Urban Road Network Traffic State Discrimination And Early Warning Research Based On Catastrophe Theory

Before the occurrence of unexpected events,the accurate prediction of traffic status of urban road network is thebasis for the traffic management departments to accurately grasp the urban road network traffic flow status,analyze the characteristics of traffic flow variation,and respond to formulatea scientific measures in advance.It is also the precondition for travelers to choosetrip modes,time and routes,and the most basic condition to relieve the traffic pressure,balance the road traffic supplies and demands,rationally use transportation resources,and give full scope tourban road network.Therefore,there are a lot of quite important theoretical and practical meanings to predict and evaluate traffic state.According to the actual demands of the traffic management department,this paper deeply researches the urban road network traffic status,stratifying and refining the macroscopic state traffic andassociating it with the basic parameters of the microscopic traffic flow.Then predict the basic parameters by using the improved prediction model based on Swallowtail Catastrophe Theoryand thendetermine the future state of the urban road network traffic state based on the predicted values.Specific work is as follows.(1)Buildthe traffic state evaluation system.Through analyzing the urban road network traffic state,and contraposing its complexity and variability,the traffic state is refined and divided into three levels including road network,roads and intersections,and traffic flow parameters on the traffic state study wherespace occupancy,traffic and saturation are still selected as basic indexes among the lowest layer traffic flow parameters to construct the city road network state evaluation system.Evaluate andclassify the traffic state by a certain evaluation criteria to determine the future traffic status of one time.(2)Modify the prediction model of traffic flow based on Catastrophe Theory.In this paper,we modify the forecast traffic flow model based on the swallowtail catastrophe theory.Considering that the road lane change behavior causes the increasing rate of road space,we add the traffic lane change behavior rate which impactsthe actualtraffic capacity as a control variable so that we can more fully take into account the factors that affect the traffic flow and the operation status of road traffic flowcan be reflected more realistically.Therefore thetraffic flow prediction will be more accurately.(3)Abnormal state traffic warns.Firstly,we analyze the causes of the abnormal traffic status from the perspectives of urban planning,transportation planning,transportation infrastructures and management.Then we give the corresponding countermeasures from the aspects of transportation hubs,public transports,river-crossing and mountain-throughchannels,the road network optimization,the traffic organization of road construction,traffic safety education and so on.In the event of abnormal traffic conditions,we will quickly deal with the traffic information,timely notice the public and expand the scopes of notifications to provide sufficient basis information and sufficient decision-making time for traffic participants to make trip plans.