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BACKGROUND: The effects of traffic sign information volume (TSIV) on the visual characteristics and workload of novice and experienced drivers were investigated in this study. TSIV plays a crucial role in road traffic safety, and understanding its impact on drivers is essential for designing effective traffic sign systems. OBJECTIVE: This research aimed to compare the visual characteristics and workload of novice and experienced drivers under varying TSIV doses through simulated driving tests. The objective was to provide insights for optimizing the design of road TSIV. METHODS: Six TSIV levels were considered: S0, S1, S2, S3, S4, and S5, representing different workload levels. Participants, including both novice and experienced drivers, were involved in simulated driving scenarios with varying TSIV levels. Eye movement data was collected using an eye tracker device. The study was conducted in China, and appropriate driving simulators and equipment were utilized. RESULTS: The findings revealed several valuable results. Experienced drivers exhibited a higher proportion of saccade behavior in the 30–90 ms time period and did not show rapid saccade behavior during the 0–30 ms period, indicating superior visual search strategies. Both novice and experienced drivers demonstrated improved visual cognitive abilities at the S3 level of TSIV, which corresponds to normal and safe driving conditions. Furthermore, a majority of both groups had saccade amplitudes in the range of 0°–4°, with experienced drivers showing a slightly higher proportion. About 82% of experienced drivers had saccade behavior within the range of 0°–2°, compared to 75% of novice drivers. CONCLUSIONS: The study concludes that the S3 level of TSIV, corresponding to 30 bits/km, is optimal for both novice and experienced drivers. This level promotes better visual performance and reduces visual workload, indicating that drivers' information acquisition capacity and visual search strategies are maximized while keeping the workload associated with driving at a minimum. These findings have significant implications for enhancing driving safety. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A tunnel shading shed is crucial in improving driving safety as a type of traffic facility to ease the transition of light environments. To study the effect of installation of a shading shed on the visual characteristics of drivers in the connecting zone of the adjacent tunnels, a total of 32 drivers were gathered to perform a real vehicle experiment. The study zone of the adjacent tunnels was divided into three sections: upstream tunnel exit; connecting zone; and downstream tunnel threshold zone. Fixation duration, saccade duration and saccade frequency were selected as research indexes. The results suggest that installation of a shading shed in the connecting zone significantly reduced the fixation (saccade) duration in the upstream tunnel exit and downstream tunnel threshold zones, with a significantly higher saccade frequency. In addition, fixation is better improved at the downstream tunnel entrance, and saccade is better enhanced at the upstream tunnel exit. [ABSTRACT FROM AUTHOR]

• Different visual environments at freeway tunnel entrance zones have varying effects on driver's visual attention, cognitive workload, and subjective mental workload. • The billboard condition attracts the highest level of visual attention from drivers, while the tip slogan condition results in the highest cognitive workload. • Evaluation using the NASA-TLX scale indicates that the tip slogan condition has the greatest impact on drivers' subjective mental workload. This study aims to evaluate the impact of different visual attraction environments at the entrance zone of freeway tunnels on drivers' visual performance and subjective mental workload. Through a naturalistic driving experiment conducted on actual roads, participants experienced various visual attraction environments at the entrance zones of freeway tunnels. The selected visual environments included baseline, landscape-style architecture, tip slogan, and billboard scenarios. Objective visual performance was assessed using eye-tracking devices to collect participants' eye movement data, while subjective mental workload was evaluated through the NASA-TLX measurement reports administered after the driving experiment. The results indicate that the visual attraction environments at the entrance zone of freeway tunnels have significant impacts on drivers' visual attention level, cognitive workload, and subjective mental workload. Under the billboard condition, participants exhibited the longest first fixation duration (FFD) and paid the earliest attention to visual attraction (reflected by participants positioned their initial fixation at the visual attraction farthest from the tunnel entrance zone (DFT)). Additionally, the tip slogan condition resulted in the highest mean fixation duration (MFD), the largest percentage of total fixation duration on the visual attraction (PTFD), and the highest cognitive workload (reflected in maximum pupil diameter (PD)). Billboard at the entrance zone of freeway tunnel had the greatest effect on attracting drivers' visual attention, while tip slogan resulted in the highest cognitive workload on drivers. The results of the subjective mental workload evaluation (NASA-TLX) also indicated that tip slogan had the greatest impact on drivers' subjective mental workload. This study provides valuable insights into the potential impact of different visual attraction environments at the entrance zone of freeway tunnels on drivers' eye-catching effect. The results contribute to both theoretical knowledge and practical applications in the field of transportation safety. [ABSTRACT FROM AUTHOR]

[Display omitted] • There is a slack effect at the exit of highway tunnels. • Slack effect leads to decrease in driver's attention and abnormal vehicle speed. • Accumulation of negative driving emotions in tunnel triggers slack effect. • Complex traffic scenarios should be avoided at the exit of extra-long tunnels. This study analyzes the causes of frequent traffic accidents at the exit areas of highway tunnels. Vehicle experiments were conducted to collect data on the light environment, vehicle speed, and driver eye movement. The distribution patterns of the illumination, vehicle speed, and gaze location occupancy were analyzed, and highway tunnels of different lengths were compared. The tunnel exit area is divided into the transition, exit, and departure zones. It was observed that there was an obvious white-hole effect at the exit zone, with drastic changes in the light environment. The presence of abnormal acceleration behavior in the transition zone and decreased attention in the departure zone demonstrate the existence of psychological and physiological slack in drivers. Additionally, the tunnel length positively correlates to the slack effect, which is stronger in extra-long tunnels than in the short and medium tunnels. Multiple control scenarios were established and driving simulation experiments were conducted to further analyze the impact of the slack effect on the traffic safety. The experimental results demonstrated that the slack effect of the extra-long tunnels exhibited an evident lag which was still present after leaving the tunnel exit. The average vehicle speed and trajectory offset were larger and more discrete in the post-tunnel zone than on an ordinary open road. The speed of the curve in the post-tunnel zone is 5.1 % higher than that of the curve in the ordinary road, and the maximum trajectory offset is 54.3 % higher. Thus, this study reveals the slack effect at tunnel exits and explains the abnormal phenomenon of relatively good traffic environments but high traffic accident rates in the transition and departure zones of tunnel exits. These results present considerable practical significance for the safe operation of highway tunnels, particularly extra-long tunnels. [ABSTRACT FROM AUTHOR]

• The combined effect of longitudinal slope and curve has a greater impact on driver. • Longitudinal slope has a significant impact on the driver. • Small radius curve is not conducive to traffic safety. To explore the effects of a longitudinal slope, a curve, and their combined action on the eye movement characteristics and driving safety of drivers in extra-long underwater tunnel, vehicle tests are conducted. Their purpose is to obtain data on the pupil area change rate, blink duration, fixation duration, and average saccade time when a driver passes through each longitudinal slope and curve combination section. The change laws of' the eye movement characteristics in different curves and longitudinal slopes are analyzed. Moreover, the change models of the pupil area change rate, blink duration, fixation duration, and average saccade time of drivers under the combined action of a longitudinal slope and a curve are established. Considering multiple eye movement characteristics comprehensively, the TOPSIS method is used to analyze the drivers' visual load of different longitudinal slope and curve combination sections. The results show that the interaction between a longitudinal slope and a curve has a significant impact on the eye movement characteristics of the drivers, with their combined effect being greater than that of a single factor, i.e., longitudinal slope or curve. A large longitudinal slope and a small curve radius imply a high pupil area change rate, long fixation duration, short blink duration, short average saccade time, and high visual load. [ABSTRACT FROM AUTHOR]

• Confined driving environment of the tunnel will aggravate driver's nervousness. • Longitudinal right-of-way is mainly reflected in the tunnel alignment perception. • Driver's attention mainly focuses on the far front area. • For some facilities, alignment and contour guidance varies in inverse proportion. • Alignment and contour guidance facilities are conducive to spatial right-of-way. Urban road tunnel construction is becoming ever more prevalent, and traffic safety in tunnel operation is even more important. This study evaluates the influence of different visual guiding facilities on drivers' spatial right-of-way perception by combining quantitative and qualitative methods in order to provide a basis for traffic safety optimization in the tunnel. Simulation scenes were designed for six common types of visual guiding facilities as comprising no facility (baseline), horizontal strips, edge markers, LED arch, vertical stripes, and combination (multiple) facilities. An eye tracker was used to obtain eye movement data of subject drivers exposed to various scenes. After each driving test, psychological feeling of the subjects in tunnel driving, and their ratings of alignment and contour guidance of various facilities were obtained by questionnaires. The research results showed that setting locations and facility types have a great impact on drivers' glance location and glance duration. When horizontal stripes, edge markers, LED arch and vertical stripes were set separately, alignment guidance and contour guidance performance were found to vary in inverse proportion. Horizontal stripes and edge markers are the preferred and necessary facilities, which are conducive to ensuring longitudinal and horizontal rights-of-way. LED arch and vertical stripes are also good supplements to spatial right-of-way. The combination of these 4 types of facilities can provide multi-level alignment guidance and contour guidance functions, which is beneficial to traffic safety in the tunnel. [ABSTRACT FROM AUTHOR]

• Presence of the psychological and physiological inconsistency phenomenon at tunnel exit. • Slack effect induces an abnormal acceleration of the tunnel exit. • Coupling of slack effect and white hole effect. • Slack effect threatens traffic safety. In this paper, the causes of frequent traffic accidents at the exits of highway tunnels are investigated. This study recruited 34 subjects to conduct vehicle experiments using an illumination meter, eye tracker, Smarter Eye and OBD to measure the illumination, eye movement characteristics, driving trajectory, and speed while driving in a tunnel exit. A questionnaire was used to investigate drivers' subjective feelings while driving. The change trend of each indicator in the area near the tunnel exit was analyzed, and the relationships among the light environment, driver physiology, driving behavior, and driver psychology were explored. The psychological and physiological inconsistency phenomenon and abnormal acceleration behavior were observed at the tunnel exit, and the slack effect was verified. As the tunnel exit area is driven through, with the rapid increase in illumination, the rate of change of the driver's pupil area increases, and the distance between the vehicle and the tunnel sidewall increases. It is unreasonable that in a tunnel exit with a poor traffic environment, some drivers experience psychological slack and tend to increase their speed and accelerate out of the tunnel. The slack effect is observed in most drivers, approximately 79.4% of the total. The white hole effect interferes with drivers' vision and reduces their ability to obtain traffic information. The slack effect reduces drivers' attention and increases vehicle speed. A coupling effect exists between the white hole and slack effects, which together threaten traffic safety at the tunnel exit. [ABSTRACT FROM AUTHOR]