Optimal Signal Control in Urban Road Networks with High Priority Congested Centers

Keeping the density of traffic flow and air pollution in an acceptable level and developing a good capacity for transit in the high priority areas of the city, is really a big deal in large and crowded cities. To address this problem, a new method of intersection signal optimization is presented in this paper. Based on network fundamental diagrams, an Internal–External Traffic Metering Strategy (IETMS) is developed for controlling density of traffic in high priority areas globally. Protecting the network from gridlock, optimizing the queue ratios in entrance arterials and utilizing the reserved capacity are the main objectives of the problem. The methods of mixed integer linear programming and quadratic programming are used for solving the problem. A traffic simulator software (VISSIM) has been used for simulation in which the coded program is developed in VISSIM-COM interface. Finally the model is applied in a part of urban network of Tehran, Iran. The results show that redistributing of traffic density in the whole network and protecting high density areas from gridlock can efficiently improve traffic flow measurement in high priority areas.