Study On The Spatial Distribution Characteristic And Safety Of Traffic Conflict In Merging Area Of Arterial Road

The arterial road merging area is a special area formed by auxiliary roads connecting the main roads in urban roads.There is a higher likelihood of traffic conflicts or accidents in the merging area due to the frequency with which vehicles change lanes and speeds,the complexity of the traffic environment,and the different traffic flow characteristics from the basic road section.This has a significant impact on how smoothly traffic moves along the main road.A vital component of the urban road system,the main road connects the city’s major thoroughfares and serves as a vital link in the network.Understanding the characteristics of traffic conflicts in the merging area of major roads,analyzing their spatial distribution and influencing factors,developing an internal risk identification model in the confluence area,and implementing targeted improvement measures are all necessary to increase traffic safety.Therefore,based on Traffic Conflict Technique(TCT),this thesis analyzes the spatial distribution of rear-end collision and side collision conflicts in the merging area,analyzes the impact of traffic volume and traffic composition on the spatial distribution,establishes the internal risk identification model of the merging area based on the principal component analysis method,establishes a polynomial interpolated lane change trajectory model according to the vehicle trajectory to determine the length of the gradient segment of the acceleration lane,and determines the length and width of the acceleration lane according to the simulation model.Firstly,the scope of research on the merging area of the main trunk road is divided.The merging zone is categorized based on the type of acceleration lane,and the parallel acceleration lane merging area is chosen as the research subject.With the aid of traffic conflict technology,the traffic conflict in the merging area is defined,and the conflict formation process is introduced.The forms of traffic conflicts in the merging area are classified according to the angle and severity of conflicts,and the characteristics and efficacy of traffic conflict techniques are examined.Time to Collision(TTC)was chosen as the conflict discrimination index for this study by the introduction of various widely used traffic conflict indicators,and the cumulative frequency curve approach was chosen as the method for judging the severity of traffic conflicts.Secondly,a specific merging area of Jingshi Road was chosen as the site for data collecting after taking into account the survey conditions at the time and the objectives of the study.The process for determining a traffic conflict is described.The video tracking program Tracker is used to preprocess the video that was captured by the drone.The TTC index of rear-end collision and side collision is calculated,and the severity threshold of rear-end collision and side collision conflict is determined using the 85% cumulative frequency curve method.According to the results of the threshold determination,the distribution of lanes in each section of the rear-end collision conflict and side collision conflict space in the main trunk road merging area was statistically analyzed,and the impact of traffic volume and composition on the spatial distribution of rear-end collision conflict and side collision conflict was examined.Thirdly,in order to identify the internal risk of the confluence zone,the principal component analysis method was selected as the main body of the internal risk identification model in the confluence zone by comparing the advantages and disadvantages of several common risk model construction methods.The segmentation method is used to split the confluence zone and make model creation easier.The risk categories utilized to replace the conventional single conflict risk index are general rear-end collision conflict,serious rear-end collision conflict,general side collision conflict,severe side collision conflict,traffic conflict equivalent ratio,and serious traffic conflict equivalent ratio.The steps of constructing the internal risk identification model of the merging area are given,the comprehensive risk evaluation value is calculated,and the internal risk level of the confluence area is evaluated according to the results.Through the analysis of the current traffic situation,the effectiveness of the model is verified.Finally,the design characteristics of the acceleration lane are chosen as the optimization target based on the analysis of traffic conflict distribution and risk identification model results in the merging region.The length of the gradient segment of the acceleration lane is calculated using the vehicle trajectory and the built trajectory model,and a polynomial interpolated lane change trajectory model is established for the trajectory of the merging vehicle entering the main road from the acceleration lane.The best length and width of the acceleration lane are identified through the calibration of the VISSIM and SSAM software parameters,which is done on the basis of determining the gradient segment.The orthogonal experimental method is then used to simulate traffic operation under various traffic organization patterns multiple times.The findings indicate that the optimized acceleration lane can greatly lower the likelihood of traffic collisions in the merging area,and the pertinent findings can offer some theoretical support for raising the arterial road’s safety level.