Have helmet laws worked elsewhere?

Some proponents of helmet laws like to claim that helmet laws are common and have worked in other countries. This is not quite true.

Do helmet laws work?

The most widely studied laws are in Australia and New Zealand. These are the “poster children” for helmet laws, with New Zealand being the first country to introduce an all-ages helmet law. And they enforce it.http://www.cyclehelmets.org/1008.html

One statement you might read is that the Australian law reduced head injuries by 40%. This is slightly disingenuous: what happened was that the number of head injuries dropped. But so did the number of non-head injuries. And the number of cyclists. By slightly more, actually. The proportion of head injuries – the head injury rate – displays about the same trend as for pedestrians (actually pedestrians fared slightly better). The simultaneous introduction of some other road safety laws has been credited with the reductions in pedestrian injuries.

You might hear that Australian cycling levels are now back up to pre-law standards. Up to a point: the numbers might be nearly the same, but the Australian population has increased by about 20%, and they’ve had an Olympic Games to increase fitness awareness, and most other countries have also seen substantial growth in cycling over the same time. So the Australian law did not so much work as knock back cycling by something over a decade. Plus, the balance of cycling has changed – there is more leisure cycling and less cycle commuting and utility cycling. Studies have shown that utility cycling is beneficial even for otherwise fit individuals.

New Zealand paints the same picture, but even clearer. Helmet use in New Zealand rose from around 40% to over 90% in a single year, and this change is not visible in the head injury percentage. Plot the head injury percentage for cyclists and pedestrians over time, you can’t guess which is which, let alone spot the year where helmet use doubled.

helmet laws in new zealand
Adult cyclist head injuries versus helmet use following crashes involving motor vehicles in New Zealand

It’s been calculated that the helmet law in New Zealand cost the country more in helmets than it saved by even the most optimistic estimates of injury reduction. And that’s assuming that all the helmets bought pre-law would have been bought anyway, which is doubtful since the pre-law period had already seen NZ usage rates rise well above world average.

Again, there was a numerical drop in numbers of cyclists head injured, and again this was about the same proportionally as the drop in cycling.

It is said that the recent experience of one Canadian province supersedes these experiences. But that is false. Not only is the count data inconsistent, the law there is unenforced, and helmet usage rates are not significantly different to pre-law levels.

In fact, as the Road Safety Minister David Jamieson said in a letter to another MP, the DfT knows of no case where cyclist safety has improved with increasing helmet use.

For the reasons why this is, you might want to take the tour of why helmet laws fail.

Are helmet laws common?

Not especially. They are least common in places where cycling is widespread and most common where it is most marginalised. This is probably an effect of the cyclist population; try telling a Dutchman that cycling is a dangerous activity requiring special protective equipment and he will laugh in your face. Whether a helmet law in South Africa can be considered significant I could not say.

Cost-Benefit Analysis

One way of evaluating the effect of a measure is to conduct a cost-benefit analysis (CoBA). A few reports have assessed helmet laws in this way.

  • DeJong, P (Macquarie University, Actuarial Studies): Evaluating the health effect of bicycle helmet laws estimates the net cost of a helmet law to the UK economy would be approximately $0.4bn.
  • The cost-effectiveness of compulsory bicycle helmets in New Zealand, Hansen P, Scuffham PA (1995. Aust J Public Health: 1995 Oct;19(5):450-4 – NZ [P82]) calculates that the cost per life saved was approximately $88,379 – $113 744 for primary school children, $694,013 – $817,874 for secondary school children, and $890,041 – $1,014,850 for adults. This assumes a 19% reduction in injuries (time series and comparisons with pedestrians shows 0%) and assumes that all helmets bought in the few years before the law, would have been bought anyway. (analysis)

These analyses are unusual. Normally when a helmet law is proposed, it is predicated on “up to 85% of injuries prevented” and no systematic effort is made after the law to measure the deterrent effect cycling or to assess whether the law has lived up to the claims of proponents. When it is challenged, it is claimed to be a success on the basis that more cyclists are now wearing helmets. You could do the same with lucky rabbits’ feet or St. Christopher medals, of course.