Study On Evaluation And Scheme Selection Of Left-turn Non-motor Vehicle Traffic Organization At Two-phase Intersections

In recent years,with the further promotion of city green travel concept and the development of Shared cycling,the number of non-motor vehicles on urban roads is also increasing.Tt brings to people in the travel convenience,at the same time also can contend with motor vehicles over time and space resources,the cause of the traffic safety and traffic efficiency problems began.China’s "Regulations on the Implementation of Road Traffic Safety Law" stipulates that "when turning left,turn right at the junction center point",that is,non-motor vehicles directly use the "big turn" to turn left at the intersection.However,as some within the city intersection now rising number of motor vehicles and non-motor vehicles,machine the conflict within the intersection is also growing.Some cities put forward "non-motor vehicles twice crossing the" new left,the way in reducing machine of conflict but at the same time increase the non-motor vehicles around and waiting for the signal frequency and length.There are few studies on the respective costs and applicable conditions of traditional non-motor vehicle direct left turn and second crossing.In this regard,this paper takes the left-turn non-motor vehicle at a two-phase intersection as the research object,and establishes the operating cost model to analyze the operating cost of left-turn non-motor vehicle under different traffic organization methods from the perspectives of traffic safety and traffic efficiency.On this basis,the threshold of choosing traffic organization mode under different traffic flow composition is determined to obtain the optimal traffic organization mode of non-motor vehicle.The main research contents and conclusions of this paper are as follows:(1)By studying the driving process of the non-motor vehicle in the two modes of direct left turn and second crossing,the types and quantity of traffic conflicts and the length of various delays under different traffic organization modes are obtained.Based on the actual survey data,the basic parameters of the signalized intersection and the traffic flow characteristics of motor vehicles and non-motor vehicles in the intersection are determined.(2)Based on the basic theories such as traffic conflict theory and queuing theory,the safety cost and delay cost are linked by economic loss per unit accident and time cost per capita to determine the total operating cost of non-motor vehicles under different left-turn modes.Matlab programming was used to design the solution algorithm to compare the total operating costs of non-motor vehicles with different traffic organization modes under different traffic flow conditions.The results show that the total operating cost of the two organizational modes of turning left and crossing the street will increase with the increase of the flow of motor vehicles and non-motor vehicles,but the growth rate is different.In the case of small motor vehicle and non-motor vehicle flow,the total operating cost of direct left-turn of non-motor vehicle will be lower than the total operating cost of the double-crossing mode;when the traffic flow at the intersection is large,the total operating cost of the double-crossing mode will be lower than the direct left-turn mode.Through cost comparison and data fitting,this paper also gives the threshold value of non-motor vehicle left-turn mode selection under different traffic flow conditions.(3)The traffic data of the intersection of Yannan Road and Yanxi Road in Chengguan District of Lanzhou city is selected.The traffic simulation software VISSIM is used to measure the actual intersection in different left-turn ways and verify the threshold function.The study found that according to the actual traffic flow of motor vehicles and non-motor vehicles on the road,the optimized traffic organization mode was selected by using the threshold function.It can reduce the total operating cost of the surveyed intersection by 13.4%.