Ramp metering of freeway network based on dynamic graph hybrid automata

In this paper, we present a ramp metering strategy to reduce urban freeway network traffic congestion. In order to implement the control method on the large-scale urban freeway network, we apply the Dynamic Graph Hybrid Automata (DGHA) and Modified Cell Transmission Model (MCTM) to describe the evolution laws of traffic flow. Based on the DGHA macroscopic traffic model, we design a complete ramp metering system for the freeway network. The local ramp metering control strategy is proposed to reduce the freeway congestion, in addition, the queue constraint scheme is employed to prevent the queue from exceeding the ramp storage space. At last, this approach is applied to the Beijing third ring road by Modelica language on the OpenModelica. Experimental results validate the DGHA modeling method and demonstrate the effectiveness of the ramp metering strategy.