Zero BAC legislation affecting learners, first year probationary licence holders, unlicensed and disqualified drivers was introduced on 22 may 1984. Subsequently first year drivers reduced their driving during week end nights when drink driving is most prevalent but their p plate use remained unchanged at 40-60 per cent. The involvement in serious casualty accidents (SCA's) by all car drivers subject to the zero BAC restriction was compared with the involvement by a group of standard licence holders. The accidents were also divided into "alcohol" and "non alcohol" times. To detect a 10 per cent reduction in SCAs during "alcohol periods", approximately forty months post legislation data would be needed. This report contains the analysis of only 18 months data using time series methods and the results are confirmed using the traditional pre post method. A reduction of about 4 per cent was found which was not statistically significant. Time series analysis also showed no statistically significant effect when SCA data for learners plus first year probationary licence holders were compared with second and third year probationary licence holders. (Author/publisher)
Abstract