Assessing cognitive load in drivers during tunnel approach under combined fog and nighttime conditions based on fixation behavior.

OBJECTIVE: This study aims to investigate the impact of combined fog and nighttime conditions on drivers' cognitive load during tunnel approach, as reflected through fixation behavior. Specifically, it examines how these compounded adverse conditions influence visual attention patterns, including fixation duration, frequency, and spatial dispersion. METHODS: tests were employed to compare these metrics across scenarios. CONCLUSIONS: The combined effects of fog and nighttime conditions significantly elevate drivers' cognitive load during tunnel approaches, manifesting as prolonged information processing, reduced attentional shifting, lateral visual field narrowing, and compensatory vertical search. These findings confirm the sensitivity of fixation-based metrics as indicators of cognitive load under compounded environmental stressors. The study provides empirical evidence for developing context-aware safety interventions, such as optimized tunnel lighting, adaptive traffic management, and enhanced driver assistance systems, tailored to mitigate cognitive overload in high-risk driving scenarios.