The Effectiveness of Anti-Lock Brake Systems: a statistical analysis of Australian data

This assesses the effect of anti-lock brake systems (ABS) on driver injury risk and injury severity through analysis of real crash outcomes reported by Police in Victoria, NSW and Queensland. Information on the presence or absence of ABS on crashed vehicles was provided by participating vehicle manufacturers and matched to the Police reported crash data. A total of 40,739 records were available for analysis.

The statistical analysis examined the effectiveness of ABS in terms of both primary and secondary safety. Primary safety effects have been assessed using induced exposure methods employing crashes where the focus vehicle is impacted in the side by another vehicle as the induced exposure measure. Secondary safety effects were evaluated using Poisson and logistic regression models that examined the effectiveness of ABS on the risk and severity of driver injury in the event of a crash whilst controlling for other factors that may affect the safety outcome such as driver age and sex, vehicle model and speed limit at the crash location.

ABS braking systems were generally found to have no statistically significant effects on secondary safety outcomes. In terms of primary safety, changes in the distribution of crash type for ABS equipped vehicles were detected as were changes in absolute risk for certain crash types. Vehicles fitted with ABS had lower risk of crashing with other vehicles. However, a higher risk of run of road type crashes for ABS equipped resulted in a net zero change in risk across all crash types. These results are consistent with those estimated in previous overseas studies.