Abstract: The rate of traffic accidents at the entrance section of expressway tunnels is higher than that at other sections, especially the accidents of rear end collision and tunnel portal collision are frequent, which would easily cause mass casualties. In order to improve the traffic safety of the entrance section of expressway tunnel, the basic principle that the layout of traffic engineering facilities at the entrance section of tunnel should meet the space right of way, human factors and driving tasks is proposed based on the relevant provisions of the traffic engineering facilities in Technical Guide for Improving the Upgrade of Highway Tunnels. The typical problems of the tunnel entrance section mainly exist in the variable information board, sign information and guidance facilities, which include poor combination of sign information, improper location of traffic signs and discontinuous and inconsistent guidance information. And then the setting suggestions for the content, form and location of the sign at the entrance section are further proposed. It is determined that the visual environment transition at the entrance section of the tunnel can be enhanced by adding sight-line guidance facilities such as ring elevation mark, tunnel contour belt, warning linear guidance signs, flexible warning columns, and collision barrels. Finally, the improvement effect of traffic engineering facilities is evaluated based on the basic principles of space right of way, human factors, and driving tasks.

Key words: expressway tunnel, tunnel entrance, traffic engineering facilities, traffic safety, improvement countermeasure