Study On The Speed Limit Of Long Steep Downgrades And Freeway Tunnels

With the continuous expansion of the scale of highway construction,especially in the western mountainous highway construction process,the emergence of many tunnel group.Highway traffic accidents occur frequently,according to public security traffic management statistics,in addition to vehicle and technical factors,the highway traffic accident is the main reason for the vehicle speeding.Tunnel as a special structure of the section,the long tube shape space and closed,so that the traffic environment is complex,resulting in tunnel accidents,especially major accidents occurred,reasonable vehicle speed has become the western mountain highway management outstanding problem.Based on the measured data of tunnel group and the results of domestic and foreign research,the paper first gives the concept of different speed,and then from the slope,slope length The factors such as the visual characteristics,the road shape,the ambient noise,the traffic volume and the weather conditions,and so on.The factors influencing the speed of the tunnel group are analyzed,and the long-Downhill Tunnel Group Operation Speed Impact Assessment List.Then,according to the different operating environment of the vehicle,the mountainous highway tunnel group is divided into two types: general road section and special road section.The design speed,road line and traffic accident history are selected as the influencing factors,and the theory of speed limit is put forward.model.From the speed limit process,put forward the general sections and special sections of the road.This paper puts forward a comprehensive decision-making model of speed limit,and puts forward the long-term comprehensive decision-making model.Based on the analysis and comparison of the maximum recommended speed limit,the proposed low-speed tunnels and the speed limit,The concrete implementation flow of the speed limit of the slope tunnel group.Finally,considering the change of driving risk of each risk characteristic point of the expressway tunnel(tunnel),the tunnel group is divided into several unit sections composed of a single tunnel,each tunnel is divided into six characteristic points,combined with the traffic simulation software VISSIM,The velocity model of the tunnel group is established,and the model is compared with the actual collection data of the tunnel group of Qinglan Expressway,and the accuracy of the model is demonstrated.The proposed method is applied to the actual section of the project-Yaozhai tunnel section,and the proposed speed limit and speed limit method and speed limit safety improvement measures are given.