Comprehensive Evaluation of Visual Guiding Systems for Enhancing Traffic Safety in Freeway Tunnels: An Improved Matter-Element Method with Case Study

Provision of visual guiding facilities to improve traffic safety is in disarray. This paper proposes a comprehensive system for evaluating the effectiveness of visual guiding facilities in freeway tunnels. Aimed at addressing the current problems, this paper presents an evaluation system based on three key factors: spatial right-of-way, driving human factors, and driving performance. To evaluate the proposed system, data were collected in tunnels under varying conditions during daytime and nighttime, before and after improvement. The evaluation system categorized spatial right-of-way into lateral, longitudinal, and vertical aspects, which mainly depend on the installation of visual guiding facilities. Driving human factors were evaluated based on visual performance, and the installation method of visual facilities focused on sight distance, sight zone, and visual load. Driving performance was also evaluated by considering vehicle operational characteristics, including the maintaining of speed, distance, and lane. The results demonstrated a considerable improvement in the evaluation level of the visual guiding system, achieving Level B compared with traditional improvement schemes during both daytime and nighttime scenarios. This evaluation system could be a valuable guide for managing and designing traffic engineering in tunnels.