Unraveling the impact of fog on driver behavior in highway tunnel entrances: A field experiment.

OBJECTIVES: This research aims to (1) study the visual and psychological characteristics of drivers in foggy tunnel entrances, (2) compare driver behavior inside and outside foggy tunnels, and (3) propose improvement ideas based on the study results. METHODS: A realistic vehicle trial was conducted. Eight participants completed trials in both foggy and clear zones on the same roadway. Drivers' physiological and psychological properties were analyzed using gaze, saccade, pupil, and heart rate as primary indicators. Pupil area change rate and heart rate variability (HRV) were used as secondary indicators. RESULTS: Visibility and tunnel area had a significant impact on drivers' visual and psychological traits. For instance, drivers in the foggy zone exhibited longer fixation duration, larger pupil area, faster heart rate, and greater HRV. Moreover, the foggy zone inside the tunnel heightened drivers' visual discomfort and psychological tension. CONCLUSION: The study suggests a high risk associated with driving in the entrance area of highway tunnels during foggy conditions, particularly after entering the tunnel. This situation significantly increases drivers' visual and psychological load. Furthermore, the effectiveness of retro-reflective facilities diminishes. Therefore, employing more self-illuminated or actively illuminated visual guiding facilities is recommended to aid drivers in acquiring traffic information.

Evaluation of traffic signs information volume at highway tunnel entrance zone based on the visual sample entropy of novice and experienced drivers.

OBJECTIVE: Traffic signs play a crucial role in ensuring road traffic safety, particularly in high-risk driving zones like the entrance zone of highway tunnels. However, the impact of traffic signs information volume (TSIV) on the performance of experienced and novice drivers in this specific zone remains unclear. This study aims to investigate the influence of TSIV on the visual sample entropy (SampEn) of both experienced and novice drivers in the entrance zone of highway tunnels. METHODS: A real vehicle driving trial was conducted with 60 participants approaching tunnels under various TSIV conditions. Fixation duration SampEn, saccade duration SampEn, and saccade amplitude SampEn were analyzed for both driver groups. RESULTS: As both driver groups approached the tunnel entrance, fixation duration SampEn, saccade duration SampEn, and saccade amplitude SampEn gradually increased. Initially, visual SampEn declined, followed by an increase as the TSIV level increased. The lowest value of visual SampEn was observed under the T3 TSIV condition (48.31 bits). Experienced drivers exhibited lower visual SampEn compared to novice drivers under similar TSIV conditions. CONCLUSIONS: TSIV and driving experience significantly influence the visual SampEn of drivers approaching the tunnel entrance. Optimal visual search patterns and performance were observed under the T3 TSIV condition (48.31 bits), which is critical for ensuring driving safety in the entrance zone of highway tunnels. Additionally, experienced drivers demonstrate better adaptation to tunnel environments and TSIV, while novice drivers may benefit from additional training to enhance their visual perception and performance.