Study On Safe Technical Measures At Transition Section Of Import And Export In The Road Tunnel

Because of the tunnel option shortened mileage, improve the advantages of linearstandards, protection of natural environment; it has been used in the mountainous highwaymore and more. But in the process of tunnel operators, there is a big problem of road safety ata section of import and export transition of a tunnel. Traffic accidents have increasedsteadily. It deeply influences to the tunnel’s normal operation. Therefore a variety design andmeasures of the import and export transition in highway tunnel based on traffic safety isa very important and urgent problem.Through analysis of highway tunnel traffic accident statistics to determine that thesections of import and export transition of a tunnel are the frequent accident parts. This partcontains the entrance outside tunnel portal200m inside the portal300m and the exit sectionof tunnel portal100m outside the portal200m.The linear design, waterproofing anddrainage design, traffic signs and management is the key to the impact of theaccident, Analysis the horizontal alignment and longitudinal linear, give outreasonably linear indexes, the generally minimum radius of flat curve at import andexport transition in a tunnel; the minimum distance between the tunnel hole and the point oflongitudinal slope changed; on each design speed, the idea maximum vertical gradient in thefront of tunnel import with the tunnel’s speed limited; drainage measures requirements andrecommendations of import and export; how to set traffic signs and facilities at thefour different segments including outside and inside of import and export, and give asuggestion of maintenance approach which think from the roads, and management. Provide areference for the highway tunnel construction.