Research On Optimal Control Strategy Of Expressway Ramps Based On MFD

With the improvement of the quality of life of urban residents and the rapid increase in the number of motor vehicles,the city's traffic congestion has become from the point of congestion and local congestion into large-scale regional congestion.And due to the diversity and complexity of large and medium-sized city road network structure,the existing traffic facilities and control methods are difficult to meet the travel demand of urban residents.Therefore,in order to improve the efficiency of urban residents,reduce the incidence of urban traffic accidents,improve the operating efficiency of the expressway and the utilization rate of urban roads,and then alleviate the problem of large-scale urban traffic,the most practical significance is to study the traffic congestion of urban road network which contains expressway or main roads.This paper studies on control strategy optimization of ramps for urban expressway based on the MFD of the road network.Supported by the National Natural Science Foundation of china " Study on the feature extraction and fast evacuation algorithm of congestion network based on spatio temporal detection(No.61304195)",Based on the analysis of the macro transformation relationship between the traffic flow of the expressway and the ground network,an integrated control model of expressway is established based on the macroscopic guidance of the road network,and the simulation analysis is carried out based on the actual road network.The main contents of this paper include the following aspects:(1)Through the study of the interaction between the road network and expressway,from the view of whole traffic state,the coordinated control model of ramp of exits and entrance for urban expressway was established;Then,using the characteristics of the macroscopic fundamental diagram,the road network was divided into sub regions,based on the optimization of the whole road network traffic flow,established the macroscopic guidance model of ground network.(2)On the basis of the mutual transformation relationship between the traffic volume of the expressway and the road network and the theory of the macroscopic fundamental diagram,the paper established the traffic equilibrium equation of the whole road network;Introducing the separation ratio of the main road traffic flow and combining the coordinated control of the ramp for the exits and entrances with the macroscopic guidance on the ground,with the aim of minimizing the total travel time and the total travel distance,the integrated control model was established,and the control flow was designed.The model was solved by Lagrange quasi-Newton method.(3)The simulation experiment was carried out by using the actual road network,and the three methods of integrated control,ramp coordination control and no control were analyzed and compared.The simulation results show that: the efficiency of the whole network by using integrated control than that of the single ramp coordination control and no control,it effectively alleviated the regional traffic congestion,and improved the utilization rate of the entire network of roads.