A Coordinated Traffic Control on Urban Expressways with Modified Particle Swarm Optimization

A coordinated traffic control method on urban expressways is proposed, which combines ramp control and Variable Speed Limits (VSL). A modified Particle Swarm Optimization (PSO) algorithm is presented to implement the coordinated control. We employ a model predictive control schema to offer online control on expressways. With spatial and temporal constraints on speed limits values during optimization, the modified PSO algorithm aims to search the optimal control signals for the coordinated control method. Instead of continuous VSL values, discrete VSL signals are used, which is more applicable for practical expressway control. The objective function in this paper considers a weighted summation of total time spent and total travel distance, which balances the expressway traffic density and the traffic outflow. Simulation results verifies that the proposed approach has its applicability and a better control performance.