Research On Traffic Conflict Prediction And Safety Assessment Method In Merging Area Of Expressway Interchange

Urban expressways carry more and more motor vehicle traffic,provide services for citizens’ long-distance travel,and plays a very important role in solving urban traffic congestion.In the urban transportation system,The merging area of expressway interchange is the main node connecting the expressway and other roads.The driving characteristics of vehicles in the merging area are more complicated,and the vehicles are more likely to have mutual influence.Moreover,the structure of the merging area is different,and traffic accidents often occur.Therefore,it is necessary to understand the characteristics of traffic flow in the merging area and analyze the main reasons that affect traffic safety.In order to avoid the inherent shortcomings of traffic accident data,this paper conducts traffic conflict prediction and safety evaluation in the merging area of urban expressway interchanges,and proposes corresponding improvement methods.First of all,this article takes the merging area of expressway interchanges as the research object and determines the specific research scope.This paper analyzes the driving laws of vehicles in the merging area in depth,uses the use of traffic conflict technology to determine the concept of traffic conflict in the merging area,and analyzes the effectiveness of the conflict technology.This paper studies the whole process of conflict formation and classifies it;sorts out and compares several conflict indicators,and selects Time to Collision(TTC)to measure the traffic conflict in the merging area of interchanges.Secondly,according to the research purpose and existing investigation conditions,Banpo Interchange,Intersection of Zhuhong Road and North Second Ring Road were selected as the case sites.Combining drone aerial photography and manual observation,the traffic data collection and traffic conflict observation during peak periods are combined from a subjective and objective perspective.Based on the traffic data,this paper explores the characteristics of the traffic flow in the merging area,determines the threshold and location distribution of various types of traffic conflicts of different severity,and summarizes the influencing factors of traffic conflicts.Third,in order to deeply study the characteristics of motor vehicles in the merging area,this paper uses VISSIM software to simulate the merging of vehicles in different road geometric parameters and traffic flow parameters.With the help of SSAM software,the vehicle trajectory is processed,and the traffic conflicts under different simulation conditions are obtained in this paper.This article further quantifies the relationship between various influencing factors and traffic conflicts.On this basis,this paper constructs the prediction model of total conflict and severe conflict,and verifies it with measured data.Finally,the total conflict rate of main line vehicles,the serious conflict rate of main line vehicles,the total conflict rate of ramp vehicles,and the serious conflict rate of ramp vehicles are used as evaluation indicators.Based on the improved gray clustering safety evaluation model,this paper determines the safety level of each merging area and proposes Improved measures.