DO VISIBILITY AIDS REDUCE THE RISK OF MOTOR-VEHICLE INJURY IN BICYCLISTS?

The role of conspicuity in preventing bicycle crashes involving a motor vehicle

Background: Bicycle use, despite its proven health and other benefits, is rarely part of everyday travel for many people due to the perceived risk of injury from collision crashes. This article investigated the role of physical vs. attention conspicuity in preventing bicycle crashes involving a motor vehicle in New Zealand. Methods: The Taupo Bicycle Study involved 2590 adult cyclists recruited in 2006 (43.1% response rate) and followed for bicycle crash outcomes through linkage to four national databases. A composite measure of physical conspicuity was created using latent class analysis based on the use of fluorescent colours, lights and reflective materials, and the main colour of top, helmet and bike frame. Attention conspicuity was assessed based on regional differences in travel patterns and the amount of riding in a bunch. Cox regression modelling for repeated events was performed with multivariate adjustments. Results: During a median follow-up period of 6.4 years, 162 participants experienced 187 bicycle–motor vehicle crashes. The crash risk was not predicted by the four latent classes identified and the amount of bunch riding but was higher in Auckland, the region with the lowest level of bicycle use relative to car use. In subgroup analyses, compared to other latent classes, the most physically conspicuous group had a higher risk in Auckland but a lower risk in other regions. Conclusion: Conspicuity aids may not be effective in preventing bicycle–motor vehicle crashes in New Zealand, particularly in Auckland, where attention conspicuity is low.

Incidence, risk, and protective factors of bicycle crashes: findings from a prospective cohort study in New Zealand

OBJECTIVE

To estimate the incidence and risk of medically or police attended bicycle crashes in a prospective cohort study in New Zealand.

METHOD

The Taupo Bicycle Study involved 2590 adult cyclists recruited from the country's largest cycling event in 2006 and followed over a median period of 4.6 years through linkage to four administrative databases. Incidence rates with Poisson distribution confidence intervals were computed and Cox regression modelling for repeated events was performed.

RESULTS

The 66 on-road crashes and 10 collisions per 1000 person-years corresponded to 240 crashes and 38 collisions per million hours spent road cycling. The risk increased by 6% and 8% respectively for an extra cycling hour each week. There were 50 off-road crashes per 1000 person-years. Residing in urban areas and in Auckland (region with the lowest level of cycling), riding in a bunch, using a road bike and experiencing a previous crash predicted a higher risk. Habitual use of conspicuity aids appeared to lower the risk.

CONCLUSION

The risk is higher in urban areas and where cycling is less common, and increased by bunch riding and previous crashes. These findings alongside the possible protective effect of conspicuity aids suggest promising approaches to improving cycle safety.