Study On Reasonable Distance And Evaluation Of Elevated Expressway Exit Ramp And Downstream Intersection

With the continuous development of urban construction in our country,the urban elevated expressway,with its fast passing function,is more economical and applicable than the underground railway system,which makes it develop rapidly in various cities,and greatly improves the transportation service function of different districts of the city.At the same time,the increasing connection problem between expressway and old road system is also gradually highlighted.In cities with large traffic volume,the problem of traffic congestion in the junction section between expressway exit and ground road is becoming more and more serious,which leads to the obstruction of vehicles entering and leaving expressway,resulting in traffic congestion at the ground road of expressway entrance ramp and expressway exit ramp.When the expressway exit ramp is close to the downstream intersection of the ground road,it is easy to cause traffic congestion because of the unreasonable setting of the connecting section.This paper first defines the concept of the junction section between the exit ramp and the downstream intersection of the urban elevated expressway,analyzes the traffic organization forms of each component,and combines theoretical analysis with field investigation.By VISSIM simulation,the traffic characteristics of the connecting section of the investigation point are analyzed.According to the running process of vehicle,the reasonable length of transition section and interwoven area is obtained by combining the theory of acceptable gap,time-distance distribution of vehicle front and the theory of vehicle safety lane change.The rationality of the link section length is also closely related to the traffic capacity and the flow rate.By studying the capacity balance requirement of the link section of the exit ramp of the elevated expressway,the capacity of the link section and the downstream intersection is analyzed,and the key position is determined.From the point of view of traffic conflict,this paper optimizes the previous data screening principles and methods,uses python software to screen the conflict data,evaluates the link length of the survey points based on fuzzy evaluation,and obtains the recommendedvalue of the intersection length of the transition section based on traffic conflict.Finally,the optimal measures for the queue dissipation of the link section are put forward by combining the signal timing and traffic organization of the upstream and downstream intersections.This paper evaluates and studies the reasonable value of the connecting section length from the point of view of the running process,capacity and traffic safety of the connecting section.