Study on drivers’ visual and physiological characteristics after fire accidents in operational highway tunnels

In response to the problem that residual disasters from highway tunnel fires cause deterioration of the tunnel structure surface, which in turn affects drivers’ traffic behavior decisions and triggers driving safety risks, this study uses simulated driving technology to construct scenarios of tunnel structural damage after fires. It collects and analyzes drivers' eye movement data during driving, and uses factor analysis to establish a quantitative model of their mental workload based on eye movement indicators, thereby evaluating drivers' mental workload levels under different tunnel scenarios. The results show that when drivers pass through the tunnel sections affected by fire residues, the number of fixations, fixation frequency, and average fixation duration all increase, the saccade amplitude decreases, and the mental workload rises significantly—with more notable changes in unskilled drivers. After leaving these sections, all indicators gradually recover, but skilled drivers recover faster. In addition, the sections with fire residues lead to an average increase of 17.96% in the drivers’ heart rate variability, and the heart rate variability of skilled drivers is lower than that of unskilled drivers. This study provides theoretical and data support for tunnel reinforcement, repair, and operational safety management.