Motorways have improved mobility and safety in the road transport system. However, their safety relative to other roads is often overstated: drivers are probably only 50% safer on motorways, compared with non-built-up A roads. Most motorway accidents are attributed to 'errors' in driver behaviour, such as speeding, close following, poor lane discipline and failure to adapt to adverse conditions. Some of these problems undoubtley result from recklessness and carelessness. However, there is evidence suggesting that the design and normal use of motorways can be a contributory factor in accidents. Their relatively featureless nature poses problems for the perception of speed and distance, the judgment of safety margins and, particulary, the maintenance of alertness. Continuous high-speed driving causes speed to be underestimated and, in heavy traffic, contributes to speed stress effects. All these problems are exacerbated among proffessional drivers working irregular hours and suffering from sleep disruption. Behavioural problems of this kind are presented as the natural response of the human brain when driving is prolonged in a motorway environment. Remedial measures involving education, training and enforcement will therefore be of only limited effictiveness. There appears to be more scope for accident prevention involving engineering measures, ranging from road surface markings (aiding speed and distance perception) to information technology (aiding communication and decision taking).
Abstract