Abstract:

The construction speed and number of vehicles passing through multi-portal underpass tunnels are increasing, and special driving environments such as long downhill slopes at the portals and underground merging areas cause frequent traffic accidents. To deeply analyze the variation characteristics of lateral offset in tunnel special sections, a test vehicle equipped with inertial navigation and Mobileye was used to perform a real-car natural driving test in a typical multi-entry underpass tunnel. Based on the tunnel's alignment and spatial variation characteristics, the test section was divided into the external tunnel section, the downhill section, the internal section, the underground merging section, and the internal tunnel section. The results indicated that the vehicle trajectories in the other four sections were more complex than the external section of the tunnel, and the lateral offset increased significantly, reaching up to 1.888 to 2.184 times the external section of the tunnel. The lane offset variation rate of the underground merging section and the inner section of the entrance was the smallest. The land discreteness of the underground merging section in the tunnel was the largest, and the discreteness of the entrance downhill section was the smallest with a standard deviation of only 0.111. The average width of the predicted interval of the entrance downhill and underground merging sections were 0.2 m and 0.24 m, respectively. Therefore, the driving safety hazards of the entrance downhill and underground merging sections were higher than other sections.

Key words: Multi-entry underpass tunnel, underground merging area, lateral offset, tunnel entrance, traffic safety