Drug effects on driving performance.
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Automobile Driving↗
Biomedical subjects
D de Waard
Publications and source records attributed to D de Waard.
A comparison of different ways to approximate time-to-line crossing (TLC) during car driving.
Three experiments are presented in which the accuracy of different methods to approximate time-to-line crossing is assessed the first experiment TLC was computed, using a trigonometric method, during normal driving while the vehicle stayed in lane. The minima of TLC were compared with two approximations and it was found computing TLC as lateral distance divided by lateral velocity gave poor results. It was concluded that this simple approximation is not suitable for measuring TLC minima in studies of driver behaviour. A way of computing TLC that takes account of the curved path of the vehicle resulted in a good fit of TLC minima. In two other experiments the vehicle exceeded the lane boundary, either intentionally as a result of a lane change manoeuvre, or unintentionally as a result of impaired driving. In these cases no TLC minima exists since these only occur as a result of correcting steering actions to stay within the lane. In contrast to normal lane keeping, it was found that prior to crossing the lane boundary, the simple approximation resulted in more accurate estimation of available time before the lane boundary is exceeded compared to the more complex approximation. This indicates that for lane keeping support systems and systems that detect when the driver has fallen asleep and drifts out of lane, a simple algorithm for TLC estimation may give reliable results, while this algorithm is not accurate enough for more fundamental studies of driver behaviour. However, the reliability of the approximation is only satisfactory over a very short time range before the lane boundary is actual exceeded. This may result in warnings that come too late and result in too little time to respond for the driver.
Accidents, Traffic↗
Road-edge delineation in rural areas: effects on driving behaviour.
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.
Automobile Driving↗
Elderly and young driver's reaction to an in-car enforcement and tutoring system.
A system that contrasts driver behaviour with normative behaviour was tested in an advanced driving simulator. Drivers were provided with auditory and visual tutoring messages if deviations were detected from normative, i.e. legally allowed behaviour with respect to a selection of offences. Results showed that the system was very effective in increasing law-abiding behaviour, which has a major positive effect on traffic safety. However, driver mental effort, as indicated by self-reports and drivers' physiological states, was slightly increased in conditions where drivers received feedback. Opinion about the tutoring system was positive in terms of usefulness. Self-reports on satisfaction differed between age groups; young drivers rated it low, while elderly drivers held a positive attitude.
Accidents, Traffic↗
Effect of road layout and road environment on driving performance, drivers' physiology and road appreciation.
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.
Acceleration↗
An experimental study to evaluate the effectiveness of different methods and intensities of law enforcement on driving speed on motorways.
Two field experiments were conducted to establish the most effective method of enforcement in reducing driving speed and to establish the most efficient strategy in terms of police force personnel required. In the first experiment, the effect of three variables on driving speed on motorways was studied. The first variable, intensity of enforcement, was manipulated by creating three different objective levels of apprehension for detected speeding drivers. The second variable was method of enforcement. On-view stopping and ticketing of offenders was compared to mailing of fines on the basis of the car's licence plate number. The third variable manipulated was the time delay in the mailing of fines. Time delay between detection of the offence and feedback to the driver was shortened in one condition. In a second experiment, police enforcement effort was optimized by relating intensity level of enforcement to the proportion of speeding vehicles. In the first experiment, police enforcement was applied for four weeks; in the second experiment, enforcement activities were continued for 12 consecutive weeks. In both cases the main dependent variable was driving speed. Before, during, and after the application of enforcement, speed was registered using induction loops. In addition, driver opinion about speeding and speed enforcement was studied using postal questionnaire surveys. The results show the largest and longest lasting reduction in driving speed in the highest intensity level-condition, giving support for a relation between objective chance of apprehension and speed choice. On-view stopping of offenders was shown to be a more effective method to reduce driving speed than mailing of fines. Some of these results are discussed in the light of game theory. The questionnaire surveys indicated that most drivers did not notice the recurrence in enforcement activities due to infrequent passing of the sections of motorways studied. The preventive effect of police enforcement appeared to be far more substantial than its repressive effect. Enforcement primarily deters the current nonoffender from speeding.
Automobile Driving↗
The use of psychophysiology to assess driver status.
Twenty subjects completed an on-the-road driving experiment, consisting of two different tests conducted on two separate days. A two-part test was administered while subjects were under the influence of alcohol (BAC < = 0.05%); a four-part test was administered without alcohol consisting of a 2.5 h driving test under vigilance conditions on a quiet highway. The order of the tests was balanced across subjects. Changes in relevant physiological parameters, such as ECG and EEG, reflected changes in driver status and predicted driving impairment. Impairment of driving performance was measured in a standard driving test (SD lateral position and SD steering wheel movements) and in a recently developed car-following test (reaction to speed changes of a leading car).
Adult↗
Assessing driver status: a demonstration experiment on the road.
Twenty subjects completed an on-the-road experiment that consisted of two parts on two separate days. One was a one-hour driving test under the influence of alcohol (BAC less than = 0.05%), the second a two-and-a-half-hour driving test under vigilance conditions. Impairment of driving performance was measured in a car-following test as well as in a standard driving test. Changes in relevant physiological parameters, such as ECG and EEG, reflected changes in driver status and predicted driving performance impairment.
Adult↗
The effects of mobile telephoning on driving performance.
The effects of telephoning while driving were studied in three different traffic conditions, i.e. in light traffic on a quiet motorway, in heavy traffic on a four-lane ring-road, and in city traffic. Twelve subjects, unfamiliar with mobile telephones, drove an instrumented vehicle for one hour each day during three weeks and while in each of the three traffic conditions, had to operate the mobile telephone for a short while. To ensure a fixed "heavy traffic load" in the second condition, the subjects were instructed to follow another instrumented vehicle (at a safe distance). The results showed a significant effect of telephoning while driving as opposed to normal driving (i.e., not involving telephone conversation), on the effort subjectively measured by an effort scale and objectively measured by heartrate indices and on some of the measured parameters of driving performance. One half of the subjects had to operate the telephone manually, the other half performed the telephone task with a handsfree mobile telephone set. The subjects who operated the handsfree telephone showed better control over the test vehicle than the subjects who operated the handheld telephone, as measured by the steering wheel movements. Also, a clear improvement over time in the course of the 15 test days was found for some of the measurements. As a consequence of the results, some advice concerning mobile telephoning can be given to authorities, manufacturers, and users.
Adult↗