Influence of continuous edge-line delineation on drivers' lateral positioning in curves: a gaze-steering approach.

Recent research indicates that installing shoulders on rural roads for safety purposes causes drivers to steer further inside on right bends and thus exceed lane boundaries. The present simulator study examined whether continuous rather than broken edge-line delineation would help drivers to keep their vehicles within the lane. The results indicated that continuous delineation significantly impacts the drivers' gaze and steering trajectories. Drivers looked more towards the lane centre and shifted their steering trajectories accordingly. This was accompanied by a significant decrease in lane-departure frequency when driving on a 3.50-m lane but not on a 2.75-m lane. Overall, the findings provide evidence that continuous delineation influences steering control by altering the visual processes underlying trajectory planning. It is concluded that continuous edge-line delineation between lanes and shoulders may induce safer driver behaviour on right bends, which has potential implications for preventing run-off-road crashes and cyclist safety.Practitioner summary: This study examined how continuous and broken edge lines influence driving behaviour around bends with shoulders. With continuous delineation, drivers gazed and steered in the bend further from the edge line and thus had fewer lane departures. Continuous marking can therefore help prevent run-off-road crashes and improve cyclists' safety.

Gaze and steering strategies while driving around bends with shoulders.

The installation of shoulders on rural roads to create more forgiving roads encourages drivers to cut corners on right-hand bends, but the underlying mechanisms are poorly understood. Since eye movements and steering control are closely coupled, this study investigated how the presence of a shoulder influences drivers' gaze strategies. To this end, eighteen drivers negotiated right-hand bends with and without a shoulder on a simulated rural road. In the presence of a shoulder, participants modified their visual sampling of the road by directing their gaze further inside the bend. At the same time, their lane position was deviated inward throughout the bend and the vehicle spent more time out of the lane. These results suggest that the shoulder influences the visual processes involved in trajectory planning. Recommendations are made to encourage drivers to keep their eyes and vehicle in the driving lane when a shoulder is present.

Young and older adult pedestrians' behavior when crossing a street in front of conventional and self-driving cars.

Self-driving vehicles are gradually becoming a reality. But the consequences of introducing such automated vehicles (AVs) into current road traffic cannot be clearly foreseen yet, especially for pedestrian safety. The present study used virtual reality to examine the pedestrians' crossing behavior in front of AVs as compared to conventional cars (CVs). Thirty young (ages 21-39) and 30 older (ages 68-81) adults participated in a simulated street-crossing experiment allowing for a real walk across an experimental two-way street. Participants had to cross (or not cross) in mixed traffic conditions where highly perceptible AVs always stopped to let them cross, while CVs did not brake to give them the right of way. Available time gap (from 1 to 5 s), approach speed (30 or 50 km/h), and the lane in which the cars were approaching (near and/or far lane of the two-way street) were varied. The results revealed a significantly higher propensity to cross the street, at shorter gaps, when AVs gave way to participants in the near lane while CVs were approaching in the far lane, leading to more collisions in this condition than in the others. These risky decisions were observed for both young and older participants, but much more so for the older ones. The results also indicated hesitation to cross in front of an AV in both lanes of the two-way street, with later initiations and longer crossing times, especially for the young participants and when the AVs were approaching at a short distance and braked suddenly. This study highlights the potential risks for pedestrians of introducing AVs into current road traffic, complicating the street-crossing task for young and older people alike. Future studies should look further into the role of repeated practice and trust in AVs. The design of these vehicles must also be addressed. Some practical recommendations are provided.

Effects of motorcycle simulator configurations on steering control and gaze behavior in bends.

The recent development of motorcycle simulators has made it possible to study rider behavior in safe conditions. However, their use still raises validity issues. Our study examined how riders' steering and gaze behaviors and subjective experience are influenced by motorcycle roll tilt and reverse steering, which are considered to be essential factors in real-life motorcycle riding. The results revealed that tilting the motorcycle in the roll plane did not lead to significant changes in rider behavior, gaze sampling, or perceived realism. The steering control strategy adopted by riders did, however, significantly influence these results. A direct steering control strategy meant that riders took a racing path and scanned the road far in advance. When reverse steering was implemented, however, riders chose to take a "safety path", as recommended by training manuals. Reverse steering also received the highest realism score. However, steering control was more difficult, as shown by the larger number of lane departures recorded and a change in the trade-off between guiding and look-ahead fixations. This suggests that although reverse steering matches riders' real control behavior and improves the subjective experience of simulator riding, it is hindered by an inadequate internal model of vehicle dynamics. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Steering Control in a Low-Cost Driving Simulator: A Case for the Role of Virtual Vehicle Cab.

OBJECTIVE: The aim of this study was to investigate steering control in a low-cost driving simulator with and without a virtual vehicle cab. BACKGROUND: In low-cost simulators, the lack of a vehicle cab denies driver access to vehicle width, which could affect steering control, insofar as locomotor adjustments are known to be based on action-scaled visual judgments of the environment. METHOD: Two experiments were conducted in which steering control with and without a virtual vehicle cab was investigated in a within-subject design, using cornering and straight-lane-keeping tasks. RESULTS: Driving around curves without vehicle cab information made drivers deviate more from the lane center toward the inner edge in right (virtual cab = 4 ± 19 cm; no cab = 42 ± 28 cm; at the apex of the curve, p < .001) but not in left curves. More lateral deviation from the lane center toward the edge line was also found in driving without the virtual cab on straight roads (virtual cab = 21 ± 28 cm; no cab = 36 ± 27 cm; p < .001), whereas driving stability and presence ratings were not affected. In both experiments, the greater lateral deviation in the no-cab condition led to significantly more time driving off the lane. CONCLUSION: The findings strongly suggest that without cab information, participants underestimate the distance to the right edge of the car (in contrast to the left edge) and thus vehicle width. This produces considerable differences in the steering trajectory. APPLICATION: Providing a virtual vehicle cab must be encouraged for more effectively capturing drivers' steering control in low-cost simulators.

The effects of lane width, shoulder width, and road cross-sectional reallocation on drivers' behavioral adaptations.

Previous research has shown that lane-width reduction makes drivers operate vehicles closer to the center of the road whereas hard-shoulder widening induces a position farther away from the road's center. The goal of the present driving-simulator study was twofold. First, it was aimed at further investigating the respective effects of lane and shoulder width on in-lane positioning strategies, by examining vehicle distance from the center of the lane. The second aim was to assess the impact on safety of three possible cross-sectional reallocations of the width of the road (i.e., three lane-width reductions with concomitant shoulder widening at a fixed cross-sectional width) as compared to a control road. The results confirmed that lane-width reduction made participants drive closer to the road's center. However, in-lane position was affected differently by lane narrowing, depending on the traffic situation. In the absence of oncoming traffic, lane narrowing gave rise to significant shifts in the car's distance from the lane's center toward the edge line, whereas this distance remained similar across lane widths during traffic periods. When the shoulders were at least 0.50m wide, participants drove farther away from both the road center and the lane center. Road reallocation operations resulted in vehicles positioned farther away from the edge of the road and less swerving behavior, without generating higher driving speeds. Finally, it is argued that road-space reallocation may serve as a good low-cost tool for providing a recovery area for steering errors, without impairing drivers' behavior.

The contribution of visual and proprioceptive information to the perception of leaning in a dynamic motorcycle simulator.

Compared with driving or flight simulation, little is known about self-motion perception in riding simulation. The goal of this study was to examine whether or not continuous roll motion supports the sensation of leaning into bends in dynamic motorcycle simulation. To this end, riders were able to freely tune the visual scene and/or motorcycle simulator roll angle to find a pattern that matched their prior knowledge. Our results revealed idiosyncrasy in the combination of visual and proprioceptive information. Some subjects relied more on the visual dimension, but reported increased sickness symptoms with the visual roll angle. Others relied more on proprioceptive information, tuning the direction of the visual scenery to match three possible patterns. Our findings also showed that these two subgroups tuned the motorcycle simulator roll angle in a similar way. This suggests that sustained inertially specified roll motion have contributed to the sensation of leaning in spite of the occurrence of unexpected gravito-inertial stimulation during the tilt. Several hypotheses are discussed. Practitioner Summary: Self-motion perception in motorcycle simulation is a relatively new research area. We examined how participants combined visual and proprioceptive information. Findings revealed individual differences in the visual dimension. However, participants tuned the simulator roll angle similarly, supporting the hypothesis that sustained inertially specified roll motion contributes to a leaning sensation.

Towards identifying the roll motion parameters of a motorcycle simulator.

This study aimed at identifying the roll motion parameters of a motorcycle simulator prototype. Experienced motorcyclists tuned the angular physical movement of the mock-up and that of the visual scene to achieve an optimal riding experience during curves. The participants exceeded the rolling angles that would be required in real-world riding, while avoiding leaning the mock-up beyond 10°. In addition, they were more influenced by the speed of the virtual motorcycle than by road curvature, especially in a wide field of view. Heterogeneity was found in the roll applied to the visual scene. The overall patterns suggest that at least when washout is not applied to remove the side forces that in real-world riding are compensated by a centrifugal force, greater roll of the visual at the expense of the mock-up is mandatory to avoid performance biases that might be enhanced due to fear of falling off the simulator. Future roll motion models must take into consideration factors such as riding postures, which might not only influence the forces operating on the rider-motorcycle system, but also how motorcyclists perceive the visual world.

The effects of age and traffic density on street-crossing behavior.

Past research has shown that road users accept shorter time gaps when the waiting time/number of vehicles they let pass before attempting to merge into the traffic increases. While elderly pedestrians are known to be an extremely vulnerable group of road users, very few studies dealt with the effect of environmental constraints and crossing complexity on this population's safety. The present study aimed at determining whether or not street-crossing decisions and behavior of younger and older pedestrians were differently affected by a traffic flow. In an interactive street-crossing task, we assessed whether mean time gap and crossing decisions depended on the position of the gap pedestrians selected into the traffic stream. Results revealed that irrespective of their age pedestrians accepted a smaller time gap when they chose the second interval of the traffic compared to the first one. Contrasting with previous hypotheses, this traffic-related behavior was not accompanied by an increase in the decisions risk. The findings also showed that the transition threshold from rejecting to accepting time gaps was shorter when the second interval was selected compared to the first one. This increment in task constraints might help younger and older pedestrians alike to perceive action possibilities more accurately and to be better attuned to traffic conditions by comparing gaps between each other. This opens an interesting perspective in the understanding and the training of the ability of elderly road users to remain accurate in their judgements.

The effects of aging on street-crossing behavior: from estimation to actual crossing.

Based on an interactive road-crossing task, this study examined age-related effects on crossing decisions and whether or not age affects behavioral adjustments to the time gap. It also compared crossing-task decisions to previously observed estimation-task decisions [Lobjois, R., Cavallo, V., 2007. Age-related differences in street-crossing decisions: the effects of vehicle speed and time constraints on gap selection in an estimation task. Accident Analysis and Prevention 39 (5), 934-943]. The results showed that older adults selected a greater mean time gap and initiated their crossing sooner than the younger ones, indicating an attempt to compensate for their increased crossing time. However, older adults accepted shorter and shorter time gaps as speed increased, putting them at a higher risk at high speeds. Regarding adaptive behavior, the analyses showed that all groups adjusted their crossing time to the available time. Comparison of crossing decisions and estimations revealed that the young group had a greater number of tight fits and missed fewer opportunities on the crossing task, whereas these differences did not appear in the elderly. This suggests that the crossing decisions of younger adults are much more finely tuned to time gaps in actual crossing tasks than in estimation tasks and that older adults have trouble calibrating perception and action and perceiving possibilities for action.

Collision avoidance behavior as a function of aging and tennis playing.

Daily living often requires pedestrians and drivers to adapt their behavior to the displacement of other objects in their environment in order to avoid collision. Yet little research has paid attention to the effect of age on the completion of such a challenging task. The purpose of this study was to examine the relationship between age and collision avoidance skill and whether a sporting activity affects this. Three age groups (20-30, 60-70, and 70-80 years) of tennis players and non-players launched a projectile toward a target in order to hit it before it was hit by another "object" (a stimulus represented by apparent motion of lights). If the participant judged that time-to-collision (TTC) of the moving stimulus was not long enough for him/her to launch the projectile in time to arrive before the stimulus, the participant had to inhibit the launching. Results showed that for the non-players the number of errors in the 70-80 year-old group was significantly higher than those of the 20-30 and 60-70 year-old groups, which did not differ from each other. However, this increase was not observed in the 70-80 year-old tennis players, demonstrating a beneficial effect of playing tennis on collision avoidance skill. Results also revealed that the older groups of both tennis players and non-players were subject to the typical age-related increase in response time. Additional analyses indicated that the 70-80 year-old non-players did not adjust their actions to these age-related changes in response time. The older tennis-playing participants, however, were more likely to adjust collision avoidance behavior to their diminished response times.

Age-related differences in street-crossing decisions: the effects of vehicle speed and time constraints on gap selection in an estimation task.

Two experiments were conducted to study how age affects street-crossing decisions in an estimation task, with particular emphasis on how oncoming vehicle speed and a time constraint influence the time gap deemed acceptable for crossing. Experiment 1 showed that when there was a time constraint, all age groups selected a shorter time gap for the higher speed. This was associated with a large number of missed opportunities for the low speed and many unsafe decisions for the high speed. In the second experiment, which had no time constraint, young pedestrians operated in a constant-time mode regardless of speed, whereas older pedestrians accepted shorter and shorter time gaps as speed increased. The results seem to indicate that the effect of speed is due to a mixed operating mode of participants, whose decisions may be based on either time or vehicle distance, depending on the task requirements and on the participant's own ability to meet those requirements.

The effect of aging and tennis playing on coincidence-timing accuracy.

This study examined the effect of tennis playing on the coincidence timing (CT) of older adults. Young, younger-old and older-old (20-30, 60-69, and 70-79 years old, respectively) tennis players and nonplayers were asked to synchronize a simple response (pressing a button) with the arrival of a moving stimulus at a target. Results showed that the older tennis players responded with a slight bias similar to that of the young players. Two experiments were conducted to determine whether the elimination of age effects through tennis playing was a result of maintaining basic perceptuomotor and perceptual processes or of some possible compensation strategy. The results revealed that the age-related increase in the visuomotor delay was significantly correlated with CT performance in older nonplayers but not in older tennis players. These results suggest that playing tennis is beneficial to older adults, insofar as they remained as accurate as younger ones despite less efficient perceptuomotor processes. This supports the compensation hypothesis.

Aging and tennis playing in a coincidence-timing task with an accelerating object: the role of visuomotor delay.

The purpose of the present study was to determine whether playing a specific ball sport, such as tennis, could maintain the coincidence-timing (CT) performance of older adults at a similar level to that of younger ones. To address this question, tennis players and nonplayers of three different age ranges (ages 20-30, 60-70, and 70-80 years) performed a simple CT task consisting of timing their response (pressing a button) to coincide with the arrival of a stimulus at a target. The stimulus moved at either an accelerating, constant, or decelerating velocity. As expected, all participants were affected by the velocity manipulation, which led to late and early responses to accelerating and decelerating stimuli, respectively. Whereas this response bias was increasingly pronounced with advancing age in nonplayers, no difference was found among player groups of different ages. Finally, we showed that the length of the visuomotor delay could explain the effect of nonconstant velocities.