Assessing the Impact of Transit Signal Priority Strategies on a Network

This research presents the implementation of two different transit signal priority strategies and assesses their impact on the whole network through a bi-modal three-dimensional Macroscopic Fundamental Diagram. The first TSP strategy is the green extension, which is implemented using the microscopic simulation software AIMSUN. Initially, activated in a single intersection, its impact is positive as it reduces the total passenger delay of the intersection in comparison with the base-case scenario. Afterwards, it is implemented on a few intersections, then on multiple arterials, and its impact is assessed by generating a 3D-passenger and vehicle MFD. On multiple arterials, the green extension performs better than the base case scenario as it increases the passenger flow. The second TSP strategy implemented is a person-based traffic-responsive signal control system, which aims to reduce the total passenger delay in a single intersection by accounting for the passenger occupancy of autos and transit vehicles, while prioritizing transit vehicles. This system was first implemented in a single intersection, and then on 4 intersections. Its efficiency was compared with the base-case scenario and with the active TSP strategy. The person-based TSP proved its efficiency as it performed better than both the base case scenario and the green extension. In fact, the person-based TSP allows more autos and transit vehicles to be served in the network and also achieves higher values of passenger flow.