Optimal Perimeter Control for Multi-Region Traffic Networks Based on Macroscopic Fundamental Diagram

In order to improve the urban traffic operational state of traffic networks, this paper proposed a new optimal perimeter control strategy based on macroscopic fundamental diagram (MFD). Firstly, the traffic flow equilibrium model for monocentric region networks was established by analyzing the matching in-flow and out-flow relationship of adjacent regions, as well as the traffic flow equilibrium model for multi-region networks. Secondly, an optimal perimeter control model was built, based on the traffic network state equation and perimeter control condition, to optimize the overall operation benefit of the macroscopic networks. According to the optimal control condition, the critical in-flow and out-flow rates on the boundary of the sub-regions could be calculated. And then the optimization method of signal timing for the boundary intersections was presented with the aim of reducing their saturation degree rapidly. Lastly, the local network at 1st Ring Road, Chengdu was chosen as the test object to compare the effect of no perimeter control (NPC), Bang-Bang perimeter control (PC) and optimal perimeter control (OPC) proposed in this paper by simulation. The result showed that compare with NPC, PC could improve the overall operation benefit of the macroscopic networks with 33.73%, while OPC is 57.09%. In the meantime, compare with PC, the accumulating volume of every sub-region was reduced even bigger under OPC, which meant that OPC could improve road network operation efficiency and alleviate regional traffic congestion more effectively.