Southall Broadway Public Realm - Post Implementation Study
Samya Ghosh, AECOM, Phil Arnold, AECOM
A post-implementation study of the Southall Broadway Boulevard scheme has been completed. The study presents an opportunity to calibrate the innovative shared space modelling technique developed to test the scheme, against post-implementation data.
This paper will start with a brief background describing the scope and objectives of the Southall Broadway Boulevard scheme and any differences between the planned scheme and that finally implemented. A summary will also be made of a previous paper presented by AECOM at the 2015 ETC conference ‘Development of Shared Space Micro-simulation Modelling and Application within Scheme Development and Assessment’ as this forms the background to this paper.
The paper will then describe the objectives of the Southall Broadway Boulevard post-implementation study that AECOM was commissioned to undertake. It will cover post implementation scheme data analysis/ observations made to assess the actual performance of the scheme. The paper will also outline how AECOM was commissioned to refresh the Southall VISSIM model to a base year of 2015, which presented an opportunity to calibrate the bespoke modelling methodology developed to support approval for the Southall Broadway Boulevard scheme to observed conditions.
The paper will describe the analysis of traffic flows and speeds, car and bus journey times and pedestrian crossing data and observations of pedestrian and vehicle interaction and general scheme performance. The performance of the scheme will be assessed against the original objectives.
The operation of the Southall Broadway Boulevard scheme predicted by the VISSIM models will be examined in the paper, and the reasons for any differences between predicted/ observed car and bus journey times will be explored. The coding of courtesy crossing behaviour at the ‘Boulevard Zones’ was coded using VisVAP so that different parameters governing crossing decisions, crossing locations and give-way behaviour could be tested. The analysis of the model outputs demonstrated that the impact on bus/ car journey times would lie within an acceptable range to gain scheme approval. The paper will review that analysis, in light of the actual observations of the post-scheme car and bus journey times, collated as part of this study.
The paper will conclude by reviewing whether the public realm scheme has met its objectives. The paper will also present the ’Lessons Learnt’, comparing actual road-user behaviour with model input assumptions, outlining how we propose to incorporate those lessons in our future model development exercises for assessment of similar schemes.
Association for European Transport