Evaluation of a New Real-time Congestion Control Policy Using Simulation

This paper presents an overview of a new real-time traffic signal timing policy, named RT/IMPOST, that is designed to provide optimal signal timing over the entire range of traffic environments from undersaturated to oversaturated flow conditions. This paper describes the control policy design for the oversaturated traffic environment. For this traffic environment, a policy objective that seeks to maximize throughput (vehicle trips serviced) is suggested. To meet this objective, it is argued that managing queues to avoid intersection blockage and to fully exploit the available green time, constitutes a sound basis for such a control policy. A description of the analytical approach is presented and its implementation procedures in real time are detailed. Simulation results are presented which support this policy design, demonstrating that this kind of control can provide good performance even under severe congested conditions.