St Austell to A30 Link - Cornwall Council
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St Austell to A30 Link Traffic Forecasting Report Project reference: 0128 Project number: 60571547 March 2020
St Austell to A30 Link Project reference: 0128 Project number: 60571547 Quality information Prepared by Checked by Verified by Approved by Alex Bertram Tom Holian Maurice Houkes Thea Wattam Consultant Senior Consultant Associate Director Associate Director Revision History Revision Revision date Details Authorized Name Position V0.1 16/09/19 Draft Issue 16/09/2019 Thea Wattam Associate Director V0.2 12/03/20 DfT comments 31/03/2020 Maurice Houkes Associate Director V0.3 19/08/20 Table 3-3 19/08/2020 Maurice Houkes Associate correction Director Prepared for: CORMAC Solutions Ltd AECOM
St Austell to A30 Link Project reference: 0128 Project number: 60571547 Prepared for: CORMAC Solutions Ltd Prepared by: AECOM Limited 3rd Floor, Portwall Place Portwall Lane Bristol BS1 6NA United Kingdom T: +44 117 901 7000 aecom.com © 2020 AECOM Limited. All Rights Reserved. This document has been prepared by AECOM Limited (“AECOM”) for sole use of our client (the “Client”) in accordance with generally accepted consultancy principles, the budget for fees and the terms of reference agreed between AECOM and the Client. Any information provided by third parties and referred to herein has not been checked or verified by AECOM, unless otherwise expressly stated in the document. No third party may rely upon this document without the prior and express written agreement of AECOM. Prepared for: CORMAC Solutions Ltd AECOM
St Austell to A30 Link Project reference: 0128 Project number: 60571547 Table of Contents 1. Executive Summary ................................................................................ 7 2. Study Overview ....................................................................................... 8 2.1 Background........................................................................................................................... 8 2.2 Scheme Objectives ............................................................................................................... 8 2.3 Model Purpose and Assessment Option ................................................................................ 9 2.4 Report Structure.................................................................................................................... 9 3. Overview of Base Year Model ............................................................... 10 3.1 Introduction ......................................................................................................................... 10 3.2 Model Time Periods and Network Structure ......................................................................... 10 3.3 2016 Base Year Trip Matrices.............................................................................................. 16 4. Uncertainty Log and Forecast Years ..................................................... 18 4.1 Demand Forecasting for Specific Developments.................................................................. 18 5. Forecasting Future Year Demand ......................................................... 22 5.1 Overview of Demand Forecasting Procedure....................................................................... 22 5.2 Forecast Time Periods and Years ........................................................................................ 22 5.3 The National Transport Model and NTEM ............................................................................ 22 5.4 Demand Forecasting for Specific Developments.................................................................. 25 5.5 Forecasting Scenarios......................................................................................................... 29 6. Forecasting Future Year Supply ............................................................ 31 6.1 Infrastructure....................................................................................................................... 31 6.2 Future Network: Do Minimum Scenario ............................................................................... 32 6.3 Future Network: Do Something Scenario ............................................................................. 37 7. Variable Demand Modelling .................................................................. 47 7.1 Introduction ......................................................................................................................... 47 7.2 VDM Test: Methodology ...................................................................................................... 47 7.3 VDM Test: Demand Response ............................................................................................ 49 7.4 VDM Tests: Impact to Scheme Benefits ............................................................................... 51 7.5 Conclusion: The Need for VDM ........................................................................................... 53 8. Assignment Results ............................................................................... 54 8.1 Convergence ...................................................................................................................... 54 8.2 Traffic Flows........................................................................................................................ 54 8.3 Screenline Flows................................................................................................................. 60 8.4 Journey Times .................................................................................................................... 63 9. Summary and Conclusions ................................................................... 66 9.1 Summary ............................................................................................................................ 66 9.2 Conclusions ........................................................................................................................ 66 Appendix A Uncertainty Log ............................................................................ 67 Appendix B Convergence Results................................................................... 68 Appendix C Key Link Results .......................................................................... 69 Appendix D Traffic Flow Diagrams .................................................................. 70 Appendix E Screenline Flows .......................................................................... 71 Appendix F Journey Time Results................................................................... 72 Prepared for: CORMAC Solutions Ltd AECOM
St Austell to A30 Link Project reference: 0128 Project number: 60571547 Figures Figure 2-1: Proposed Scheme Overview ............................................................................................ 9 Figure 3-1: Area of Detailed Study .................................................................................................... 11 Figure 3-2: Zone Plan (detailed Study Area)..................................................................................... 12 Figure 3-3: Zone Plan (Cornwall) ..................................................................................................... 13 Figure 3-4: Zone Plan (Rest of Modelled Area)................................................................................. 14 Figure 3-5: Cornwall Network........................................................................................................... 16 Figure 3-6: South UK Network ......................................................................................................... 16 Figure 4-1: Uncertainty Log Development Locations ........................................................................ 20 Figure 6-1: Duporth Traffic Signals ................................................................................................... 33 Figure 6-2: A390 Sawles Road Traffic Signals .................................................................................. 34 Figure 6-3: Edgcumbe Triangle ........................................................................................................ 34 Figure 6-4: Pentewan Roundabout .................................................................................................. 35 Figure 6-5: Higher Trewhiddle Development Roundabout ................................................................ 36 Figure 6-6: Holmbush Development Signals .................................................................................... 37 Figure 6-7: Do Something General Arrangement .............................................................................. 38 Figure 6-8: General Arrangements Drawing 01 of 06........................................................................ 39 Figure 6-9: General Arrangements Drawing 02 of 06........................................................................ 40 Figure 6-10: General Arrangements Drawing 03 of 06...................................................................... 40 Figure 6-11: General Arrangements Drawing 04 of 06 ...................................................................... 41 Figure 6-12: General Arrangements Drawing 05 of 06...................................................................... 42 Figure 6-13: General Arrangements Drawing 06 of 06...................................................................... 43 Figure 6-14: General Arrangements, Complementary Measures and TROs...................................... 44 Figure 6-15: Bugle, Complementary Measures and TROs................................................................ 45 Figure 6-16: Roche, Complementary measures and TROs .............................................................. 46 Figure 7-1: Own Cost Elasticity Test Zone Status ............................................................................. 49 Figure 8-1: Key Links Map ............................................................................................................... 55 Figure 8-2: Screenline Locations...................................................................................................... 60 Figure 8-3: Journey Time Routes ..................................................................................................... 63 Tables Table 3-1: Modelled Time Period Classification ................................................................................ 10 Table 3-2: Model User Classes ........................................................................................................ 17 Table 3-3: 2016 Base Trips Summary .............................................................................................. 17 Table 4-1: WebTAG Uncertainty Classifications................................................................................ 18 Table 4-2: Uncertainty Log ............................................................................................................... 19 Table 4-3: Development to be Included in Growth Scenarios ............................................................ 21 Table 5-1: Forecast Model Time Periods .......................................................................................... 22 Table 5-2: Development Zone Growth .............................................................................................. 24 Table 5-3: NTEM 7.2 Projections...................................................................................................... 24 Table 5-4: NTEM 7.2 Forecast Growth (Households and Jobs) ........................................................ 24 Table 5-5: Development Zones ........................................................................................................ 25 Table 5-6: Core/Low Growth Development Trip Generation .............................................................. 27 Table 5-7: High Growth Development Trip Generation (Difference to Low/Core Highlighted Blue) ..... 27 Table 5-8: Additional HGV Trips ....................................................................................................... 29 Table 5-9: Core Forecast Matrix Summary ....................................................................................... 30 Table 5-10: High Growth Forecast Matrix Summary ......................................................................... 30 Table 5-11: Low Growth Forecast Matrix Summary .......................................................................... 30 Table 6-1: Future Year Infrastructure Changes ................................................................................. 31 Table 7-1: Elasticity Power Functions ............................................................................................... 48 Table 7-2: Do Minimum Trip Matrix Totals: Fixed vs Elastic ............................................................... 50 Table 7-3: Do Minimum and Do Something Trip Matrix Comparison: Fixed vs Elastic ....................... 51 Table 7-4: Total Distance Travelled: Do Minimum. Fixed vs Elastic ................................................... 51 Table 7-5: Total Distance Travelled: Do Something. Fixed vs Elastic................................................. 51 Table 7-6: Scheme Benefits with Fixed and Elastic Demand ............................................................ 53 Prepared for: CORMAC Solutions Ltd AECOM
St Austell to A30 Link Project reference: 0128 Project number: 60571547 Table 8-1: WebTAG Convergence Criteria........................................................................................ 54 Table 8-2: Convergence Statistics (2022 Core, Do Minimum and Do Something) ............................. 54 Table 8-3: Key Study Links List ........................................................................................................ 55 Table 8-4: Key Link Flow Results, Core Scenario, 2022 AM Peak..................................................... 57 Table 8-5: Key Link Flow Results, Core Scenario, 2022 Inter Peak................................................... 58 Table 8-6: Key Link Flow Results, Core Scenario, 2022 PM Peak .................................................... 59 Table 8-7: Screenline Results, Core Scenario, 2022 AM Peak .......................................................... 60 Table 8-8: Screenline Results, Core Scenario, 2022 Inter Peak ........................................................ 62 Table 8-9: Screenline Results, Core Scenario, 2022 PM Peak.......................................................... 62 Table 8-10: Journey Time Comparison, AM Peak ............................................................................. 64 Table 8-11: Journey Time Comparison, Inter Peak ........................................................................... 64 Table 8-12: Journey Time Comparison, PM Peak ............................................................................. 65 Prepared for: CORMAC Solutions Ltd AECOM
St Austell to A30 Link Project reference: 0128 Project number: 60571547 1. Executive Summary The existing route between St Austell and the A30 is of a variable standard, passing through a number of villages, with congestion and delays leading to poor journey time reliability. The new route is needed to help meet Cornwall Council’s objectives of relieving traffic issues along the current route and unlocking economic potential within St Austell and the surrounding area. Cornwall Council and local stakeholders hold an aspiration to create an improved strategic link between St Austell and the A30. St Austell is Cornwall’s largest town and is not currently served by a high-quality road link to the A30. The proposed scheme is a new high-quality, single carriageway route linking St Austell to the A30 and to divert traffic (including Heavy Goods Vehicles) away from settlements along the existing route(s). Cornwall Council’s overarching aims for the scheme are to: • Reduce journey times and improve journey reliability between Newquay, the A30 and St Austell; • Create a better link between two of Cornwall’s largest towns (St Austell and Newquay), the airport and Aerohub Enterprise Zone; • Make access to Cornwall’s new, large employment sites easier, therefore supporting the expanding employment sites Victoria Business Park, Indian Queens Industrial Estate and the Aerohub Enterprise Zone; • Improve the competitiveness of St Austell as a location to do business via new employment space or interest in land that can be developed into employment space; • Support housing growth, including the delivery West Carclaze Garden Village ecocommunity, which is expected to create 1,500 new homes and 500 jobs; and • Support the regeneration of Roche, Bugle and St Dennis by addressing traffic related issues within the villages and creating better opportunities for businesses. This Traffic Forecasting Report details the development of the forecast year demand matrices and future year traffic models that will be used within the appraisal of the proposed scheme. The model results forecast that the proposed scheme will provide an improvement to the performance of traffic flow between St Austell and the A30. Journey times for vehicles travelling between St Austell to the A30 via the proposed scheme are predicted to reduce, and traffic flows through the villages of Roche and Bugle are forecast to be significantly reduced, with Heavy Goods Vehicles experiencing a reduction of up to 100%. Overall, the forecast model results demonstrate traffic patterns that would be reasonably expected to occur. As the models have been produced with reference to WebTAG and sense checked for validity, it is felt that they provide a suitable basis for assessing the impacts of the proposed scheme. The 2022 and 2037 future year traffic forecasts produced from the forecasting assessment within the main body of this report have been taken forward for use within the economic appraisal of the St Austell to A30 Link. Prepared for: CORMAC Solutions Ltd AECOM 53
St Austell to A30 Link Project reference: 0128 Project number: 60571547 2. Study Overview 2.1 Background Cornwall Council and local stakeholders have an aspiration to create an improved strategic link between St Austell and the A30. Although St Austell is Cornwall’s largest town, it is not currently served by a high-quality road link to the A30. The current route is the A391, which is a variable standard single carriageway route passing through a number of settlements between St Austell and the A30. Given its status as the largest town in Cornwall, St Austell is a major attractor of trip origins and destinations within mid-Cornwall, with heavy industry within the China Clay Area attracting a high number of Heavy Goods Vehicle (HGV) trips. The low standard of the current route connections to the A30 result in congestion, delays and traffic safety issues within affected areas. The route requires improvement to meet Cornwall Council’s objectives of improving journey reliability, safety and raising economic competitiveness. The current poor connectivity is seen as the major block to the economic growth of the St Austell area. The scheme is inherently expected to impact the travel arrangements within St Austell, settlements along the current route, and to the wider transport network within Cornwall. Travel patterns would be anticipated to be affected because of route performance improvements, attracting traffic from other routes. The traffic model has been designed to forecast the potential impact of these travel patterns across a wide area. 2.2 Scheme Objectives The overarching aim of the scheme is to provide a higher quality link between St Austell and the A30, and to divert traffic (including HGVs) away from the towns and villages along the existing routes. The scheme objectives are aligned with the key policies identified within Cornwall Council’s regional transport policies, and the Cornwall and Isles of Scilly Strategic Economic Plan (Vision 2030). The Council’s objectives for the mid-Cornwall area are: • Create a better link between two of Cornwall’s largest towns – St Austell and Newquay, the airport and Aerohub Enterprise Zone; • Make it easier to access Cornwall’s new, large employment sites and support the expanding employment sites Victoria Business Park, Indian Queens Industrial Estate and the Aerohub Enterprise Zone; • Improve competitiveness of St Austell as a location to do business via new employment space or interest in land that can be developed into employment space; • Support housing growth, including the delivery West Carclaze Garden Village ecocommunity (with the creation 1,500 new homes and 500 jobs); and • Support the regeneration of Roche, Bugle and St Dennis by addressing traffic related issues within the villages and creating better opportunities for businesses. To help achieve these overarching aims, the scheme’s transport-specific objectives are to: • Reduce journey times and improve journey reliability between St Austell and A30; • Reduce the impact of traffic congestion on local communities and businesses; and • Improve the safety of road users, pedestrians and cyclists. Prepared for: CORMAC Solutions Ltd AECOM 53
St Austell to A30 Link Project reference: 0128 Project number: 60571547 2.3 Model Purpose and Assessment Option The model has been used to appraise the preferred route for the St Austell to A30 Link Road scheme. The evaluation process for determining the preferred option is set out in the Options Assessment Report (dated March 2017). The forecasting processes documented in this report follow the methodology set out in the Appraisal Specification Report (dated November 2016) and WSP|PB’s Traffic Forecasting Report (dated March 2017) (TFR), produced as part of the Outline Business Case (OBC) evidence base. A detailed review of the scheme can be found in Section 6.3, but it broadly follows the ‘Roche Option’ assessed in the OBC TFR. The highway has been designed to accommodate vehicles travelling at 60mph and will replace the B3274 from Stenalees to Trezaise to form a bypass around Roche, linking to the old A30 west of Victoria (Figure 2-1). Figure 2-1: Proposed Scheme Overview In general, the St Austell to A30 Link Road will be single carriageway, with climber lanes provided at key locations as required. Four new roundabouts will be constructed at Stenalees, Trezaise, Harmony Road and at the old A30 (C0120). 2.4 Report Structure This TFR sets out information relating to the development of the forecast scenarios and is structured as follows: • Chapter 3: Overview of Base Year Model; • Chapter 4: Uncertainty Log and Forecast Years; • Chapter 5: Forecasting Future Year Demand; • Chapter 6: Forecasting Future Year Supply; • Chapter 7: Variable Demand Modelling; • Chapter 8: Assignment Results; and • Chapter 9: Summary and Conclusions. Prepared for: CORMAC Solutions Ltd AECOM 53
St Austell to A30 Link Project reference: 0128 Project number: 60571547 3. Overview of Base Year Model 3.1 Introduction This chapter provides an overview of the Base Year model. The Local Model Validation Report (March 2017) details the base model that has been developed by PTV to inform the appraisal of the scheme. The Base Year model formed the basis for the forecast models detailed in this report. Forecast models have been built for 2022 (the proposed opening year of the scheme) and 2037 (future case fifteen years from the opening year). The forecast models detailed in this report have been built in compliance with Department for Transport WebTAG Unit M4 ‘Forecasting and Uncertainty’ (May 2018). 3.2 Model Time Periods and Network Structure Neutral month peak and inter-peak time periods have been modelled to fully understand the operation and economic benefits of the proposed scheme. The modelled time periods are shown in Table 3-1. Table 3-1: Modelled Time Period Classification Time Period Modelled Period Neutral Month AM Peak 08:00 - 09:00 Neutral Month Inter Peak Ave hour 10:00 – 16:00 Neutral Month PM Peak 17:00 – 18:00 The main study area covers St Austell and includes the towns of Roche and Bugle to the north, Lostwithiel and Fowey to the east, Mevagissey to the south, and St Stephens and St Dennis to the west. The extent of the detailed study area is illustrated Figure 3-1 and Figure 3-2. Prepared for: CORMAC Solutions Ltd AECOM 53
St Austell to A30 Link Project reference: 0128 Project number: 60571547 Figure 3-1: Area of Detailed Study Prepared for: CORMAC Solutions Ltd AECOM 53
St Austell to A30 Link Project reference: 0128 Project number: 60571547 Figure 3-2: Zone Plan (detailed Study Area) The remainder of Cornwall has been modelled in varying levels of detail ( Prepared for: CORMAC Solutions Ltd AECOM 53
St Austell to A30 Link Project reference: 0128 Project number: 60571547 Figure 3-3). This area is not as detailed as the main study area but allows for the control of traffic routes into Cornwall. The wider model area includes the rest of the UK ( Figure 3-4). Outside of Devon and Cornwall the zones become much larger . Figure 3-3: Zone Plan (Cornwall) Prepared for: CORMAC Solutions Ltd AECOM 53
St Austell to A30 Link Project reference: 0128 Project number: 60571547 Figure 3-4: Zone Plan (Rest of Modelled Area) The simulation network ( Prepared for: CORMAC Solutions Ltd AECOM 53
St Austell to A30 Link Project reference: 0128 Project number: 60571547 Figure 3-5 and Figure 3-6) is formed of the following sections: • Cornwall (all roads); • Major and intermediate routes in Devon, with slightly more detail in Plymouth and Exeter; and • Major routes covering the rest of the UK. Prepared for: CORMAC Solutions Ltd AECOM 53
St Austell to A30 Link Project reference: 0128 Project number: 60571547 Figure 3-5: Cornwall Network Figure 3-6: South UK Network 3.3 2016 Base Year Trip Matrices The development of base year matrices for 2016 is described in detail in the Local Model Validation Report (March 2017) which has been produced by PTV. Three user classes (UCs) are used in the Base Year validation process, with each UC corresponding to the vehicle type detailed in Table 3-2. Prepared for: CORMAC Solutions Ltd AECOM 53
St Austell to A30 Link Project reference: 0128 Project number: 60571547 Table 3-2: Model User Classes User Class Purpose UC1 Car UC4 Light Goods Vehicles (LGV) UC5 Heavy Goods Vehicles (HGV) Table 3-3 shows the base case matrices total trips. Table 3-3: 2016 Base Trips Summary User Class AM Peak Inter Peak PM Peak Car 17,381 15,947 28,307 LGV 3,188 2,689 2,666 HGV 1,025 1,041 470 Total 21,594 19,677 31,443 Prepared for: CORMAC Solutions Ltd AECOM 53
St Austell to A30 Link Project reference: 0128 Project number: 60571547 4. Uncertainty Log and Forecast Years 4.1 Demand Forecasting for Specific Developments The following base and forecast years have been adopted: • Base Year: 2016; • Opening Year: 2022; and • Design Year: 2037. Cornwall Council-owned Cormac Solutions Limited (Cormac) provided information for potential residential and employment development sites within the St Austell area, based upon the development plan outlined in the Cornwall Local Plan. Local planning documents for the detailed study area outlined earlier were also obtained from Cornwall Council (CC) and the CC Planning Portal. This provided information including size of development (gross floor areas, dwelling numbers), development type (use class), and development phasing. These developments have been considered alongside, and constrained to, growth factors obtained from TEMPro v7.2. As the distribution of development outside of the detailed study area is of less importance to growth on the proposed link road between St Austell and the A30, specific development information was not obtained. Growth outside of the detailed study area has instead been derived from, and constrained to, TEMPro v7.2 at a district level. Development sites within the study area have been recorded and analysed in an Uncertainty Log (Appendix A), in accordance with WebTAG Unit M41. The Uncertainty Log outlines the developments which are to be explicitly modelled as part of the core scenario and the evidence behind this inclusion. The Uncertainty Log is presented in Appendix A, alongside rationale behind the uncertainty classification choices (Table 4-1) and the phasing of each of the developments. The Uncertainty Log development classification choices have been based upon correspondence with Cormac. Table 4-1: WebTAG Uncertainty Classifications2 Probability of the Input Status Core Scenario Assumption Near certain: The - Intent announced by proponent to This should form part of the core outcome will happen or regulatory agencies. scenario there is a high - Approved development proposals. probability that it will happen. - Projects under construction. More than likely: The - Submission of planning or consent This should form part of the core outcome is likely to application imminent. scenario happen but there is some - Development application within the uncertainty. consent process. Reasonably foreseeable: - Identified within a development plan. These should be excluded from the The outcome may - Not directly associated with the core scenario but may form part of happen, but there is transport strategy/ scheme but may the alternative scenarios significant uncertainty. occur if the strategy/scheme is implemented. - Development conditional upon the transport strategy/scheme proceeding. 1 Forecasting and Uncertainty (May 2018) 2 WebTAG Unit M4, Table A2 Classification of Future Inputs Prepared for: CORMAC Solutions Ltd AECOM 53
St Austell to A30 Link Project reference: 0128 Project number: 60571547 - Or, a committed policy goal, subject to tests (e.g. of deliverability) whose outcomes are subject to significant uncertainty Hypothetical: There is Conjecture based upon currently available These should be excluded from the considerable uncertainty information. core scenario but may form part of whether the outcome will Discussed on a conceptual basis. the alternative scenarios ever happen. One of a number of possible inputs in an initial consultation process. Or, a policy aspiration. Table 4-2 lists the developments in the detailed modelled area, with only those defined as ‘Near Certain’ and ‘More than Likely’ included in the 2022 and 2037 core scenario forecast models. Figure 4-1 presents these developments spatially. Table 4-2: Uncertainty Log Site Location Land Use Classification number Mixed Use (C3 Residential, D1 1 West Carclaze Community and Education, Retail, Near Certain Offices) Reasonably 2 Par Docks C3 Residential Foreseeable 3 Menear Road C3 Residential Near Certain 4 Mount Crescent, Par C3 Residential Near Certain Mixed Use (C3 Residential, Drinking 5 Holmbush Road Near Certain Establishment, Office) 6 Porthpean Road Mixed Use (C3 Residential, Office) Near Certain 7 Elliot Road C3 Residential Near Certain 8 Pentewan Road Mixed Use (Retail, Office) Near Certain Prepared for: CORMAC Solutions Ltd AECOM 53
St Austell to A30 Link Project reference: 0128 Project number: 60571547 9 Eden Project B8 (Geothermal power plant) Near Certain Rural (between Scredda and 10 B1 Offices and B2 General industrial Near Certain Carluddon) 11 Plastic Plant Buckler B1 Offices More Than Likely 12 Cuddra A1 Retail More Than Likely Mixed Use (C3 Residential, B1 Reasonably 13 Pentewan Road Offices) Foreseeable Mixed Use (C3 Residential, B1 Reasonably 14 Edgecumbe Offices) Foreseeable Reasonably 15 Par Moor B1 Offices Foreseeable Mixed Use (C3 Residential, C1 17 St Mewan Near Certain Hotel, Retail, Offices) 18 Carlyon Bay C3 Residential Near Certain 19 Mountside Rd, Par C3 Residential More Than Likely Kingsley Village, near 20 A1 Retail, A3 Food Near Certain Fraddon 21 Land East of Lodge B1 Offices and B2 General industrial Near Certain 22 Kernow Veor, Carclaze Road C3 Residential More Than Likely Land at Former Totem 23 A1 Retail Near Certain Building 24 Sedgemoor Campus C3 Residential Near Certain Figure 4-1: Uncertainty Log Development Locations In addition to the Core scenario, High Growth (HG) and Low Growth (LG) scenarios have been constructed, in line with DfT guidance3. Some developments have been included in the 3 WebTAG Unit M4: Forecasting and Uncertainty (May 2018) Prepared for: CORMAC Solutions Ltd AECOM 53
St Austell to A30 Link Project reference: 0128 Project number: 60571547 HG scenario, but not in the Core and LG scenarios, as there is significant uncertainty as to how and whether they will proceed. The additional developments included in the High Growth scenario are those classified as ‘Reasonably Foreseeable’. Table 4-3 lists the development classifications that are included in each growth scenario. Core and Low Growth scenarios are the same in terms of the developments considered, but Low Growth scenario assumes a pessimistic inner growth scenario (see Section 5.4.11). Table 4-3: Development to be Included in Growth Scenarios Growth Scenario Development Classifications Included Near Certain Core More Than Likely Near Certain Low Growth More Than Likely Near Certain High Growth More Than Likely Reasonably Foreseeable Prepared for: CORMAC Solutions Ltd AECOM 53
St Austell to A30 Link Project reference: 0128 Project number: 60571547 5. Forecasting Future Year Demand 5.1 Overview of Demand Forecasting Procedure This section details the approach used to produce future year demand matrices. The demand forecasting procedure involved the creation of an Uncertainty Log to identify developments to be included within the future year growth scenarios, as described in Chapter 4. Once all relevant developments were recognised and quantified, development trips were created for the applicable zones. The following steps were undertaken to produce the demand forecasts: 1. Development trip totals were calculated/obtained from local plans and TAs for each development zone by year, time period and UC. Further information on the trip generation process is in Section 0. To find a suitable trip distribution, average distributions from existing zones with similar land uses were applied using the trip ends from these zones. 2. Development trip matrices were added to their relevant base matrices to produce the Core forecast matrices. 3. LGV and HGV forecasts (UC4 and UC5) have been calculated using the September 2018 National Road Traffic Forecast (RTF18). 5.2 Forecast Time Periods and Years As outlined in Section 4.1, the forecast years are 2022 (scheme opening year) and 2037 (design year). The forecast time periods are shown in Table 5-1. Table 5-1: Forecast Model Time Periods Time Period Modelled Period Neutral Month AM Peak 08:00 - 09:00 Neutral Month Inter Peak Ave hour 10:00 – 16:00 Neutral Month PM Peak 17:00 – 18:00 5.3 The National Transport Model and NTEM The National Transport Model compares the national consequences of alternative transport policies or widely applied transport policies and forms the basis of the RTF. These are then compared against a range of background scenarios which account for major factors affecting future patterns of travel. The OBC TFR used RTF data from 2015 as it was the most recently available at the time. However, to ensure the most-up-to-date data (at the time of writing) informs the Full Business Case appraisal, RTF18 has been utilised for this study. The National Trip End Model (NTEM) provides predictions for the growth of car ownership and traffic, influenced by planning data projections. The predictions are a forecast of vehicle movements and not of personal travel. The NTEM v7.2 (March 2017) datasets, accessed through the TEMPro v7.2 program, have been used to calculate the car-based forecast growth matrices. The total growth expected from local developments within the detailed study area in terms of future household and job numbers is shown in Prepared for: CORMAC Solutions Ltd AECOM 53
St Austell to A30 Link Project reference: 0128 Project number: 60571547 Table 5-2, while the NTEM forecast is shown in Table 5-3 and Table 5-4. Prepared for: CORMAC Solutions Ltd AECOM 53
St Austell to A30 Link Project reference: 0128 Project number: 60571547 Table 5-2: Development Zone Growth 2022 Core/LG 2022 HG 2037 Core/LG 2037 HG Development TEMPro Zone Dev Dev Dev Dev Dev Dev Dev Dev Zone HH Jobs HH Jobs HH Jobs HH Jobs Cornwall 019 2031, 229 0 0 0 0 705 457 705 457 2000, 2001, 2002, Cornwall 027 180 1,500 180 1,500 51 1,250 51 1,250 2003, 2018 Cornwall 031 2004, 2017, 60 144 233 294 533 0 0 0 0 2011, 2012, 2013, Cornwall 036 2019, 2023, 2029, 259 259 259 259 260 284 260 557 2033, 9 Cornwall 038 81 143 143 168 168 0 0 0 68 2006, 2014, 2014, Cornwall 039 2016, 2020, 2022, 291 291 291 291 40 228 40 228 13, 68, 109 Cornwall 041 2028 0 0 0 0 0 0 0 137 Table 5-3: NTEM 7.2 Projections Houses Jobs TEMPro Zone 2016 2022 2037 2016 2022 2037 Cornwall 019 4,407 4,592 5,020 5,828 5,964 6,215 Cornwall 027 4,419 4,661 5,234 3,880 3,956 4,125 Cornwall 031 2,996 3,160 3,548 2,172 2,237 2,334 Cornwall 036 4,081 4,315 4,869 4,539 4,647 4,848 Cornwall 038 2,734 2,890 3,262 3,751 3,802 3,968 Cornwall 039 4,443 4,698 5,301 6,237 6,377 6,653 Cornwall 041 3,553 3,703 4,048 3,836 3,930 4,093 Table 5-4: NTEM 7.2 Forecast Growth (Households and Jobs) 2022 2037 TEMPro Zone HH Jobs HH Jobs Cornwall 019 185 613 136 387 Cornwall 027 242 815 76 245 Cornwall 031 164 552 65 162 Cornwall 036 234 788 108 309 Cornwall 038 156 528 51 217 Cornwall 039 255 858 140 416 Cornwall 041 150 495 94 257 Prepared for: CORMAC Solutions Ltd AECOM 53
St Austell to A30 Link Project reference: 0128 Project number: 60571547 5.4 Demand Forecasting for Specific Developments Development Model Zones As per the method outlined in the OBC TFR, most developments were assigned a new zone within VISUM (starting from zone 2000). It was deemed suitable for some development trips to simply be added to existing (base) zones (numbered up to zone 413). Table 5-5 shows all forecast zones with new development trips. Table 5-5: Development Zones Zone Development Name 9 Menear Rd Housing 13 Old Bus Depot Housing Mount Crescent Housing, 60 Mountside Rd Housing 68 Sedgemoor Apartments 81 Carclaze Housing 109 STA-M2 Housing 229 Kingsley Retail Park Expansion 2000 West Carclaze Housing West Carclaze Health, Community 2001 Centre 2002 West Carclaze Nursery, School 2003 West Carclaze Shops 2004 ECO M2 Par Docks Housing 2006 STA-M1 Office 2011 Holmbush Rd Housing Holmbush Rd Office, 2012 Polymermedics 2013 Holmbush Rd Pub 2014 Porthpean Rd Housing 2015 Porthpean Rd Office 2016 Pentewan Rd Morrisons 2017 Eden Project Geothermal Plant 2018 Carluddon Technology Park 2019 Cuddra Retail 2020 STA-M1 Housing 2022 STA-M2 Office 2023 STA-E3 Office 2028 Higher Trewhiddle Farm 2029 Carlyon Beach Housing 2031 Indian Queens Industrial Estate 2033 Holmbush LIDL Prepared for: CORMAC Solutions Ltd AECOM 53
St Austell to A30 Link Project reference: 0128 Project number: 60571547 Forecast Trip Generation As per the method outlined in the OBC TFR, TRICS v7.3.4 was used to obtain trip rates for the various developments included in the forecast models when a relevant Transport Assessment (TA) could not be used. The trip rates were based upon similar development types to most reasonably represent the potential future year development trip generation. As TRICS does not disaggregate trips generated by UC, the source zone UC percentage splits were then applied. In instances where a TA was available, trip generations were extracted directly. These trip numbers were also derived from TRICS data and were agreed with the local authority as part of the planning consent for the development. New trips were assumed to be split across all UCs, and subsequent UC splits obtained from existing zones. In the case of retail units, extra HGV trips were generated using HGV only trip rates (and discussed in greater detail in 5.4.10). As many non-residential trip rates are calculated using Gross Floor Area (GFA), and because of conflicting sources and a lack of some information, it was necessary to convert or approximate some figures from other measurements. GIA (Gross Internal Area), GIF (Gross Internal Floorspace), and NTA (Net Trade Area, for supermarkets) were all considered equivalent to GFA for the purpose of trip generation, and GEA (Gross External Area) was applied a factor of 0.954 to convert to GFA. Table 5-6 and 2022 2037 Zone AM Peak Inter Peak PM Peak AM Peak Inter Peak PM Peak Orig Dest Orig Dest Orig Dest Orig Dest Orig Dest Orig Dest 9 10 27 24 22 29 16 10 27 24 22 29 16 13 5 16 0 0 16 8 5 16 0 0 16 8 60 31 79 50 46 72 47 31 79 80 74 72 47 68 10 32 0 0 32 16 10 32 0 0 32 16 81 18 39 28 26 35 22 18 39 28 26 35 22 109 0 0 0 0 0 0 0 0 0 0 0 0 229 73 45 166 140 183 181 73 45 166 140 183 181 2000 23 65 7 57 69 37 195 540 518 478 575 311 2001 5 5 0 0 5 6 10 8 54 59 7 9 2002 20 14 0 0 2 2 20 14 162 298 2 2 2003 0 0 0 0 0 0 44 42 69 61 55 56 2004 0 0 0 0 0 0 0 0 0 0 0 0 2006 0 0 0 0 0 0 0 0 0 0 0 0 2011 28 87 66 60 80 44 28 87 66 60 80 44 2012 12 1 4 4 1 13 19 2 7 7 2 18 2013 0 0 0 0 16 12 0 0 0 0 16 12 2014 42 114 90 83 124 67 42 114 90 83 124 67 2015 13 3 4 4 2 9 13 3 4 4 2 9 2016 0 0 0 0 0 0 158 119 328 317 310 297 2017 0 0 0 0 0 0 14 3 5 6 2 12 2018 0 0 6 3 0 0 84 22 9 6 11 61 2019 59 45 37 31 97 99 59 45 37 31 97 99 2020 0 0 0 0 0 0 0 0 0 0 0 0 2022 0 0 0 0 0 0 0 0 0 0 0 0 4 Home and Communities Agency Employment Density Guide (3rd edition). Prepared for: CORMAC Solutions Ltd AECOM 53
St Austell to A30 Link Project reference: 0128 Project number: 60571547 2023 0 0 0 0 0 0 0 0 0 0 0 0 2028 125 244 593 527 408 333 125 244 593 527 408 333 2029 0 0 0 0 0 0 87 266 0 0 271 138 2031 186 40 42 34 26 158 186 40 42 34 26 158 2033 44 37 113 112 89 98 44 37 113 112 89 98 Table 5-7 show the total trips generated for each development zone. Note that zones numbered 2000 and above are new zones present only in the forecast year scenarios, but zones numbered up to 413 are base zones and extra development trips were added to those existing zones. Table 5-6: Core/Low Growth Development Trip Generation 2022 2037 Zone AM Peak Inter Peak PM Peak AM Peak Inter Peak PM Peak Orig Dest Orig Dest Orig Dest Orig Dest Orig Dest Orig Dest 9 10 27 24 22 29 16 10 27 24 22 29 16 13 5 16 0 0 16 8 5 16 0 0 16 8 60 31 79 50 46 72 47 31 79 80 74 72 47 68 10 32 0 0 32 16 10 32 0 0 32 16 81 18 39 28 26 35 22 18 39 28 26 35 22 109 0 0 0 0 0 0 0 0 0 0 0 0 229 73 45 166 140 183 181 73 45 166 140 183 181 2000 23 65 7 57 69 37 195 540 518 478 575 311 2001 5 5 0 0 5 6 10 8 54 59 7 9 2002 20 14 0 0 2 2 20 14 162 298 2 2 2003 0 0 0 0 0 0 44 42 69 61 55 56 2004 0 0 0 0 0 0 0 0 0 0 0 0 2006 0 0 0 0 0 0 0 0 0 0 0 0 2011 28 87 66 60 80 44 28 87 66 60 80 44 2012 12 1 4 4 1 13 19 2 7 7 2 18 2013 0 0 0 0 16 12 0 0 0 0 16 12 2014 42 114 90 83 124 67 42 114 90 83 124 67 2015 13 3 4 4 2 9 13 3 4 4 2 9 2016 0 0 0 0 0 0 158 119 328 317 310 297 2017 0 0 0 0 0 0 14 3 5 6 2 12 2018 0 0 6 3 0 0 84 22 9 6 11 61 2019 59 45 37 31 97 99 59 45 37 31 97 99 2020 0 0 0 0 0 0 0 0 0 0 0 0 2022 0 0 0 0 0 0 0 0 0 0 0 0 2023 0 0 0 0 0 0 0 0 0 0 0 0 2028 125 244 593 527 408 333 125 244 593 527 408 333 2029 0 0 0 0 0 0 87 266 0 0 271 138 2031 186 40 42 34 26 158 186 40 42 34 26 158 2033 44 37 113 112 89 98 44 37 113 112 89 98 Table 5-7: High Growth Development Trip Generation (Difference to Low/Core Highlighted Blue) 2022 2037 Zone AM Peak Inter Peak PM Peak AM Peak Inter Peak PM Peak Orig Dest Orig Dest Orig Dest Orig Dest Orig Dest Orig Dest Prepared for: CORMAC Solutions Ltd AECOM 53
St Austell to A30 Link Project reference: 0128 Project number: 60571547 9 10 27 24 22 29 16 10 27 24 22 29 16 13 5 16 0 0 16 8 5 16 0 0 16 8 60 31 79 50 46 72 47 31 79 80 74 72 47 68 10 32 0 0 32 16 10 32 0 0 32 16 81 18 39 28 26 35 22 18 39 28 26 35 22 109 4 13 5 5 13 7 4 13 5 5 13 7 229 73 45 166 140 183 181 73 45 166 140 183 181 2000 23 65 7 57 69 37 195 540 518 478 575 311 2001 5 5 0 0 5 6 10 8 54 59 7 9 2002 20 14 0 0 2 2 20 14 162 298 2 2 2003 0 0 0 0 0 0 44 42 69 61 55 56 2004 26 78 33 28 80 41 51 156 65 56 159 81 2006 0 0 0 0 0 0 38 3 14 15 3 31 2011 28 87 66 60 80 44 28 87 66 60 80 44 2012 12 1 4 4 1 13 19 2 7 7 2 18 2013 0 0 0 0 16 12 0 0 0 0 16 12 2014 42 114 90 83 124 67 42 114 90 83 124 67 2015 13 3 4 4 2 9 13 3 4 4 2 9 2016 0 0 0 0 0 0 158 119 328 317 310 297 2017 0 0 0 0 0 0 14 3 5 6 2 12 2018 0 0 6 3 0 0 84 22 9 6 11 61 2019 59 45 37 31 97 99 59 45 37 31 97 99 2020 0 0 0 0 0 0 17 52 22 19 53 27 2022 0 0 0 0 0 0 19 2 0 0 1 16 2023 0 0 0 0 0 0 76 7 28 29 6 63 2028 125 244 593 527 408 333 125 244 593 527 408 333 2029 0 0 0 0 0 0 87 266 0 0 271 138 2031 186 40 42 34 26 158 186 40 42 34 26 158 2033 44 37 113 112 89 98 44 37 113 112 89 98 Prepared for: CORMAC Solutions Ltd AECOM 53
St Austell to A30 Link Project reference: 0128 Project number: 60571547 Trip Distribution As per the trip distribution method outlined in the OBC TFR, one or more distribution zones were chosen for each development, and had origin-destination UC percentage splits extracted and applied to the total generated trips from new developments. In the case of development zones with multiple source zones, the UC proportions obtained from each source zone were averaged. Checks were undertaken to ensure the resulting distributions provided a sensible representation of the expected behaviour of vehicles arriving and leaving each development. Additional HGV trips were calculated for supermarkets and large retail developments, as the respective TAs provided insufficient information (Table 5-8). Table 5-8: Additional HGV Trips 2022 2037 Development Zone AM Peak Inter Peak PM Peak AM Peak Inter Peak PM Peak Name Orig Dest Orig Dest Orig Dest Orig Dest Orig Dest Orig Dest 201 Pentewan Road 0 0 0 0 0 0 4 5 2 2 2 2 6 Morrisons 203 Holmbush LIDL 4 4 2 2 1 1 4 4 2 2 1 1 3 Higher 202 Trewhiddle 5 5 8 7 2 2 5 5 8 7 2 2 8 Supermarket As all of the developments in Table 5-8 are classified as near certain, the trip generation totals are the same across the three growth scenarios. 5.5 Forecasting Scenarios As outlined in WebTAG Unit M45, LG and HG scenarios have been developed to allow for a degree of uncertainty in forecasting of demographic, economic and behavioural trends. Core Scenario All developments considered ‘Near Certain’ and, ‘More than Likely’ are included within the Core scenario (Table 5-6). The developments included in all scenarios are shown in Appendix A. High Growth Scenario The HG scenario provides a forecast based upon a proportion of base year demand added to the core scenario demand. This proportion includes extra development trips generated by the inclusion of ‘Reasonably Foreseeable’ developments, as well as those classified as ‘Near Certain’ and ‘More than Likely’ (Table 5-7). Adjustment factors were calculated using the following formula from WebTAG6 (where n is the number of years ahead of the base year). ± 2.5% ∗ √ The HG matrices therefore applied an adjustment of 6.12% in 2022 and 11.46% in 2037 from the Core scenario matrices. 5 Paragraph 4.1.3 6 Section 4.2 Prepared for: CORMAC Solutions Ltd AECOM 53
St Austell to A30 Link Project reference: 0128 Project number: 60571547 Low Growth Scenario The LG scenario applies the same adjustment calculation process as the HG scenario but with negative adjustments. An adjustment of -6.12% in 2022 and -11.46% in 2037 has therefore been applied to each cell of the core scenario reference case matrix. The LG development trips are identical to the Core development trips, i.e. ‘Near Certain’ and ‘More than Likely’ (Table 5-6). Matrix Totals Table 5-9, Table 5-10 and Table 5-11 present the final forecast matrix totals used, constrained to TEMPro growth factors. Growth has been constrained to TEMPro, in accordance with OBC TFR feedback from the DfT. Table 5-9: Core Forecast Matrix Summary 2022 2037 User Class AM Peak Inter Peak PM Peak AM Peak Inter Peak PM Peak UC1 - Commute 11,576 2,845 11,885 12,708 3,205 13,042 UC2 - Employer’s Business 1,321 1,365 2,021 1,456 1,508 2,223 UC3 - Other 5,559 12,783 16,060 6,093 14,106 17,616 UC4 - LGV 3,540 3,072 3,018 4,233 3,691 3,594 UC5 - HGV 1,026 1,073 477 1,047 1,117 496 All User Classes 23,021 21,138 33,460 25,538 23,627 36,970 Table 5-10: High Growth Forecast Matrix Summary 2022 2037 User Class AM Peak Inter Peak PM Peak AM Peak Inter Peak PM Peak UC1 - Commute 12,244 3,011 12,569 13,950 3,507 14,318 UC2 - Employer’s Business 1,395 1,441 2,135 1,594 1,649 2,436 UC3 - Other 5,881 13,517 16,994 6,704 15,489 19,370 UC4 - LGV 3,930 3,401 3,344 4,964 4,307 4,204 UC5 - HGV 1,089 1,137 506 1,165 1,236 550 All User Classes 24,539 22,507 35,549 28,377 26,188 40,877 Table 5-11: Low Growth Forecast Matrix Summary 2022 2037 User Class AM Peak Inter Peak PM Peak AM Peak Inter Peak PM Peak UC1 - Commute 10,907 2,678 11,196 11,458 2,893 11,754 UC2 - Employer’s Business 1,244 1,287 1,904 1,312 1,361 2,004 UC3 - Other 5,240 12,051 15,132 5,496 12,737 15,879 UC4 - LGV 3,525 3,052 3,004 4,206 3,657 3,569 UC5 - HGV 1,021 1,067 475 1,038 1,107 492 All User Classes 21,937 20,136 31,710 23,511 21,755 33,699 Prepared for: CORMAC Solutions Ltd AECOM 53
St Austell to A30 Link Project reference: 0128 Project number: 60571547 6. Forecasting Future Year Supply 6.1 Infrastructure As outlined in section 5.4.1, most developments have been allocated new zones. There are a small number of exceptions where developments are an extension or densification of existing land uses within a zone, with development trips added to the existing zone in these instances. New access junctions have been included for new zones located within the simulation network. These new junctions have been coded as priority junctions, except where plans indicating otherwise have been provided or were available from planning applications/access statements. Table 6-1 confirms the infrastructure changes which have been included in the forecast scenarios. Table 6-1: Future Year Infrastructure Changes Development/ Description 2022 2037 DM LG Core HG Mitigation Duporth Traffic Reconfiguration of traffic lights, reopening N Y Y Y Y Y Signals of right turn lane. Sawles Road Addition of pedestrian “all red” stage. N Y Y Y Y Y signals upgrade Edgecumbe Replacing priority junction with roundabout Triangle N Y Y Y Y Y redesign and 3-way traffic signal. Pentewan Replacing two roundabouts with one bigger N Y Y Y Y Y roundabout roundabout. Higher Roundabout for access to Higher Trewhiddle N Y Y Y Y Y roundabout Trewhiddle development Holmbush Traffic lights to access Holmbush access traffic N Y Y Y Y Y development. lights West Carclaze A391, Great Treverbyn Rdbt, reconfigure Eco Town Y Y Y Y Y Y Access Carluddon double mini roundabouts Par Docks Eco Primary entry onto Harbour Rd Y Y Y N N Y Town access Holmbush Mixed New signalised junction off Holmbush Rd N Y Y Y Y Y Use dev. access Wainhomes Proposed compact roundabout on Tregonissey Tregonissey Y Y Y Y Y Y Rd (north of Hillside Td) to college Access Wainhomes Widen entry width on Carlyon Rd (W) arm Tregonissey Mit of Carlyon Rd (W)/Carlyon Rd (E )/ Poltair Y Y Y Y Y Y #1 Rd roundabout Wainhomes Reduce speeds on Menacuddle Hill and Mt Tregonissey Mit Y Y Y Y Y Y #2 Stamper Rd to 30mph from 70mph Wainhomes Revise Slades/Tregonissey Rd crossroad Tregonissey Mit Y Y Y Y Y Y #3 to double mini roundabout Porthpean Rd New roundabout on Porthpean Rd Y Y Y Y Y Y Phase 1 Access Prepared for: CORMAC Solutions Ltd AECOM 53
St Austell to A30 Link Project reference: 0128 Project number: 60571547 STA-M1 Pentewan Rd N Y Y N N Y Access Pentewan Road/ Link Road from A390 to B3273 Pentewan Rd, Trewhiddle Link bypassing A390 Pentewan Rd junction Y Y Y Y Y Y Road (accessed from Trewhiddle Farm dev.) STA-E3 Par Access onto Par Moor Road N Y Y N N Y Moor Access Carlyon Beach New junction onto Sea Rd, opp. Crinnis Close. N Y Y Y Y Y Access Cuddra Retail New junction with A390 Holmbush Rd Y Y Y Y Y Y access Main access by new roundabout at NW corner Higher of site, off the A390, continues to main ‘street’ Trewhiddle Y Y Y Y Y Y through dev. area with potential to link onto Farm Access B3273 to East Indian Queens Access via Lodge Way onto B3279 Y Y Y Y Y Y access Carluddon Tech Y Y Y Y Y Y Park Access Holmbush LIDL Access to from Daniels Ln via priority junction Y Y Y Y Y Y access in similar position to the existing site access. Edgcumbe Realignment of 3 junctions where traffic triangle from A3058, A390 and B3274 converges. N Y Y Y Y Y improvement Realignment to relieve congestion A390/B3273 Improvement to A390 Penwinnick Pentewan Rd/B3273 Pentewan Rd junction to max. Rd/South N Y Y Y Y Y capacity and safety, conversion of existing Street rdbt jn double minis to larger single roundabout Review options for jn improvement, could Slades Rd/Sandy Hill inc. conversion from signals to mini N Y Y Y Y Y dbl mini roundabout to Slades Rd/Sandy Jill junction to maximise capacity and safety Study to review options for junction and Tregonissey network improvements in north St Austell, inc. Rd/Slades Rd N Y Y Y Y Y Tregonissey signals, Scredda roundabout and signals surrounding roads 6.2 Future Network: Do Minimum Scenario Duporth Traffic Signals In the base scenario, Porthpean Road is a one-way, northbound street between Victoria Road and the A390. This road provides access to Mount Charles School. There is no right turn into Porthpean Road, meaning that vehicles wishing to access the road are required to undertake a U-turn on the ASDA roundabout. The reconfiguration of Duporth traffic signals (A390/Porthpean Road crossroads) is a Cornwall Council scheme, as shown in Figure 6-1, which would include: • Re-open the right turn to Porthpean Road, by adding an additional lane on the west bound arm on the A390, removing the requirement to U-turns at the ASDA roundabout; • Provision of two ahead lanes for westbound movements on the A390; and • Move the existing pedestrian crossing westward so it is better integrated into the junction, to minimise delays to traffic flow. Prepared for: CORMAC Solutions Ltd AECOM 53
St Austell to A30 Link Project reference: 0128 Project number: 60571547 Figure 6-1: Duporth Traffic Signals A390 Sawles Road Traffic Signals Sawles Road forms part of St Austell’s active travel ‘advisory cycle route’ and provides the main pedestrian and cycling link between the town centre and the Pentewan Valley Trail to the south. Crossing the A390 therefore provides a significant barrier for pedestrians and cyclists using this link. An addition of a pedestrian stage ‘all red’ at the Sawles Road / A390 traffic signals has been identified to make the junction safer and encourage active travel (see Figure 6-2). Traffic signal groups have been updated accordingly in the forecast models to reflect the new phasing. Prepared for: CORMAC Solutions Ltd AECOM 53
St Austell to A30 Link Project reference: 0128 Project number: 60571547 Figure 6-2: A390 Sawles Road Traffic Signals Edgcumbe Triangle In the base model, Edgcumbe triangle consists of three junctions, (two priority junctions and a traffic lights crossroads), where traffic converges from the A3058, A390 and B3274. The edgcumbe triangle is currently experiencing congestion and is expected to experience severe congestion in the near future under the current set up according to the St Austell Transport Strategy Development report. The following measures (see Figure 6-3) have been identified in order to ease congestion: • A390 / Truro Road priority junction replaced by a roundabout; and • Edgcumbe Road severed, with 4-way traffic signal junction at Truro Road / Edgcumbe Road replaced by a 3-way traffic signal. Figure 6-3: Edgcumbe Triangle Prepared for: CORMAC Solutions Ltd AECOM 53
St Austell to A30 Link Project reference: 0128 Project number: 60571547 Pentewan Roundabout The existing A390 / Pentewan Road double mini-roundabout is to be upgraded to a single roundabout as part of the proposals in the do minimum scenario. The TA for development of a superstore along Pentewan Road found that the existing double mini-roundabout is above capacity and subject to numerous accidents. The proposed scheme (see Figure 6-4) encompasses the following highway modifications: • Replace the double mini-roundabout at A390 / South Street/ Pentewan Road with a bigger, single roundabout; • Entry lanes will be reduced from 3 to 2 lanes from the B3273 (Southbound) and South Street (Northbound); • A new traffic signal-controlled pedestrian crossing will be created west of the proposed junction on the A390 Penwinnick Road; and • Pedestrian crossing points with drop down kerbs will be provided at all other arms of the roundabout, with the exception of A390 Trevanion Road. Figure 6-4: Pentewan Roundabout Higher Trewhiddle Development Roundabout A new roundabout is proposed at the junction of A390 Truro Road and Hill Park Crescent to provide access to a new development at Higher Trewhiddle. The new roundabout will serve as the main access point for associated vehicle trip origins and destinations within the model. The features of the proposed highway amendments (see Figure 6-5) are as follows: • Construction of a roundabout allowing access to/from the proposed Higher Trewhiddle development, and north to Hill Park Crescent; • Approaches to the roundabout from the A390 will allow for turning lanes towards the new development; • Existing road width of the A390 approaching the roundabout will be reduced, removing central hatching; and • Amendments to the existing 30mph speed limit west of the proposed roundabout to create a buffer zone, subject to Traffic Regulation Orders (TROs) being obtained through Cornwall Council. Prepared for: CORMAC Solutions Ltd AECOM 53
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