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600451-00014-1 Report Abstract

A Real-time Transit Signal Priority Control system that Considers Stochastic Bus Arrival Times

Xiaosi Zeng, Kevin Balke, Praprut Songchitruksa, and Yunlong Zhang, October 2013

Transit Signal Priority (TSP) is an effective strategy for providing preferential treatment to move transit vehicles through intersections with minimum delay. However, TSP can disrupt traffic on non-priority phases if not properly implemented. To produce a good TSP strategy, advance planning with enough lead time is usually preferred; however, this means added uncertainty about the bus arrival at the stop bar, which has been difficult to be accounted for. In this research, we proposed a stochastic mixed-integer nonlinear model (SMINP) to be used as the core component of a real-time transit signal priority control system. The SMINP was implemented in a simulation evaluation platform. An analysis was performed to compare the proposed control model with the standard check-in/check-out TSP system implemented in the VISSIM Built-in Ring-Barrier Controller (RBC-TSP). The results showed the SMINP produced as much as 30% improvement of bus delay from the RBC-TSP in low to medium volume conditions. In high-volume conditions, the SMINP model automatically recognizes the level of congestion of the intersection and gives less priority to the bus so as to maintain a minimum impact to the traffic on its conflicting phases. In the case of multiple conflicting bus lines, a rolling optimization scheme was developed. A comparison indicated the RBC-TSP systems cannot handle high degree of saturation when there are significant amount of conflicts between bus lines, while the SMINP can automatically give less priority to bus so as to cause much less impact to other traffic.

Keywords: Transit Signal Priority, Mixed-integer Nonlinear Model, Stochastic Optimization, Degree of Saturation, Simulation Evaluation

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