Consultancy Framework Agreement for Transport Planning Services
SE Dorset Model Development & Regional Transport Study
Business Case
May 2007
JOB NUMBER: 5033826/251 / DOCUMENT REF: SEDMMS_Buscase_v1.doc1 / Draft Report / RCH / PJG / PJG / 30/05/07
Originated / Checked / Reviewed / Authorised / Date
Revision / Purpose
Description /
Consultancy Framework Agreement for Transport Planning Services /
SE Dorset Model Development & Regional Transport Study – Business Case
Contents
Section Page
1. Introduction 1-1
Scoping Brief 1-1
2. Proposed Transport Model 2-3
Existing SE Dorset Traffic Model 2-3
Model Scope 2-4
VaDMA Requirements 2-5
Key Elements of the Model 2-5
Software Issues 2-7
Summary 2-7
3. Data Requirements 3-1
Roadside Interview Surveys 3-1
Car Park and Other Interview Surveys 3-1
Traffic and Passenger Counts 3-2
Journey Time Surveys 3-2
Cost of Surveys 3-2
4. Proposed Regional Transport Study 4-1
Study Objectives 4-1
Key Policy Issues to be Addressed 4-2
Study Benefits 4-3
5. Outline Work Programme and Study Costs 5-1
Work Programme 5-1
Study Costs 5-3
Longer Term Costs 5-3
List of Tables
Table 3.1 – Cost of Proposed Surveys 3-3
Table 5.1 – Outline Costs of Model Development and Sub-Regional Study 5-4
List of Figures
Figure 5.1 – Outline Work Programme 5-2
5033826.251 / TFADS /SE Dorset i
C061120073 Appendix 1.doc
Consultancy Framework Agreement for Transport Planning Services /SE Dorset Model Development & Regional Transport Study – Business Case
1. Introduction
1.1 Atkins Planning Consultants was commissioned by the Highways Agency (HA) in February 2007 to undertake a scoping study for an improved SE Dorset Traffic Model (SEDTM) and Multi-Modal Transport Study for the SE Dorset Joint Study Area (JSA). This area, which covers the Bournemouth-Poole-Christchurch conurbation and a number of outlying satellite towns, has been designated as one of the region’s Strategically Significant Cities and Towns (SSCTs) by the South West Regional Assembly (SWRA) and is defined as a separate sub-region within the Regional Spatial Strategy (RSS).
1.2 The study brief was prepared jointly by the HA, Dorset County Council, Bournemouth Borough Council, and Poole Borough Council, the four highway authorities for the sub-region. However, the scoping study itself was funded by the HA through it’s Consultancy Framework Agreement for Transport Planning Services.
Scoping Brief
1.3 The study brief identifies the following key objectives:
(i) To scope the technical requirements for upgrading or renewing the SEDTM:
– giving a broad indication of the costs of doing so, including the main component costs, such as data collection, and identifying significant cost increases relating to the essential or desirable outputs; and
– to provide full life costs of different approaches to the modelling process and the advantages and disadvantages of each.
(ii) To provide a non-technical business case for the improved SEDTM so that elected members and prospective funding partners can make informed decisions on financing and timing.
(iii) To give costs and timing of producing a sub-regional transport strategy, using outputs from the updated/new SEDTM, to 2026 and beyond for the South East Dorset JSA.
1.4 The SE Dorset Transport Model Scoping Report of May 2007 presents the Task (i) findings. It considers the requirements of the proposed model upgrade, and provides an outline specification for model development. It also includes estimates of the likely data collection and staff resource costs, and study time-scales.
1.5 The SE Dorset Regional Transport Study Scoping Note of May 2007 similarly addresses Task (iii). It provides an outline methodology for reviewing and developing a transport strategy for the SE Dorset sub-region, based on outputs from the updated transport model. It also provides an estimate of staff resource costs and major project expenses (including consultation), and a recommended work programme.
1.6 The specifications and recommendations contained in these reports are based on:
¨ the study brief, which defines essential and desirable model outputs, and the overall aims and outputs of the sub-regional transport strategy;
¨ discussions with officers of Dorset CC, Bournemouth and Poole BCs, and Dorset Engineering Consultancy (who operate and maintain the current SEDTM);
¨ our understanding of the wider sub-regional transport issues, and the likely scenarios and schemes to be tested in the short, medium and long term, based on information provided by the local authorities, the second Local transport Plan for SE Dorset, and the draft RSS;
¨ wider HA and Department for Transport (DfT) advice and guidance on model development; and
¨ our experience and knowledge of the requirements and processes involved in undertaking strategic planning projects of this nature.
1.7 Although the specification of the model has been closely aligned with the requirements of the sub-regional study and the transport strategies, schemes and measures which would need to be tested, the two strands of work would not need to be undertaken at the same time or as part of the same contract.
1.8 This report addresses Task (ii). It provides a non-technical business case for the proposed model update and sub-regional transport study, summarising the findings of the more detailed scoping reports. Its aim is to inform members and stakeholders of the study recommendations, setting out our proposals for model and strategy development, together with costs and time-scales.
5033826.251 / TFADS /SE Dorset i
C061120073 Appendix 1.doc
Consultancy Framework Agreement for Transport Planning Services /SE Dorset Model Development & Regional Transport Study – Business Case
2. Proposed Transport Model
2.1 The existing SE Dorset Traffic Model (SEDTM), which is currently maintained and operated by the Dorset Engineering Consultancy (DEC), has a number of significant deficiencies, and could not be used with confidence to test and assess the long term effects of regional and local planning strategies, general traffic growth, or the wide range of transport schemes and measures (including demand management and improved public transport provision) which may be needed to reduce traffic congestion. Furthermore, it would not meet the current criteria to support a bid for DfT funding. A new SE Dorset Transport Model is therefore proposed, as fully described in the SE Dorset Transport Model Scoping Report of May 2007.
Existing SE Dorset Traffic Model
2.2 The existing traffic model covers the urban areas of Bournemouth, Poole, and Christchurch, together with the adjacent settlements of Ringwood, Ferndown, Verwood, Wimborne Minster, and Wareham. It was originally developed (with DfT support), based on origin-destination (OD) data collected at more than 30 roadside interview (RSI) sites in 1989/90. Since then it has been updated several times; firstly in 1995 based on new RSI data collected on an east-west screenline within the urban area, and subsequently in 1998 and 2002 based on traffic counts only.
2.3 The SEDTM was used by the SE Dorset JSA to inform decisions on settlement strategy and development levels for the RSS sub-regional study. However, model output was not the dominant factor in any of the key decisions, in part because tests of different growth scenarios proved inconclusive and there was little confidence in the results.
2.4 A review of the transport models used by the various JSA’s to inform and support their RSS submissions was commissioned by the HA and SWRA and undertaken by Atkins in 2005. This criticised the SEDTM because although the networks are reasonably up-to-date, the trip matrices rely on OD data which is now 12-18 years old (RSI data from 1989/90 and 1995), whereas the HA’s Design Manual for Roads and Bridges (DMRB) recommends that this core data should not be more than 5-6 years old. The model was also criticised because it does not meet the validation criteria set down in the DMRB. Other deficiencies of the current model relate to its forecasting capability, as follows.
¨ the model can assign traffic to the modelled highway network, and simulate the movement of vehicles in detail to forecast their effects on queues and delays at junctions, but it is not able to forecast the impacts of increasing road congestion and proposed public transport improvement schemes on bus and rail patronage. Given the need to assess a range of public transport improvements and demand management measures as part of the proposed strategic transport study, and the DfT’s new guidance on modelling undertaken in support of funding bids, the SEDTM now needs to have multi-modal capability;
¨ the existing SEDTM does not include a sub-model for trip distribution. Forecast trip matrices have therefore been developed by factoring up the base year trip-ends, copying patterns of distribution from adjacent zones to represent new development zones, and balancing the matrices to the forecast origins and destinations. Given the need to test and assess the proposed RSS housing and employment allocations, and the DfT’s recent guidance which suggests that re-distribution is likely to be the dominant behavioural response to increasing highway congestion (moreso than modal transfer), the SEDTM update will now need to be more robust in this respect.
¨ the existing SEDTM takes no account of either trip suppression, which would result from increasing congestion, or the induced traffic effects of new schemes. The DfT now insists that a fixed matrix approach of this kind should only be employed where demand responses are shown to be negligible. Otherwise these responses should be modelled explicitly.
2.5 The county and local authorities (and the HA) are aware of the existing model’s deficiencies, and have therefore agreed that it should be updated (probably to a 2008 base year) and extended to provide a multi-modal capability. They are seeking a step change in the quality of the modelling tools, which will be needed to provide robust assessments of transport strategies, schemes and measures, both to inform the LTP and RSS processes and to support major scheme bids and other applications for funding.
Model Scope
2.6 The study brief for the model scoping exercise sets out a number of essential and desirable outputs that will be required from the model and the likely timescales for these, where relevant.
2.7 On this basis and work undertaken for the scoping study, the proposed model would need to facilitate the testing and assessment of a wide range of alternative land-use and transport strategies in the short, medium, and longer terms. It would also need to operate at both strategic and local levels, and be capable of testing and assessing the impacts of proposed developments, highway and public transport improvement schemes, and other transport measures. In particular, specific model tests are likely to include:
¨ alternative land-use development scenarios, including RSS proposals for an additional 28,000-32,000 houses in SE Dorset between 2006 and 2026, mostly located in the Poole, Bournemouth, and Christchurch urban areas, but with about 3,000 houses proposed for Ferndown, Wimborne Minster, and other towns to the north of the conurbation;
¨ new highway infrastructure, including widening of sections of the A31, the A31 to Poole improvement scheme, and improved access to the airport, including a new link from the A338;
¨ bus priority measures and implementation of intelligent transport systems in Prime Transport Corridors, including A35 Poole-Bournemouth, A3049 East-West corridor, A341/A347/A3060 Northern corridor and A35 Eastern corridor;
¨ park and ride schemes to reduce car travel within urban areas;
¨ railway improvement schemes, including Poole Station interchange, a new station at Boscombe, reconnection of the Swanage line, and improved east-west cross-conurbation services;
¨ road user charging and tolling of strategic routes;
¨ work-place parking charges, parking restrictions, reallocation of road space, and other forms of restraint.
2.8 Some of these scenarios and schemes lend themselves to assessment within a modelling framework better than others. However, it should be possible to model the impacts of most of them in broad terms, if the necessary sub-models are developed.
VaDMA Requirements
2.9 Volume 12 of the DMRB provides detailed guidance on the development and use of highway models, and defines flow and journey time criteria for their acceptability. This has long been used as a standard for the calibration and validation of traffic models. However, it includes only limited information on multi-modal modelling. Therefore, when the first of the multi-modal studies was commissioned in 2000, the DfT provided specific Guidance on the Methodology for Multi-Modal Studies (GOMMMS).
2.10 More recently, the DfT has introduced detailed guidance and advice to cover the development of transport models, where transport demand is likely to be variable as a result of increasing highway congestion (which tends to suppress travel demand) and network improvements (which may induce additional demand). This Variable Demand Modelling Advice (VaDMA) sets out procedures to be followed and advises on likely and acceptable parameter ranges. It is very important in the SE Dorset context, because any transport model used to assess and justify schemes seeking DfT funding after June 2007 will need to be VaDMA compliant.
2.11 One key element of this advice is that demand responses to congestion and scheme provision should be modelled separately. These will probably include:
¨ trip frequency;
¨ trip distribution, which is considered to be a more sensitive response than main mode choice and should therefore be modelled below it in the demand hierarchy, unless there are good local reasons for doing otherwise; and
¨ choice of mode, including car, bus, rail, LRT (if appropriate), park and ride, and possibly park and walk (if central area congestion charging is to be considered).
Key Elements of the Model
2.12 Based on the requirements of the scoping brief, proposed sub-regional transport study, and VaDMA, as outlined above, a transport model for SE Dorset would have the following key characteristics.
¨ It would cover in detail the whole of the SE Dorset Joint Study Area, and Local Transport Plan area, as defined for Regional Spatial Strategy and Local Plan purposes;
¨ It would include passenger movements by motorised modes, such as car, bus, rail, LRT (if appropriate) and park and ride (P&R);
¨ Heavy goods vehicles (HGVs) would be identified as a separate user class to assist in the development of a freight strategy;
¨ Modelled time periods would include the AM peak hour, PM peak hour, and an average inter-peak hour;