A simple forward-backward procedure for real-time signal timing adjustment on oversaturated arterial networks

Under oversaturated traffic conditions, signal timing needs to be adjusted based on real-time traffic performance measures. Building upon the recently proposed oversaturation severity index (OSI), we develop a simple forward-backward procedure (FBP) to manage oversaturation. The forward process aims to increase green time by searching available green time which can be taken from side streets or conflict phases, therefore improve the throughput for main streets; and the backward process is to gate the traffic at some intersections to prevent residual queues and downstream queue spill-back when available green time increase is insufficient. The FBP is designed for real-time implementation, although it is also applicable for off-line signal timing adjustment. The simulation tests for the network in the City of Pasadena, CA indicate that the FBP can effectively and efficiently reduce oversaturation.