Simulation-Based Planning Framework for Choosing Where to Implement Bus Signal Priority in Mixed-Mode Operations

Planning is the first phase in a systematic approach toward better implementation of the bus signal priority (BSP) strategy and is required by the U.S. Department of Transportation as the first step of a standard system engineering approach for any federally funded intelligent transportation system project. Numerous studies have focused on various aspects of BSP design and operation; however, less attention has been paid to the planning phase of a BSP project. This study concentrated on planning for a BSP implementation project. The proposed framework is a heuristic approach to the combinatorial problem and is based on microsimulation; it requires a basic concept design for the BSP system, which is in planning. This concept design should be available from the planning steps that precede the choice of intersections to be equipped. The framework evaluated various scenarios for BSP at individual intersections by considering their marginal impact on the entire network and on the intersection. The intersection-level scenarios that resulted in the maximum total marginal improvement were selected for BSP implementation. The final output of the framework provided information on the intersections that should be equipped with BSP and the bus lines that were eligible to receive this priority at each intersection. The proposed framework was demonstrated in the network of downtown Dover, Delaware. An 18% savings in network average bus delay and no significant disbenefit to automobile traffic were achieved. The benefits translated into minimum savings of about $0.25 million a year through implementation of this framework during a peak traffic hour.