Broughton Bypass Model Forecasting Report FINAL
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Broughton Bypass Model Forecasting Report FINAL April 2014 Contents 1 Introduction 1 1.1 Background 1 1.2 Study Area 2 1.3 Forecast Model Scope 3 1.4 Purpose of the Report 4 1.5 Report Structure 4 2 Future Year Growth Scenarios 5 2.1 Overview 5 2.2 Forecasting Scenarios 5 2.3 Data Sources 7 3 Network Development 8 3.1 Overview 8 3.2 Do Minimum Network 8 3.3 Do Something Network 9 4 Development Traffic 11 4.1 Development Overview 11 4.2 Development Sites 12 4.3 Development Phasing 13 4.4 Development Trip Generation 13 4.5 Development Trip Distribution 14 5 Background Traffic Growth 15 5.1 Outline 15 5.2 TEMPRO Factors 15 5.3 NTM Growth 16 6 Development and Background Traffic Growth Combined 17 7 Future Year Assignment 19 7.1 Assignment 19 7.2 Convergence 19 7.3 Production of 12-Hour Flows 20 7.4 Production of AADT and AAWT Flows 21 8 Model Outputs 22 8.1 Future Year Traffic Flows 22 8.2 Forecast Network Performance 25 9 Summary 27 Figure 1-1 - Broughton Traffic Model – Extents of Detailed Model Area 2 Figure 1-2 - Model extents 3 Broughton Bypass Model – Forecasting Report Figure 2-1 - Modelled components for forecast scenarios. 6 Figure 3-1 - Proposed Bypass Alignment 10 Figure 6-1 - Visual Representation of Matrix Factoring 18 Figure 8-1 - Broughton Crossroads Selected Links 22 Table 4-1 - Preston Housing Sites 12 Table 4-2 - Preston Employment Sites 12 Table 4-3 - Wyre Housing Sites 12 Table 4-4 - Wyre Employment Sites 12 Table 4-5 - Trip Rates 13 Table 4-6 - Housing and Employment Development Site Trips 14 Table 5-1 - TEMPRO areas modelled 15 Table 5-2 - NTM based Growth Factors and Vehicle Trip Totals 16 Table 6-1 - TEMPRO and Development Site Growth Comparison 17 Table 7-1 - Calculated generalized cost parameters for 2017 19 Table 7-2 - Calculated generalized cost parameters for 2032 19 Table 7-3 - Factors to Convert AM and PM to 12-Hour 20 Table 7-4 - Factors to Convert AM and PM to 12-Hour 21 Table 8-1 - A6 Garstang Road (North), 2017 and 2032 Forecast Flows 23 Table 8-2 - B5269 Whittingham Lane, 2017 and 2032 Forecast Flows 23 Table 8-3 - A6 Garstang Road (South), 2017 and 2032 Forecast Flows 24 Table 8-4 - B5269 Woodplumpton Lane, 2017 and 2032 Forecast Flows 25 Table 8-5 - Model Statistics 26 Appendix A – Housing and Employment Development Sites Appendix B – Distribution Plots Appendix C – Peak Hour Flow Plots Appendix D – AADT Flow Plots Appendix E – Peak Hour Difference Plots Broughton Bypass Model – Forecasting Report 1 Introduction 1.1 Background In 2012 Jacobs was commissioned by Lancashire County Council (LCC) to build a traffic model of Broughton and its surrounding area. Since 1986 LCC has promoted a bypass of the village of Broughton as a means of removing traffic from the village centre. The A6 through Broughton experiences congestion which is attributed to the traffic signalled junctions at A6 Broughton crossroads and M55 Junction 1. This is an issue particularly at peak times, including the weekday commuting peaks as well as peaks in traffic at the weekend. In May 1991 LCC consulted on two bypass routes, known as Route A (online at the southern end close to the M55) and Route B (mainly offline). In January 1992 LCC approved Route B and undertook to apply for planning permission. Planning permission was subsequently granted and has since been extended, now expiring in July 2013. The primary objective behind the development of the Broughton Transport Model is to inform the renewal of a Planning Application for the Broughton Bypass Route B. The model was developed to: • Demonstrate the impacts that the proposals are likely to have on the local and strategic road network; • Inform the environmental impacts due to traffic flow on Noise, Air Quality, Water and other environmental indices; and • Support public / stakeholder consultation (including the Highways Agency). Secondary objective: • Provide a platform for testing master planning proposals in the north of Preston and associated junction / network improvements. In March 2013 a strategic macro base model constructed using PTV’s VISUM software was completed and then used to produce traffic forecasts for 2017 and 2032, the proposed bypass opening and design years, for both a Do Minimum and a Do Something scenario. The forecast demand process was fixed with variable demand not being undertaken. This model considers only private vehicles, including HGVs; no public transport was required to be modelled. Forecast flows from these models were supplied to Jacobs’ environment team in May 2013 to undertake the assessment for the planning application. Broughton Bypass Model – Forecasting Report 1 1.2 Study Area The detailed study area was chosen to allow for analysis of traffic flows through Broughton and the impact of development pressures on the existing highway infrastructure. Temporary and permanent Automatic Traffic Counts (ATC) and Traffic Flow Data System (TRADS) counts from the M6, M55, A6, B5269 and other local roads have been used to aid the validation of flows from these areas. The extents of the detailed study area can be considered to be: • North – just south of the village of Barton on the A6; • East – the junction of Whittingham Lane and Langley Lane; • South – just south of the Black Bull junction in Fulwood on the A6; and • West – to the western edge of the B5411. The extent of the detailed study area modelled is shown below in Figure 1-1 Figure 1-1 - Broughton Traffic Model – Extents of Detailed Model Area Beyond the detailed study area the model considers demand from across the north of England. The northern extents of the model was the Scottish border while the southern extent of the model was a line between Chester and Grimsby including Cheshire, South Yorkshire, North Lincolnshire and North East Lincolnshire. The extent of the model is shown in Figure 1-2 overleaf. Broughton Bypass Model – Forecasting Report 2 Figure 1-2 - Model extents 1.3 Forecast Model Scope Developing the forecast models involves using the 2012 base model as a starting point, applying the necessary background traffic growth, including future developments, and using PTV’s Visum software to simulate highway conditions in the future; both with and without the proposed bypass. The purpose of the Forecast Models is to provide forecast flows to support the resubmission of the bypass planning application and to be used as a development tool by LCC to test the impact of future developments on the local road network. The Forecast Models must aim to accurately predict flows on all roads which are within the detailed area so that they can successfully fulfil the objectives detailed in Section 1.1. Broughton Bypass Model – Forecasting Report 3 In order to reach a satisfactory level of accuracy, the models not only need to reflect the impact of the bypass, but also need to take into account the impact of any developments and highway schemes within the modelled area. To fulfil the aforementioned objectives the Forecast Models must therefore: • Accurately predict the volume of traffic on each significant road in the designated Forecast Years, particularly those situated within the detailed modelled area; • Account for both the scheme itself and potential future developments in the surrounding area; • Compare the performance of the network both with and without the bypass and any improvements to identify changes in delay and flow patterns resulting from the scheme; and • Inform the renewal of the Planning Application by providing accurate information on forecast traffic flows. 1.4 Purpose of the Report The Forecasting Report describes the methodology used to develop the future year matrices and to verify conformance with current appraisal guidance. 1.5 Report Structure This report follows the suggested structure given in the Design Manual for Roads and Bridges (DMRB), Vol 12, Section 2, Part 1 Appendix C. This is: • Section 2 – Future Year Growth Scenarios; • Section 3 – Network Development; • Section 4 – Development Traffic; • Section 5 – Background Traffic Growth; • Section 6 – Development and Background Traffic Growth Combined • Section 7 – Future Year Assignments; • Section 8 – Model Outputs; • Section 9 – Summary. Broughton Bypass Model – Forecasting Report 4 2 Future Year Growth Scenarios 2.1 Overview The Forecast Models were derived from the validated 2012 Base Model developed in March 2013. Further details on the development of the Base Model can be found in the Local Model Validation Report (LMVR). The study area covered by the model centres on the location of the proposed bypass, and has been coded to different levels of detail, depending on the proximity of the area to the scheme, as illustrated in Figure 1-2 in Section 1.2. At the centre of the model is the detailed model area, this is modelled in the finest level of detail and accuracy. Outputs from this area of the model will be fed into other assessments and will be used to make informed decisions on the future of the bypass. Outside the detailed model area lies the buffer area where network coding and zoning structure is much less detailed but still contributes to the wider modelling processes. This part of the model is designed to ‘smooth out’ traffic coming into the model from the external model area. The external model area is used to represent traffic traveling in and out of the buffer area along the main corridors. For this model the external zone helps to ensure realistic flows on the M6 and M55. In order to update the Base Model to the Forecast Models, a number of changes are required to the two fundamental components of the modelled area: the network and the demand; • Network: Addition and coding of new links and nodes which are associated with the scheme and surrounding developments and any changes to existing links.