BRIDGWATER TRANSPORT OPTIONS FORECAST REPORT October 2016 BRIDGWATER TRANSPORT OPTIONS FORECAST REPORT Somerset County Council Project no: 287584CQ-PTT Date: October 2016 WSP | Parsons Brinckerhoff Riverside Chambers Castle Street Taunton TA1 4AP www.wspgroup.com www.pbworld.com iv TABLE OF CONTENTS 1 PROJECT BACKGROUND ..........................................................1 1.1 INTRODUCTION ............................................................................................. 1 1.2 POTENTIAL DEVELOPMENT SITES ............................................................. 1 1.3 MODELLING METHOD STATEMENT ............................................................ 2 1.4 PURPOSE OF THE REPORT ......................................................................... 2 2 FORECAST SCENARIOS ............................................................4 2.1 FORECAST YEARS ....................................................................................... 4 2.2 MODELLED SCENARIOS .............................................................................. 4 3 MODEL OVERVIEW .....................................................................6 3.1 MODEL HISTORY .......................................................................................... 6 3.2 TIME PERIODS .............................................................................................. 6 3.3 USER CLASSES ............................................................................................ 6 4 MODEL LINK VALIDATION .........................................................7 4.1 LINK VALIDATION ......................................................................................... 7 4.2 TRAFFIC DATA .............................................................................................. 7 4.3 VALIDATION RESULTS ................................................................................. 7 4.4 CONCLUSION ................................................................................................ 8 5 FORECASTING METHODOLOGY.............................................10 5.1 NETWORK CODING ..................................................................................... 10 5.2 DEMAND MATRICES ................................................................................... 10 6 ASSIGNMENT CONVERGENCE ...............................................14 6.1 SCENARIOS ................................................................................................. 14 6.2 CONVERGENCE CRITERIA ......................................................................... 14 Bridgwater Transport Options - Forecast Report WSP | Parsons Brinckerhoff Somerset County Council Project No 287584CQ-PTT October 2016 7 ASSIGNMENT RESULTS ..........................................................16 7.1 FORECAST SCENARIOS ............................................................................. 16 7.2 NETWORK WIDE STATISTICS .................................................................... 16 7.3 ASSIGNMENT RESULTS FOR THE CORE SCENARIO ............................... 17 7.4 ASSIGNMENT RESULTS FOR PROPOSED SITES 1 TO 5.......................... 19 7.5 ASSIGNMENT RESULTS FOR SCENARIOS A, B AND C ........................... 28 8 CONCLUSIONS ..........................................................................33 8.1 FORECASTING SCENARIOS....................................................................... 33 8.2 FORECASTING METHODOLOGY................................................................ 33 8.3 ASSIGNMENT RESULTS ............................................................................. 33 8.4 LIMITATIONS ............................................................................................... 34 8.5 FURTHER WORK ......................................................................................... 34 TABLES TABLE 4.1 - TRAFFIC FLOW DATA USED FOR LINK VALIDATION ................................. 7 TABLE 4.2: AM PEAK HOUR LINK VALIDATION .............................................................. 8 TABLE 4.3: PM PEAK HOUR LINK VALIDATION .............................................................. 8 TABLE 5.1: PROPOSED DEVELOPMENTS – TRIP GENERATION................................. 11 TABLE 6.1: WEBTAG CONVERGENCE CRITERIA ......................................................... 14 TABLE 6.2: CONVERGENCE RESULTS ......................................................................... 15 TABLE 7.1: NETWORK WIDE STATISTICS..................................................................... 16 TABLE 7.2: JUNCTIONS WHICH ARE FORECAST TO EXPERIENCE CONGESTION IN THE CORE SCENARIO .............................................................. 18 FIGURES FIGURE 1.1: LOCATION OF THE PROPOSED DEVELOPMENT SITES ........................... 2 FIGURE 5.1: PROCESS TO CREATE DEMAND MATRICES........................................... 10 FIGURE 7.1: JUNCTIONS FORECAST TO BE OVER CAPACITY IN THE CORE SCENARIO ..................................................................................... 19 FIGURE 7.2: LOCATION PLAN FOR SITE 1.................................................................... 20 Bridgwater Transport Options - Forecast Report WSP | Parsons Brinckerhoff Somerset County Council Project No 287584CQ-PTT October 2016 FIGURE 7.3: LOCATION PLAN FOR SITE 2.................................................................... 22 FIGURE 7.4: LOCATION PLAN FOR SITE 3.................................................................... 24 FIGURE 7.5: LOCATION PLAN FOR SITE 4.................................................................... 25 FIGURE 7.6: LOCATION PLAN FOR SITE 5 MAP ........................................................... 27 FIGURE 7.7: LOCATION PLAN FOR SCENARIO A ......................................................... 29 FIGURE 7.8: LOCATION PLAN FOR SCENARIO B ......................................................... 31 FIGURE 7.9: LOCATION PLAN FOR SCENARIO C......................................................... 32 Bridgwater Transport Options - Forecast Report WSP | Parsons Brinckerhoff Somerset County Council Project No 287584CQ-PTT October 2016 APPENDICES APPENDIX A MODELLING METHOD STATEMENT APPENDIX B HIGHWAYS ENGLAND RESPONSE TO MODELLING METHOD STATEMENT APPENDIX C UNCERTAINTY LOG, TRIP RATES AND TRIP GENERATION APPENDIX D TEMPRO GROWTH FACTORS APPENDIX E RTF GROWTH FACTORS APPENDIX F CONVERGENCE STATISTICS APPENDIX G SITE 1 ASSIGNMENT RESULTS APPENDIX H SITE 2 ASSIGNMENT RESULTS APPENDIX I SITE 3 ASSIGNMENT RESULTS APPENDIX J SITE 4 ASSIGNMENT RESULTS APPENDIX K SITE 5 ASSIGNMENT RESULTS APPENDIX L SCENARIO A ASSIGNMENT RESULTS APPENDIX M SCENARIO B ASSIGNMENT RESULTS APPENDIX N SCENARIO C ASSIGNMENT RESULTS Bridgwater Transport Options - Forecast Report WSP | Parsons Brinckerhoff Somerset County Council Project No 287584CQ-PTT October 2016 EXECUTIVE SUMMARY Modelling work has been undertaken to assess the impact of proposed development sites beyond the current Core Strategy period. Forecasts were created for the 2032 AM (08:00 to 09:00) and PM (17:00 to 18:00) peak hours to test the impact of five potential development sites within Sedgemoor, in comparison with a ‘Core Scenario’: à Core Scenario à Site 1: Land to the west of Bridgwater – Core Scenario plus 1,200 dwellings, primary school and the relocation of Haygrove School. à Site 2: Land at East Bridgwater – Core Scenario plus 800 dwellings and a primary school à Site 3: Land north of Chilton Trinity – Core Scenario plus 2,500 dwellings plus a primary school, 2,500m2 B1 development and 27,000m2 B8 development à Site 4: Land at South Bridgwater – Core Scenario plus 300 dwellings à Site 5: Land at Huntworth – Core Scenario plus 5,338m2 B1 development and 22,257m2 B8 development à Scenario A – Core Scenario plus the inclusion of Sites 1, 2, 3, 4 and 5 à Scenario B – Core Scenario plus the inclusion of Sites 1 and 3 à Scenario C – Core Scenario plus the inclusion of Sites 2, 4 and 5 The results of the individual site assessments forecast that Sites 1 (Land to the West of Bridgwater) and Site 3 (Land at Chilton Trinity) would have the greatest traffic impacts. The modelling also demonstrates that a single point of access for Site 3, from Dunball Roundabout or elsewhere on Bristol Road, is unlikely to be sufficient. Site 2 (Land at East Bridgwater) is forecast to have the least impact upon the highway network and is not anticipated to result in increased congestion or delay. This report identifies issues but not potential solutions. Following discussion with stakeholders it is expected that work will be undertaken to identify appropriate transport improvements to support the development sites, with modelling to determine those which are most suitable. Bridgwater Transport Options - Forecast Report WSP | Parsons Brinckerhoff Somerset County Council Project No 287584CQ-PTT October 2016 1 1 PROJECT BACKGROUND 1.1 INTRODUCTION 1.1.1 WSP | Parsons Brinckerhoff has been commissioned by Somerset County Council (SCC) to undertake traffic modelling in relation to the formulation and assessment of Transport Options for Bridgwater on behalf of Sedgemoor District Council (SDC). The outcome of this study will ultimately be used as part of the evidence base for the upcoming Local Plan (Core Strategy Review) to be developed by Sedgemoor District Council. This report outlines the traffic forecasting that has been undertaken using the existing TSTM3 SATURN Traffic Model, owned by SCC. 1.1.2 Due to the potential need to test schemes to