It is impossible to set a legal limit to the degree of fatigue permissible for traffic participation. Fatigue is hard to measure, which means legislation and enforcement in this field (contrary to alcohol use for instance) are hard to implement. Several other measures to reduce driver fatigue and its consequences are, however, possible (see for instance [2] [3] [36]). A distinction can be made between measures for professional drivers and non-professional drivers and between options by means of infrastructural measures, advanced driver assistance systems and fatigue detection systems.
Professional drivers
For professional drivers, regulations on driving time and rest period apply (see the question Do regulations on driving times and rest period help prevent fatigue-related crashes?). Although, obviously, these legal requirements cannot entirely prevent fatigue, they do, in principle, reduce chances of extreme fatigue caused by being behind the wheel for too long stretches of time and not taking enough breaks. It is of course essential that drivers abide by these driving times and rest periods. At present, there are large differences between European countries in the extent to which this is the case and the extent to which the requirements are enforced [30].
Employers also have an important role to play: they should plan the work in such a way that their drivers can abide by the driving times and rest periods, and they should actively stimulate drivers to indeed comply with these requirements. In this, self-employed drivers also have their own responsibility. Moreover, haulage companies should inform their drivers about causes and consequences of fatigue. As far as the onset of fatigue is concerned, the impact of drivers’ individual circumstances (life style) and their own responsibilities should not be forgotten. Finally, screening drivers for (untreated) sleep disorders, particularly sleep apnoea, may be considered a company task.
Fatigue Management programmes, especially in Australia and North America, are based on these starting points. Examples may be found in a special edition of the magazine Accident Analysis and Prevention. Ideas about a safety culture for haulage companies clearly tie in with this [37] [38].
Non-professional drivers
Measures targeting non-professional drivers primarily focus on education: education and information about causes, effects, fatigue symptoms and advice on how to limit fatigue effects at least for a while. An example of an education campaign is the Dutch national 2008-2011 campaign ‘Don’t be a Sleep Driver’. Education and information could at least raise awareness of causes and road safety effects of fatigue, which is an important, albeit insufficient, step towards behavioural change.
Infrastructural measures
An infrastructural measure aimed at reducing fatigued driving is the provision of sufficient locations and facilities allowing truck and car drivers to take a rest while not jeopardising traffic safety or social safety.
Most infrastructural measures, however, are aimed at mitigating crash consequences for vehicles running off the road or threatening to do so, for instance on account of fatigue. This mainly involves longitudinal rumble strips to warn drivers, both auditorily and kinetically, that their vehicle is about to run off the road. In addition, roadside barriers and obstacle-free zones are very important to limit the consequences of running off the road.
Advanced driver assistance systems (ADAS)
Advanced driver assistance systems (ADAS) may contribute to reducing the number of fatigue-related crashes, e.g., by warning the driver or by actually intervening. Examples of warning systems are Lane Departure Warning (LDW) and Forward Collision Warning (FCW) systems. Examples of intervening systems are (Cooperative) Advanced Cruise Control and Lane Keeping Systems (LKS). Although these systems do not prevent fatigue itself (in some cases they may even be conducive to fatigue (see the question Do road users get tired sooner when task loads are low? )), they do in principle limit the consequences, viz running off the road or driving into vehicles in front.
At present, the effectiveness of warning systems is unclear [39] and there are doubts about the support for intervening systems. For its new regulation concerning motor vehicle type approval [40] the European Committee has nevertheless proposed making an intervening LKS mandatory for cars and delivery vans and a warning LDW systems for trucks and buses/coaches (see SWOV fact sheet Intelligent transport and driver assistance systems (ITS and ADAS).
Automatic fatigue detection systems
In recent years, a lot of research has been done into the possibilities offered by automatic fatigue detection systems, and several studies in this field are still in progress [41]. These systems should notice that the driver is getting so tired that he can no long drive safely, and should then warn the driver or intervene. Some of the systems take input from driving behaviour: does the car swerve more than usually, does speed fluctuate more, are brakes more often used abruptly? Other systems take input from physical driver characteristics, such as blinking, facial muscle spasms and yawning. For now, none of the systems appear to be rock-solid [39]. The major challenge is avoiding false positives (warning or intervening when there is no question of fatigue) and false negatives (failing to warn or intervene when fatigue is indeed at issue). The former will lead to irritation and possible system sabotage, the latter will erode confidence in the system. It is feared that fatigue detection systems tempt tired drivers to keep driving until the system responds. There is, however, no empirical evidence to support this fear [39].
At present, several car brands are equipped with fatigue detection systems. These systems generally take input from driving style changes, notably steering movements. The European Committee has proposed making an warning fatigue detection and attention detection system mandatory for all vehicle categories [40].
