• helmet laws
• cycle

Except for one study reporting decreased cycling by children aged 12–17 in Victoria, Australia, Macpherson et al stated: “no other study about the relationship between legislation and exposure to cycling has been published”.¹ Macpherson’s paper has already been cited several times as evidence that helmet laws do not discourage cycling, so it is important to examine the evidence.

In fact, several published studies of cycle use and helmet laws are cited and described in refereed journals. Some were attitude surveys. The equivalent of 64% of adult cyclists in Western Australia said they’d ride more except for the helmet law.^2,3 In New South Wales (NSW) 51% of schoolchildren owning bikes, who hadn’t cycled in the past week, cited helmet restrictions, substantially more than other reasons, including safety (18%) and parents (20%).⁴ Street surveys by cyclists’ organisations in the Australian Capital Territory and Northern Territory found 28%–42% of cyclists would ride less/had ridden less because of helmet laws.³

Large scale roadside counts were also conducted. Pre-law surveys counted 6072 child cyclists in NSW,^3,5 3121 cyclists (all ages) in Victoria;^3,6 and over 200 000 cyclist movements on two key routes in Western Australia.³ Equivalent counts a year after enforced helmet laws showed declines of 36% (NSW), 36% (Victoria) and 20% (Western Australia).^3,5,6 Sunday recreational cycling in Western Australia (24 932 cyclists pre-law) dropped by 38%.⁷ Increases in numbers wearing helmets, 1019 (NSW) and 297 (Victoria) were substantially less than declines in numbers counted (2215 and 1110).³ These surveys were at the same time of year, in similar weather, and used the same sites and observation periods, so can be considered reliable indicators that enforced helmet laws discourage cycling. Reduced cycling activity is associated with increased injury rates per cyclist.⁸ Australian data suggest injury rates per cyclist increased after helmet laws³; the consequences of reduced cycling because of enforced helmet laws should therefore be fully investigated.

Non-enforced laws may have a lot less impact. One state (Queensland), delayed enforcement for 18 months.⁹ Helmet wearing increased initially, but 17 months after legislation, rates were little different from pre-law (primary schoolchildren 72%; secondary schoolchildren 21%, commuter cyclists 37%, recreational cyclists 22%, compared with 59%, 13%, 21%, and 22% pre-law).⁹ Non-enforced laws can be widely flouted, conveying the undesirable message that road safety rules need not be taken seriously, perhaps encouraging dangerous riding and causing more injuries per cyclist than with no law. Enforcing laws unpopular with cyclists may require substantial effort. Queensland issued nearly 23 000 bicycle helmet offence notices annually, 6.7% of all traffic offence notices.⁹ Per km, cyclists were three times more likely to receive a notice for not wearing a helmet than other road users for all other offences—speeding, drink-driving, failure to stop, give way, or obey other regulations. It is debatable whether this represents the best possible use of police road patrol time.

The Ontario law was not enforced¹⁰ and the effect on helmet wearing rates was not reported.¹ The results should be interpreted with caution for three reasons. First, the study excluded 15–17 year olds, perhaps the most rebellious age group, despite Australian findings that teenagers were most affected by helmet laws (48% reduction for 12–17 year olds), then adults (29%) with the smallest effect on children under 12 (10%).⁶ Indeed, in Ontario, only 16–17 year olds could be given direct penalties for non-wearing.¹¹

Second, the annual sample size was much smaller than the Australian studies, only 1128 cyclists observed in 1999 (not 747 as reported,¹ for 112 hours of observation; A K Macpherson, personal communication).

Third, the Australian surveys reported weather conditions and used the same sites, time of year and observation periods, to ensure variation due to these factors was not confused with effects of the law. The Canadian study had 111 pre-selected sites, each recorded for one hour, but weather conditions were not reported¹ (though elsewhere 1999 was described as a particularly sunny summer; A K Macpherson, personal communication). Table 1 in the Macpherson et al paper shows that, in some years, some sites were recorded more than once.¹ Moreover, observations were not at the same time of day and day of the week each year (A K Macpherson, personal communication). Analysis of such data requires careful scrutiny of counts and helmet wearing rates to estimate and allow for differences in observation sites and times, as well as weather conditions, to avoid confusing them with year-to-year variation and the effects of the law. This does not appear to have been done.

Another Canadian survey found “large variations in the number of cyclists per unit time, depending on the time of day, the day of the week, or the month”.¹² Perhaps all we should conclude is that the Ontario survey was relatively small, with substantial year-to-year variation, possibly related to year-to-year differences in sites, observations time or weather conditions, these differences swamping any effects of the non-enforced helmet law.