A number of recent studies in Victoria have evaluated the effects of countermeasures and other factors which appear to be responsible for the substantial reduction in road trauma since 1989. A need was identified to combine the results of these studies into a single model which could explain the overall reduction. The contributions of random breath testing, speed camera operations, road safety television publicity, unemployment rates and alcohol sales were estimated. Whilst the contributions of the last three countermeasures listed above were not estimated explicitly, their contributions to reducing crashes were accounted for. The models estimating reductions in serious casualty were then validated using 1993 monthly crash data. Subsequently, the contributions of random breath testing, speed camera tickets issued, levels of road safety television publicity, unemployment rates and alcohol sales to reducing the number of serious casualty crashes were estimated for the period 1990-93. A method of separately estimating the effect of accident blackspot treatments and disaggregating this from the trend was described and applied. As an example of an application to a crash sub-group, the methodology was also applied to the figures for young drivers.
Abstract