Infrastructural changes were implemented on rural 80 km/h roads in The Netherlands in an effort to reduce speeding. The road infrastructure changes were designed to produce discomfort for the speeding driver by providing noxious auditory and haptic feedback. On experimental roads, smooth-surface road width was reduced by using blocks of gravel chippings placed along the centre line and at intervals on road edges. It was predicted that these changes would increase mental load while driving, and thereby decrease speeding. In a field experiment 28 subjects drove an instrumented vehicle over experimental and control roads. A decrease in driving speed and swerving behaviour was found on the experimental roads, and this was coupled with a decrease in heart rate variability, consistent with an increase in mental load. Roads in two different road-side environments (woodland vs. moorland) were also tested. There were differences in driver appraisal of the two environments, but no interactions were observed between these appraisals and driving performance on the experimental roads. It is concluded that the infrastructural measures have a useful role to play in road safety through a reduction in driver speeding.

This study explores whether KR (knowledge of results) and reward compensate for the negative joint effects of sleep deprivation and signal degradation in a choice-reaction task. The negative effect of signal degradation on performance was aggravated by sleep loss and time-on-task, whereas KR improved performance, especially when signals were degraded. Reward changed the effects of time-on-task owing to lack of sleep. Performance was also improved by a brief task interruption after 30 minutes' work, with 5 more minutes to go. These results can be interpreted in terms of the performance model of Sanders (1983), which links energetic mechanisms to stages of information processing. A lack of energetic supply from the arousal mechanism to perceptual processing, induced by signal degradation, sleep deprivation, and time-on-task, was effectively counteracted by KR:KR enables the mobilization of effort to compensate for this lack of arousal. The relation between reward and KR is not yet clear. The interruption effect suggests that the influence of time-on-task is not due to loss of arousal, but causes a reallocation of resources by effort.

When driving on lower-category Dutch rural roads without any delineation, drivers are likely to drift off the road with their right-side wheels, thus incurring damage to the pavement edge or even leading to accidents. In two experiments, two types of road-edge delineation, with continuous or dashed edge lines, were compared with two control roads without lines or with only a dashed line on the road axis. The first experiment consisted of non-obtrusive video recordings of passing traffic. Vehicle position on the experimental roads was more to the road's centre than on the control roads. The second experiment was a driving test with an instrumented vehicle, during daytime lighting and during darkness. Again, vehicle lateral position was more central on the experimental roads, especially during darkness. Subjects could safely pass oncoming vehicles. Driving speed increased on the experimental roads compared with the unlined control road, but not beyond speeds found on the axis-lined control road. Driver's mental effort while driving over the experimental roads did not differ from the effort while driving over the control roads. Subjectively rated effort was higher for the unlined control road than for the three other roads. Subjects preferred the edge-lined roads to the unlined control road, but not more than the axis-lined control road. It was concluded that edge-lines may provide a simple and effective way of inducing a more favourable lateral position on rural roads without having negative effects on subjective appraisal, driving performance or mental workload.

Visually impaired people (VIP) have to rely on different information to generate a cognitive map of their environment than normally sighted people. This study explored the extent to which a cognitive map could be generated by auditory information of route-type and survey-type descriptions of a fictitious environment. A total of 27 visually impaired and 28 normally sighted participants listened to either a survey-type or a route-type description of a fictitious zoo. They then answered both route-type and survey-type questions. This listening/question-and-answer sequence was repeated twice (total n ¼ 3). The visually impaired participants showed no difference in error frequency between the two description types, while the normally sighted individuals performed better after listening to the survey-type description. In addition, the learning curve of the normally sighted individuals was steeper than that of the visually impaired and they made fewer errors. The error scores indicated two subgroups in both the normally sighted and the visually impaired groups. These two groups, the 'good' learners and the 'poor' learners, showed marked differences in generating a cognitive map from auditory descriptions of an environment.

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