EVALUATION OF A RANDOM BREATH TESTING INITIATIVE IN VICTORIA

This report provides a summary of the fmdings of two evaluations, with differing methodologies, to determine the impact of a random breath testing (RBT) initiative (including publicity) in Victoria on severe crashes in high alcohol times of the week during 1990 and 1991. Bus-based RBT stations using highly visible "Booze Buses" largely replaced car-based stations, and a multi-million dollar, Statewide anti-drink driving publicity campaign through all mass media, was launched in mid December 1989, and reinforced throughout 1990 and 1991. It was found the initiative reduced fatal crashes (in high alcohol times of the week) in Melbourne during 1990 by around 19-24% relative to what was expected. Serious casualty crashes (in high alcohol times) in the rural areas around Melbourne were reduced by 15% relative to other rural areas of Victoria where the RBT initiative was expected to have had minimal effect. It was also estimated that there was a 13% reduction in serious casualty crashes (during high alcohol times) in the whole of rural Victoria. The effect on Melbourne serious casualty crashes (during high alcohol times) was more difficult to estimate, given that a new decreasing trend in these crashes emerged shortly before the intervention. The choice of the appropriate model to represent the expected post-intervention trend, and hence estimated change, differed between the two studies. The first study, using an estimate which emphasised the new road safety trend prior to the intervention, found no statistically significant evidence that the RBT initiative had an effect over and above that which would have occurred if the pre-intervention trend had continued downward. In contrast the second study, using a model which basically placed equal weight on the trend for the previous twelve month pre-intervention period, suggested that RBT reduced serious casualty crashes during high alcohol times in Melbourne by between 8 and 27%. The second evaluation also attempted to assess the effect of the initiative on these crashes in 1991. The results suggested that there was a statistically significant reduction in serious casualty crashes (in high alcohol hours) in rural Victoria only, and no change in fatal crashes (in high alcohol hours) in either Melbourne or the rural area. The confidence limits were very wide for fatal crash estimates in this period however, reducing the chance of showing a significant effect. The fmdings for the 1991 period are also less conclusive because other (new or changing) factors may mask or weaken the effects further away in time from the beginning of the intervention.