A robust quasi-dynamic traffic signal control scheme for queue management

For vehicle-actuated traffic signal systems in which both cycle lengths and phases are control variables, it is well known that the best control strategy for minimizing total system delay is to end a phase as soon as queues served during that phase vanish. We extend this logic to intersections where signal coordination or other considerations may warrant a signal timing plan with a stable cycle length. Different from fully dynamic control strategies, the proposed scheme is made up of a set of fixed timing plans with a common cycle length. The decision for choosing a specific plan from this set for each cycle is made at the beginning of the cycle. Our results reveal that though the proposed scheme does not minimize total system delay directly, it provides a good solution for reducing total system delay as well. The proposed scheme is robust with respect to random fluctuation in vehicle arrivals or to changes in vehicle arrival distribution. The preservation of a stable cycle length in the proposed signal timing plan has made it possible to incorporate the proposed scheme into a signal timing plan for an arterial where signal coordination is essential to the performance of the system.