Research On Traffic Safety Evaluation About Entrance Section Of Expressway Tunnel

With the development of our national economy,the construction of expressway network is becoming more and more perfect.Especially in the mountainous southwest region,where tunnels occupy a large part of the expressway network.Highway tunnel group has a higher accident rate than other sections,especially in the tunnel entrance and exit zone,which not only has a higher accident rate,but also has a higher accident severity.Due to the geometric alignment and traffic operation characteristics of the highway tunnel entrance section are complex,so how to evaluate the traffic safety about these sections and ensure the safe operation of vehicles have become one of the significant topics studied by highway management department and traffic safety scholar.Therefore,the study about tunnel entrance section safety,judgment about the potential safety hazards and enhancing the traffic safety level about tunnel entrance section are of great practical and practical significance for reducing the traffic accident rate in the region.In this paper,for the problem of the safety evaluation of highway tunnel entrance area,the new evaluation method are given based on linear elements and traffic conflict technology.The research content of this paper consists of the five aspects:Firstly,through analyzing the research achievement and standard specifications about tunnel entrance sections,this paper would classify the tunnel entrance according to the connection characteristics,and analyse the space-time research scope of tunnel entrance and the spatial-temporal distribution rule of traffic accidents.Secondly,analyzing the reasons affecting the safety of highway tunnel entrance section from the road geometric alignment elements,environmental conditions,traffic operation characteristics,operation management and other factors,meanwhile,the formation mechanism and causes of traffic accidents would be analyzed.Thirdly,in response to the fact that the safety level of highway alignment factors under different design speeds has not been quantitatively studied.This paper would propose the model based on the logistic regression theory,and the specific equation would be calibrated by the mathematical statistics software SPSS and its applicability tested;the influence relationship among the road alignment indexes would be analyzed by the reliability theory,and the evaluation methods of tunnel entrance road would be established.In addition the traffic safety evaluation grade would be given.Fourthly,according to the formation mechanism of traffic conflict,the impact index of traffic conflict in confluence area would be selected,and the numerical value of simulation input would be determined by orthogonal experiment.Besides the traffic conflict data would be obtained by VISSIM and SSAM simulation,the parameters of traffic conflict prediction model would be calibrated by SPASS,the applicability of the model and the distribution form of traffic conflict number woud be tested.According to the result of test,the criteria of traffic safety evaluation in confluence area belongs to Poisson distribution.Finally,the related entrance section of highway tunnel would be selected,and the traffic safety situation in this area is evaluated.