Further modelling of some major factors influencing road trauma trends in Victoria: 1990-96

Monash University Accident Research Centre - Report #129 - 1998

Authors: S. Newstead, M. Cameron & S. Narayan

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Abstract

Based on previous work that has estimated the contribution of some major factors in reducing road trauma in Victoria over the period 1990-1993, this project has made use of the statistical analysis methods developed to extend these estimates to 1996. The major factors considered in the study have stemmed from the results of a number of studies in Victoria which have evaluated the effects of countermeasures and other factors which appear to be responsible for the substantial reduction in road trauma since 1989. The factors for which contributions have been estimated were:

  • Increased random breath testing, supported by mass media publicity
  • Speed cameras, supported by mass media publicity
  • Reduced economic activity
  • Reduced alcohol sales
  • Improvements to the road system through treatment of accident black spots

The percentage change in road trauma levels, as measured by serious casualty crash numbers, due to each factor has been estimated for each year over the period 1990-1996.

Models linking variations in serious casualty crashes to various factors were computed using monthly crash data from the years 1983 to 1996. Subsequently, the contributions of random breath testing, speed camera tickets issued, levels of road safety television publicity, unemployment rates and alcohol sales to the reduction in the number of serious casualty crashes were estimated for the period 1990-96. A method of separately estimating the effect of accident black spot treatments and desegregating this from the trend was described and applied.

Executive Summary

Based on previous work that has estimated the contribution of some major factors in reducing road trauma in Victoria over the period 1990-1993, this project has made use of the statistical analysis methods developed to extend these estimates to 1996. The major factors considered in the study have stemmed from the results of a number of studies in Victoria which have evaluated the effects of countermeasures and other factors which appear to be responsible for the substantial reduction in road trauma since 1989. The factors for which contributions have been estimated were:

  • Increased random breath testing, supported by mass media publicity
  • Speed cameras, supported by mass media publicity
  • Reduced economic activity
  • Reduced alcohol sales
  • Improvements to the road system through treatment of accident black spots

The percentage change in road trauma levels, as measured by serious casualty crash numbers, due to each factor has been estimated for each year over the period 1990-1996.

Models linking variations in serious casualty crashes to various factors were computed using monthly crash data from the years 1983 to 1996. Subsequently, the contributions of random breath testing (RBT), speed camera tickets issued, levels of road safety television publicity, unemployment rates and alcohol sales to the reduction in the number of serious casualty crashes were estimated for the period 1990-96. A method of separately estimating the effect of accident black spot treatments and desegregating this from the trend was described and applied.

The major contributors and the apparent percentage reduction in serious casualty crashes due to each measure/factor were estimated as:

  • Speed camera operations (principally speeding tickets issued): 10-11% each year
  • "Speeding" and "concentration" television advertising: 5-7% each year
  • Drink-driving program (bus-based RBT together with "drink-driving" publicity campaigns)9-10% each year
  • Reduced alcohol sales: 3% in 1990; 6% in 1991; 7% in 1992; 9% in 1993; 8% in 1994; 9% in 1995; 10% in 1996
  • Reduced economic activity (measured by unemployment rates): 2% in 1990; 12% in 1991; 15% in 1992; 16% in 1993; 14% in 1994; 1 0% in 1995; 10% in 1996
  • Accident Black Spot treatments 1.6% in 1990; 2.5% in 1991; 3.2% in 1992; 5.3% in 1993; 6.2% in 1994; 6.2% in 1995; 5.6% in 1996

The anti-speeding and drink-driving programs together are estimated to have contributed reductions in serious casualty crashes of at least 22-25% during these seven years. Including the accident black spot treatments, the overall contribution of road safety initiatives is estimated to have risen from 23% reduction in 1990 to nearly 30% reduction in 1993-1996.

Sponsoring Organisation: Baseline Research Program - Department of Justice, Transport Accident Commission, Royal Automobile Club of Victoria (RACV) Ltd, VicRoads