Evaluation of Bus Priority Signal Strategies in Ann Arbor, Michigan

Abstract

With the emergence of intelligent transportation system technologies there has been a renewed interest in the bus priority signal (BPS). The effect of providing the BPS treatment on the Washtenaw Avenue Corridor in Ann Arbor, Michigan, was studied. The NETSIM graphic animation feature was used to detect the bus arrival and award preemption. The signal timing plan was then restored to the original signal setting in subsequent cycles. The model was calibrated using field data, and the sensitivity of the model to several variables was tested. The corridor's signal timing was first optimized using the TRANSYT-7F model. The green extension and red truncation with and without compensation, the skip phase with and without compensation, and the conditional preemption plans were evaluated. It was found that in all cases signal preemption disrupts traffic progression and, thus, increases overall vehicle delay. The results of preemption were analyzed at each intersection as well as over the entire simulation network. The most appropriate preemption strategy for each intersection was determined and used in the simulation. Bus travel time and delay were reduced when this optimal BPS plan was used.