Improving driving safety in freeway tunnels: A field study of linear visual guiding facilities

This study endeavors to assess the efficacy of retroreflective linear visual guiding facilities in enhancing traffic safety within freeway tunnels. While simulation tests have traditionally served as the primary means for investigating traffic engineering solutions aimed at improving driving behaviors within tunnels, empirical studies validating these methods in real tunnel environments have been notably lacking. To bridge this research gap, our study developed two cost-effective linear visual guiding facilities equipped with retroreflective features and evaluated their effectiveness in authentic freeway tunnel settings. We employed various indicators, including visual behaviors such as the speed of pupil area change and the distribution time of gaze points, as well as driving behaviors encompassing speed and lateral deviation, to assess the impact of these facilities on drivers. Our findings unequivocally demonstrate that the integration of linear visual guiding facilities significantly enhances driving safety within tunnels compared to conventional facilities. Specifically, the speed of pupil area change decreases, while the distribution time of gaze points increases following the implementation of linear visual guiding facilities. Moreover, we observe mitigations in the speed differentials among vehicles, both within and between tunnel zones, alongside reductions in vehicular lateral deviations. The synergistic deployment of linear visual guiding facilities in conjunction with conventional delineators and raised pavement markers can expedite visual perception, promote accurate driving decisions, and facilitate the safe passage of vehicles through tunnels. In conclusion, our study has proved that retroreflective linear visual guiding facilities effectively can enhance driving safety in freeway tunnels.