Impact of sidewall information on drivers' visual load among different lanes: Traditional guiding facilities and decorated pattern.

Objectives: This research aims to: (i) compare the effects of different sidewall entrainment facilities on drivers' visual behavior; (ii) compare the effects of the same sight entrainment facilities on drivers in different lanes; (iii) give recommendations for engineering applications based on the results of the study.

Methods: The study designed four different scenes, each with symmetrically designed visual facilities on the both sidewalls of the tunnel, scene a represents a typical urban tunnel in China (horizontal stripes on sidewalls), scene b includes vertical stripes on sidewalls in addition to scene a, scene c introduces an LED-arch based on scene b, and scene d features a rhythmic pattern (Wave pattern on sidewalls). 30 participants, 21 men and 9 women, aged 21-54, drove the four scenes. Eye movement data of participants in each lane for different scenes were collected using an eye-tracking device. Visual performance indicators including fixation duration, number of fixations, saccade duration, and saccade amplitude were utilized to comprehensively evaluate drivers' visual behavior. Factor analysis was employed to analyze the impact of different visual guiding facilities on drivers' visual searching abilities.

Results: There is a significant effect of sidewall guiding facilities and lane location on drivers' visual behavior and loading. Across scenes, drivers' visual load is ranked as follows, from highest to lowest: scene a (baseline) > scene b (horizontal stripes added to scene a) > scene c (LED-arch added to scene b) > scene d (Wave pattern). Furthermore, under the same scene, drivers' visual load in each lane is ranked in descending order: Middle lane > Right lane > Left lane.

Conclusion: Due to the effect of the tunnel structure on the drivers' visual field, drivers in the left lane have the highest visual load in any scenario compared to the other two lanes, which can be ameliorated but not eliminated. Traditional guiding facilities and decorated pattern both improve the visual behavior and reduce drivers' visual load in urban tunnels, especially in scene c and scene d, but scene d should not be used for the entire length of the tunnel in order to prevent driver distraction. In engineering practice, scene c (LED-arch added to scene b) can be set up in general sections of urban tunnels, and decorated pattern can be added to fatigue reminder regions to alleviate driving fatigue.