Research on the coordinated setting and evaluation model of variable speed limit signs and visual deceleration markings at the entrance section of undersea tunnels.

To improve traffic safety at the entrance section of undersea tunnels, this research analyzes the effectiveness of the coordinated setting of variable speed limit signs(VSLs) and visual deceleration markings(VDMs) at the entrance section of the undersea tunnels. This research sets various parameters of VSLs and VDMs under the condition of a speed limit of 80 km/h. Twelve types of coordinated schemes of VSLs and VDMs are set. Qingdao Jiaozhou Bay Undersea Tunnel entrance section was simulated using modeling tools such as UC-win/Road and Sketch Up. Twenty-four drivers were invited to conduct simulation experiments, and the vehicle speed reduction rate, vehicle deceleration, driver gaze point proportion, and pupil diameter data were collected. This research constructs an effectiveness evaluation model of the coordinated schemes on the basis of the entropy weight method and the matter-element extension model. The data analysis results show that as the coordinated distance between the VDMs and the VSLs increases, the vehicle speed reduction rate, vehicle deceleration, driver's gaze point proportion, and pupil diameter all increase accordingly. The effectiveness evaluation model results show that there are six schemes at the "good" and above level. The overall effectiveness is optimal for the scheme where the end of the VDMs is located 40 m behind the VSLs and the VDMs is a fishbone deceleration marking. This research quantified the effectiveness of the coordinated setting of VSLs and VDMs at the undersea tunnel entrance section on driving safety. The results provide practical guidance for the design of undersea tunnel entrance section, indicating that the proper setting of traffic signs and markings can effectively control vehicle speeds and significantly improve tunnel traffic safety.