Study On Traffic Safety Analysis And Improvement Methods Of Urban Road At Close-quarter Intersections Based On Traffic Conflict

Intersections are an important part of the urban road system and are the throat of road traffic.Vehicle traffic repeatedly diverts,merges,changes lanes at intersections.Conflicts occur,close-quarter intersections are special combinations of intersections.All traffic flows play an important role.At present,the research on close-quarter intersections is still lacking.The existing research is mainly on the impact of the static attribute of road conditions on the conflict,and the lack of the dynamic attributes of traffic conditions such as flow and speed on the conflict.This article takes urban roads close-quarter intersections as the research object,and aims to reduce the severity of traffic conflicts,improve traffic efficiency and traffic safety,and verify the improvement effects through simulation platforms.Firstly this article defines the close-quarter intersections,analyzes the traffic operation characteristics of the close-quarter intersections from traffic flow parameters such as vehicle speed,headway time,and traffic density,and uses the measured data for chi-square fitting goodness test and MAPE value calibration VISSIM software and SSAM The main parameter threshold of the software,on this condition,analyzes the traffic conflict type characteristics and regional characteristics of close-quarter intersections,and calculates the capacity of close-quarter intersections to provide a basis for calculating road saturation.Secondly,carry out a traffic survey on the combination of two close-quarter intersections in the Nan’an area.After the simulation,the model validity test is carried out.The gray correlation model is used to calculate the comprehensive correlation of the factors affecting the traffic conflict at different times,and the strong correlation factors are drawn from large to small.In order of intersection spacing,V/C,vehicle speed,traffic composition and number of lanes,analyze the relationship between each safety influencing factor and traffic conflict and verify the correlation,and get the weight of each safety influencing factor through XGBoost calculation.Then,the traffic conflict intensity model of the close-quarter intersections is established,and the relationship between the traffic conflict index and the traffic operation index is analyzed using the typical correlation to quantify the threshold value of the traffic conflict time intensity M_TITC at the close intersection is 5.5 times/（veh·h）.The gray clustering assessment model is used to classify the four close-grade intersection hazard levels as good,mild,moderate and severe according to the degree of conflict.Use the ordered probability model to determine the influencing factors of conflict severity,and use the marginal effect to calculate its direction and magnitude.Taking different combinations of close-quarter intersections as the starting point,we will clarify the implementation of different improvement methods for different close-quarter intersections,and describe in detail the implementation of each improvement method.The combination of misaligned intersections and double T-shaped intersections uses left-turning and right-channelization Method:The hybrid and double cross intersections use the array traffic control method to determine the respective applicable conditions of left-turn right and array traffic control.Finally,a simulation platform was built to simulate the combination of different types of intersections in the Nan’an,and the corresponding improvement methods were used to verify the examples and verify the conflict status before and after the improvement.The results show that the improvement measures for different types of close-quarter intersections combinations can effectively alleviate the serious traffic conflict problem.The research results of this paper can provide a reference for the design of left-turn and right-turn at close-quarter intersections.The traffic conflict intensity method can be used to energy-analyze the state of traffic conflicts at the intersections of close-quarter intersections of urban roads,which can be used to find serious traffic conflicts at close-quarter intersections of urban road networks.Road sections,and the right-turn design of the left-turn lane can effectively improve traffic safety at close-quarter intersections.