A Model for Transit Signal Priority Considering Stochastic Bus Arrival Time

Transit Signal Priority (TSP) strategy is an effective preferential treatment to move transit vehicles through an intersection with minimum delay. However, TSP can become a disturbance to traffic on non-priority phases if not properly implemented. To produce a good TSP strategy, advanced planning with enough lead time is usually required. This, however, means added uncertainty about the bus arrival at the stop bar, which is difficult to be accounted for. In this paper, the authors 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 model adopts a novel approach to capture the impacts of the priority operation to other traffic by using the deviations of the phase split times from the optimal background split times. In addition, when a near-side bus stop is present, the model explicitly accounts for the randomness of a bus arrival time to the stop bar, by considering the bus stop dwell time, the current signal timing and the delay caused by standing vehicle queues. The SMINP is implemented in a simulation evaluation platform developed using a combination of a microscopic traffic simulator, VISSIM, and a commercially available optimization solver, CPLEX. A comparison analysis was performed to compare the proposed control model with TSP feature implemented in the built-in controller in VISSIM (i.e. RBC). The results showed the SMINP has rendered as much as 30% improvement of bus delay from the RBC controller 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. This use of deviation to proximate the impact to other traffic is straightforward and does not require complicate computations of vehicle delays. Meanwhile, the formulation of stochastic arrival time allows much more time to devise good signal timing plan that provides priority while keep its impact minimal.

• Supplemental Notes:
  • This paper was sponsored by TRB committee AHB25 Traffic Signal Systems.
• Corporate Authors:

  Transportation Research Board

  500 Fifth Street, NW
  Washington, DC  United States  20001
• Authors:
  • Zeng, Xiaosi
  • Zhang, Yunlong
  • Balke, Kevin
  • Songchitruska, Praprut
• Conference:
  • Transportation Research Board 93rd Annual Meeting
  • Location: Washington DC
  • Date: 2014-1-12 to 2014-1-16
• Date: 2014

Language

• English

Media Info

• Media Type: Digital/other
• Features: Figures; References; Tables;
• Pagination: 16p
• Monograph Title: TRB 93rd Annual Meeting Compendium of Papers

Subject/Index Terms

• TRT Terms: Bus priority; Real time control; Traffic delays; Traffic signal priority; Traffic signal timing; Traffic simulation; Transit buses; Uncertainty
• Subject Areas: Highways; Operations and Traffic Management; I73: Traffic Control;

Filing Info

• Accession Number: 01520200
• Record Type: Publication
• Report/Paper Numbers: 14-5017
• Files: TRIS, TRB, ATRI
• Created Date: Mar 26 2014 2:00PM