The effect of queuing representations on modeling transit signal priority systems in mixed mode operation

This paper examines quantitatively the effect of modeling assumptions on transit signal priority (TSP) control in mixed mode operation. The primary sources of delays to buses at intersections are queues formed at intersections (queuing delay) and traffic signals (signal delay). We show that models based on point queues and models based on spatial queues would lead to different control strategies and yield different results for the benefit to buses in terms of delay reduction. Situations in which the spatial content of queues is crucial to modeling TSP systems are identified in the paper. We conclude that given that models with the spatial queue representation are more realistic in capturing the queuing dynamics at intersections they should be incorporated in the decision-making process for initiating priority calls in a TSP system.