Long term trends in drink/driving are subjects of great public concern, yet they are difficult to analyse because of changes in procedures for identifying drivers with illegally high alcohol levels. The difficulty is overcome in this report by studying in particular accident trends for the part of the day when drink/driving is most common, namely 10pm - 4am. The report concludes that the number of casualties in drink/drive accidents fell by approximately one half between 1979 and 1988. The fall has been fairly regular since 1980, but with a sharp decline in 1983 when the law relating to drink/driving was changed and evidential breath-testing was introduced by the 1981 Transport Act. This Act also introduced compulsory seat belt wearing and new procedures for licensing learner motorcyclists. It is estimated that 490 fewer people were killed in the year after the Act took effect, and 36000 fewer people were injured. The contributions of the individual measures are evaluated, which shows that some previous estimates of the casualty reductions were probably too low.
Abstract