An Evaluation of Integrated Freeway Traffic Control and Route Diversion using Microscopic Simulation

This paper presents methodology and case studies for a system-wide evaluation of an integrated traffic control and route diversion strategy. Experiments are performed for the Central Artery/Tunnel (CA/T) network in Boston and use a microscopic traffic simulator to test and evaluate the traffic control design. The advantage of this microscopic simulation laboratory is that it simulates the interaction of individual vehicles with other vehicles, network geometry, and traffic control devices, thus providing a detailed analysis of the impact of traffic control. Two case studies are presented. One places an incident in a weaving section and uses control designs comprised of lane control signs (LCS), variable speed limit signs (VSLS), ramp meters, and route diversion for incident management. The other case places an incident in a tunnel, and uses controls comprised of LCS, VSLS, and route diversion to a parallel tunnel. The experiments demonstrate that the simulation laboratory can serve as an effective tool for evaluation of integrated Dynamic Traffic Management Systems (DTMS). The results show marginal or no improvement due to an integrated design. Thus, it is found that a naive integration approach for DTMS may not provide expected benefit. Another significant finding of this study indicates the disadvantage of a simple route guidance information system which is based on existing traffic patterns, implying the need for a prediction-based information system.