Research On Optimization Method Of Left-turn Non-motor Vehicles Traffic Organization Under Mixed Traffic Conditions

Urban intersection is the node of urban road network.Its safety performance and operation efficiency determine the overall operating state of road network.Because of its long distance and complex streamline,the left-turn non-motor vehicles flow mixed with bicycles and electric bicycles has many serious conflicts with the motor vehicles flow,which has an important influence on the operating state of the intersection.The optimization method of left-turn nonmotor vehicles traffic organization can not only improve the safety performance of the intersection,but also improve its operating efficiency,which has important practical significance.Based on the theory of traffic flow and traffic conflict,the optimization method of left-turn non-motor vehicles traffic organization under mixed traffic conditions is studied in this paper.On the basis of the actual investigation,this paper first studies the speed characteristics of bicycles and electric bicycles.With the arrival distribution of non-motor vehicles flow,the expansion characteristics is defined and the expansion width model of the non-motor vehicles flow is constructed.The conflict conditions between the expanded non-motor vehicles flow and the motor vehicles flow can be got based on the streamline equation of motor vehicles and non-motor vehicles.Secondly,this paper improves the conflict number prediction model of the straight going non-motor vehicles and constructs the cross conflict number model of left turn non-motor vehicles and motor vehicles.With the measured data,the parameters of the models are fitted and the rationality of the models are verified.Based on the acceptable cross time gap theory,the traffic capacity influence coefficient model of motor vehicles under motor-non-motor conflicts is constructed.The influence of non-motor vehicles occupying conflict zone on the initial stage of green light and non-motor vehicles crossing conflict zone to the traffic capacity of motor vehicles is quantitatively described.Thirdly,the expansion conflict model of left-turn non-motor vehicles and left-turn motor vehicles on the entrance lanes of the same direction is constructed and fitted.The relationship between the maximum lateral width of left-turn non-motor vehicles and the delay of motor vehicles is analyzed by video data.Also,the traffic capacity influence coefficient model of leftturn motor vehicles under different maximum lateral width of left-turn non-motor vehicles is calculated.Finally,set four-phase signalized intersection as example,the conflict number model of left turn non-motor vehicles and the traffic capacity influence coefficient model of conflicting motor vehicles are constructed under the direct left-turn method and four optimization models.From the perspective of traffic safety and traffic efficiency,each method is compared and the applicable conditions of each optimization method from the perspective of overall optimization are analyzed.Choose an actual intersection as example to theoretical optimize and the VISSIM simulation software is used for modeling and simulation,which proves the scientificity of the optimization method.In this paper,the optimization method of left-turn non-motor vehicle traffic organization under mixed traffic conditions has certain practical value,which can be helpful to the theory and application of traffic organization at intersections.