BUS PREEMPTION SIGNAL (BPS) - AN APPLICATION OF AN ADVANCED PUBLIC TRANSPORTATION SYSTEM (APTS)

With the emergence of Intelligent Transportation System (ITS) technologies, there has been a renewed interest in the bus priority signal (BPS). However, at present there is no model capable of simulating various BPS strategies and then restoring the original signal settings after bus preemption is awarded. 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, award preemption, and the signal timing plan was restored to the original setting manually. The model was calibrated using field data and the sensitivity of the model to several variables was tested. It was found that signal preemption disrupts traffic progression, and thus increases overall network vehicle and person delay. The bus travel time and delay were reduced when the optimal BPS plan was used. The BPS was tested under different network traffic volumes, different main to cross street traffic ratios for an isolated intersection, and signal preemption for carpools. It was found that maintaining progression is most critical under heavy traffic conditions. The traffic volume criteria that warrant signal preemption were established. There appears to be advantages to providing carpools with preemption capability up to between 5 and 10% of the main traffic volume.