide a bus subsidy until the

development has progressed to a suitable point.

2.6.3 The Local Plan will set out policies used to determine planning applications, set site allocations and

propose new development in the Chiltern and South Bucks areas. The document will eventually

replace the Adopted Core Strategy for South Bucks District (2011).



2.7 Local Parking Standards

2.7.1 Although BCC's Buckinghamshire County Wide Parking Guidance forms part of the evidence base

for the emerging Local Plan it has not been formally adopted by SBDC. Acting as Local Parking

Authority, SBDC's requirements for parking are therefore set out in the adopted South Bucks

District Local Plan, which has been consolidated in 2011. The provision of car parking spaces at new

developments is emphasised in Policy TR7 - Parking Provision of the Local Plan and states:

"Development will only be permitted where: -

• it complies with the parking standards set out in Appendix 6;

• the proposals would not reduce the level of parking provision serving other development;

• parking provision is made on the development site or, where this is not possible, on other land in

the immediate vicinity provided that is likely to be used to meet parking needs associated with

the development; and

• it would not be likely to result in non-residential on-street parking in residential areas."

2.7.2 The provision of parking on the site will be agreed in line with the adopted standards as part of a

subsequent reserved matters application after outline permission has been granted.



3 Existing Condition

3.1 The Site

3.1.1 The site is located on Green Belt land to the north of the A40 London Road approximately 500m to

the east of Beaconsfield Old Town. The existing site and surrounding area is characterised by various

land uses, including arable fields, pasture, parkland, wood pasture, rough grassland, amenity

grassland, a lake and several areas of woodland. The Wilton Park site extends to 37.5ha.

3.1.2 Until recently, the Wilton Park Site was occupied by the Ministry of Defence School of Languages

(DSL), and is owned by Inland Ltd, whose parent company also controls land between Wilton Park

and Pyebush Roundabout. A gated entrance and security fence at the junction between Minerva

Way and Gorell Road represents the former separation point between the ‘secure’ part of the site

to the east and the ‘non-secure’ areas to the west. The latter accommodates the residential

properties that previously provided Service Family Accommodation (SFA), interspersed with areas

of open space.

3.1.3 The extent of the site outlined in the adopted Wilton Park Development Brief SPD (March 2015) is

illustrated on Figure 3-1 below.

Figure 3-1: Site Location

Inland Ltd (formerly Defence

Infrastructure Organisation)

Inland Ltd



3.2 Surrounding Highway Network

Minerva Way

3.2.1 Minerva Way is a 550m long private road that connects Wilton Park to Beaconsfield Old Town at

the London End Roundabout. The carriageway is of 5.5m width, narrowing in places to 5.1m, with

a footway of 1.5m on the southern side of the road. As set out in the Wilton Park SPD, the primary

function of this unadopted road was to provide vehicle, cycle and pedestrian access to the former

DSL, SFA housing and to the community facilities and sports pitches currently accessible to the

public. The western end of Minerva Way falls within the Beaconsfield Old Town Conservation Area.

3.2.2 Minerva Way is now closed to vehicles, other than for access to the small cluster of houses off

Minerva Way, immediately east of Park Lane.

A40

3.2.3 The A40 runs east to west beyond the southern boundary of the site, linking to the Pyebush

Roundabout and the A335 connection to the Junction 2 of the M40 from where access to

strategically important destinations, such as London, Oxford and Birmingham can be gained. The

London End Roundabout is a small four arm junction between Minerva Way, A355 Park Lane, A40

London End and A40 London Road. Core Policy 14 of SBDC’s Core Strategy recognised that this

junction is an existing congestion hot spot which the Highway Authority has indicated would not be

acceptable for accommodating any increase in traffic arising from the redevelopment of Wilton

Park. To mitigate against this and address concerns of the Council a new access off the Pyebush

Roundabout has been designed to form the first phase of a relief road northward to the A355 which

will also provide access to the Wilton Park scheme.

A355

3.2.4 The A355 provides the main north-south route through the South Bucks District, connecting

Amersham and the A413 in the north to Beaconsfield and the M40, and on to Slough in the south.

It is a two-way single carriageway road with the speed limit reducing from 40mph to 30mph as it

passes through Beaconsfield.

3.2.5 The A355 forms the southern arm of the Pyebush Roundabout, which is located approximately

500m east to the London End Roundabout. Planning consent has been granted for the construction

of a relief road leading from the A355 to the north of the centre of Beaconsfield and down to the

Pyebush roundabout. As discussed in Section 1.3, the Transport Assessment prepared by Jacobs in

support of the delivery of the Relief Road which included an estimate of traffic generated by the

Wilton Park development, identified that the scheme would offer a significant capacity

improvement on the A355 particularly at London End.



Figure 3-2: Surrounding Road Network

3.3 Sustainability of the Site

3.3.1 GIS software has been used to demonstrate the sustainability of the development site and to

highlight the site's location in the vicinity of a range of local amenities. This includes existing links

to public transport and the local highway network as well as details of pedestrian and cycle

provisions in the vicinity of Wilton Park.

3.3.2 Beaconsfield is a market town within South Buckinghamshire which contains the infrastructure and

facilities required to meet local and day to day shopping needs of over 4,700 households. It lies

halfway between Oxford and London; a prime location for access to the M4, M25 and M40; good

rail links between London and Birmingham and convenient connections to Heathrow Airport.

Access to Local Amenities

3.3.3 The results of the GIS analysis demonstrate that the development site is within a highly sustainable

location, providing links to a wide range of local amenities. A selection of local amenities located in

the vicinity of the Wilton Park site is listed below.

Key:

1 – Wilton Park

2 – A40 London Road

3 – London End

4 – Park Lane

5 – M40 Junction 2

6 – Indicative Relief Road Alignment

① ③

②

⑥

④

⑤



Employment Facilities

3.3.4 The proximity of the site to Beaconsfield Town Centre offers access to a wide range of employment

opportunities, which also include the following educational facilities:

• Beaconsfield High School (approx. 1.5km);

• The Beaconsfield School (approx. 1.2km); and

• Beaconsfield Town Centre (approx. 2km).

3.3.5 It should be noted that the development proposals to which this report refers entail the provision

of office space and other non-residential land uses, which further contribute to the accessibility of

the site to local employment opportunities for future residents at Wilton Park.

Educational Facilities

3.3.6 The development site benefits from good access to a number of primary and secondary schools

located in Beaconsfield.

• The Beaconsfield School (approx. 1.2km);

• Butlers Court School (approx. 1.5km);

• St Mary & All Saints CofE Primary School (approx. 1.5km);

• Beaconsfield High School (approx. 1.5km);

• Davenies School (approx. 2km);

• High March School (approx. 3km); and

• Holtspur School (approx. 4km).

3.3.7 The National Film & Television School as well as the 'artsmart' School of Art are located within

Beaconsfield Old Town. Access to higher education is available at the Pentacle Virtual Business

School in Beaconsfield and the Buckinghamshire New University Campus located in High Wycombe.

Retail Facilities

3.3.8 There are a number of convenience retail stores, high street shops as well as supermarkets located

along the local road network in the vicinity of the site, a summary of which is listed below:

• Convenience Stores near London End Roundabout (approx. 500m);

• London End High Street Shops (approx. 800m);

• Beaconsfield Town Centre (approx.2km); and

• Four Supermarkets (<2km).



3.3.9 As part of the development proposals set out in the following Chapter, it is acknowledged that

future residents at Wilton Park will be able to access food retail facilities on-site, further reducing

journey times and the need to travel by car.

Health Facilities

3.3.10 The following health facilities are accessible by foot from the Wilton Park site:

• Millbarn Medical Centre (approx. 500m);

• NHS Dentist (approx. 800m);

• Beaconsfield Travel Clinic (approx. 800m); and

• The Simpson Centre (approx. 800m)

3.3.11 For advanced health care, Wycombe Hospital is located within High Wycombe. Google Maps

routing analysis has identified that the hospital can be accessed by car via the M40 with a journey

time of 13 minutes.

Leisure Facilities

3.3.12 To the north, the site is bounded by the Beaconsfield Golf Club and to the west by Beaconsfield

Cricket Club, which may provide a local recreation or employment opportunity for some residents.

In addition, the provision of sport changing facilities, an art gallery as well as some café/restaurant

space included in the development proposals will add to the recreational offers at Wilton Park. The

proximity of the residential element of the scheme to these facilities further reduce the need to

travel by car.

3.3.13 Figure 3-3 on the next page illustrates the site's location in relation to a selection of local schools,

employment opportunities, GPs surgeries, Beaconsfield station and food stores. Also illustrated on

Figure 3-2 are walking isochrones that demonstrate 5/10/15/20 minute journeys on foot.

3.3.14 Although walking speeds can vary greatly depending on many factors, ArcGIS assumes an average

walking speed of 5.0 kilometres per hour. This accords with the guidance set out in IHT's guidelines

for 'Providing for journeys on foot' (2000) and is therefore deemed acceptable when applying ArcGIS

or Google routing analysis.



Figure 3-3: Local Amenities in the vicinity of the site (5/10/15/20/25 minutes)

Pedestrian and Cycle Infrastructure

3.3.15 The way people travel from one place to another is an essential part of our everyday lives and is

central to ensuring sustainable development. This is recognised by BCC as part of Policy 12 –

‘Walking’ and Policy 13 – ‘Cycling’ of Local Transport Plan 4 which aim to build a high-quality

network throughout the County that encourages the use of sustainable modes of transport,

especially for shorter journeys. The tangible effects that sustainable transport infrastructure can

have on personal health, safety, economic viability and social inclusion has also been emphasised

in the Department for Transport’s recent publication of the ‘Cycling and Walking Investment

Strategy’ (2017).

3.3.16 Thus, good planning and design of sustainable transport infrastructure is required to influence

travel behaviour whilst at the same time ensuring convenient and safe access to health services,

education, jobs and other amenities.

Food Retail

GP Surgery

Secondary School

Primary School

Railway Station

Walking Time



Walking

3.3.17 The adequate provision of pedestrian infrastructure in the vicinity of new development and the

promotion of walking as an alternative mode of transport is one of the key objectives set out in

BCC’s Local Transport Plan 4.

3.3.18 Pedestrian access to the site is currently via Minerva Way and takes the form of a 1.5m wide

continuous footpath with street lighting that stretches along the southern side of the road. As set

out in the Wilton Park Development Brief SPD, Minerva Way “should form a key part of the delivery

of the scheme and provide a high quality, attractive and safe pedestrian/cycle route between

Beaconsfield and the site”.

3.3.19 Figure 3-4 shows that two Public Rights of Way (PRoW) connect the urban area of Old Beaconsfield

to the countryside east of the town. A north-eastward route crosses fields from Amersham Road

and provides a link between the northern residential areas of Beaconsfield and Minerva Way. A

second public footpath route extends from the London End/London Road edge of Beaconsfield to

Pitlands Wood and Potkiln Lane crossing the A40 near Pyebush roundabout and the A335 link to

the M40.This footpath runs along the southern part of the Wilton Park site.

Figure 3-4: Public Rights of Way

Footpath

Minerva Way



3.3.20 At its western extent, Minerva Way adjoins the A355 Park Lane and the A40 via the London End

Roundabout junction. Dropped kerb crossing points are present on all arms and allow pedestrians

to cross the carriageway road and continue their journey towards Beaconsfield Town Centre. There

is a zebra crossing point on the A40 London End approximately 115m west to the London End

Roundabout.

3.3.21 As set out in Chapter 4 of this report, the development proposals at Wilton Park entail the provision

of new footpaths and crossing points that improve connections between Wilton Park and the

existing pedestrian infrastructure in the vicinity of the development site.

Cycling

3.3.22 In many cities, cycling has become a popular mode of transport on streets traditionally dominated

by individual motorised vehicles. Academic research collated by SUSTRANS or case studies

undertaken by Cycling UK allude to the fact that cycling can be an integral element of solutions to

support economic growth, tackle congestion, improve personal mobility and address health

problems associated with obesity and lack of physical activity. As such, cycling, like walking becomes

a great way to travel short distances as an alternative to using the car.

3.3.23 Cycle access to the site currently is from Minerva Way, which provides access to the development

site off the London End Roundabout. The local road network in the vicinity to the development

connects future residents to Beaconsfield railway station (2km), Beaconsfield Town Centre (2km)

and a range of local education and retail facilities.

3.3.24 The site offers access to leisure and commuting trips undertaken by bike via the Milton Route that

passes on Longbottom Lane approximately 1.5km east to the site. The route forms part of the

Chiltern Heritage Cycling Trail and links the nearby Seer Green with Amersham and Little Chalfont.

An overview of the cycle route is attached in Appendix B.

3.3.25 As set out in Section 2.3.5 of this report, the Beaconsfield Cycle Network case study emphasises the

role of community groups to audit their local cycling and walking infrastructure and identify what

improvements are needed. The Beaconsfield Cycle Paths Action Group works closely with BCC,

SUSTRANS and Chiltern Railways to secure funding for enhancing sustainable access to railway

stations, schools and other local amenities in Beaconsfield.

Public Transport

Bus Services

3.3.26 The nearest bus stops to the site are located along the A40 London Road, approximately 50m from

the western end of Minerva Way (Figure 3-5). The stop on the southern side of the carriageway

road takes the form of a bus shelter with seating opportunities provided to waiting passengers. On



the opposite side of the carriageway, adjacent the vehicular access to the Beaconsfield Cricket Club,

a flag post indicates the bus stop for the eastbound services

Figure 3-5: Bus routes serving Wilton Park development

3.3.27 London Road is served by the 74, 581, 740, and also by the A40. London Road is served by five buses

per hour in each direction. Services running from these bus stops offer access to surrounding towns

and local centres such as Slough and Uxbridge, as well as Heathrow Airport.

3.3.28 In addition, there are further stops on Amersham Road approximately 500m north of the London

End Roundabout, which take the form of bus stop flags. The stops are served by routes 74, 377, 581

and 740 and serve Beaconsfield Old Town, New Town and Beaconsfield Railway Station. The bus

routes combine to provide at least four buses per hour. Their route is via Maxwell Road and

Amersham Road, and at London End roundabout the 74, 581 and 740 use London Road, whilst the

377 uses London End.

3.3.29 Other services in Beaconsfield worth noting are:

• X336, 336 and 580, which route via the A40, Station Road, Maxwell Road and Amersham Road

combining to provide at least 1 bus per hour in each direction; and

• 647, which is a school bus service departing from Aylesbury End.



3.3.30 Table 3-1 details the frequency of local bus services that operate in the vicinity of the site.

Table 3-1: Existing Bus Services in the vicinity of the site

Route Destination Peak Hour Frequency Operating Hours Days of Operation

74 Slough – High Wycombe Every 45 – 60 minutes 07:36 – 19:54 Mo - Sat

High Wycombe – Slough Every 45 – 60 minutes 06:25 – 18:53 Mo – Sat

336 Watford – Amersham – High Wycombe Every 60 minutes 10:04 – 18:59 Mo – Sat

High Wycombe – Amersham – Watford Every 45 – 60 minutes 06:48 – 18:27 Mo – Sat

X336 Watford – High Wycombe Three Services a Day 07:39 / 09:20 / 19:39 Mo – Fr

High Wycombe – Watford One Service a Day 05:58 Mo – Fr

377 Loudwater – Tylers Green Three Services a Day 10:21 / 11:27 / 12:18 Mo – Fr

580 High Wycombe – Uxbridge One service per day 07:46 (08:05 on Sat) Mo – Sat

Uxbridge – Beaconsfield One service per day 17:55 (18:24 on Sat) Mo – Sat

581 Uxbridge – Beaconsfield One service per day 15:08 (17:14 on Sat) Mo – Sat

Beaconsfield – Uxbridge One service per day 09:19 Mo – Sat

647 Aylesbury – High Wycombe One service per day 08:19 Mo – Fr

High Wycombe – Aylesbury One service per day 15:40 Mo – Fr

740

Heathrow Airport – High Wycombe Uxbridge – High Wycombe Beaconsfield – High Wycombe

Every 30 – 60 minutes Every 60 minutes Every 60 minutes

06:48 – 21:03 08:14 – 19:04 08:45 – 17:45

Mo – Fr Sat Sun

High Wycombe – Heathrow Airport High Wycombe – Uxbridge High Wycombe – Beaconsfield

Every 30 – 60 minutes Every 45 – 60 minutes Every 60 minutes

05:34 – 19:40 07:06 – 18:54 08:38 – 17:36

Mo – Fr Sat Sun

A40 Heathrow Airport – High Wycombe Every 60 minutes 07:33 – 19:29 Mo – Sun

High Wycombe – Heathrow Airport Every 60 minutes 05:44 – 17:32 Mo – Sun

3.3.31 As demonstrated in Figure 3-6 on the next page, the local bus stops are outside the recommended

400m walking distance from the development site as set out in in CIHT’s ‘Guidelines for Providing

Journeys on Foot’. Indeed, future residents will have to walk up to 1.5km to access the nearest bus

service to and from the site (i.e. those residents living at the far eastern end of the Wilton Park site).

3.3.32 The Wilton Park SPD emphasises the importance of ensuring good accessibility from the Wilton

Park site to local bus services and emphasises the opportunity to bring some of the existing bus

services into Wilton Park in order to minimise walking distances to local bus stops and encourage

future residents to use sustainable modes of transport. Section 4.4 of this report provides further

information about the proposed improvements in relation to the access to and provision of public

transport facilities at Wilton Park.



Figure 3-6: Bus Stops in the vicinity of the site (400m Buffer)

Rail Services

3.3.33 Beaconsfield railway station is approximately 2km from the London End roundabout and therefore

is within 25 minute walking distance from the site based on an average walking speed of 5km/h.

The proximity of the site to the railway station also means that cycling as a choice of transport is

encouraged, with a cycle time of 10 minutes based on an average cycling speed of 12km/h. Services

provided by Chiltern railways link to Kidderminster, Birmingham, Warwick, Leamington Spa,

Wembley Stadium and London Marylebone. There are five trains during the AM Peak Hour in each

direction. At the station secure, CCTV-monitored, covered storage areas for 170 bicycles are

provided. The station car park has capacity for 696 vehicles.

3.3.34 Chiltern Railways also operate from Seer Green and Jordans railway station which provide less

frequent services on the same line as Beaconsfield. The station is situated approximately 500m

north-east to the development site and can be accessed via the north-eastward PRoW that

currently crosses the fields from Amersham Road.

400m Buffer

Wilton Park



3.4 Summary Sustainability

3.4.1 The Wilton Park site benefits from a sustainable location due to its accessibility to a range of

education, retail, health and employment facilities. The proximity of the site to Beaconsfield Town

Centre will encourage journeys to be undertaken by sustainable modes of transport rather than the

private car. It should be noted that the development scheme at Wilton Park will provide some retail,

employment and leisure facilities on-site which will complement the existing facilities in the town

centre and further reduce the need to travel.

3.4.2 Existing pedestrian and cycle infrastructure in the vicinity of the site as well as the aim to upgrade

Minerva Way to a traffic-free access road into Wilton Park will enhance the accessibility of the site

by foot or bike and integrates the Wilton Park site into the wider sustainable transport network

within Beaconsfield and beyond.

3.4.3 It is acknowledged that current access to bus services routing past the site is beyond the

recommended walking distance. However, this can be addressed as part of the development

proposals as outlined in Chapter 4 of this report.

3.4.4 Overall, the site presents an opportunity to further promote sustainable transport infrastructure

within Beaconsfield through the provision of safe and convenient traffic free links between the

town centre and the Wilton Park site. The existing shortcoming of crossing points and accessibility

to bus services in Beaconsfield will be addressed through the delivery of the Wilton Park scheme.

3.5 Existing Traffic Flows

3.5.1 To establish the existing traffic conditions relevant to the proposed development Manual Classified

Counts (MCCs) were undertaken at the following two junctions:

• London End Roundabout; and

• Pyebush Roundabout.

3.5.2 The MTCs were undertaken on Tuesday 13th June 2017, between the hours of 07:00 - 10:00 and

16:00 - 19:00 outside of school holidays to observe neutral conditions. The traffic survey results

also provide detailed information of queue lengths observed on each arm of the junctions. The

results of the MCC's and queue survey are included in Appendix C of this report.

3.6 Highway Safety

3.6.1 As part of the 2014 TA, Personal Injury Accident (PIA) data has been obtained for the surrounding

road network of the Wilton Park site for the period 01/01/2009 - 31/12/2013. A total of 38 injuries

were recorded, three of which resulted in serious injuries and one accident resulted in fatal injuries.

Seven incidents included pedestrians and two accidents occurred vehicles failed to anticipate the



path of cyclists. The summary of incidents as well as a map of the study area used in the 2014 TA is

contained in Appendix D for reference.

3.6.2 For the purpose of this TA, the highway safety record in the vicinity of the site has been examined

using personal injury collision (PIC) data obtained from Crashmap.co.uk and roadcrash.co.uk over

the three-year period between 2014 and 2016. It is important to note that detailed information of

the Stats19 database regarding road safety on public roads for the year 2016 will be finalised and

made available later in 2017.

3.6.3 The results shown on Figure 3-7 below indicate that a total of four accidents were recorded on the

approaches to London End Roundabout, one of which included a cyclist and resulted in serious

injuries. In addition, a total of ten accidents were recorded at the Pyebush Roundabout junction,

two of which resulted in serious injuries to car drivers.

Figure 3-7: Personal Injury Accidents (PIA) on Local Road Network 2014 - 2016

3.6.4 The results in Figure 3-7 indicate that the Pyebush Roundabout continued to experience incidents

at the entry and exit lanes, which can mainly be attributed to the drivers failing to anticipate slowing

traffic in front of collisions following sudden lane changes.

3.6.5 An analysis of accidents at four arm roundabouts has been undertaken by Maycock and Hall (1984)1

and is regarded as a benchmark paper on this subject. The findings of a study of personal injury

1 Maycock and Hall (1984) ‘Accidents at 4-Arm Roundabouts’, Department of the Environment Department of Transport, TRRL Laboratory Report 1120: Crowthorne



accidents at a sample of 84 four-arm roundabouts on main roads in the UK show how the accident

frequencies by type are related to traffic flow and roundabout geometry using regression methods.

The results indicate that at roundabouts of conventional design accidents were relatively evenly

divided between entering-circulating accidents, approaching accidents, and single-vehicle

accidents. Indeed, aside from the common causation factor of 'loss of control' most of the accidents

in and around London End and Pyebush roundabout were rear end shunts on roundabout

approaches, resulting from sudden lane changes, braking or loss of concentration. This is typical of

a situation where delays and queuing are a frequent occurrence. In some occasions, abnormal

conditions caused accidents resulting in slight injuries.

3.6.6 Based on the most recent data available, no accidents were recorded on the northern arm of the

Pyebush Roundabout from where vehicle access to the site is taken. Thus, the number of accidents

in relation to the large traffic volumes navigating the roundabouts on a daily basis and level of

severity suggests that the road layout in the immediate vicinity of the site does not present a

highway safety issue. Moreover, it is expected that the proposed cycle and pedestrian

infrastructure improvements on Minerva Way and at the London End Roundabout junction will

further improve highway safety in the vicinity of the site.



4 Development Proposals

4.1 Development Mix and Layout

4.1.1 The current development proposals are for the comprehensive mixed-use redevelopment

comprising:

• 304 residential properties (Class C3);

• Employment and community uses including new ATC facility (Classes A1, A3, B1, B2, D1 & D2);

• Formal and informal public open space, including local park and sports pitches with changing

facilities;

• Network of footpaths and cycleways including alterations to Minerva Way;

• Car and Cycle parking; and

• Landscaping works.

4.1.2 The re-development of Wilton Park includes the demolition of all existing buildings except those

relating to sewage treatment works, maintenance building and 46 service family accommodation

houses in the southern area of the scheme.

4.1.3 It is important to note that this TA supports the planning application for a quantum of development

lesser than that already tested in relation to the access road to Wilton Park off the Pyebush

Roundabout (see Chapter 1). Thus, Table 4-1 provides an overview of the proposed proportion of

land uses compared to the assumptions made in previous assessments. The biggest difference

regards the proposals for the non-residential use on-site, which currently comprises 2,525sq.m of

GEA compared to a previous proposal for a total of 6,575sq.m of GEA.

Table 4-1: Change in Development Proposals at Wilton Park

Previous Assumptions (2014) Current Development Proposals (2016)

350 residential dwellings 46 retained SFA units

4,375sq.m office space 304 residential dwellings

1,600sq.m Community centre 100sq.m of A1 Retail

400sq.m nursery 130sq.m A3 Pavilion Cafe / D1 Art Gallery

100sq.m retail 170sq.m Maintenance

100sq.m restaurant 1,425sq.m Offices

300sq.m Crèche / Day nursery

175sq.m D2 Sports changing facilities

302sq.m D2 ATC facility



Residential Element

4.1.4 The development will provide 304 new residential units, in addition to the 46 existing and retained

SFA houses (the retained SFA housing do not form part of this application). The residential mix is

displayed in Table 4-2 below and the layout of the masterplan and as well as details about the

development mix is provided on the figures in Appendix E.

Table 4-2: Residential Development Mix

Size Total

Flats

1 bedroom 22

2 bedrooms 55

Houses

2 bedrooms 58

4 bedrooms 86

5 bedrooms 75

6 bedrooms 8

Total 304

Non-Residential Element

4.1.5 Small scale retail and business uses of up to 100sq.m of retail (Class A1) and 1,125sq.m of offices

(Class B1) respectively will be provided as part of the mixed uses within the Community Hub located

towards the western end of the site. The Community Hub will therefore also become accessible to

residents already living in Beaconsfield with convenient pedestrian and cycle links provided on

Minerva Way.

4.1.6 A further 300sq.m of office (Class B1) space and a day nursery (Class D1) of up to 300sq.m will be

provided within the Walled Garden area of the scheme. The 175sq.m of sports changing facilities

(Class D2) will be situated along the internal road network at the south-western edge of the site

and serve the sport fields and open public space. At the northern boundary of the Wilton Park site,

an art exhibition and café (130sq.m D1/A3 land use) will be situated near the existing lake.

4.1.7 Full planning application has already been submitted for the construction of replacement Army

Cadet Force (ACF)/Air Training Corps (ATC) facility and parade ground (17/01054/FUL) at the Wilton

Park site. The existing site adjacent the recently built access road off Pyebush Roundabout will be

demolished and the new ATC facility (302sq.m of Class D2) will be situated within the most southern

parcel of the site and will entail a parade ground adjacent the facilities. The demolition of the

existing ACF/ATC facilities is required to allow for extension of the access road into the Wilton Park

site and, hence, a standalone full planning application has been submitted as well as this facility



forming part of this outline application to which this TA refers. The new facilities will provide eight

car parking spaces, including one disabled parking bay.

4.1.8 An indicative plan showing the location of the proposed non-residential land uses is attached in

Appendix E.

Phasing of Development

4.1.9 As set out in the introductory chapter of this TA, the development at Wilton Park will be constructed

in separate phases, a summary of which is provided in Table 4-3.

Table 4-3: Phasing of Development at Wilton Park

Development Mix

Phase 1 99 residential units + D1 Day Nursery

Phase 2 57 residential units

Phase 3 41 residential units + A1 Food Retail + B1 Offices + D2 Sport Facilities

Phase 4 46 residential units + D1 Gallery/A3 Café

Phase 5 51 residential units

Phase 6 10 residential units + B1 Offices

Phase 7 46 Retained SFA Houses

4.2 Access Arrangement

Vehicular Access

4.2.1 Consistent with the expectations set out in the Wilton Park Development Brief SPD, the Wilton Park

development is currently accessed via the newly constructed site access off the Pyebush

Roundabout. The new road, which forms the fourth arm on the north side of the roundabout

junction extends 120m northwards towards the of Wilton Park site where the new southern

roundabout will provide the primary access into the development area. The access road will then

extend approximately 170m north to the new Minerva Way roundabout, which will provide a

secondary access to the Wilton Park development area with crossing points on the northern and

eastern arms of the junction to allow for pedestrian and cycle movements to and from the site.

4.2.2 Design guidance set out in Manual for Streets 1 & 2 has been applied, which considers the

environmental, arboriculture and landscape context of the highway and is reflected in the character

of the road. As the road will pass through a residential development, attention has been given to

the road surfacing material, junction layout, curvature and width of the carriageway to slow down

vehicles as they pass through the site.



Pedestrian and Cycle Access

4.2.3 Access to the site for cyclists and pedestrians currently is via Minerva Way, which is a narrow tree-

lined route off the London End roundabout with a footway on the southern side of the road.

Minerva Way also forms the vehicle access for dwellings adjacent to the A355 Park Lane and London

Road as well as a fishing pond. As set out in the Wilton Park Development Brief SPD, Minerva Way

is deemed to be an unsuitable means of access for regular large vehicle traffic or a high mix of car

and pedestrian traffic and, thus, has already been closed to private vehicle traffic accessing the

Wilton Park site. Minerva Way, however, is perceived by SBDC as an integral part of the

development proposals at Wilton Park as it will be upgraded to a traffic free pedestrian and cycle

route linking the development site with Beaconsfield. The details of this route will be subject to

further reserved matters application at the relevant Phase.

4.3 Parking Provision

Car Parking

4.3.1 Parking provision will adhere with the minimum car parking requirements contained in SBDC's

Parking Guidance as set out in Chapter 2 of this report. The proposed allocation of car parking

spaces in relation to their respective land uses is outlined in Table 4-4 below. The car parking

provision at the new development will replace the existing 940 spaces that previously served the

MOD facilities at Wilton Park. Moreover, additional on-street parking will be provided on-site

bringing the overall car parking provision to a total of 1,210 spaces.

Table 4-4: Proposed Car Parking Provision at Wilton Park

Land Use Parking Provision

Residential Dwellings 885 spaces

Community Hub & Offices 131 spaces

SFA (retained units) 141 spaces

Total 1,157 spaces

Additional On-Street Parking ~50 spaces

Overall Car Parking Provision 1,210 spaces

4.3.2 Car parking spaces will be designed in the dimensions 4.8m x 2.4m with a distance of 6m between

rows for access where the parking spaces are right angles to the traffic as set out in SBDC' Guidance

document. As the non-residential elements of the Wilton Park scheme are publicly accessible,

disabled car parking spaces will be provided at a ratio of 6% of overall car parking provision. The

dimension of the disabled parking bay will be 2.4m x 4.8m for a standard end bay and 6m x 4.8m

for parallel parking bays.



4.3.3 The Wilton Park SPD recommends that provision should be made for electric vehicle charging in the

design of community car parking areas, where feasible. Thus, it is anticipated that electric vehicle

charging points will be initially provided on-site with passive provision made to accommodate

future demand. That is, power supplies are made available inside a building wall near to any parking

bay or in a conduit underneath so that the relevant charging equipment can be fitted without

requiring large amounts of additional wiring.

Cycle Parking

4.3.4 Safe and secure cycle parking will be provided on site in accordance with the standards set out in

Chapter 2 of this report. They will be sited in a manner that encourages the use of cycling as a first

choice for short trips and will be easily accessible and visible onsite. The design of the cycle parking

will be 2m x 1m with adequate turning spaces provided to allows cyclists to access all stands.

4.4 Servicing

4.4.1 As part of the consented site access arrangement off Pyebush Roundabout, the layout of the access

road into Wilton Park has been designed in accordance with standards set out in the Design Manual

for Roads and Bridges (DMRB) and Manual for Streets (MfS). Thus, the road layout can

accommodate the movements of construction traffic as well as servicing vehicles at Wilton Park.

4.4.2 The internal road network and development layout will be designed to ensure that refuse vehicles

can access the residential and non-residential units in a safe manner and are within required 10m

carry distances of bin stores as set out in the 'Waste Management Planning Design Guide' (2015)

published by SBDC.

4.5 Sustainable Transport Strategy

Accommodating Walking and Cycling Demand

4.5.1 To encourage an increase of active travel and provide a viable alternative to using motorised

vehicles, opportunities and incentives will be provided within the planning process to make cycling,

walking and public transport the modes of choice.

4.5.2 One of the objectives of the Wilton Park development scheme is to improve the points of access

for cyclists and pedestrians and create safe links to public transport facilities and Beaconsfield town

centre. In accordance with the objectives set out in the Wilton Park SPD, Minerva Way will provide

a high quality, attractive and safe pedestrian/cycle route between Beaconsfield and the site. The

detailed layout of Minerva Way will form part of a reserved matters application at a later stage.

4.5.3 Wilton Way will take the form of a pedestrian and cycle route spine that gives access to all public

areas of the Wilton Park site and links the town centre of Beaconsfield with the wider countryside.



Pedestrian Crossing Points

4.5.4 As part of the consented Phase 1 Relief Road design, the Minerva Roundabout junction will be

provided with pedestrian crossings on the northern arm. During scoping discussions with TfB it was

stated BCC's preferred option would be the provision of a toucan crossing with an uncontrolled

crossing point on the southern arm. This will allow pedestrians and cyclists travelling on Minerva

Way to cross the carriageway safely and continue their journey into the Wilton Park development.

An indicative layout of pedestrian infrastructure provision at this location is shown on the plans

attached in Appendix E.

4.5.5 As discussed in subsequent sections, the potential signalisation of the London End junction will

entail a signalised pedestrian crossing on the northern A355 Park Lane arm to allow for convenient

and safe links between Beaconsfield Town Centre and the Wilton Park site via Minerva Way.

4.5.6 However, if the mitigation scheme for the London End junction is not required as a result of the

delivery of the Phase 2 Relief Road and if considered necessary by the Highway Authority, a scheme

to improve pedestrian and cyclist connectivity between Minerva Way and London End/Park Lane

will be designed and the Applicants will make an appropriate financial contribution so the works

may be carried out by the Highway Authority. A planning obligation to this effect will be included

in the Section 106 Agreement.

Access to Local Bus Services

4.5.7 Beaconsfield is served by seven different inter-urban bus services, three of which use Amersham

Road. As part of scoping discussions with TfB, accessibility of the site by public transport has been

taken into consideration. Given the permeability of the site, the possibility of accommodating a bus

stop along the access road off Pyebush Roundabout is currently being investigated. The location of

the bus stop in the vicinity of the access junction at Wilton Park would significantly reduce the

walking distance to public transport services for future residents and employees and further reduce

the need to travel by car.

4.5.8 During pre-application discussions, PJA consulted local bus operators in Beaconsfield regarding the

potential re-routing of exiting services via the access road off Pyebush Roundabout. An initial

response from Carousel Buses suggests that subject to securing funding for an additional bus there

is an option to make a diversion to the 740/A40 service in the Beaconsfield area in order to serve

the Wilton Park development. Arriva have also been consulted and have indicated that there is

potential to divert the 74 service to serve the development.

4.5.9 These services currently route through the Pyebush Roundabout and would be diverted onto the

initial section of the relief road before returning to their current route. Bus stops would therefore

be provided on the relief road to facilitate this diversion.



Framework Travel Plan

4.5.10 As detailed in Section 3, the proposed development is within walking and cycling distance to local

retail, leisure, education and employment facilities. Notwithstanding this, the promotion of smarter

travel choices is central to the transport strategy for the proposals.

4.5.11 A separate Framework Travel Plan (FTP) document has been prepared by PJA and should be read

in conjunction with this TA. The Travel Plan adheres to the framework set out in the NPPF and

Planning Practice Guidance on Travel Planning. Furthermore, BCC's Local Transport Plan 4

emphasises that travel planning has an important role to play in promoting, effective, reliable, safe

and sustainable travel behaviour.

4.5.12 The FTP details the tasks involved in developing initiatives, including management and

coordination, which are set in the context of clear objectives. The purpose of the FTP is to

accommodate the likely trips generated by the residential and commercial development at Wilton

Park, with the aim of reducing the need to travel by car and promoting sustainable alternatives such

as walking, cycling, and public transport as well as car sharing.

4.5.13 The benefits associated with the successful implementation of a Travel Plan can be realised as

follows:

• A more attractive environment for development and enhanced public realm;

• A reduction in traffic, congestion and accidents;

• Reduces air and noise pollution;

• Improves the environment through a reduction in CO2 emissions;

• Reduces time spent travelling; and

• Improves health through promotion of active travel.

• Objectives provide the focus for the identification and development of measures and actions

within a Travel Plan. The main objectives of this TP and the following detailed Travel Plan are to:

• Improve accessibility and travel choice for a full range of facilities for work, education, health,

leisure and shopping;

• Facilitate residents to be able to travel by sustainable modes;

• Reduce traffic generated by the proposed development to significantly lower levels of car tips;

• Promote healthy lifestyles and sustainable, vibrant local communities; and

• Encourage good urban design principles that open up the permeability of the development for

walking and cycling.



4.5.14 The initiatives contained within the FTP will be supported by the developer for a five-year period

from first occupation of the development or until the sales office on the site is closed, whichever is

the latest. This will give the initiatives sufficient time to embed the ethics of 'greener travel' in

residents and should promote greater awareness of travel choice.



5 Travel Demand

5.1 Introduction

5.1.1 This chapter provides an overview of the methodology used to calculate the travel demand

associated with the development proposals and the likely distributions of trips from the site.

Residential Trip Generation

5.1.2 As has been agreed with TfB as part of the previous planning application (14/01467/FUL), the likely

trip generation for the residential element of the Wilton Park site has been calculated by conducting

traffic surveys on four local residential sites:

• The Spinney (detached houses, 1km south of the station)

• Heath Road (semi-detached houses, 2.25km south-west of the station)

• Old Town Close (terraced houses, 1km south of the station)

• Gurney Close (detached houses, 0.5km south-west of the station)

5.1.3 A summary of the survey results is detailed in Table 5-1. The displayed number of vehicle trips is

based on a weekday average. The survey area of 'Heath Road' also includes Longview, South Way,

East Way, West Way and Wood Way. The full results of the surveys are included in Appendix F for

reference

Table 5-1: Residential Traffic Survey – Results 2014 TA

Street No. Properties AM Peak PM Peak

Arrivals Departures Arrivals Departures

Gurney Close 6 1 1 1 2

Heath Road 159 21 59 60 38

Old Town Close 38 4 9 11 7

The Spinney 36 41 44 8 5

Total 239 67 113 81 51

5.1.4 The survey results shown in Table 5-1 give rise to the following trip rates in Table 5-2, which have

been used to estimate residential trips at Wilton Park, based on 304 dwellings. Trip rates have been

identified for privately owned dwellings only which provides for a robust 'worst case' scenario when

assessing the likely transport implications of the proposed development at Wilton Park.



Table 5-2: Forecast Trip Rates and Vehicle Trips (304 dwellings)

Land Use AM Peak PM Peak

Arrivals Departures Two-way Arrivals Departures Two-way

Trip Rates 0.280 0.473 0.753 0.337 0.214 0.551

Vehicle Trips 85 144 229 103 65 168

5.1.5 The results in Table 5-2 show that the proposed residential element of the development at Wilton

Park is forecast to generate 229 two-way vehicle trips in the AM Peak Hour and 168 two-way vehicle

trips in the PM Peak Hour.

5.1.6 Proposed residential development mix subject to this application differs from the proposals

contained in previous assessments and assessed as part of the consented application for the access

road. As a result, a comparison between the residential trip generation of the two development

proposals, the results of which are displayed in Table 5-3 below.

Table 5-3: Trip Generation Comparison – Residential Element

Relief Road App (350 dwellings) Current Proposals (304 dwellings) Difference

Arrivals Departure Total Arrivals Departure Total

AM Peak Hour (08:00 – 09:00) 98 166 264 85 144 229 - 35

PM Peak Hour (17:00 – 18:00) 118 75 193 103 65 168 - 25

5.1.7 The results in Table 5-3 show that the current proposals for the residential elements at Wilton Park

will result in 35 less, two-way vehicle trips during the AM Peak Hour and 25 less, two-way vehicle

trips during the PM Peak Hour than the quantum of development already assessed as part of the

consented Wilton Park access road off Pyebush Roundabout.

Residential Trip Purpose

5.1.8 Journey purpose information for the forecast development trips has been derived and is shown in

Table 5-4. This split has been calculated using the National Travel Survey (NTS) data obtained from

TEMPro v7.2. The information regarding trip purposes during the peak hours contained in the 2014

TA has been amended to reflect updated NTS datasets. The NTS data is summarised on Appendix

G.

5.1.9 It is important to note that the NTS dataset does not distinguish between vehicle trips made for the

purpose of primary and secondary education. Thus, the ‘National Travel Survey: Travel to School‘

(2014) factsheet has been used to determine the proportion of vehicle trips undertaken to primary

and secondary schools in the U.K. during the morning and afternoon Peak Hours. The results

indicate that in the U.K. on average 66% of vehicle trips for education purposes are linked with



primary schools and 34% of all school related trips are linked with secondary schools. An extract of

the factsheet is attached in Appendix G together with the NTS data for reference.

Table 5-4: Residential Vehicle Trip Generation – Journey Purpose

Trip Purpose AM Peak PM Peak Trip Generation (Two-Way Trips)

AM Peak PM Peak

Employment 70% 57% 160 96

Primary Education 7% 3% 16 5

Secondary Education 3% 1% 7 1

Retail 14% 20% 32 34

Other 6% 19% 14 32

Total 100% 100% 229 168

5.2 Non-Residential Trip Generation

Office Development - Trip Attraction

5.2.1 The industry standard Trip Rate Information Computer System (TRICS) has been used to estimate

weekday AM (08:00 - 09:00) and PM (17:00 - 18:00) multi-modal vehicle trip rates for B1 Office land

uses. The criteria used to identify comparable sites are summarised below:

• 'Employment - Office' Land Use;

• All sites in England (except for Greater London);

• Selection Parameter: 200 to 1,000,000sq.m GFA;

• Only weekday survey days; and

• Location: Edge of Town Centre; Suburban Area; Edge of Town.

5.2.2 The trip rates and resultant vehicle trips are summarised in Tables 5-5 and 5-6, and the full TRICS

outputs are contained within Appendix H.

Table 5-5: B1 Offices – TRICS Vehicle Trip Rates

Land Use AM Peak (08:00-09:00) PM Peak (17:00-18:00)


B1 Offices 1.505 0.251 1.756 0.190 1.275 1.465

Table 5-6: Forecast Office Vehicle Trip Attraction at Wilton Park (1,425sq.m GEA)

Land Use AM Peak (08:00-09:00) PM Peak (17:00-18:00)


B1 Offices 21 4 25 3 18 21



5.2.3 The results above show that the proposed B1 Office use at Wilton Park is forecast to generate 25

two-way vehicle trips during the AM Peak Hour and 21 two-way vehicle trips during the PM Peak

Hour period.

5.2.4 Given the reduced provision in B1 Office space in comparison to the previous planning application

in 2014, Table 5-7 shows the reduction in forecast vehicle trips associated with the office use on-

site during both Peak Hour periods.

Table 5-7: Vehicle Trip Generation Comparison – B1 Office Use at Wilton Park

Relief Road App (4,375sqm) Current Application (1,425sq.m) Difference

Arrivals Departures Total Arrivals Departures Total

AM Peak Hour (08:00 – 09:00) 66 11 77 21 4 25 - 52

PM Peak Hour (17:00 – 18:00) 8 56 64 3 18 21 - 43

Community Hub - Vehicle Trip Attraction

5.2.5 The development proposals at Wilton Park entail the provision of a Community Hub consisting of

the following land uses:

• 100sq.m of A1 Retail

• 130sq.m A3 Pavilion Cafe / D1 Art Gallery

• 170sq.m Maintenance

• 300sq.m Crèche / Day nursery

• 175sq.m D2 Sports changing facilities

• 302sq.m D2 ATC facility

5.2.6 To respond to comments raised by the BCC as highway authority in relation to the likely trip

attraction of the proposed Community Hub, the TRICS data base has again been interrogated to

identify the potential number of vehicle trips associated with the proposed non-residential land

uses at Wilton Park. The trip rates and resultant trip generation associated with the respective land

use are summarised in Table 5-8 and Table 5-9 on the next page and a detailed overview of the

TRICS outputs is attached in Appendix H.



Table 5-8: Community Hub Vehicle Trip Rates (per 100sq.m)

Land Use AM Peak (08:00 – 09:00) PM Peak (17:00 – 18:00)

Arrivals Departures Two-Way Arrivals Departures Two Way

A1 Retail 8.765 8.280 17.045 11.526 11.003 22.529

A3 Pavilion / D1 Art Gallery 0.000 0.000 0.000 2.120 2.283 4.403

D1 Creche / Day Nursery 3.104 3.057 6.161 1.929 1.976 3.905

D2 ATC Facility (Community Centre) 0.533 0.356 0.889 0.988 0.642 1.63

Table 5-9: Community Hub Vehicle Trip Attraction

Land Use GFA AM Peak (08:00 – 09:00) PM Peak (17:00 – 18:00)

Arrivals Departure Two-Way Arrivals Departure Two Way

A1 Retail 100sq.m 9 8 17 12 11 23

A3 Pavilion / D1 Art Gallery 130sq.m 0 0 0 3 3 6

D1 Creche / Day Nursery 300sq.m 9 9 18 6 6 12

D2 ATC Facility (Community Centre) 302sq.m 2 1 3 3 2 5

Total 20 18 38 24 22 46

5.2.7 The results in Table 5-9 show that the proposed Community Hub at Wilton Park is likely to generate

38 two-way vehicle trips during the AM Peak Hour and 46 two-way vehicle trips during the PM Peak

Hour.

5.2.8 However, the following sections will show that a large proportion of trips to and from these land

uses will be internal trips and therefore will not generate any additional trips on the surrounding

road network. That is, the proposed Food Retail facility as well as Day Nursery are designed to

primarily serve the residential element of the site with a limited number of staff trips and deliveries,

but mostly not during the AM and PM Peak Hours.

Retail Unit

5.2.9 With regard to the proposed A1 Food Retail unit, the TRICS Pass-by and Diverted Trip Research

Report 95/22 states that "All research confirms that very little new traffic is generated by new store

developments. Figures compiled in this document suggest that in most circumstances 10% or less of

the total trips are completely new and in practice the value is so small it can be discounted."

Furthermore, the TRICS Research Report 14/13 states that "Convenience stores are more likely to

produce pass-by trips, whilst comparison stores are more likely to produce diverted trips. People are

prepared to travel further to access a comparison store than a convenience store (20 minutes for a

comparison store, compared to 10 minutes for convenience)." Based on this research, it is therefore

2 TRICS Research Report 95/2 – A Resume (August 1995) 3 TRICS Research Report 14/1 Pass-By and Diverted Trips” (December 2014)



assumed that only 10% of the total trips associated with the food retail unit will be new, additional

vehicle trips on the road network.

Day Nursery

5.2.10 There currently are a number of day nurseries located in Beaconsfield serving the residential areas

in the south of Beaconsfield. The First Place Nursery is located within the Wilton Park development

site on Gorell Road. Planning application for this day nursery was approved in November 2011

(11/01366/FUL) and the Case Officer Report states that “the main purpose of the proposal is to

provide a much needed discounted nursery facility for the residents of the Defence School of

Languages (DSL)…as such, 50% of the children attending the nursery would live within Wilton Park,

Defence School of Languages.” A planning condition set out that the maximum number of children

attending would be limited to 20 infants at any time. Information obtained from the existing

nursery confirmed that after the relocation of the DSL to Shrivenham in 2013, the capacity has

increased from 20 to 45 children. The majority of children currently registered at the nursery are

travelling from Beaconsfield and surrounding areas with parents dropping their children off on their

way to work. The strategic location of the nursery in the vicinity of the motorway means that the

nursery has been attractive to families residing outside of Wilton Park.

5.2.11 Based on 2011 Census information (KS102EW – Age Structure) for the ‘South Bucks 001’ output

area (E02003688), the population aged 0-4 accounts for 7% of all residents residing within the

southern residential area of Beaconsfield within which the site is located. Assuming a similar

proportion of children eligible for day car nurseries at the proposed Wilton Park site, this equates

to approximately 50 children aged 0-4 years4.

5.2.12 The proposed expansion of the nursery to 80 spaces will therefore be able to accommodate any

future demand associated with the proposed residential site at Wilton Park. Due to the location of

the nursery this encourages trips to be undertaken on foot. For children attending nurseries outside

of Wilton Park, it is anticipated that these trips will form part of linked trips where children are

dropped-off at or picked-up from the nursery by parents that then continue on to work or are

returning from work.

5.2.13 The withdrawn DfT ‘Guidance on Transport Assessment’ document discusses the use of linked trips

and states: “Where there is a high probability that there will be a proportion of linked trips between

two uses on a development, it is customary only to 'count' those trips once for the development as

a whole, and not effectively double-count them by attributing two visits and departures affecting

the sections of highway network being assessed.”

4 This is based on persons/household information obtained from the 2011 Census data set ‘Tenure by household size

by number of bedrooms’ (DC4405EW) for the Beaconsfield South Ward.



5.2.14 Given that the proposals entail the relocation of the existing nursery, it is expected that existing

travel patterns of the currently registered 45 children will remain unchanged and, hence, existing

trips to and from the nursery are already accounted for in the baseline traffic data presented in this

report. Based on 2011 Census information and nature of linked trips for day nurseries set out in this

chapter, it is therefore assumed that only 10% of the total trips associated with the proposed day

nursery will be new, additional vehicle trips on the road network. That is. the remaining vehicle

trips are either already existing on the road network or will be undertaken as part of linked trips

accounted for in the residential trip generation methodology.

Sport Changing Facilities

5.2.15 The Sport Changing Facilities (D2 land use) and the ATC Facility (D2 land use), which could

potentially attract vehicles trips from Beaconsfield and beyond are considered to occur outside the

designated Peak Hour periods set out in this assessment.

Adjusted Trip Generation - Community Hub

5.2.16 The trip generation results in Table 5-9 therefore have been adjusted to reflect the likely travel

demand associated with the Community Hub and the adjusted forecast for new additional vehicle

trips associated with the retail unit and day nursery during the peak AM and PM periods can be

seen in Table 5-10 below.

Table 5-10: Community Hub – Adjusted Vehicle Trip Attraction

Land Use GFA AM Peak (08:00 – 09:00) PM Peak (17:00 – 18:00)

Arrivals Departures Two-Way Arrivals Departures Two Way

A1 Retail 100sq.m 1 1 2 1 1 2

A3 Pavilion / D1 Art Gallery 130sq.m 0 0 0 3 3 6

D1 Creche / Day Nursery 300sq.m 1 1 2 0 1 1

D2 ATC Facility (Community Centre) 3015sq.m 2 1 3 3 2 5

Total 4 3 7 7 7 14

5.2.17 As shown in Table 5-11, this results in a reduction in 61and 62 two-way vehicle trips during AM and

PM Peak Hours respectively when compared to the trip generation calculations associated with the

Community Hub presented in the 2014 TA.

Table 5-11: Vehicle Trip Generation Comparison – Community Hub at Wilton Park

Relief Road Application Current Application

Difference Arrivals Departure Total Arrivals Departure Total

AM Peak Hour (08:00 – 09:00) 38 30 68 4 3 7 -61

PM Peak Hour (17:00 – 18:00) 40 36 76 7 7 14 -62



5.3 Wilton Park Total Trip Generation

5.3.1 Table 5-12 summarises the overall vehicle trip generation associated with the current development

proposals at Wilton Park.

Table 5-12: Total Forecast Development Trip Generation at Wilton Park

AM Peak Hour (08:00 – 09:00) PM Peak Hour (17:00 – 18:00)

Arrivals Departures Two-Way Arrivals Departures Two-Way

Residential Element 85 144 229 103 65 168

B1 Offices 22 4 26 3 18 21

Community Hub 4 3 7 7 7 14

Total 111 151 262 113 90 203

5.3.2 The results shown in Table 5-12 indicate that the current development proposals for Wilton Park is

forecast to generate 262 two-way vehicle trips during the AM Peak Hour and 203 two-way vehicle

trips during the PM Peak Hour.

5.3.3 Table 5-13 indicates that the development proposals to which this TA refers are likely to generate

69 less two-way vehicle trips in the AM Peak Hour and 66 less two-way vehicle trips in the PM Peak

Hour than the quantum of development already tested and assessed in the 2014 TA as part of the

consented site access road application.

Table 5-13: Development Trip Generation at Wilton Park – Comparison with previous assumptions

AM Peak Hour (08:00 – 09:00) PM Peak Hour (17:00 – 18:00)

Arrivals Departures Two-Way Arrivals Departures Two-Way

Previous Application (2014) 203 128 331 115 154 269

Current Application (2016) 111 151 262 113 90 203

Difference -92 +23 -69 -2 -64 -66

5.4 Net Traffic Impact

5.4.1 To assess the net traffic impact of the proposed development, a comparison is made of the trips

generated by the existing site (Table 5-14) and the forecast vehicle trips associated with the

redevelopment at Wilton Park (Table 5-12).

5.4.2 The existing trips have been extracted from the 2017 traffic survey results introduced in Chapter 3

and attached in Appendix C of this report.



Table 5-14: Net Traffic Impact at Wilton Park

AM (08:00 – 09:00) PM (17:00 – 18:00)


Existing 61 65 126 56 59 115

Current Proposals (2017) 111 151 262 113 90 203

Change +50 +86 +136 +57 +31 +88



6 Trip Distribution

6.1 Residential Trip Distribution

Journey to Work (JtW)

6.1.1 The distribution of residential commuting trips to and from the Wilton Park site has been derived

from Journey to Work (JtW) origin and destination information obtained from the 2011 Census. For

the purpose of this assessment, the existing ‘Journey to Work’ patterns of residents living within

the output area 'South Bucks 001' (E02003688) have been identified as this covers adjacent

residential areas within Beaconsfield and the development site itself and is therefore considered to

be representative of the proposed development.

6.1.2 The data contains vehicle work trips by destination. The number of trips made to each output area

in the U.K. has then been weighted against the distance travelled to each destination output area

in order to assign the forecast commuting trips (see Chapter 5) on the surrounding road network.

The routes have been recorded and mapped using GIS software with the principal routes likely to

be taken from and to Wilton Park summarised in Table 6-1 and displayed in Figure 6-1 on the next

page.

6.1.3 A detailed summary of the Census data is attached in Appendix I of this report.

Table 6-1: Routes likely to be taken from development site

Routes

Two-way trips

% AM Peak PM Peak

North on the A355 Park Lane/Amersham Road 7% 4 4

East on the A40 London Road 10% 5 6

South on the A355 towards J2 of the M40 33% 17 19

West on the A40 London End 50% 25 29



Figure 6-1: JtW Trip Distribution Routes (ArcGIS)

Retail and Education Trip Distribution

6.1.4 The distance from the site to each of the relevant destinations was recorded in order to create a

gravity model. Information provided as part of the 2014 TA has been obtained and updated where

necessary. A gravity model results in popular and/or closer destinations being given a greater

weighting whilst destinations further away and/or unpopular are assigned a lower weighting. This

results in a trip distribution that is more representative of travel patterns of future residents.

Retail Trip Distribution

6.1.5 A total of ten food retail destinations have been identified within the designated catchment area

of 10 km. The food retail units were assigned to different gravity zones through which key routes

to and from the Wilton Park site run. Each destination was assigned a proportional weighting based

②

①

③

④



on the travel distance to and from the Wilton Park site. This calculated value accounts for potential

trips to all retail destinations and, hence, represents a forecast of likely proportion of journeys to

and from a particular store. The cumulative weightings for each route within the particular gravity

zones were then used for the distribution and assignment of trips on the surrounding road network.

Education Trip Distribution

6.1.6 Similar to the retail trip distribution, information regarding existing primary and secondary schools

within Beaconsfield and surrounding villages has been obtained. The gravity analysis identified four

primary and five secondary schools that are likely to be trip destinations for future residents at the

Wilton Park site. The education facilities were assigned to different gravity zones through which

key routes to and from the Wilton Park site run. Each destination was assigned a proportional

weighting based on the travel distance to and from the Wilton Park site as well as numbers of pupils

currently enrolled at these schools. Information obtained from the Department for Education

service to compare schools in the U.K. Data available is for the 2015/2016 academic year, which is

the latest year for which performance results have been published5.

6.1.7 The calculated proportional weighting accounts for potential trips to all school destinations and,

hence, represents a forecast of likely proportion of journeys to and from a particular school. The

cumulative weightings for each route within the particular gravity zones were then used for the

distribution and assignment of trips on the surrounding road network. Summary

6.1.8 The forecast distribution of residential vehicle trips to education and retail facilities is outlined in

Table 6-2. An overview of the methodology and data is contained in Appendix J.

Table 6-2: Residential Vehicle Trips – Education and Retail Trip Distribution

Origin/Destination Primary Education Secondary Education Retail Other

To A355 North 34.4% 3.2% 35.8% 29.6%

To A355 South - 6.6% 31.1% 1.6%

To A40 West 42.2% 69.9% 25.0% 13.4%

To A40 East 23.5% 20.3% 8.0% 55.4%

6.2 Commercial Trip Distribution

6.2.1 It is anticipated that the proposed commercial element at Wilton Park will attract commuting trips

from Beaconsfield as well as surrounding towns and villages during morning and afternoon Peak

Hours. To estimate the likely distribution of trips routing to Wilton Park, 2011 Census JtW has again

been obtained for the output area ‘South Buck 001’ within which the development site is located.

5 https://www.compare-school-performance.service.gov.uk/find-a-school-in-england



Journeys from output areas towards Wilton Park have been tracked and weighted against the

distance travelled in order to assign the vehicle trips on the surrounding road network.

6.2.2 A summary of the distribution of trips is provided in Table 6-3 below and displayed in Figure 6-2 on

the next page. The detailed summary of the 2011 Census data is attached in Appendix K.

Table 6-3: JtW Routes to Wilton Park – Commercial Trip Attraction

Routes

Two-way trips

% AM Peak PM Peak

North on the A355 Park Lane/Amersham Road 14% 3 3

East on the A40 London Road 12% 3 2

South on the A355 towards J2 of the M40 31% 8 7

West on the A40 London End 43% 11 9

Figure 6-2: Employment Trip Attraction Routes (ArcGIS)

②

①

③

④



7 Assessment Parameters

7.1 Modelling Approach

Aim & Purpose

7.1.1 As part of the 2014 TA prepared by PJA, junction capacity assessments have been undertaken for

the Pyebush Roundabout, London End Roundabout and consented road sections of the Relief Road

Phase 1 and associated roundabouts using VISSIM micro-simulation model developed by the

Highway Authority, Buckingham County Council.

7.1.2 As established in Chapter 5 of this report, the capacity assessments undertaken in the 2014 TA

report have been based on development traffic flows significantly higher than the ones calculated

in this report. That is, the reduction in residential units, B1 office space as well as Community Hub

land uses in comparison to what was previously assumed has resulted in a lower number of

additional two-way vehicle trips associated with the Wilton Park development site during the peak

hour periods.

7.1.3 However, in response to comments raised by TfB, separate junction capacity assessments of the

London End Roundabout and the Pyebush Roundabout have been undertaken in this TA to account

for updated baseline flows and revised assumptions made about future traffic growth in the area.

7.1.4 The aim of this chapter is to assess the likely transport impact associated with the delivery of the

Wilton Park scheme and identify the potential increase in journey time delay on the surrounding

road network. The purpose of this chapter is to demonstrate that the Wilton Park development

scheme can be delivered without the need to rely on the construction of the A355 Relief Road.

Nonetheless, if the Phase 2 Relief Road was to be constructed the following section shows that the

delivery of such relief road would definitely enhance the transport conditions along the A355

corridor.

Relief Road Phase 2

7.1.5 Modelling has been undertaken by Jacobs in support of the planning application for Phase 2 of the

Relief Road (CC/65/16). The Transport Assessment prepared by Jacobs in August 2016 sets out the

impacts of the proposed scheme and demonstrates the substantial benefits that will occur as a

result of the Relief Road. The report follows a series of other reports prepared for BCC by Jacobs as

part of the initial Business Case and funding submission for the scheme.

7.1.6 An analysis of the existing situation identified that the A355 accommodates the highest volumes of

traffic on the local road network in the area. In the southbound direction, greater volumes of traffic

were observed in the AM peak and northbound volumes increase in the PM peak. As such Jacobs'

report notes that the London End Roundabout is operating at or over capacity during peak times



with high volumes of conflicting movements and limited capacity at the junction resulting in

extensive queues and delays on all arms. Thus, the transport objectives of the delivery of the Relief

Road are to provide relief to the current Amersham Road and address the congestion experienced

and capacity limitation of the London End Junction.

"The A355 Relief Road has been planned on an alignment that connects the existing A355 south

of the point where it crosses the railway line, the route then connects with the consented Wilton

Park access road at Minerva Way, adjacent to the proposed Wilton Park land use development

and through to the Pyebush roundabout."

7.1.7 The modelling results presented by Jacobs in relation to the delivery of the Relief Road demonstrate

"a shift in the dominant north-south traffic away from the Amersham Road onto the new Relief

Road." This subsequently would result in a reduction in traffic volume travelling across the London

End Roundabout during peak times. Indeed, Jacobs forecasts a reduction of around 800 vehicles

heading southbound during the AM Peak Hour on the A355 at the point the route meets the London

End junction. In the PM, Jacobs forecasts almost 600 fewer vehicles approaching the London End

junction from the north, and approximately 500 fewer from the A40 east. Thus, the report

concludes that "London End Junction is the area of the network expected to see the greatest benefit

in performance as a result of the implementation of the Relief Road."

7.1.8 On 31st July 2017 BCC's Development Control Planning Committee indicated support for the

proposed Relief Road and delegated authority to the Head of Planning and Environment to approve

the planning application subject to conditions yet to be confirmed.

7.2 Junctions to be Assessed

7.2.1 To assess the impact of the proposed development, detailed capacity assessments have been

undertaken at the following two junctions using the Junctions 9 (ARCADY) modelling software:

• London End Roundabout; and

• Pyebush Roundabout.

7.2.2 The results obtained from Junctions 9 for the roundabouts are reported in Ratio of Flow to Capacity

(RFC), delay measured in seconds and queue length measured in PCUs on each junction approach.

7.2.3 Geometric parameters for the junction models have been obtained from the modelling outputs of

the consented planning application for the access road off Pyebush Roundabout.

7.3 Assessment Horizons & Traffic Growth

7.3.1 Given the proposed phasing of the development scheme as set out in Chapter 4 of this report, the

following model scenarios have been tested:



• 2017 Baseline Scenario;

• 2020 Future Baseline Scenario;

• 2020 Future Base + Phase 1 of the Development;









• 2025 Future Baseline Scenario; and

• 2025 Future Base + Phase 6 of the Development.

7.3.2 In order to estimate the likely increase in background traffic up to the respective 'Future Baseline'

scenarios, TEMPro factors have been applied to the 2017 baseline flows. The growth factors have

been determined for the geographical output area 'South Bucks 001' within which the development

site is located.

7.3.3 Given that the development proposals will account for a large proportion of forecast housing

growth within this designated geographical area, assumptions about future household growth have

been removed from the TEMPro factors and set to base levels. The factors used within the

assessment are detailed in Table 7-1 below. The resultant future baseline and 'with development'

traffic flow scenarios are included on the traffic flow diagram figures attached in Appendix L.

Table 7-1: TEMPro v7.2 - Growth Factors

Growth Period AM Peak PM Peak

2017 --> 2020 1.0269 1.0242

2017 --> 2021 1.0379 1.0343

2017 --> 2022 1.0492 1.0456

2017 --> 2023 1.0603 1.0570

2017 --> 2024 1.0713 1.0680

2017 --> 2025 1.0824 1.0792

2017 --> 2031 1.1073 1.1055



8 Junction Capacity Modelling

8.1 London End Roundabout

2017 Base

8.1.1 As outlined in Chapter 3 of this TA, baseline traffic data has been obtained from Manual Classified

Counts (MCC’s) that were undertaken on Tuesday 13th June 2017 between 07:00 – 10:00 and 16:00

- 19:00. The MTCs identified the AM Peak Hour (08:00 – 09:00) and PM Peak Hour (17:15 – 18:15)

at the London End Roundabout junction. In addition, queue survey information is available as part

of the turning count data, the detailed summary of which is provided together with the turning

count data in Appendix C.

8.1.2 The results of the junction capacity assessment undertaken at the London End roundabout for the

2017 Base scenario are summarised in Table 8-1 below. The detailed modelling results are attached

in Appendix M.

Table 8-1: London End Roundabout - 2017 Baseline Capacity Assessment

Arm AM Peak (08:00 – 09:00) PM Peak (17:15 – 18:15)

Queue (PCUs) Delay (sec) RFC Queue (PCUs) Delay (sec) RFC

A355 Park Lane 120 382.35 1.21 28 89.50 1.05

Minerva Way 6 - - 9 - -

London Road 326 721.52 1.31 358 799.04 1.33

London End 12 66.34 0.96 42 199.84 1.20

8.1.3 The results displayed in Table 8-1 show that the roundabout currently operates at or above its

theoretical capacity in the 2017 Baseline scenario during both peak hour periods with queues of up

to 326 PCUs forming on the London Road approach during the AM Peak Hour and 358 PCUs in the

PM Peak Hour respectively. Furthermore, queues of 120 PCUs on the A355 Park Lane approach

have been modelled in the AM Peak Hour, resulting in a delay of more than six minutes per vehicle

at this location.

8.1.4 The model currently indicates that there is no capacity for vehicles to exit from Minerva Way hence

the lack of RFC and delay values. In reality, this is not the case as evidenced by the values recorded

in the traffic surveys.

8.1.5 A comparison between the observed and modelled queue lengths is presented in Table 8-2 on the

next page. It can be seen that during the AM peak period none of the modelled queue length values

are within the range of the average observed queue length values. The model overestimates queues

on the A355 Park Lane and London Road approaches whilst underestimating queues on the London

End approach. During the PM Peak Hour, the modelled queue length value for London End



approach is within the range of the modelled queue length value. However, the model

overestimates queue lengths on all other arms during the PM Peak Hour.

Table 8-2: Observed Queue Lengths & Modelled Queue Lengths – London End Roundabout

Arm

AM Peak (08:00 – 09:00) PM Peak (17:15 – 18:15)

Observed Max

Q. (PCUs)

Observed Ave

Q. (PCUs)

Modelled Q.

(PCUs)

Observed Max

Q. (veh)

Observed Ave

Q. (PCUs)

Modelled

Q.(PCUs)

A355 Park Ln 80 51 120 15 7 28

Minerva Way 0 0 6 0 0 9

London Road 45 19 326 45 23 358

London End 46 43 12 45 35 42

8.1.6 ARCADY modelling software has known issues relating to the constraints of the software when

considering junction geometry that is outside of the parameters in its calibrated model. Therefore,

ARCADY provides a feature to adjust the Intercept Slope of individual arms to get more realistic

model values comparable to the observed ones.

8.1.7 The capacity assessment at the London End Roundabout junction has applied the Intercept

Adjustment tool to allow adjustments to be applied directly to the intercept, and represent changes

to the maximum flow that could cross the give-way line in the absence of any circulating traffic. The

use of the intercept slope option results in observed maximum queue lengths to be reflected in the

updated model as shown in Table 8-3. Not adjusting the intercept of the roundabout would result

in underestimating the queue lengths at London End Roundabout.

8.1.8 The ‘DIRECT’ flow input function has been used as the most accurate method of entering traffic

flows into the model. Given that the analysis of the 2017 traffic counts show consistent and

predictable travel trends during the weekday Peak Hours, the ‘DIRECT’ profile has been applied to

model the baseline traffic results as well as all future scenarios. The detailed modelling outputs are

attached in Appendix M for reference.

Table 8-3: London End Roundabout – 2017 Baseline Adjusted Capacity Assessment



A355 Park Lane 50 145.5 1.08 7 26.88 0.90

Minerva Way 0 19.36 0.06 0 122.27 0.13

London Road 23 42.66 1.00 22 45.88 1.00

London End 43 232.56 1.06 35 141.18 1.15

8.1.9 As shown in Table 8-4 the calibrated queues lengths in the adjusted ARCADY model reflect the

observed queue lengths at the London End Roundabout junction in both peak hour periods.



Table 8-4: Observed Queue Lengths & Validated Queue Lengths – London End Roundabout

Arm

AM Peak (08:00 – 09:00) PM Peak (17:15 – 18:15)

Observed Max

Q. (PCUs)

Observed Ave

Q. (PCUs)

Validated Q.

(PCUs)

Observed Max

Q. (veh)

Observed Ave

Q. (PCUs)

Validated

Q.(PCUs)

A355 Park Ln 80 51 50 15 7 7

Minerva Way 0 0 0 0 0 0

London Road 45 19 23 45 23 22

London End 46 43 43 45 35 35

8.1.10 The modelling results shown in Table 8-3 indicate that the London End roundabout currently

exceeds its theoretical capacity with an average queue of 51 PCUs on the A355 Park Lane approach

and 43 PCUs on the London End approach in the AM Peak Hour period, causing delays of

approximately two and four minutes per vehicle respectively.

8.1.11 A similar trend can be observed during the PM Peak Hour with queues of 35 PCUs on the London

End approach and 22 PCUs on the London Road approach. These queues result in delays in journey

time of 140 seconds and 46 seconds respectively.

8.1.12 Minerva Way experiences no queuing during both peak hours, yet journey time delays of up to two

minutes are modelled for the PM Peak Hour. This is mainly due to the low number of vehicles exiting

Minerva Way struggling to find a gap between the dominant east- and southbound traffic flow

towards London Road in order to enter the roundabout.

Future Baseline Scenarios

8.1.13 The proposed development at Wilton Park will be phased as set out in Table 4-3 in Chapter 4 of this

report. To demonstrate the impact of the development at each phase an assessment has been

undertaken relative to the respective baseline horizon for each of the phases.

8.1.14 As set out in Section 0 of this report, the future baseline scenarios have been calculated using

growth forecasts generated by TEMPro v7.2. It is important to note that the intercept adjustment

feature has been applied to all other future year scenarios presented in this report to demonstrate

the traffic impact in comparison to the validated 2017 Base model.

8.1.15 The modelling results for the future base scenarios are summarised in Table 8-5 and Table 8-6 on

the next page. A detailed summary of the results is attached in Appendix M.



Table 8-5: London End Roundabout – Future Baseline Capacity Assessment, AM

Arm 2020 Base 2021 Base 2022 Base

Queue

(PCUs)

Delay

(sec)

RFC Queue

(PCUs)

Delay

(sec)

RFC Queue

(PCUs)

Delay

(sec)

RFC

A355 Park Lane 76 225.69 1.10 81 238.65 1.11 88 256.93 1.12

Minerva Way 0 19.55 0.06 0 19.53 0.06 0 19.50 0.06

London Road 34 60.96 1.02 40 69.29 1.04 43 79.77 1.05

London End 74 396.05 1.13 83 444.32 1.16 88 507.60 1.17


Queue

(PCUs)

Delay

(sec)

RFC Queue

(PCUs)

Delay

(sec)

RFC Queue

(PCUs)

Delay

(sec)

RFC

A355 Park Lane 94 274.23 1.13 103 298.23 1.14 110 319.35 1.15

Minerva Way 0 19.50 0.06 0 19.54 0.07 0 19.50 0.07

London Road 55 90.59 1.06 65 105.42 1.07 75 121.41 1.08

London End 106 567.76 1.20 117 625.83 1.23 127 681.40 1.25

Table 8-6: London End Roundabout – Future Baseline Capacity Assessment, PM


Queue

(PCUs)

Delay

(sec)

RFC Queue

(PCUs)

Delay

(sec)

RFC Queue

(PCUs)

Delay

(sec)

RFC

A355 Park Lane 9 31.20 0.93 10 33.26 0.94 11 35.72 0.95

Minerva Way 0 210.37 0.20 0 277.58 0.25 0 427.70 0.37

London Road 34 68.88 1.02 41 80.62 1.04 50 94.79 1.05

London End 46 234.30 1.20 52 270.08 1.22 65 343.82 1.25


Queue

(PCUs)

Delay

(sec)

RFC Queue

(PCUs)

Delay

(sec)

RFC Queue

(PCUs)

Delay

(sec)

RFC

A355 Park Lane 12 38.55 0.96 13 41.19 0.97 14 43.19 0.99

Minerva Way 1 464.40 0.68 1 935.20 1.89 1 - -

London Road 60 109.95 1.06 72 127.54 1.07 83 144.32 1.58

London End 74 387.43 1.26 84 438.06 1.29 95 489.37 1.38

8.1.16 The above results show that the junction is predicted to operate over capacity during both peak

periods in all future baseline scenarios without the addition of traffic associated with the proposed

development of Wilton Park.



Development Impact – AM Peak Hour (08:00 – 09:00)

8.1.17 The impact of the individual phases of the Wilton Park development scheme has been assessed

based on forecast trip generation associated with the proposed land uses of each individual phase

set out in Chapter 5 of this report. The detailed summary of traffic flows generated by each phase

is provided on the graphs attached in Appendix N.

8.1.18 The results of the development impact assessment at the London End Roundabout for the AM Peak

Hour are summarised in Table 8-7 and detailed junction capacity modelling outputs are provided in

Appendix M.

Table 8-7: London End Roundabout – Future Year Capacity Assessment Results, AM Peak Hour

Arm 2020 Base + Phase 1 2021 Base + Phase 2 2022 Base + Phase 3

Queue

(PCUs)

Delay

(sec)

RFC Queue

(PCUs)

Delay

(sec)

RFC Queue

(PCUs)

Delay

(sec)

RFC

A355 Park Lane 76 226.00 1.10 82 242.11 1.11 90 263.26 1.12

Minerva Way 1 20.12 0.06 0 20.12 0.06 0 20.10 0.06

London Road 36 62.57 1.02 43 72.83 1.04 52 86.35 1.06

London End 75 398.56 1.13 88 470.69 1.16 104 550.38 1.19


Queue

(PCUs)

Delay

(sec)

RFC Queue

(PCUs)

Delay

(sec)

RFC Queue

(PCUs)

Delay

(sec)

RFC

A355 Park Lane 97 283.05 1.13 107 309.98 1.15 115 332.53 1.16

Minerva Way 0 20.11 0.07 0 20.16 0.07 0 20.12 0.07

London Road 62 100.32 1.07 75 120.13 1.08 87 139.44 1.09

London End 116 615.60 1.22 128 678.90 1.25 138 735.44 1.27

8.1.19 Table 8-8 on the next page compares the modelling results of the future Baseline scenarios in Tables

8-5 and 8-6 with the respective development scenarios shown in Table 8-7. The net increase in

journey time delays and queues presents forecast changes in travel experience across the London

End Roundabout as a result of the delivery of the individual phases compared to the relevant future

baseline scenario.



Table 8-8: London End Roundabout - Journey Time Delay & Queues Comparison, AM Peak Hour

A355 Park Lane Minerva Way London Road London End

Queue

(PCUs) Delay (sec)

Queue

(PCUs) Delay (sec)

Queue

(PCUs) Delay (sec)

Queue

(PCUs) Delay (sec)

2020 Base 76 225.69 0 19.55 34 60.96 74 396.05

Up to Phase 1 +0 +0.31 +1 +0.57 +2 +1.61 +1 +2.51

2021 Base 81 238.65 0 19.53 40 69.29 83 444.32

Up to Phase 2 +1 +3.46 +0 +0.59 +3 +3.54 +5 +26.37

2022 Base 88 256.93 0 19.50 43 79.77 88 507.60

Up to Phase 3 +2 +6.33 +0 +0.60 +9 +6.58 +16 +42.78

2023 Base 94 274.23 0 19.50 55 90.59 106 567.76

Up to Phase 4 +3 +8.82 +0 +0.61 +7 +9.73 +10 +47.84

2024 Base 103 298.23 0 19.54 65 105.42 117 625.83

Up to Phase 5 +4 +11.75 +0 +0.62 +10 +14.71 +11 +53.07

2025 Base 110 319.35 0 19.50 75 121.41 127 681.40

Up to Phase 6 +5 +13.18 +0 +0.62 +12 +18.03 +11 +54.04

8.1.20 The above results show that the delivery of the initial phase of the proposed development does not

result in increases in queues or journey times. In fact, there is hardly any difference in the operation

of the Junction in the AM peak period for the future year and the future year plus Phase 1 of the

Wilton Park scheme.

8.1.21 Addition of traffic associated with Phase 2 of the development results in an increase in queues of

five PCUs on the London End approach in comparison to the 2021 Base scenario. That increase in

queuing results in a net increase in journey time delay of approximately 26 seconds at this location.

8.1.22 The delivery of the subsequent development phases further increases journey time delays on all

arms relative to their respective baseline scenarios. However, the impact of delivering all six phases

at Wilton Park is an increase in delay of less than one minute on the London End approach relative

to the forecast background traffic growth in 2025 in the Beaconsfield area.

Development Impact - PM Peak Hour (17:15 – 18:15)

8.1.23 The results of the junction capacity assessment at the London End Roundabout for the PM Peak

Hour period are summarised in Table 8-9 on the next page and detailed modelling outputs are

provided in Appendix M.



Table 8-9: London End Roundabout - Future Year Capacity Assessment Results, PM Peak Hour


Queue

(PCUs)

Delay

(sec)

RFC Queue

(PCUs)

Delay

(sec)

RFC Queue

(PCUs)

Delay

(sec)

RFC

A355 Park Lane 9 32.16 0.93 10 34.89 0.94 11 37.53 0.95

Minerva Way 0 226.16 0.21 0 330.62 0.29 0 402.48 0.48

London Road 35 70.80 1.03 43 84.68 1.04 54 100.98 1.05

London End 48 244.65 1.20 57 298.63 1.22 69 362.40 1.26


Queue

(PCUs)

Delay

(sec)

RFC Queue

(PCUs)

Delay

(sec)

RFC Queue

(PCUs)

Delay

(sec)

RFC

A355 Park Lane 13 41.00 0.96 14 44.25 0.97 19 83.19 0.99

Minerva Way 1 927.41 1.52 1 - - 4 - -

London Road 65 118.00 1.07 78 137.05 1.08 333 385.30 1.58

London End 80 418.16 1.28 92 473.73 1.30 147 859.95 1.38

8.1.24 The impact of traffic associated with the delivery of the individual phases of the development has

again been considered in relation to the future baseline scenarios in order to demonstrate the net

increase in journey times and queues on all arms during the PM Peak Hour. The results are

summarised in Table 8-10 below.

Table 8-10: London End Roundabout - Journey Time Delay & Queues Comparison, PM Peak Hour

A355 Park Lane Minerva Way London Road London End

Queue

(PCUs) Delay (sec)

Queue

(PCUs) Delay (sec)

Queue

(PCUs) Delay (sec)

Queue

(PCUs) Delay (sec)

2020 Base 9 31.20 0 210.37 34 68.88 46 234.30

Up to Phase 1 +0 +0.96 +0 +15.79 +1 +1.92 +2 +10.35

2021 Base 10 33.26 0 277.58 41 80.62 52 270.08

Up to Phase 2 +0 +1.63 +0 +53.04 +2 +4.06 +5 +28.55

2022 Base 11 35.72 0 427.7 50 94.79 65 343.82

Up to Phase 3 +0 +1.81 +0 -25.22 +4 +6.19 +4 +18.58

2023 Base 12 38.55 1 464.4 60 109.95 74 387.43

Up to Phase 4 +1 +2.45 +0 +463.01 +5 +8.05 +6 +30.73

2024 Base 13 41.19 1 935.2 72 127.54 84 438.06

Up to Phase 5 +1 +3.06 +0 - +6 +9.51 +8 +35.67

2025 Base 14 43.19 1 83 144.32 95 489.37

Up to Phase 6 +5 +40.00 +3 - +250 +240.98 +52 +370.58



8.1.25 As shown in Table 8-10, the net increase in journey time delay and queues associated with the initial

phase of the scheme is minimal on all approaches in relation to the future 2020 Base scenario. An

increase in queueing on the London End approach from 46 to 48 PCUs is forecast to result in an

increase in journey time delay of approximately 10 seconds.

8.1.26 The delivery of Phase 2 of the development is forecast to result in an increase in queueing by an

additional five PCUs on the London End approach compared to the 2021 Base scenario, which

equates to a net increase in journey time delay of approximately 30 seconds. Queues are also

expected to increase from 41 to 43 PCUs on the London Road approach, resulting in an increase in

journey time delay of four seconds at this location.

8.1.27 Once the additional traffic associated with the subsequent phases is added to the future baseline

scenarios, it becomes evident that the net traffic impact in the PM Peak Hour will not result in

unpredictable journey times up to the delivery of Phase 5 at Wilton Park. That is, in the future year

of 2024 the completion of Phase 5 will result in an increase in journey time delay of only 35 seconds

on the London End approach.

London End Roundabout – Modelling Results Summary

8.1.28 Having modelled the future baseline as well as forecast development scenarios during both peak

hour periods, the results of the junction capacity assessment at the London End roundabout show

that the point at which the journey times becomes unpredictable as a result of the development at

Wilton Park would occur following the delivery of Phase 3. That is, the initial two phases of the

Wilton Park scheme are forecast to have no significant impact on the operation of the London End

Roundabout junction.

8.1.29 Table 8-8 does however show that once Phase 3 would be completed a forecast increase in queue

lengths of 16 PCUs on the London End approach would result in an increase in journey time delay

of 45 seconds at this location. It is therefore concluded that a mitigation scheme for the London

End Roundabout junction would need to be delivered as part of the Phase 3 development at Wilton

Park, if the relief road has not been constructed at this point. The details of the potential mitigation

are presented in Chapter 9 of this report.

8.2 Pyebush Roundabout

8.2.1 To address comments raised by TfB in relation to a revision of the existing transport conditions at

Pyebush Roundabout, junction capacity assessments have been undertaken based on updated

turning count data as detailed in Chapter 3 of this report. An analysis of the traffic counts identified

the AM Peak Hour (07:45 – 08:45) and PM Peak Hour (17:00 – 18:00) at this junction.



2017 Base

8.2.2 The results of the junction capacity assessment undertaken at the Pyebush Roundabout junction

are summarised in Table 8-11 on the next page. The detailed modelling outputs are attached in

Appendix O for future reference.

Table 8-11: Pyebush Roundabout - 2017 Baseline Capacity Assessment



A40 London Rd (E) 2 5.43 0.61 1 3.89 0.51

A355 South 4 7.55 0.81 3 5.08 0.72

A40 London Rd (W) 5 11.87 0.83 2 5.42 0.67

Site Access 0 8.02 0.13 0 4.65 0.07

8.2.3 The above results show that the roundabout junction operates with spare capacity in the 2017

baseline scenario during both peak hour periods. Queues of five PCUs have been modelled on the

western London Road approach during the AM Peak Hour with a journey time delay of

approximately 12 seconds. The longest queues in the PM Peak Hour have been modelled on the

southern A355 approach. The modelled queue length of three PCUs at this location equates to a

journey time delay of approximately five seconds.

8.2.4 To validate the junction model against the observed queue data obtained at the Pyebush

Roundabout, a comparison between the observed and modelled queue lengths is presented in

Table 8-12.

Table 8-12: Pyebush Roundabout - Observed Queue Lengths & Modelled Queue Lengths

Arm

AM Peak (07:45 – 08:45) PM Peak (17:00 – 18:00)

Observed Max

Q. (PCUs)

Observed Ave

Q. (PCUs)

Modelled Q.

(PCUs)

Observed Max

Q. (PCUs)

Observed Ave

Q. (PCUs)

Modelled

Q.(PCUs)

A40 London Rd (East)

9 3 2 7 2 1

A355 South 18 5 4 15 3 3

A40 London Rd (West)

45 22 5 45 16 2

Site Access 0 0 0 0 0 0

8.2.5 It becomes evident from the results in Table 8-12 that the modelled queue length value on the

eastern London Road, Site Access and southern A355 approach are within the range of the average

observed queue length values during both peak hour periods. However, the modelling results are



underestimating the level of queuing observed on the western London Road approach during both

peak hours.

8.2.6 To reflect the observed queue lengths at the Pyebush Roundabout junction, the intercept slope

option in ARCADY has again been used with results of the updated model shown in Table 8-13

below. Not adjusting the intercept of the roundabout would result in underestimating the queue

lengths on the western London Road approach.

Table 8-13: Pyebush Roundabout – Adjusted 2017 Baseline Capacity Assessment



A40 London Rd (East) 3 10.72 0.76 2 6.36 0.63

A355 South 4 7.54 0.81 3 5.08 0.72

A40 London Rd (West) 21 50.80 0.98 16 45.47 0.96

Site Access 0 7.69 0.12 0 4.58 0.07

8.2.7 As shown in Table 8-14 the calibrated queues lengths and adjusted ARCADY model reflect the

observed queue lengths at the London End Roundabout junction.

Table 8-14: Observed Queue Lengths & Validated Queue Lengths – Pyebush Roundabout

Arm

AM Peak (07:45 – 08:45) PM Peak (17:00 – 18:00)

Observed Max

Q. (PCUs)

Observed Ave

Q. (PCUs)

Validated Q.

(PCUs)

Observed Max

Q. (PCUs)

Observed Ave

Q. (PCUs)

Validated Q.

(PCUs)


9 3 3 7 2 2

A355 South 18 5 4 15 3 3


45 22 21 45 16 16

Site Access 0 0 0 0 0 0

8.2.8 The results in Table 8-13 show that the Pyebush Roundabout is operating at capacity during both

Peak Hours, with queues of 21 PCUs and 16 PCUs on the western London Road approach during the

AM Peak Hour and PM Peak Hour respectively.

Future Baseline Scenarios

8.2.9 The future Base scenarios are derived from growth forecasts generated with TEMPro v7.2. The

intercept adjustment has been retained for all future model scenarios to assess the development

impact against a validated 2017 base model. The modelling results for the future Baseline scenarios

are summarised in Table 8-15 and Table 8-16. The results are attached in Appendix O.



Table 8-15: Pyebush Roundabout - Future Baseline Capacity Assessment, AM Peak


Queue

(PCUs)

Delay

(sec)

RFC Queue

(PCUs)

Delay

(sec)

RFC Queue

(PCUs)

Delay

(sec)

RFC


4 12.51 0.79 4 12.98 0.80 4 13.39 0.81

A355 South 5 8.81 0.84 6 9.47 0.85 6 10.24 0.86


47 98.08 1.05 56 114.81 1.06 77 132.81 1.07

Site Access 0 8.36 0.13 0 8.48 0.14 0 8.53 0.14


Queue

(PCUs)

Delay

(sec)

RFC Queue

(PCUs)

Delay

(sec)

RFC Queue

(PCUs)

Delay

(sec)

RFC


4 13.80 0.81 4 14.18 0.82 5 14.63 0.82

A355 South 7 11.13 0.87 7 12.14 0.89 8 13.40 0.90


78 152.72 1.09 89 171.80 1.11 100 191.51 1.12

Site Access 0 8.58 0.14 0 8.62 0.14 0 8.65 0.14

Table 8-16: Pyebush Roundabout - Future Baseline Capacity Assessment, PM Peak


Queue

(PCUs)

Delay

(sec)

RFC Queue

(PCUs)

Delay

(sec)

RFC Queue

(PCUs)

Delay

(sec)

RFC


2 6.81 0.65 2 6.95 0.66 2 7.12 0.67

A355 South 3 5.55 0.74 3 5.75 0.75 3 6.02

0.76


25 67.06 1.00 31 78.42 1.01 38 93.50 1.03

Site Access 0 4.76 0.07 0 4.81 0.07 0 4.86

0.07


Queue

(PCUs)

Delay

(sec)

RFC Queue

(PCUs)

Delay

(sec)

RFC Queue

(PCUs)

Delay

(sec)

RFC


2 7.27 0.67 2 7.38 0.68 2 7.55 0.69

A355 South 3 6.30 0.77 4 6.62 0.78 4 6.98 0.79


45 107.81 1.05 54 125.13 1.06 63 141.69 1.08

Site Access 0 4.90 0.07 0 4.92 0.08 0 4.94 0.08



8.2.10 The above results show that the roundabout junction is predicted to operate over capacity during

both peak periods in the future baseline scenarios without the addition of traffic associated with

the proposed development at Wilton Park. That is mainly due to the queues on the western London

Road approach that grow exponentially as a result of future background traffic growth.

8.2.11 The 2014 TA prepared by PJA in support of the planning application for the first phase of the Relief

Road off Pyebush Roundabout presented modelling results for future year 2031 scenarios as part

of BCC’s wider VISSIM model for the strategic road network surrounding the Wilton Park site. The

Pyebush Roundabout was modelled using 2013 traffic flow data and queue survey information,

which suggested no queues higher than five vehicles at the previously three arm roundabout

junction. Furthermore, applying TEMPro growth factors to the base year model the results of the

assessment suggested that the design of the Relief Road Phase 1 and the access junctions perform

satisfactorily in the future years.

Development Impact – AM Peak (07:45 – 08:45)

8.2.12 To be consistent with junction modelling assessment presented in this report, this section assesses

the impact of the delivery of the Wilton Park scheme in relation to the validated future baseline

scenarios at each phase. The modelling results for the AM Peak Hour are summarised in Table 8-17

with the full outputs provided in Appendix O.

Table 8-17: Pyebush Roundabout - Future Year Capacity Assessment Results, AM Peak Hour


Queue

(PCUs)

Delay

(sec)

RFC Queue

(PCUs)

Delay

(sec)

RFC Queue

(PCUs)

Delay

(sec)

RFC


4 14.02 0.81 5 15.44 0.83 5 16.14 0.84

A355 South 6 10.05 0.86 7 11.87 0.88 9 14.66 0.90


59 120.04 1.06 77 151.67 1.09 104 200.75 1.13

Site Access 0 9.10 0.24 0 9.55 0.29 1 9.50 0.33


Queue

(PCUs)

Delay

(sec)

RFC Queue

(PCUs)

Delay

(sec)

RFC Queue

(PCUs)

Delay

(sec)

RFC


5 17.53 0.85 6 19.41 0.87 6 20.46 0.87

A355 South 11 18.03 0.92 14 23.23 0.94 16 27.49 0.96


123 235.55 1.16 142 282.49 1.19 155 319.98 1.21

Site Access 1 9.84 0.36 1 10.28 0.40 1 10.38 0.41



8.2.13 The impact of traffic associated with the delivery of the individual phases of the development has

again been considered in relation to the future baseline scenarios in order to demonstrate the net

increase in journey times and queues on all arms during the AM Peak Hour. The results are

summarised in Table 8-18.

Table 8-18: Pyebush Roundabout - Journey Time Delay & Queues Comparison, AM Peak Hour

A40 London Rd (East) A355 South A40 London Rd (West) Site Access

Queue

(PCUs) Delay (sec)

Queue

(PCUs) Delay (sec)

Queue

(PCUs) Delay (sec)

Queue

(PCUs) Delay (sec)

2020 Base 4 12.51 5 8.81 47 98.08 0 8.36

Up to Phase 1 +0 +1.51 +1 +1.24 +12 +21.96 0 +0.74

2021 Base 4 12.98 6 9.47 56 114.81 0 8.48

Up to Phase 2 =1 +2.46 +1 +2.40 +21 +36.86 0 +1.07

2022 Base 4 13.39 6 10.24 77 132.81 0 8.53

Up to Phase 3 +1 +2.75 +3 +4.42 +27 +67.94 0 +0.97

2023 Base 4 13.80 7 11.13 78 152.72 0 8.58

Up to Phase 4 +1 +3.73 +4 +6.90 +45 +82.83 0 +1.26

2024 Base 4 14.18 7 12.14 89 171.80 0 8.62

Up to Phase 5 +2 +5.23 +7 +11.09 +53 +110.69 1 +1.66

2025 Base 5 14.63 8 13.40 100 191.51 0 8.65

Up to Phase 6 +1 +5.83 +8 +14.09 +55 +128.47 1 +1.73

8.2.14 The above results demonstrate that the development traffic associated with the delivery of Phase

1 will result in queues on the western London Road approach to increase from 47 PCUs to 59 PCUs

during the AM Peak Hour. This increase in the level of queuing translates into a net increase in

journey time delay of approximately 22 seconds on this approach. The remaining arms at this

junction are forecast to experience no significant impact as result of the delivery of Phase 1 at

Wilton Park.

8.2.15 The addition of development traffic associated with the delivery of Phase 2 at Wilton Park is

forecast to add 21 PCUs to the modelled queues on the western London Road approach relative to

the 2022 Base scenario, which equates to a net increase in journey time delay of 37 seconds per

vehicle.

8.2.16 Traffic increase associated with the subsequent development phases will exacerbate the situation

on the western London Road approach whilst the three remaining arms are expected to perform

with spare capacity in all future scenarios.



Development Impact – PM Peak (17:00 – 18:00)

8.2.17 The results of the impact of the individual phases of the Wilton Park development scheme for the

PM Peak Hour are summarised in Table 8-19 and detailed modelling outputs are provided in

Appendix O.

Table 8-19: Pyebush Roundabout - Future Year Capacity Assessment Results, PM Peak Hour


Queue

(PCUs)

Delay

(sec)

RFC Queue

(PCUs)

Delay

(sec)

RFC Queue

(PCUs)

Delay

(sec)

RFC

A40 London Rd (E) 2 6.99 0.66 2 7.14 0.67 2 7.57 0.69

A355 South 3 5.87 0.75 3 6.30 0.77 4 7.02 0.79

A40 London Rd (W) 36 89.95 1.03 51 120.37 1.06 69 156.38 1.09

Site Access 0 4.79 0.10 0 4.80 0.11 0 4.92 0.15


Queue

(PCUs)

Delay

(sec)

RFC Queue

(PCUs)

Delay

(sec)

RFC Queue

(PCUs)

Delay

(sec)

RFC

A40 London Rd (E) 2 7.74 0.69 2 7.84 0.70 2 8.01 0.71

A355 South 4 7.73 0.81 5 8.52 0.82 5 9.20 0.83

A40 London Rd (W) 88 196.15 1.12 108 237.77 1.16 108 262.01 1.18

Site Access 0 4.91 0.16 0 4.89 0.17 0 4.90 0.18

8.2.18 The net traffic impact associated with the delivery of the individual phases of the development at

Wilton Park relative to the future baseline scenarios is shown in Table 8-20 on the next page.

8.2.19 The results in Table 8-20 demonstrate that the addition of traffic associated with the delivery of

Phase 1 of the development scheme will result in queues on the western London Road approach to

increase from 25 PCUs to 36 PCUs during the PM Peak Hour. The increase in queue lengths at this

approach equates to a net increase in journey time delay of 23 seconds. The remaining three arms

at this junction are forecast to experience no significant traffic impact as a result of the completion

of the initial phase at Wilton Park.

8.2.20 Adding development traffic associated with the delivery of Phase 2 of the scheme, the western

London Road approach is forecast to experience an additional queue of 20 PCUs on the western

London Road approach in relation to the 2021 Base scenario. The increase in queue lengths equates

to a net increase in journey time delay of 42 seconds at this location.

8.2.21 The subsequent development phases further exacerbate the situation at the western London Road

approach with queues and resultant journey time delay expected to significantly increase with the

delivery of Phase 3 and onwards. The remaining three arms are expected to operate well within



capacity and the delivery of the development will have no material impact on the queue lengths

and journey time delay on these arms in all future scenarios.

Table 8-20: Pyebush Roundabout - Journey Time Delay & Queues Comparison, PM Peak Hour

A40 London Rd (East) A355 South A40 London Rd (West) Site Access

Queue

(PCUs) Delay (sec)

Queue

(PCUs) Delay (sec)

Queue

(PCUs) Delay (sec)

Queue

(PCUs) Delay (sec)

2020 Base 2 6.81 3 5.55 25 67.06 0 4.76

Up to Phase 1 +0 +0.18 +0 +0.32 +11 +22.89 +0 +0.03

2021 Base 2 6.95 3 5.75 31 78.42 0 4.81

Up to Phase 2 +0 +0.19 +0 +0.55 +20 +41.95 +0 -0.01

2022 Base 2 7.12 3 6.02 38 93.50 0 4.86

Up to Phase 3 +0 +0.45 +1 +1.00 +31 +62.88 +0 +0.06

2023 Base 2 7.27 3 6.30 45 107.81 0 4.90

Up to Phase 4 +0 +0.47 +1 +1.43 +43 +88.34 +0 +0.01

2024 Base 2 7.38 4 6.62 54 125.13 0 4.92

Up to Phase 5 +0 +0.46 +1 +1.90 +54 +112.64 +0 -0.03

2025 Base 2 7.55 4 6.98 63 141.69 0 4.94

Up to Phase 6 +0 +0.46 +1 +2.22 +45 +120.32 +0 -0.04

Pyebush Roundabout - Modelling Results Summary

8.2.22 The results of the junction capacity assessment at the Pyebush Roundabout show that the point at

which the journey times becomes unpredictable as a result of the development at Wilton Park

would occur after the delivery of Phase 2. That is, the initial two phases of the Wilton Park scheme

are forecast to have no significant impact on the operation of the roundabout junction. However,

the results in Table 8-18 and Table 8-19 show that once Phase 3 would be completed queue lengths

and resultant journey time delay on the western London Road approach would have a more

significant impact on the operation of the junction.

8.2.23 It is therefore concluded that a mitigation scheme for the Pyebush Roundabout junction would be

required as part of the Phase 3 development at Wilton Park, the details of which are presented in

the following chapter. As with the improvement at London End, this would only be required if the

complete Relief Road has not been constructed as the assessments undertaken by Jacobs have

demonstrated that the roundabout junction will operate satisfactorily without further mitigation

once the relief road is completed, primarily as a result of the redistribution of traffic on the arms of

the junction.



9 Mitigation Schemes

9.1.1 In order to address junction capacity constraints at both London End and Pyebush Roundabout

junction, this chapter presents mitigation options that can be delivered should the A355 Relief Road

not be completed. The mitigation schemes address capacity constraints identified at both junctions

as a result of the delivery of Phase 3 and all subsequent phases at Wilton Park.

9.2 Signalised London End Junction - Preferred Option

Junction Layout

9.2.1 A preferred option mitigation scheme has been developed that transforms the existing 5-arm

roundabout into a signalised junction. The rationale for signalising the junction is to distribute the

green times based on majority demand flows that would then lead to an increase in the junction

capacity and provide a better balance of queues as well as improve safety for non-motorised road

users.

9.2.2 In order to achieve an optimum design solution, an iterative process involving the assessment of

traffic performance of preliminary layouts followed by appropriate modifications to the geometric

layout was undertaken. As a result, the proposed signalised junction would entail the following

changes and amendments to the current junction layout based on guidance and standards set out

in the Design Manual for Roads and Bridges (DMRB):

• Provision of traffic signals on the London End, London Road and A355 Park Lane approaches;

• Provision of traffic signals on Minerva Way with Microprocessor Optimised Vehicle Actuation

(MOVA) sensors;

• Widening of A355 Park Lane to accommodate a separate turning lane with a storage of 3 to 4

PCUs travelling to London End;

• Provision of central islands on all arms to segregate turning movements;

• Keep-Clear signs in front of Lakes Lane approach to the junction and restrictions for traffic to

turn only left out of Lakes Lane; and

• Staggered TOUCAN crossing with refuge island across the A355 Park Lane approach.

9.2.3 The indicative layout of the preferred option of such mitigation scheme is shown on Figure 9-1 and

a preliminary design layout is shown on the plans attached in Appendix P.



Figure 9-1: Signalised London End Junction – Preferred Option Mitigation

Junction Capacity Modelling Results

9.2.4 To identify the benefit from signalising the London Roundabout junction, Table 9-1 summarises the

modelling results of those future year scenarios beyond which the development at Wilton Park is

forecast to have an impact on the capacity of the London End Roundabout junction. The full sets of

LinSig modelling results are contained in Appendix Q.

9.2.5 Junction models for the London End junction have been constructed using industry standard

software, with LinSig V3 used for the capacity assessment of the signalised mitigation scheme.

9.2.6 The results obtained from LinSig are reported in Degree of Saturation (DoS), journey time delay

(sec/PCU) and mean-maximum queue lengths (PCU) on each junction approach.

9.2.7 Minerva Way has not been included in the LinSig model as, following its closure as the access to

Wilton Park, it only serves a small number of houses and therefore the limited number of vehicle

trips travelling to and from Minerva Way will not affect the junction capacity to a significant degree.

The vehicle numbers into and out of Minerva Way are set out on the Travel Flow Diagrams attached

in Appendix K.



9.2.8 The Minerva Way approach will be signalised with green times called whenever there is a demand

for it – i.e. one vehicle approaching the signals. From the surveys of the junction, the residential

units served by Minerva Way generate six vehicle trips in the AM Peak Hour and nine vehicle trips

in the PM Peak Hour. Assuming a worst-case scenario where the arrival profile of trips on the

Minerva Way approach will be distributed over the entire duration of the peak period, a green time

will be called up to a maximum of six and nine times during the morning and evening peak hour,

respectively. This would equate to a lost time of approximately 2% and 3% of the overall cycle time

during the AM and PM peak period respectively, assuming a minimum green time of seven seconds

and a lost time of five seconds. In reality, vehicles may arrive at the junction together, reducing the

time lost to the junction.

Table 9-1: London End Signalised Junction – Junction Capacity Modelling Results

Period

Arm

2022 Base + Phase 3 2023 Base + Phase 4

MMQ

(PCU)

Delay

(s/PCU)

DOS MMQ

(PCU)

Delay

(s/PCU)

DOS

AM

Peak

London Road Ahead 21 32.2 86.0% 22 34.2 87.7%

London Road Right 50 116.0 103.1% 56 137.3 104.6%

London End Ahead Left 14 79.4 92.5% 15 85.1 93.9%

London End Ahead 24 132.4 101.3% 27 149.9 102.8%

Park Lane Left Right 52 96.9 102.2% 56 110.3 103.1%

PRC: -14.5% Cycle Time: 90 Seconds


PM

Peak




London End Ahead 27 143.0 102.4% 30 160.7 103.9%




Period

Arm


MMQ

(PCU)

Delay

(s/PCU)

DOS MMQ

(PCU)

Delay

(s/PCU)

DOS

AM

Peak




London End Ahead 29 166.0 104.1% 31 180.0 105.2%






Period

Arm


MMQ

(PCU)

Delay

(s/PCU)

DOS MMQ

(PCU)

Delay

(s/PCU)

DOS

PM

Peak




London End Ahead 33 179.4 105.3% 36 195.9 106.5%




Modelling Results Comparison – AM Peak Hour

9.2.9 Table 9-2 provides an overview of the net benefit of signalising the London End junction during the

AM Peak Hour when compared to the ARCADY modelling results of the future baseline and forecast

development impact on the existing junction layout.

Table 9-2: London End Signalised Junction – Model Results Comparison, AM Peak Hour (08:00 – 09:00)

Arms ARCADY Base ARCADY Base + Phase LinSig Mitigation Difference

Delay

(sec/veh)

Queues

(PCUs)

Delay

(sec/veh)

Queues

(PCUs)

Delay

(sec/veh)

Queues

(PCUs)

Delay

(sec/veh)

Queues

(PCUs)

2022 2022 + Phase 3 2022 + Phase 3

A355 Park Lane 256.93 87 263.26 90 96.9 52 -166.36 -38

London Road 79.77 43 86.35 52 148.2 50 +61.85 -2

London End 507.60 88 550.38 104 211.8 24 -338.58 - 80

2023 2023 + Phase 4 2023 + Phase 4

A355 Park Lane 274.23 94 283.05 97 110.3 56 -172.75 -41

London Road 90.59 55 100.32 62 235.00 56 +134.68 -6

London End 567.76 106 615.60 116 171.5 27 -444.10 -89

2024 2024 + Phase 5 2024 + Phase 5

A355 Park Lane 298.23 103 309.98 107 188.4 63 -121.58 -44

London Road 105.42 65 120.13 75 215.0 63 +94.87 -12

London End 625.83 117 678.90 128 259.4 29 -419.5 -99

2025 2025 + Phase 6 2025 + Phase 6

A355 Park Lane 319.35 110 332.53 115 144.5 68 -188.03 -47

London Road 121.41 75 139.44 87 214.7 68 +75.26 -19

London End 681.40 127 735.44 138 280.5 31 -454.94 -107

9.2.10 The difficulty of comparing LinSig modelling results with ARCADY modelling results is the different

methodologies applied when presenting modelled queue lengths on the respective arms. That is,

LinSig software models Mean Maximum Queues (MMQs), which present an average of the

maximum queues modelled on each individual approach lane and, hence, present a worst-case



scenario. ARCADY modelling results, however, demonstrate an average number of PCUs queueing

on the entire approach during a peak hour period.

9.2.11 To compare the net traffic impact associated with the signalisation of the London End junction, the

most accurate assessment will therefore be the comparison between journey time delays

experienced at the junction modelled in seconds/PCUs in both ARCADY and LinSig.

9.2.12 The results in Table 9-2 show that the signalisation of the London End Junction results in a significant

improvement in the overall performance of the junction relative to the future baseline scenario at

the existing roundabout. Queuing would reduce on all arms with reductions in the delays

experienced by vehicles on the A355 and London End. Taking in consideration the modelling of

MMQs in the LinSig software, the reduction in average queue lengths is expected to be even larger

when compared to the ARCADY results of the London End Roundabout model. Increases in delay

are predicted for the London Road Arm of the junction as a function of adding the traffic signals to

an approach that currently operates without any significant conflict.

Modelling Results Comparison – PM Peak Hour

9.2.13 Table 9-3 provides an overview of the net benefit of signalising the London End junction during the

PM Peak Hour when compared to the modelling results of the forecast development impact on the

surrounding road network.

Table 9-3: London End Signalised Junction – Model Results Comparison, PM Peak Hour (17:15 – 18:15)

Arms ARCADY Base ARCADY Base + Phase LinSig Mitigation Difference

Delay

(sec/veh)

Queues

(PCUs)

Delay

(sec/veh)

Queues

(PCUs)

Delay

(sec/veh)

Queues

(PCUs)

Delay

(sec/veh)

Queues

(PCUs)

2022 2022 + Phase 3 2022 + Phase 3

A355 Park Lane 35.72 11 37.53 11 152.0 59 +114.47 +48

London Road 94.79 50 100.98 54 174.2 59 +73.22 +5

London End 343.82 65 362.40 69 216.3 27 -146.1 -33

2023 2023 + Phase 4 2023 + Phase 4

A355 Park Lane 38.55 59 41.00 13 41.00 64 +126.2 +51

London Road 109.95 59 118.00 65 118.00 65 +76.4 +0

London End 387.43 27 418.16 80 418.16 30 -178.56 -50

2024 2024 + Phase 5 2024 + Phase 5

A355 Park Lane 41.19 13 44.25 14 188.4 70 +144.15 +56

London Road 127.54 72 137.05 78 215.0 72 +77.95 -6

London End 438.06 84 473.73 92 265.2 33 -208.53 -59

2025 2025 + Phase 6 2025 + Phase 6

A355 Park Lane 43.19 14 83.19 19 203.0 75 +119.81 +56

London Road 144.32 83 385.30 333 232.5 77 -152.8 -256

London End 489.37 95 859.95 147 287.2 36 -572.75 -111



9.2.14 The results in Table 9-3 show that the signalisation of the London End junction results in an

improvement to the operation of the junction. The mitigation scheme is forecast to reduce queuing

and journey time delay on the London End and London Road approaches which experience the

highest levels of congestion. When comparing the modelling results to the ARCADY results for the

future baseline the mitigation would increase the delay experienced on the A355 however this is

partly due to the introduction of signals on a relatively uncongested arm to redistribute the capacity

of the junction.

9.2.15 Taking in consideration the modelling of MMQs in the LinSig software, the increase in queue lengths

on the A355 approach as shown in Table 9-3 is expected to be much less in reality when compared

to the average queue lengths at the London End Roundabout modelled in ARCADY.

9.2.16 The modelling set out above demonstrates that, subject to the delivery of the signalisation scheme,

the impact of the development in this location can be mitigated. The need for the scheme would

however be determined by the delivery of the relief road. As demonstrated by Jacobs, the

completion of the relief road would result in a significant reduction in traffic at London End which

would then remove the need for this mitigation scheme.

9.3 Pyebush Roundabout Mitigation - Preferred Option

Junction Layout

9.3.1 In order to address capacity constraints at Pyebush Roundabout as detailed in Chapter 8 of this

report, a mitigation scheme has been prepared that enables additional turning movements on the

nearside lane of the western London Road approach, which in turn requires an additional

circulatory lane between the northern and eastern arms of the existing roundabout junction. The

rationale for this mitigation is to provide additional entry capacity on the western London Road

which was demonstrated to experience the highest levels of congestion. The additional circulatory

lane will allow for vehicles travelling to the southern A355 arm to distribute across two lanes when

entering the junction from the western London Road approach.

9.3.2 In addition, it is proposed that the nearside lane of the southern A355 arm is marked for left turns

only, with ahead and right turning traffic using the offside lane to more evenly distribute the

demand on this approach. the roundabout.

9.3.3 The proposed mitigation option would entail the following changes and amendments to the current

junction layout based on guidance and standards set out in the Design Manual for Roads and

Bridges (DMRB):

• Provision of road markings to allow for turning movements from the nearside entry lane on the

western London Road approach towards the A355;



• Changes to the road markings on the circular carriageway between the northern and eastern

arm of the roundabout junction; and

• Provision of road markings to restrict the use of the nearside lane on the A355 southern

approach to left turning vehicles only.

9.3.4 The indicative layout of the preferred option of such mitigation scheme is shown on Figure 9-1 and

a preliminary design layout is shown on the plans attached in Appendix R.

Figure 9-2: Pyebush Roundabout – Preferred Option Mitigation

Lane Simulation Modelling

9.3.5 In order to provide an indication of the potential benefit of the proposed mitigation scheme, the

junction has been modelled using the ARCADY Lane Simulation mode as it provides a way to

compare different entry lane configurations at roundabouts.

9.3.6 Proposing the opportunity of an additional turning movement towards the southern A355 arm on

the nearside lane of the western London Road approach, the Lane Simulation model defines the

allowed movements on that particular arm and distributes travel demand accordingly. As vehicles



will have a choice of more than one lane, the model selects the lane with the shortest queue at that

moment as the expected behaviour takes precedence over any physical markings/signs.

9.3.7 In comparison to the standard roundabout model presented in Chapter 8 of this report, the Lane

Simulation mode will model a more realistic lane usage on the western London Road approach as

a result of turning restrictions provided on the two entry lanes. The Junctions 9 User Guide notes

that Lane Simulation modelling “should not be taken as forecasting junction performance to the

same level of accuracy as the main ARCADY model.” That is, Lane Simulation models are based on

the assumption that the overall capacity of each arm is the same as that predicted by the core

ARCADY model. In more complex cases, the results will differ as is the case in this instance, but the

core empirical ARCADY model is always used to provide ‘baseline’ data for the run.

9.3.8 Whilst using the Lane Simulation function, it is not possible validate the baseline model to observed

conditions by applying slope and intercept corrections. Therefore, the results presented below

cannot be directly compared to the ARCADY modelling but do provide an indication of the

redistribution of roundabout capacity that would result from the proposed changes.

Junction Capacity Modelling Results

9.3.9 To assess the likely benefit of the mitigation scheme at the Pyebush Roundabout, the impact of

future development scenarios on the junction performance will be compared with modelling results

obtained from the Lane Simulation mode based on the existing layout of the roundabout junction.

As detailed previously, these baseline scenarios have not been validated to the observed patterns

of queuing but the comparison to the ‘with development’ scenarios will illustrate the likely effect

of the mitigation on the capacity of the roundabout.

‘Do Nothing – Future Base Scenarios’

9.3.10 Table 9-4 and Table 9-5 on the following page summarise the Lane Simulation modelling results for

the forecast baseline scenarios. The full sets of modelling results are contained in Appendix S.



Table 9-4: Pyebush Roundabout – Future Base Scenarios Lane Simulation Model, AM Peak Hour

2022 Base 2023 Base

Queue (PCUs) Delay (sec) Queue (PCUs) Delay (sec)

A40 London Rd (East) 5 14.59 5 14.43

A355 South 118 201.39 126 218.45

A40 London Rd (West) 475 1380.75 497 1410.49

Site Access 0 8.63 0 8.76

2024 Base 2025 Base


A40 London Rd (East) 5 14.41 5 14.91

A355 South 135 237.21 150 271.27

A40 London Rd (West) 515 1446.75 541 1502.83


Table 9-5: Pyebush Roundabout – Future Base Scenarios Lane Simulation Model, PM Peak Hour

2022 Base 2023 Base


A40 London Rd (East) 2 8.40 3 8.72

A355 South 52 87.39 59 98.37

A40 London Rd (West) 344 1135.97 359 1171.53


2024 Base 2025 Base


A40 London Rd (East) 2 8.83 3 8.79

A355 South 67 107.81 77 123.40

A40 London Rd (West) 377 1227.81 395 1281.70


9.3.11 The validated ARCADY model results for this junction summarised in Table 8-18, indicated that

queues of 100 vehicles were anticipated on the A40(W) arm of the junction with queues of only

eight vehicles on the A355(S) arm in the 2025 future baseline AM scenario. The Lane Simulation

modelling summarised in Table 9-4 is therefore significantly overestimating the level of queuing on

these approaches.

9.3.12 The PM Lane Simulation modelling shows similar overestimations. The validated PM model results

summarised in Table 8-20 indicated queues of 63 vehicles on the A40(W) arm and four vehicles on

the A355(S) arm in the 2025 future baseline PM scenario compared to the significantly higher values

presented in Table 9-5.

9.3.13 These overestimations are the result of the limitations of the software which do not allow the

validation of the queue lengths when using the Lane Simulation modelling.



‘Do Nothing’ – Development Impact Scenarios

9.3.14 Table 9-6 and Table 9-7 summarise the Lane Simulation modelling results for the forecast

development impact on the existing Pyebush Roundabout if no mitigation scheme was to come

forward. As set out in Chapter 8 of this report, the future year of 2022 and delivery of Phase 3 marks

the point at which mitigation would be required and, hence, modelling scenarios prior to this year

are not of relevance for this assessment. The full sets of modelling results are contained in Appendix

S.

Table 9-6: Pyebush Roundabout –Development Impact Scenarios Lane Simulation Model, AM Peak Hour



A40 London Rd (East) 5 16.55 6 16.27

A355 South 149 276.47 167 325.45

A40 London Rd (West) 517 1434.81 554 1490.94

Site Access 0 10.18 1 10.71



A40 London Rd (East) 7 18.67 6 18.10

A355 South 190 369.35 211 408.74

A40 London Rd (West) 584 1539.27 607 1589.06

Site Access 1 11.55 1 11.57

Table 9-7: Pyebush Roundabout – Development Impact Scenarios Lane Simulation Model, PM Peak Hour



A40 London Rd (East) 3 9.28 3 9.55

A355 South 75 124.67 87 144.85

A40 London Rd (West) 373 1196.13 400 1279.56




A40 London Rd (East) 3 9.55 3 9.93

A355 South 101 177.36 111 202.89

A40 London Rd (West) 428 1341.73 456 1419.08


‘Do Something – Development Impact Scenarios’

9.3.15 To identify the benefit from the Pyebush Roundabout mitigation scheme Table 9-8 and Table 9-9

summarise the modelling results of those future year scenarios at which the development at Wilton



Park is forecast to have an impact on the capacity of the Pyebush Roundabout. The full sets of

modelling results are contained in Appendix S.

Table 9-8: Pyebush Roundabout Mitigation– Junction Capacity Modelling Results, AM Peak Hour (07:45 – 08:45)



A40 London Rd (East) 18 57.51 23 66.94

A355 South 124 207.64 134 238.06

A40 London Rd (West) 118 220.56 133 272.31

Site Access 2 26.98 2 32.84



A40 London Rd (East) 24 69.29 26 72.49

A355 South 156 281.94 162 299.44

A40 London Rd (West) 158 343.24 174 386.52

Site Access 2 33.62 2 33.67

Table 9-9: Pyebush Roundabout Mitigation– Junction Capacity Modelling Results, PM Peak Hour (17:00 – 18:00)



A40 London Rd (East) 5 16.96 5 16.90

A355 South 55 90.43 69 110.38

A40 London Rd (West) 82 180.79 102 227.35

Site Access 0 10.32 1 10.73



A40 London Rd (East) 5 16.70 5 17.51

A355 South 76 123.86 89 146.26

A40 London Rd (West) 122 283.75 132 316.13

Site Access 1 10.79 1 10.42

Modelling Comparison – AM Peak Hour (07:45 – 08:45)

9.3.16 Table 9-10 provides an overview of the net benefit of the mitigation scheme at the Pyebush

Roundabout during the AM Peak Hour. The modelling results of the mitigation scheme are

compared to the modelling results presented above which identified the forecast development

impact on the surrounding road network without a mitigation scheme in place.

9.3.17 A direct comparison of modelled queue lengths and journey time delays of the Lane Simulation

models allows for an indicative assessment of the net traffic impact associated with the mitigation

scheme relative to the existing layout of the roundabout.



Table 9-10: Pyebush Roundabout Mitigation – Modelling Results Comparison, AM Peak Hour (07:45 – 08:45)

Arms Lane Simulation Base Lane Sim Base + Phase Lane Sim Mitigation Difference

Delay

(sec/veh)

Queues

(PCUs)

Delay

(sec/veh)

Queues

(PCUs)

Delay

(sec/veh)

Queues

(PCUs)

Delay

(sec/veh)

Queues

(PCUs)

2022 2022 + Phase 3 2022 + Phase 3


5 14.59 5 16.55 18 57.51

+13 +40.96

A355 South 118 201.39 149 276.47 124 207.64 -25 -68.83


475 1380.75 517 1434.81 118 220.56 -499 -1214.25

Site Access 0 8.63 0 10.18 2 26.98 +2 +16.80

2023 2023 + Phase 4 2023 + Phase 4


5 14.43 6 16.27 23 66.94 +17 +50.67

A355 South 126 218.45 167 325.45 134 238.06 -33 -87.39


497 1410.49 554 1490.94 133 272.31 -421 -1218.63

Site Access 0 8.76 1 10.71 2 32.84 +1 +22.13

2024 2024 + Phase 5 2024 + Phase 5


5 14.41 7 18.67 24 69.29 +17 +50.62

A355 South 135 237.21 190 369.35 156 281.94 -34 -87.41


515 1446.75 584 1539.27 158 343.24 -426 -1196.03

Site Access 0 8.83 1 11.55 2 33.62 +1 +22.07

2025 2025 + Phase 6 2025 + Phase 6


5 14.91 6 18.10 26 72.49 +20 +54.39

A355 South 150 271.27 211 408.74 162 299.44 -49 -109.30


541 1502.83 607 1589.06 174 386.52 -433 -1202.54

Site Access 0 8.94 1 11.57 2 33.67 +1 +22.1

9.3.18 The results in Table 9-10 indicate that the proposed mitigation will significantly reduce the level of

queuing and delay experienced on the A40(W) arm of the junction and would be an improvement

relative to the future baseline scenario.

9.3.19 A slight increase in queuing is predicted on the A40(E) arm of the junction which is a result of the

additional conflicting traffic from the western arm passing the entry in-route to the A355(S) exit.

Given the low level of congestion predicted for this arm in the validated modelling, the

redistribution of a small amount of the queuing from the western arm is necessary to improve the

overall junction operation.

9.3.20 The modelling results also indicate an 8% increase in queuing on the A355(S) arm of the junction

relative to the future baseline scenario. As detailed previously the Lane Simulation modelling



significantly overestimates the level of queuing on this approach to the junction when compared

to the validated assessments. However, an increase in the validated queuing of the magnitude

predicted by the Lane Simulation modelling (8%) would not detract from the significant overall

benefit in the operation of the junction following the mitigation.

Modelling Comparison - PM Peak Hour (17:00 - 18:00)

9.3.21 Table 9-11 summarises the net benefits of the mitigation scheme at Pyebush Roundabout for the

PM Peak Hour in relation to the forecast development impact in the absence of any mitigation

scheme identified in Table 9-5of this report.

Table 9-11: Pyebush Roundabout Mitigation – Modelling Results Comparison, PM Peak Hour (17:00 – 18:00)

Arms Lane Simulation Base Lane Sim Base + Phase Lane Sim Mitigation Difference

Delay

(sec/veh)

Queues

(PCUs)

Delay

(sec/veh)

Queues

(PCUs)

Delay

(sec/veh)

Queues

(PCUs)

Delay

(sec/veh)

Queues

(PCUs)

2022 2022 + Phase 3 2022 + Phase 3


2 8.40 3 9.28 5 16.96

+2 +7.68

A355 South 52 87.39 75 124.67 55 90.43 -20 -34.24


344 1135.97 373 1196.13 82 180.79

-291 -1015.34

Site Access 0 6.38 0 6.90 0 10.32 +0 +3.42

2023 2023 + Phase 4 2023 + Phase 4


3 8.72 3 9.55 5 16.90

+2 +7.35

A355 South 59 98.37 87 144.85 69 110.38 -18 -34.47


359 1171.53 400 1279.56 102 227.35

-298 -1052.21

Site Access 0 6.39 0 6.90 1 10.73 +1 +3.83

2024 2024 + Phase 5 2024 + Phase 5


2 8.83 3 9.55 5 16.70 +2 +7.15

A355 South 67 107.81 101 177.36 76 123.86 -25 -53.50


377 1227.81 428 1341.73 122 283.75 -306 -1057.98

Site Access 0 6.40 0 6.96 1 10.79 +1 +3.83

2025 2025 + Phase 6 2025 + Phase 6


3 8.79 3 9.93 5 17.51 +2 +7.58

A355 South 77 123.40 111 202.89 89 146.26 -22 -56.63


395 1281.70 456 1419.08 132 316.13 -324 -1102.95

Site Access 0 6.52 0 7.04 1 10.42 +1 +3.38



9.3.22 As was the case for the AM peak hour, the results in Table 9-11 indicate that the proposed

mitigation will significantly reduce the level of queuing and delay experienced on the A40(W) arm

of the junction in the PM peak and would be an improvement relative to the future baseline

scenario.

9.3.23 A 15% increase in queuing on the A355(S) arm of the junction relative to the future baseline

scenario is predicted. The future baseline queue in the validated model on this arm was only four

vehicles therefore if this queue was to increase by the magnitude predicted in the Lane Simulation

assessment the overall impact of the mitigation scheme would be a significant benefit given the

large improvement on the most congested western arm.

9.3.24 The modelling set out above demonstrates that, subject to the delivery of the mitigation scheme,

the impact of the development in this location can be mitigated.

9.3.25 The need for the scheme would however be determined by the delivery of the relief road. As

demonstrated by Jacobs, the junction is forecast to operate satisfactorily in the 2031 future

assessment horizon once the relief road is in place due to the redistribution effects of the scheme

that would remove traffic from the congested A40(W) approach. Therefore, if the relief road has

been constructed the need for the mitigation would be removed.



10 Summary and Conclusions

10.1.1 Phil Jones Associates (PJA) has been commissioned by Inland Ltd to prepare a Transport Assessment

to accompany the outline planning application for the comprehensive mixed-use redevelopment at

Wilton Park comprising 304 residential properties (Class C3); employment and community uses

including new ATC facility (Classes A1, A3, B1, B2, D1 & D2); formal and informal public open space,

including local park and sports pitches with changing facilities; new access road from A40 Pyebush

Roundabout to form southern part of Beaconsfield Relief Road; network of footpaths and cycleways

including alterations to Minerva Way; car parking; on-site access roads; and landscaping works.

10.1.2 The development site is located in a sustainable and accessible location with a range of local

amenities and public transport services located within walking and cycling distance from the site.

The proximity to Beaconsfield town centre will encourage future residents and staff to use

sustainable modes of transport rather than the private car. In accordance with the objectives set

out in the Wilton Park SPD, Minerva Way will provide a high quality, attractive and safe

pedestrian/cycle route between Beaconsfield and the site.

10.1.3 The vehicular access into the site will be from the northern arm of the Pyebush Roundabout which

will form Phase 1 of the Eastern Relief Road with a traffic-free route along Minerva Way providing

access for pedestrians and cyclist travelling to and from Beaconsfield town centre. A highway safety

analysis has concluded that the low number of accidents and level of severity at the junctions in the

immediate vicinity of the development site do not suggest any highway safety issue that could be

exacerbated by the development at Wilton Park.

10.1.4 A travel demand analysis has shown that the proposed development is forecast to generate 262

two-way vehicle trips during the AM peak period and 203 two-way vehicle trips during the PM peak

period. Taking into consideration the existing operation of the site, this equates to a net traffic

impact of 136 additional two-way vehicle trips during the AM Peak Hour and 88 additional two-way

vehicle trips during the PM Peak Hour.

10.1.5 As agreed with TfB, detailed standalone modelling has been undertaken at the London End and

Pyebush Roundabout junctions. The results of this detailed modelling have identified that there are

existing capacity constraints on the surrounding highway network but that the initial phases of

development would not have a severe impact relative to the predicted future baseline scenarios.

Potential mitigation options have been prepared for both the London End Roundabout and Pyebush

Roundabout which offset the impacts of the latter phases of the development and result in

improvements relative to the future baseline scenario.

10.1.6 Modelling undertaken by Jacobs in support of Phase 2 of the Eastern Relief Road, which included

traffic generated by the proposed development, has demonstrated that the delivery of this route

would result in a significant improvement in the operation of the surrounding highway network,



with both London End and the Pyebush roundabouts operating acceptably. Therefore, the

completion of the relief road would remove the need for the mitigation measures.

10.1.7 In conclusion, it is considered that there are no highway or transport reasons why the proposed

development should not be granted planning permission.

wilton park, beaconsfieldnewwiltonpark.com/wp-content/uploads/pdf_downloads... · 3.4 summary...

Documents