Research On Signal Control Of Urban Road Network Based On MFD

As a network flow-occupancy diagram, Macroscopic Fundamental Diagram (MFD) reflects the various states of traffic flow in regional road network. MFD is a basic attribute of road network, and it can monitor the traffic states of different sub road networks. Therefore, the boundary control or perimeter control can be used to restrict the access from outside are to the protected area (i.e. the central business district). Both signal control and dynamic charging can be adopted as perimeter control strategies. In the traditional perimeter control algorithm, the maximum flow rate is always calculated. From point view of practice, the flow rate in perimeter controller should be transformed into the signal timing plan or dynamic charging policy.The research in this thesis can be divided into three parts.Firstly, according to historical traffic data of the given road network, the corresponding gate control mechanism is proposed based on the analysis of traffic congestion in the regional road network. In gate control mechanism, the thesis sets the initial perimeter controller and variation function of the perimeter controller. According to the demand for traffic and changes of the area perimeter controller, the thesis can predict the traffic flow which allowed into the protection area.Secondly, according to the gate control mechanism, the thesis transforms the area perimeter controllers into the corresponding intersection perimeter controllers, and then computes the signal timing scheme using the intersection perimeter controllers. In order to extended red time to reduce traffic flow entering the protected areas, an optimization algorithm using GA theory is proposed for calculating the optimized signal timing strategy. In our timing strategy, the thesis can obtain the optimal red phase extension.Finally, a case study is adopted using the real road network of Tianhe District in Guangzhou city. The results show that the gate control strategy has relieved the urban congestion and improved the capacity of the traffic network.