Integrated Control for a Large-Scale Mixed Network of Arterials and Freeways

An urban traffic network is typically composed of two subnetworks: freeways and arterials. When the exchange traffic flow between these two subnetworks is over concentrated on an off-ramp or on-ramp, local congestion occurs in the traffic network. We propose an integrated control (IC) method to effectively adjust and coordinate the traffic flow between the two subnetworks of a large-scale urban traffic network. The proposed method depends on a subregion partitioning scheme based on the macroscopic fundamental diagram (MFD) and the road capacity constraints and integrates macroscopic traffic guidance, ramp-coordinated (RC) control and MFD subregion perimeter control to adjust the traffic flows for exchange between the two subnetworks. A solution method for the proposed IC model is designed using a Lagrange-quasi-Newton algorithm. Simulation studies of a congestion scenario are presented, and the results indicate that in comparison with no RC control, RC control only and a combined RC and perimeter control scheme, the proposed control scheme can reduce the delay, trip distance and trip time for the entire network.