Report numberRA-2004-45
TitleDrivers control systems for fatigue and driving under the influence
SubtitleDescription and technical aspects of systems in vehicles that detect fatigue and alcohol use
AuthorsJohan Verlaak
Published byPolicy Research Centre for Traffic Safety 2002-2006
Number of pages38
Document languageDutch
Partner(s)Vlaamse Instelling voor Technologisch Onderzoek
Work packageOther: Vehicle technology

Drowsiness and driving while impaired are two important causes of traffic accidents. In both cases the driver is not capable of executing the driving task safely. By applying vehicle technology, the traffic safety can be improved by warning the driver when a dangerous situation occurs.


In the first part of this report vehicle technology that warns the driver in case of drowsiness is discussed. In the second part, technical aspects of alcohol locks are considered.


Drowsiness, which results in microsleep or even falling asleep while driving, is a problem that mainly occurs in the goods transport. Due to the high work pressure in this sector, drivers often drive too long, which results in sleepiness. This causes accidents. The problem was observed in the fifties, and resulted in the installation of the tachograph in trucks. This instrument registers the ride and rest times of the driver. It makes control of the working hours possible and prevents driving too long.


In the seventies the tachograph became mandatory in Europe for heavy duty vehicles (trucks and busses). For each driver ride times were registered analogue, by writing time and vehicle speed on a chart. A new European directive makes the digital tachograph mandatory in new vehicles from August 4th 2004. Ride and rest times are recorded digitally, and misuse will be decreased.


Data on the effect of the tachograph on traffic safety were not found.


Besides the control on driving times, technology observing the driver can be applied. One may detect, whether his attention to the traffic decreases due to drowsiness, based on the drivers behaviour. A system, with a camera and image analysis, that traces the eye movements can detect whether there is a risk of falling asleep. Several manufacturers are developing this type of technology.


Also based on the driving behaviour one can detect whether a dangerous traffic situation may occur. When unintended leaving of the lane is detected, a warning to the driver can be given. Lane departure warning systems are offered by a number of manufacturers (trucks).


One may wonder whether these systems contribute to traffic safety. Possibly these systems may result in risk compensating behaviour, by drivers who rely too much on the system.


For preventing drunk driving, alcohol locks can be used. An alcohol lock prevents the vehicle from starting when the alcohol content in the drivers blood is to high.


When this technology will be applied, one has to consider not only technical aspects. The application of alcohol locks needs to be embedded in a broader program, that also takes into account behavioural and legal aspects. Alcohol locks are installed in vehicles of drivers who were caught on drunk driving. They have to be supervised while the alcohol lock is in the vehicle. From several projects it is seen that drivers take their former habits, once the alcohol lock is removed from their vehicle.

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The Policy Research Centre for Traffic Safety carries out policy relevant scientific research under the authority of the Flemish Government. The Centre is the result of a

cooperation between Hasselt University, KU Leuven and VITO, the Flemish Institute for Technological Research.


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