Swansea Strategic Transport Assessment

Descriptions

The City and County of Swansea is currently engaged in the preparation of the Swansea Local Development Plan (LDP). The LDP will provide the development blueprint for the County for the period up to 2025 and will set out how the Council intends to achieve sustainable growth over the next decade and beyond. At the same time the Council is reviewing its strategic transportation investment requirements across the County, having regard to future development scenarios, but also in the interests of keeping traffic moving on the network and promoting a sustainable transport agenda.The LDP Preferred Strategy document (available at http://www.swansea.gov.uk/ldp) proposes a number of development areas that will individually and cumulatively have significant effects on the transport network, particularly the strategic links in the north west of the County where large scale development areas are proposed. As part of the need to underpin the LDP with a sound evidence base, there is a requirement to assess the combined transport impact of the key development proposals identified in the Plan. The Council will need to demonstrate at the forthcoming LDP Examination in Public that any potential impacts have been quantified and any necessary mitigation measures identified, in order that the highway network can continue to function adequately. It will also need to demonstrate that the sites proposed would be suitably sustainable in terms of their accessibility, now or in the future, by modes other than the private car. The LDP places significant importance on sustainable travel and optimising modal shift towards sustainable modes, which will be an integral theme to the masterplanning of proposed residential led, mixed use development areas.The LDP proposes the implementation of some significant new road infrastructure to serve two of the largest development areas identified in the Preferred Strategy. The proposed major development areas at land south of Penllergaer and land north of Waunarlwydd both propose new strategic road links to form a new junction on the A484 ‘Llanelli Link Road’.The contract will require the construction of a base model using suitable strategic modelling methodologies, together with associated individual junction analysis, in order to measure the impact of development scenarios and test potential mitigation measures. The base model will need to be County wide and include all key links considered likely to be significantly affected by the proposed development areas.It is expected that the modelling assessment would be made using Visum, although the use of alternative software is acceptable if a case can be made to demonstrate the equivalence or advantages of doing so. The Council holds a wealth of flow and junction turning count data and this would be readily supplied to the successful candidate. A detailed Transyt model for the city centre highway network was constructed in 2009. Where additional data is required for calibration and other purposes, consultants are asked to include the relevant survey costs in their submission. From the initial model, the Consultant would be expected to produce a baseline assessment of the highway network from which future year scenarios could be tested. Amendments to the model will then need to be made to add in the development proposals, and in respect of the anticipated highway infrastructure proposals, and the loads that these would introduce to the network. Demonstration of network performance should be provided through the use of arguments based upon quantitative data such as and ratio-flow-to-capacity (RFC), queue lengths and total delay. Consultants will also need to consider localised measures to improve capacity at key locations.The overarching objectives of the study are:-to produce clear evidence as to extent to which the delivery of the main LDP proposals will still allow for the effective and efficient operation of the transport network-demonstrate how existing and possible future traffic problems can be mitigated and infrastructure deficiencies addressed-assess the relative sustainability of LDP proposals, including consideration of their potential to be accessible by modes other than the private car.Evidence of the traffic impact of individual LDP proposals at the local level has been produced by means of Transport Assessments of individual sites. These have been submitted to the Council by relevant site promoters. These individual assessments provide important background information for the contract (to be provided to the appointed consultant), however they are insufficient in themselves to understand the cumulative impact of the proposed developments.The client body is seeking the Final Report no later than 28th February 2015. The maximum budget available is £160,000 for all the requirements of this commission, including relevant survey costs and expenses.