On September 1, 1985 the mandatory safety belt use law (MUL) in Texas was implemented without sanctions. Three months later, the imposition of $25-50 fines took effect. The purpose of this study was to analyse the effectiveness of the new law at reducing fatalities for motor vehicle occupants covered by the law. Fatality data for covered individuals from 1975 through 1986 were analysed using a multiple time series design. The comparison group of not-covered fatalities included occupants in the back seat of passenger cars and pick-up trucks, drivers and passengers in not-covered vehicles, pedestrians, pedacyclists, and motorcyclists. The actual number of observed fatalities for covered occupants was compared to the number of expected fatalities, based on a time series model that incorporated the comparison series of not-covered occupants. The observed and expected values prior to 1984 were in close agreement. However, beginning in 1984 and continuing through 1986, the observed number of fatalities per month was consistently below the expected number of fatalities per month by a fairly large margin. Taking into account the trend in fatality reduction that began in the latter part of 1984, a conservative estimate of the reduction in fatalities evidenced after the MUL took effect was 17 people per month. This figure is equivalent to a decrease of approximately ten percent, which is a reasonable reduction given that safety belt usage rates in Texas increased from approximately 15 percent before the MUL to 60-70 percent after the law took effect. The downward trend in fatalities among covered individuals relative to not-covered individuals was noteworthy. However, the fact that the decrease began prior to the implementation of the MUL indicates that the observed reductions in motor vehicle deaths cannot be attributed solely to safety belt legislation. Several other factors that may have been responsible for the decrease in fatalities are discussed. (Author/publisher)
Samenvatting