Bicyclist Head Injuries in Victoria Three Years after the Introduction of Mandatory Helmet Use

Monash University Accident Research Centre - Report #75 - 1994

Authors: S. Newstead, M. Cameron, S. Gantzer & C. Finch

Full report in .pdf format [1.8MB]

Executive Summary

The mandatory bicycle helmet wearing law implemented in Victoria on 1 July, 1990 was successful in building on past efforts to promote helmet use by bringing helmet wearing rates to new high levels for all cyclist age groups in the first post-law year, both in Melbourne and Victoria as a whole. Estimates of trends in helmet wearing over all three post-law years were, however, not available for this report.

The continuing influence of bicycle helmet wearing on bicyclist head injuries three years after the introduction of mandatory wearing is evaluated here by building on the results of the two previous evaluations of the bicycle helmet wearing law conducted by the Monash University Accident Research Centre (Cameron et al 1992, Finch et al 1993b). Results are presented for both metropolitan Melbourne and the whole of Victoria and the study uses data sourced from motor vehicle involved bicyclist injury claims from the Transport Accident Commission (TAC) as well as Victorian hospital admissions records of injured cyclists.

Analysis of hospital admissions records using logistic regression was not able to find a relationship between helmet wearing and head injury rates in the immediate pre-law years for bicyclists injured in accidents not involving a motor vehicle. Despite this, head injury rates for bicyclists injured in these crashes was significantly lower than the pre-law level in each of the three post-law years. A significant inverse relationship between helmet wearing and head injury rate was found for cyclists involved in accidents with motor vehicles. This relationship was found in analysis of both TAC insurance claims data and hospital admissions records.

The effect of the bicycle helmet law in reducing head injury rates below pre-law trend predictions for bicyclists injured in motor vehicle involved crashes was not clear. Analysis of the TAC claims data showed bicyclist head injury rates significantly below pre-law trend predictions in the second post-law year although this benefit appeared to have been lost in the third post-law year, with an increase in head injury rate from the second post-law year. Analysis of the hospital admission records however, failed to show any additional benefit of the law over pre-law trends in reducing head injury rates in the three post-law years (an increase in head injury rate in the third post-law year was also observed here). Comparison of the TAC claims data and hospital admission records for non-fatal motor vehicle involved bicyclist injuries revealed possible differences in injury coding between the two.

A subsequent MUARC report (Carr et al 1995), which should be read in conjunction with this report, investigates bicycle injury data and the effect of the bicycle helmet law four years after its introduction. This report has revealed biases in the bicyclist injury data, certainly affecting the analysis and results presented here. This is shown by the analysis of Carr et al (1995) which adjusts for the bias in the bicyclist injury data and reaches different conclusions to those drawn here.

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