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 impact of perceptual treatments on driver's behavior: from driving simulator studies to field tests--first results.

Our study focused on the lateral position of drivers in relation to risk on rural crest vertical curves, using a field site proposed by a local operator of the French road network (Conseil Général de Maine-et-Loire, 49). The final goal was to test one road treatment on this field site. The study consisted of three stages. The first, using driving simulators, selected two perceptual treatments (i.e., rumble strips on both sides of the centerline and sealed shoulders) from five that were tested in order to help drivers maintain lateral control when driving on crest vertical curves. The rumble strips were installed first on the field site. The second stage was to develop a diagnostic device specifically in order to evaluate, on the field site, the impact of a perceptual treatment on the driver's performance (i.e., lateral position). This diagnostic device was installed in the field upstream and downstream of the target crest vertical curve. The third stage was to collect the data during two periods, before and after the centerline rumble strips were installed. We then compared the results obtained in the field study with those from the driving simulator studies. The comparison showed that, as in the simulator studies, the centerline rumble strips on the crest vertical curve affected lateral positions, causing the participants to drive closer to the center of the lane. Finally, the results showed the usefulness of driving simulators in the road design process.

The impact of perceptual treatments on lateral control: a study using fixed-base and motion-base driving simulators.

This research was carried out as part of the French national multidisciplinary research project, PREDIT-SARI. Using a driving simulator, it aimed to test the effectiveness of road treatments intended to inform drivers about the risk of losing control on rural roads with "crest vertical curves" (Landis et al., 2004). [Rosey, F., Auberlet, J.M., Bertrand, J., Plainchault, P., 2008. Impact of perceptual treatments on lateral control during driving on crest vertical curves: a driving simulator study. Accid. Anal. Prev. 40, 1515-1523, Scopus.] used a fixed-base driving simulator to test four perceptual treatments intended to help drivers maintain lateral control when driving on crest vertical curves and found that two of them, rumble strips on both sides of the centerline and sealed shoulders, were more effective than the others. This first study prompted us to ask if non-visual sensory cues (e.g., vestibular or proprioceptive perceptions) could influence driver perception and consequently lateral control. We therefore conducted a second study on a motion-base driving simulator, using the same virtual 3D database. The results showed that: (1) drivers drive closer to the center of their lane when there are rumble strips on both sides of the centerline, or when there are sealed shoulders, than they do with the current marking system (i.e., continuous lines), and (2) the impact of the two tested perceptual treatments was replicated on both types of driving simulator.

Impact of perceptual treatments on lateral control during driving on crest vertical curves: a driving simulator study.

Approximately 48% of all fatal collisions in Europe are classified as single-vehicle run-off-road or head-on collisions. These crashes relate to trajectory control (road departure) and represent a safety challenge. In France, single-vehicle run-off-road crashes represent 21% of all crashes and head-on collisions represent 11%. This study evaluated the effectiveness of four perceptual treatments (i.e., a painted center line, post-delineators, rumble strips on both sides of the center line and sealed shoulders) in supporting the driver to maintain lateral control; that is, to support the driver to keep in the center of his/her lane. Forty-three participants drove a fixed-base driving simulator, on a simulated straight 3 km rural road with two crest vertical curves (CVC). Four sections were chosen for analysis: a reference section (i.e., the first CVC), a test section (i.e., the second CVC), a pre-test section (i.e., immediately before the second CVC) and a post-test section (i.e., immediately after the second CVC). The results showed that drivers drive more at the center of their lane with the rumble strips on both sides of the center line and with the sealed shoulders than with the actual marking (here center line) or other treatments.

Precocity of fine motor control and task context: hitting a ball while stepping.

To determine if children under 5 years were able to intercept a moving object while stepping, the authors had 9 3-year-olds hit a ball that the authors dropped from a ramp from 5 heights (1.5, 2.0, 2.5, 3.0, and 3.5 m). The statistical analysis showed that the hand movement times were similar regardless of ball rolling heights and that the hand initiation times were dependent on the ball rolling times. Children under 5 years were able to hit a moving ball, and they performed this hitting according to a temporal coupling between ball displacements and the hand contact with it. The participants' behavior of hitting while stepping supports the idea that the motor system implicitly knows what the cognitive system ignores.

Spatio-temporal constraints on upright children's coordination when hitting a moving target.

To determine if the spatial and/or temporal context affected the coordination patterns of children under five in upright interceptive tasks, 3-year-olds hit a ball dropped from a ramp from five heights (1.5, 2, 2.5, 3, and 3.5 m) to control drop time. We studied the initiation time of hitting a ball with a cinematic analysis of the different joint movements (foot, knee, hip, shoulder, and hand). Two patterns of joint coordination were observed according to the rolling height of the ball: a de-synchronized pattern for heights of 2 m or above where the foot was the first to move and the hand the last, and a "synchronized" pattern, for the lowest height (1.5 m) where all joints started moving at the same time due to a strong temporal pressure. These two coordination patterns highlight a functional adaptation of body joints according to the spatio-temporal constraints among children from the age of three.

Effect of an interference task on a ball-hitting skill by 6- to 10-yr-old children.

We explored the functionality of interference on a forehand tennis shot among 145 6- to 10-yr.-old children using the retroactive interference procedure. First, the children were asked to execute 10 forehand drives with a small tennis racquet (prime test). They were then asked to execute 10 frontal returns (interference test). The final probe test was similar to the first test, but children executed only 3 forehand drives. Children were assessed using a developmental category for the forehand drive skill. Each developmental step reflected a common sequence of body configurations exhibited by all individuals and was evaluated point-by-point. Multivariate analysis showed that boys had higher ratings of developmental steps of coordination than girls and that the rated developmental step initially increased with age before stabilizing. The developmental steps of coordination decreased after the interference task. We also showed that interference mechanisms are operative for this gross motor skill in childhood, but no interaction was found with age and sex. Post hoc analysis showed that developmental steps were not significantly different after the interference task for the oldest children, suggesting the onset of the inhibitory process.