Helston Transport Strategy Development
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Helston Transport Strategy Development Appendix B – Town Model Report May 2017 Prepared by Ben Smith-Laing Checked by Rob Hayward Note 10 Approved by Ian Beavis CORNWALL COUNCIL CORNWALL TOWNS MODELS HELSTON SATURN MODEL TECHNICAL NOTE 20 – DRAFT 4 25TH JUNE 2014 PROJECT: 3513000AT 1 EXECUTIVE SUMMARY This report examines how the highway network within Helston is predicted to operate in 2030 with the levels of development growth proposed in the emerging Core Strategy. Allowances have been made for background traffic growth and development-related traffic. A series of strategic sustainable transport measures are proposed to mitigate the impacts of this growth. A traffic model has been developed for Helston which has been used to predict where congestion and delays may occur in 2030. An assumed level of modal switch from the private car was then modelled to reflect what could be achieved through the proposed sustainable transport measures. This highlighted any remaining key issues on the highway network. The modelling indicated that no strategic highway improvements would be required to support the proposed level of growth. The recommended measures to form part of the transport strategy are: Package of sustainable measures including: o Improved cycling and walking infrastructure (yet to be considered in detail); o Improved bus service provision and frequency (associated with the Cornwall Bus Vision); o Real Time Passenger Information and improved waiting facilities; o Travel Planning and smarter choices. No junction improvement schemes are required. The assessment work concludes that these measures would allow any of the 3 development scenarios in Helston to come forward without significantly compromising the operation of the local and highway network. In addition to accommodating the planned expansion of dwellings and businesses within Helston, the traffic model has been used to test options to reduce rat running through Cross Street and Penhallez Hill and also to examine the potential pedestrianisation of the town centre. These are described overleaf. Over a Century of Engineering Excellence -1- Heston Saturn Model Technical Note 20 Rat Running A number of options were tested. The recommended way forward would be to restrict movements at the Penhellaz Hill/Penzance Road (A394) junction. This would involve narrowing down the junction to make it look less like a major turning and restricting it to a right in/left out junction. This reduces rat running by approximately 80% and did not result in any excessive traffic increases or capacity issues elsewhere on the highway network. Pedestrianisation The local business community has also put forward a proposal for a pedestrianisation scheme for Meneague Street. Meneague Street would be pedestrianised, Godolphin Road would revert to two- way use, with a clockwise one-way gyratory formed around Penrose Road and Wendron Street. This has also been tested in the model and shows no negative impacts on the surrounding network. The pedestrianisation scheme would be compatible with the Penhellaz Hill/Penzance Road works described above. Over a Century of Engineering Excellence - 2 - Heston Saturn Model Technical Note 20 2 INTRODUCTION 2.1 Background 2.1.1 Parsons Brinckerhoff (PB) has been commissioned by Cornwall Council (CC) to test future development allocations in 13 towns in Cornwall, and develop transport strategies for these towns that will mitigate the impact of growth proposed through the emerging Core Strategy. This work is Phase 3 of the project, and builds on the work carried out for Phases 1 and 2 which have now been completed. 2.1.2 Phases 1 and 2 of the project involved developing or updating existing transport models for the towns and assessing a series of development scenarios in each town for the year of 2030. Phase 3 of the project has involved modelling the preferred development scenario for each town (identified using the outputs from the previous work) to assess the impact of future development, and identifying measures, including sustainable measures and highway improvements, to allow the impact of development growth to be mitigated. The sustainable measures were provided by CC and modelled using the methodology detailed in ‘Technical Note 01 – Application of Mode Shift’ (available. 2.1.3 Models have been developed for the following towns: Bude and Stratton; Falmouth and Penryn; Hayle, St Ives and Carbis Bay; Launceston; Liskeard; Newquay; Penzance; Saltash; St. Austell; Truro. 2.1.4 Models which have previously been developed for Camborne Pool Redruth (by Mott MacDonald) and Bodmin (by WSP) for other projects have also been used in this project. 2.1.5 The sustainable measures aim to encourage and promote sustainable travel in all towns by improving walking, cycling, and bus and rail services. This supports the goals set out in Cornwall‟s transport strategy, Connecting Cornwall: 2030. Further details regarding the sustainable transport strategy for Helston can be found in Section 4.8 of this report. 2.1.6 The sustainable measures, further public transport improvements and highways schemes will form a transport strategy for each town, with the aim of mitigating the impact of future development growth and encouraging sustainable travel. 2.1.7 This technical note focuses on the model of Helston. Over a Century of Engineering Excellence - 3 - Heston Saturn Model Technical Note 20 2.2 Structure of Report 2.2.1 The purpose of this report is to summarise the work carried out by PB in the development of the Helston base year SATURN model and to demonstrate that it is a fair and accurate representation of existing traffic conditions in the study area. It also examines the likely future impact on the network resulting from proposed development and establishes the transport strategy to 2030. The report is structured as follows: Section 3 – provides an overview of the model Section 4 – provides details of the development of the 2030 Do Nothing Model Section 5 – provides details of the development of the 2030 Do Something Scenarios Section 6 – summarises the individual junction modelling Section 7 – sets out the recommended transport strategy Over a Century of Engineering Excellence - 4 - Heston Saturn Model Technical Note 20 3 MODEL DEVELOPMENT 3.1 Model Software 3.1.1 The Helston Town Model has been developed using the SATURN highways assignment model version 10.9.17. 3.1.2 The Helston SATURN model is based on a series of manual classified counts (MCCs) at key junctions in Helston. In addition to this 5 automatic traffic counts (ATCs) where undertaken in June 2013. The model update and validation is described further in “Helston Local Model Validation Report”. 3.1.3 Whilst the model has been constructed using DfT best practice and guidance detailed in WebTAG and the Design Manual for Roads and Bridges (DMRB), and calibrated using DMRB model calibration criteria, the model is not fully WebTAG compliant. To make the model fully WebTAG compliant would have resulted in significant data collection costs. Given the relatively free-flowing nature of the local highway network and limited additional development proposed, it was considered that this would not be proportionate to the level of detail required or promote the public interest. A more modest survey program was therefore undertaken, appropriate to the town and level of assessment required. 3.1.4 The 2013 revised model was found to validate well on link flows within the whole of Helston and is therefore deemed to be an adequate model to assess the base year situation and be used as the basis for predicting future year traffic flows and detailed junction modelling. Over a Century of Engineering Excellence - 5 - Heston Saturn Model Technical Note 20 3.2 Model Area and Development Scenarios 3.2.1 A plan of the area modelled is shown in Figure 3-1. The model extends from Sithney to the northwest, past the Hellescoth Way roundabout on the B3297 to the north, north east to the Trevenen area, south towards Culdrose Airfield and west on Porthleven road. Study Area Proposed Employment Area Scenario 1 Scenario 2 Scenario 3 Committed Developments Scenario 1 Committed Developments Employment Area Scenario 3 Scenario 2 Figure 3-1: Helston Model Study Area Over a Century of Engineering Excellence - 6 - Heston Saturn Model Technical Note 20 3.2.2 There are 3 different locations (Scenarios) for the future developments as outlined in the map above and described in the notes below. Individual maps for Scenarios 1, 2 and 3 can be found on Appendix A. Scenario No Development Location 311 Committed Dwellings Tesco Supermarket area on Falmouth road Central Helston, close to Helston 10 Committed Dwellings Community College Scenario 1 North east of Helston, near the A394 356 Proposed Dwellings roundabout with Falmouth Road. 7,450 sqm Office space South of Helston near Clodgey Lane 10,200 sqm Industrial Space roundabout. 311 Committed Dwellings Tesco Supermarket area on Falmouth road Central Helston, close to Helston 10 Committed Dwellings Community College Scenario 2 356 Proposed Dwellings South of Helston near Clodgey Lane 7,450 sqm Office space roundabout. 10,200 sqm Industrial Space 311 Committed Dwellings Tesco Supermarket area on Falmouth road Central Helston, close to Helston 10 Committed Dwellings Community College 230 Proposed Dwellings South west of Helston near the cemetery. Scenario 3 126 Proposed Dwellings 7,450 sqm Office space South of Helston near Clodgey Lane roundabout. 10,200 sqm Industrial Space Table 3-1: Scenarios 1, 2 and 3 with development details 3.3 Zone System 3.3.1 The zone system remains as set out in the Local Model Validation Report (LMVR) for the town (Phase 1 and 2 of the current project). 3.3.2 In distributing the traffic generated by the new development zones, the following methodology was employed: For new residential zones, traffic was distributed in line with the distribution of a neighbouring residential zone; For new commercial zones traffic was distributed in line with neighbouring commercial zones.