Research On Traffic Safety Risk Assessment Of Freeway Tunnel Sections In Mountain Areas

With the continuous improvement of China’s freeway network,freeway construction gradually extends to mountainous areas,and the number of tunnels increases continuously.Mountainous freeway has complex and changeable climatic environment,and there are many unfavorable combinations such as steep bends and steep slopes,as well as the special space environment of the tunnel itself,which makes the traffic accidents of the tunnel section prone to occur and cause serious accident consequences.Based on the traffic accident data of highway tunnel section in mountainous area,in view of the current situation that the safety risk assessment system of highway tunnel section in mountainous area is not perfect,this thesis carries out the following research from the cause mechanism,risk level evaluation and traffic safety guarantee technology of tunnel section.Firstly,traffic accident sections of freeway tunnels in mountainous areas are divided into three dimensions: accident time,accident space and accident form.Distribution law of traffic accidents in tunnel sections is analyzed and generation mechanism of traffic accidents is explored.By means of real-vehicle driving,the actual traffic operation conditions such as road alignment and traffic volume of tunnel section are investigated,vehicle speed data of tunnel section are collected,and the distribution of operating speed and the law of speed dispersion on traffic safety in tunnel sections are analyzed.Secondly,in order to analyze the potential law of traffic accident in tunnel section of mountainous expressway,based on The R Programming Language,Apriori association rule algorithm is adopted to clean up and transform the original data set,and then the association rules are excavated from two perspectives of accident causal orientation relationship and accident cause interaction relationship by constraining left hand side and right hand side.The interpretation and analysis of association rules indicate that when the longitudinal slope of a tunnel section is large,it can easily lead to serious traffic accident consequences and road property losses,and there is a potential correlation between accident consequences and road anti slip performance.Accident black spot often have lower anti slip performance indicators.Then,evaluation indicators were selected based on the identified risk causal attributes,and a tunnel traffic safety evaluation index system was established.Referring to relevant specifications and research results,the range of indicator values and the criteria for dividing the grade interval were determined.Through the combination of information entropy theory and CRITIC method,the objective weight of each evaluation index is determined.According to the extension matter-element theory and set pair analysis theory,two tunnel traffic safety evaluation models are established respectively to realize the discrimination of traffic safety risk grade of mountain expressway tunnels.Finally,taking the tunnel section of an expressway in Yunnan Province as an example,the extension matter element model and set pair analysis model are used to evaluate and compare the traffic safety risk.It is found that the evaluation results of the two models are basically the same,and there are many similarities in principle.In the actual evaluation application,attention should be paid to the influence of the position of the maximum value point of the membership function on the evaluation results.In addition,based on the results of the tunnel risk assessment,the tunnel traffic safety risk response scheme was determined.By comparing the risk changes before and after the improvement measures,the effectiveness of the improvement scheme and measures was verified,which provided the basis for taking scientific improvement measures for the traffic safety of highway tunnels in mountainous areas.