Chester1 <[email hidden]> wrote:
: Personal choice is fine I suppose..a bit like smoking..your choice. But not wearing a helmet is
: about as smart as riding at night without lights. When it became mandatory in Sydney, I was
: against it..ugly..didn't want to look silly etc. And then those stories that everyone would stop
: riding if they had to wear helmets. I know there have been surveys, but can't see that it has made
: any difference to numbers.
Personal impressions can be unreliable - sometimes we may go a different route, or ride at a
different time and see a lot more cyclists, so we may think the number of cyclists has changed,
when the numbers we see actualy changed because we did something different - moved house, changed
workplace, uni, or school, or changed where we ride.
Surveys data are important because they are designed to avoid such pitfalls by counting the same
sites at the same time of day, same time of year and as near as possible to the same weather.
In Melbourne, 36% fewer cyclists were counted at the same sites and times, compared to the year
before the law. In NSW, the authorities stuffed up the survey design, so comparable pre- and
post-law data is available only for children. 36% fewer children were counted at the same sites
and times after the law with across the board reductions at school gates, recreational areas and
road intersections, in inner and outer metropolitan areas and regional sites.
agbu.une.edu.auvelo.htmlOpen ↗
A longer series of data for Sydney is graphed at: cmaj.ca338Open ↗
It's not an ideal dataset - there's only one data point pre-law for both adults and children
(Oct 90), a second point in April 1991 when there was a law for adults but not children, with
further surveys until 1996. Other reports show a substantial (250%) increase in cycling in
Sydney throughout the 1980s, suggesting that helmet laws had a significant and continued
detrimental effect.
Perhaps one of most interesting illustrations of the effect of helmet law on cycling is the graph
of head and non-head injuries at: agbu.une.edu.auvelo.htmlOpen ↗
The data comprise *numbers* of cyclists admitted to hospital
a) with injuries to the head and b) with no head injury. The effect of the helmet law sticks out
like a sore thumb. But curiously, the law has pretty much the same effect on numbers of head and
non-head injuries. Can you tell which line is which? The most plausible explanation for the
decline in both is that fewer people cycled after the law - as was also evident from the pre- and
post-law street counts.
: So I don't think mandatory or not is such a big deal, and wearing one is still really your choice,
: but surely the risks of serious injury are greatly increased.
We have been led to believe that, but there's no really good evidence that helmets make a great
deal of difference. Another dataset (WA) is graphed at:
agbu.une.edu.auwagph.htmOpen ↗ These are percentages of hospitalized road users with
an injury to the head. The helmet law increased helmet wearing rates from less than 39% of all
cyclist to more than 80%. Can you identify when the law was introduced?
Research suggests that the important factors determing the risk of head injury are how you ride
and where you ride, including the average speed of motor vehicles and whether drivers expect to
see cyclists when thet look out for traffic in order to give way at intersections or turing left
or right into side roads.
This may seem surprising, but hospital data show that, even though a lot of cyclists get injured
by falling off their bikes, only a small proportion of these involve anything other than grazes
to the head. If you define head injury as a minor concussion, other brain injury or skull
fracture, the majority of these are caused by collisions with motor vehicles. I'd be pretty
certain that a helmeted cyclist hit at 50 km/hr has a higher risk of serious head injury (or even
death) than a non-helmeted rider hit at 40 km/hr.
This means that it's far safer to ride without a helmet in areas where cyclists' rights are
respected than wearing a helmet in areas where motorists may forget to look out for cyclists.
This explains the problem with helmet laws. The relationship between numbers of cyclists and
accident rate per cyclist has been modelled and found to obey what is known as a 'growth rule'.
Very briefly, if the number of cyclists doubles, the accident rate per cyclist goes down by 37%.
Conversely, if you apply the rule backwards and half the amount of cycling, the same rule shows
that risk increases by 60% - which is a huge increase. (If you don't believe this, do the
calculation yourself!).
So, even though helmets may offer the individual cyclist some benefit, the overall effect of the
laws was bad for the country, because people were discouraged from cycling and, with fewer people
cycling, the injury rate per cyclist actually increased (relative to the same statistic for
pedestrians).
Another problem of discouraging cycling is that it is good for health. A new UK report has just
been published with lots of references. You can read it at:
agbu.une.edu.auUKCycling health.pdfOpen ↗
The research into the growth rule is very new (it should be published soon in the international
journal Injury Prevention) so the UK report can't cite it. However, p26 says: There is also the
potential for reduced danger to cyclists through critical mass. This occurs when there are so
many cyclists on the road that they can reasonably expect to be seen by motorists, who tend then
to give them greater consideration. This is partly so because when there are relatively high
levels of cycling (perhaps over 20%) then it is common for some motorists to also be cyclists. At
present the case for a critical mass effect is largely intuitive although lowered risk to each
cyclist per unit of exposure, as in cities such as York, Groningen and Copenhagen suggests that
critical mass may have a positive influence in reducing danger to cyclists. Of course in
locations where cycling is commonplace cycle friendly infrastructure is generally also
commonplace.
Of course, helmet laws aren't the only thing that affects the amount of cycling. The BikeWest
team in WA has spent the past decade trying to encourage cycling. They have lots of recreational
bike routes around the river and have spent a lot of money on other things, usually after
comprehensive discussions with local cyclists groups. This doesn't imply that the helmet law
isn't discouraging cycling - there'd almost certainly be even more people riding if there had
been no law!
So don't be too hard on those who ride without a helmet. They may be breaking the law (except
adults in NT), but compared to people who don't cycle, they are saving us healthcare costs,
producing less pollution, and, by reminding drivers to look out for cyclists, making the road
safer for the rest of us. It's a pity that we can't get our Governments to do something sensible
and publicise the safety benefits of having lights at night, riding on the correct side of the
road, and obeying 'give way' and other traffic regulations, instead of putting out the idiotic
message that the most important saftey step by cyclists is to wear a helmet!
Ride safely, Dorre
