Research on drivers’ color preference for alert zones in extra long tunnels and its effect on fatigue relief

To address driver fatigue caused by the monotonous visual environment in long tunnels in mountainous areas, this study aims to investigate the effect of tunnel alert segment lighting (red, blue, yellow, and white) on alleviating driver physiological fatigue and enhancing alertness and provide theoretical and empirical evidence for the optimal design of tunnel lighting. A driving simulation test was conducted to simulate a long tunnel environment. Four background luminous colors (red, blue, yellow, and white) were tested. Drivers' physiological indicators (HRV) and Karolinska Sleepiness Scale (KSS) were recorded. The HRV indicators changes under each lighting condition were analyzed using the non-parametric Wilcoxon test to quantitatively assess the effects of the lighting colors on physiological fatigue reduction and alertness enhancement. The driving simulation test revealed that blue background light significantly enhanced driver alertness, followed by red and yellow background lights, which showed the second most pronounced effects. In contrast, white background light did not significantly improve fatigue indicators. The highest levels of fatigue were observed in the non-alert zone of the tunnel, highlighting the necessity for background color interventions. Blue background light proved to be the most effective in alleviating driver fatigue in the alert zones of long tunnels. Therefore, it is recommended that blue background light be prioritized in tunnel safety lighting design. The study provides scientific evidence for optimizing human factors in tunnel lighting environments. Future research should verify the long-term effectiveness of these interventions in real-world road conditions.