Strategies Of Inputting Multi-ramp Coordinated Control Signal For Urban Expressway Under Accident Condition

Urban expressway with its fast speed,large capacity and other characteristics has become the skeleton of urban road traffic system.Traffic accident is one of the main causes of traffic congestion in urban expressway networks.According to different traffic accidents and the actual traffic demand,take reasonable coordinated control signals strategy,as far as possible to improve traffic flow is one of the urgent problems,especially in the morning and evening rush hours,traffic demand of urban expressway is greater,its relatively closed to increase the difficulty of handling the accident,the impact of the accident time may be longer;upstream of the affected vehicle alternative path road is less,so the accident influence scope will be more widely.In the aspect of theory,although there are some studies on road coordination control,it is aimed at the general traffic congestion don't involve the strategies problem of inputting ramp coordinated control signal under the traffic accident.Based on this,this paper studies the urban expressway as the research object,through the investigation and analysis of the influencing factors of the possible adjustment of the driver's path,determine the probability of driver's path change under different conditions,establishment of coordinated control of urban expressway CAM(Cellular Automaton Model),the traffic flow characteristics of different ramp coordinated control signals are simulated,and the optimal strategy is determined to provide some decision support for traffic management.The main work can be summarized as the following aspects:(1)Analysis of urban expressway traffic system under accident.Traffic flow characteristics of urban expressway are analyzed,and the influence of traffic accidents on road traffic flow is discussed.This paper discusses the structure and the principle of the coordinated control system on the urban expressway.(2)Investigation and analysis on the driving behavior of urban expressway.At first,an investigation and analysis on the influencing factors of the possible adjustment of the driver's path based on the method of stated preference survey,determine the probability of driver's path change under different conditions.Then the analysis of driver's characteristics,driving behavior and the path changes under the accident were analyzed,provide the determination of the parameters in the following CAM.(3)Setting up CAM for Urban expressway.Based on the symmetric two-lane Nagel-Schreckenberg(STNS)model,this paper combined with the results of the questionnaire survey,the basic STNS model are development,improvement and refinement,the coordinated control of multi ramp metering in urban expressway,which is composed of multi ramp(including inlet and outlet),overpass and main line connected is established.The algorithm of multi ramp coordinated controller for urban expressway is discussed.(4)Strategies of inputtingcoordinated ramp control signal forurban expressway under accident condition.In the case of a single lane traffic accident,two lane traffic accidents,under different traffic demands,the multi-ramp coordinated control are simulated and analyzed,and the optimal control signal is determined by the goal of enhancing road actual traffic volume.