About 25% of all road fatalities in Europe are alcohol related whereas about only 1% of all kilometres driven in Europe are driven by drivers with 0.5 g/l alcohol in their blood or more. As the Blood Alcohol Concentration (BAC) in the driver increases, the crash rate also rises. The increase in crash rate that goes with increasing BAC is progressive. Compared to a sober driver the crash rate of a driver with a BAC of 0.8 g/l (still the legal limit in 3 of 25 EU-member states) is 2.7 times that of sober drivers. When a driver has a BAC of 1.5 g/l his crash rate is 22 times that of a sober driver. Not only the crash rate grows rapidly with increasing BAC, the crash also becomes more severe. With a BAC of 1.5 g/l the crash rate for fatal crashes is about 200 times that of sober drivers.
Alcohol diminishes one's driving skills at all possible levels. The driving task can be divided in three different levels. At the lowest level there are the tasks dealing with keeping a proper speed and keeping course (steering, accelerating, braking, etc.). Most of the skills related to this level, such as tracking performance, reaction times, and visual detection, already begin to deteriorate at a BAC below 0.5 g/l. At the intermediate level decisions are made dealing with concrete traffic situations (can I safely overtake that other car, do I have to give way, etc.). Skills related to this level are dividing attention, scanning capabilities, and, more in general, information processing. These skills also begin to deteriorate at very low BAC levels. At the highest level decisions are made whether one should drive or not. It is well known that after having consumed alcohol, self control becomes less stringent and when even a little bit drunk, people are more inclined to think that they are still able to drive safely.
The problem of drink driving is not new and very many measures have been taken. A very successful measure was the introduction of pocketsize breath testing devices by the police back in the 1970s. Despite the fact that drink drivers now know that they can be caught and that sanctions are tough, and despite public opinion regarding drink driving having changed considerably (most people in Europe nowadays wholeheartedly disapprove of drink driving), alcohol impaired road users are still involved in about a quarter of all fatal crashes in Europe. New and better measures are needed.
At the core of the measures are the legal limits. This limit should be 0.5 g/l or lower for the general driver population, but not so low that, due to insufficient police capacity, it starts to hamper the detection of drivers with the highest BAC levels. The legal limit for novice drivers should be 0 or just above 0 when enforceability is taken into account.
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