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Cycling

Nov 13, 2014

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Video: Chris Boardman got into trouble last week for not wearing a helmet while giving safety tips to BBC viewers. Source: BBC News

Tour de France winner and Olympic gold medallist Sir Bradley Wiggins reckons bicycle helmets should be compulsory in the UK:

I think certain laws for cyclists need to be passed to protect us more than anything. Making helmets compulsory on the roads, making it illegal to maybe have an iPod in while you’re riding a bike, just little things like that would make a huge difference.

But fellow Olympian Chris Boardman opposes even promoting helmets, much less making them mandatory. Last week he took to the net to answer criticism he’d appeared on BBC television riding a bicycle without a helmet:

I won’t promote high vis and helmets; I won’t let the debate be drawn onto a topic that isn’t even in the top 10 things that will really keep people who want to cycle safe.

Mr Boardman points to the virtual absence of helmets in cities like Utrecht to support his position. The obvious lesson is that it’s possible to make cycling so safe that the great majority of riders don’t wear a helmet; in cities like Utrecht helmets simply aren’t necessary.

I think Bradley Wiggins is wrong; countries where helmet wearing is currently voluntary should resist the pressure to make them mandatory. But it’s important to get the arguments clear.

The obvious issue is that British cities, like their counterparts in Australia, aren’t much like Utrecht. They don’t have the infrastructure, sympathetic road rules, supportive institutional environment, and constraints on car use that could ultimately make helmets redundant.

Cycling on the roads in car-oriented places like the UK is much more dangerous than it is in the centre of Dutch and Danish metropolises where cars are often the minority mode.

That’s in part because of the much more hostile road conditions confronting British cyclists. But another reason is that the average cyclist in Britain is in a different demographic relative to his or her counterpart in the Netherlands.

The comparatively small numbers of Britons who cycle on roads are disproportionately drawn from risk-takers like Wiggins (and so are more likely on average to be in a crash). The much larger number of Dutch who cycle is necessarily more representative of the whole population and hence is more risk averse than the British cohort. (1)

It’s therefore very likely introduction of a helmet law would reduce the number of head injuries in the UK as it has in Australia. It’s also likely it would deter some existing and prospective cyclists as it has in Australia.

But I don’t think the number of discouraged riders would be anywhere near as large as opponents of the law make out. The impact of the law on cycling levels in Australia following its introduction in the early 1990s is routinely over-stated (see here and here for further discussion).

It had no lasting impact on cycling by adults, especially in the demographic that shows most growth today. Its main negative effect was to accelerate the abandonment of cycling by high school boys and regional blue collar workers (see here and here for further discussion).

These groups were in any event destined to lose interest in cycling due to wider structural economic and social changes, such as the growth of video gaming, the fall in the real cost of motoring, and the decline of regional manufacturing.

I expect the benefits in terms of avoided head injury from making helmets mandatory in the UK would outweigh the number of cyclists who might be deterred. But it doesn’t automatically follow that helmets should therefore be compulsory.

There are innumerable instances where societies tolerate excess social costs because the burden of regulation would be too expensive, too intrusive, have unintended consequences, or would be too inconvenient and annoying. Citizens put a high value on their right to make their own choices whatever the consequences for them. (2)

There’s also another argument against removing the existing right of British cyclists to choose whether or not to wear a helmet.

It could signal that cycling can be made safe without the need to make hard and painful decisions. It could reinforce the narrative that cyclists themselves create the danger; that the only change that’s needed is for cyclists themselves to change.

There’s a risk is it could lessen the pressure to build cycling infrastructure, reallocate road space away from vehicles to bicycles, and rebalance road rules to favour cyclists at the expense of motorists.

All those prospective UK cyclists waiting in the wings aren’t deterred by the absence of a helmet law; they’re put off by the (accurate) perception that cycling on British roads at present is unsafe relative to other modes.

We know from the Australian experience that making helmets mandatory – notwithstanding the benefits in terms of fewer head injuries – doesn’t increase the sense of subjective safety anywhere near enough to drive a big increase in the proportion of the population cycling on roads.

The argument isn’t as black and white as some opponents make out, but I think making helmets compulsory in places where they’re currently voluntary isn’t a good idea.

Of course that inevitably prompts the question of what to do about Australia’s longstanding helmet law; do the same arguments apply in places where the law is already in place? That’s a big question I’ll have to address separately.

______________

  1. Which suggests the observed ‘safety in numbers effect’ can’t be entirely put down to being a small target. It might be explained in part by a selection effect i.e. larger cycling populations necessarily have a more risk-averse profile.
  2. My example of choice is middle aged men using ladders; high social cost but too hard and bothersome to regulate.

Cycling

Nov 28, 2012

5 comments

Some of Melbourne bikeshare's idle Bixis

Up until Melbourne Bikeshare launched in 2010, the idea that Australia’s mandatory helmet laws might have a net negative effect was a non-issue. Anyone who opposed the law was presumed to be a crank or a mad libertarian.

The abject failure of Melbourne Bikeshare and Brisbane CityCycle changed that. While the overwhelming majority of Australians simply aren’t interested, there’s now a small but vocal movement seeking to repeal the law.

In my view, there’s no doubt the helmet law is a serious hindrance to bikeshare. It’s not that most potential users aren’t prepared to wear a helmet, it’s rather that getting immediate access to a clean one is too hard.

But to repeal the helmet law in order to save ailing bikeshare schemes, as some argue should be done, would be to abandon any pretence of rational and inclusive debate.

Repeal is a much bigger and wider decision affecting the 90% or more of the population who aren’t likely to ever use a bikeshare scheme.

Perhaps there is a valid argument to repeal the law, but it would be out of all proportion to do it if the primary reason is to save bikeshare.

As I’ve argued before, it’s doubtful the potential benefits of bikeshare in the Australian context could justify such a far-reaching course of action.

Now I’ve come across some research that gives more substance to those doubts. It indicates that whatever other positives it might have, bikeshare doesn’t offer much in the way of environmental and health benefits, despite the many claims to the contrary.

The research is by Elliot Fishman, a doctoral candidate at the Centre for Accident Research and Road Safety in Qld. He’s also the co-author of a new paper evaluating Brisbane CityCycle.

Here’s an extract from a letter written by Mr Fishman and published last year in the British Medical Journal. He’s responding to an article that evaluated the Barcelona Bicing (bikeshare) scheme.

Data published by Anaya & Bea (and) collected by the City of Barcelona show users of the Bicing scheme to be substituting from other modes of transport in the following proportions: Public transit 55.1%, motor vehicle 9.6%, walking 26.1%, private bike 6.3% and new trip 2.8%.

Only the 9.6% of trips that would otherwise have been taken by car could be regarded as offering a significant environmental improvement.

The shift from car to bikeshare is modest in other cities too.

In a paper published by the US Transport Review Board, Evaluation framework for assessing public-bicycle share schemes, Mr Fishman and his co-authors provide data on the mode shift for bikeshare schemes in Dublin and Minnesota:

A recent study of the Dublin scheme found that 15% of users would not have made the trip had it not been for the (public bikeshare scheme). Of those changing modes, 66% had previously walked, 7% shifted from private car, 14% previously rode public transit and 11% migrated from private bicycles…..In Minnesota, 57.8% of users would have walked or taken public transit if the scheme had not been available. Almost 20% indicated they would have driven a car and 8.3% would have used their own bicycle.

He provides more evidence in an article published earlier this week in The Conversation, Fixing Australian bikeshare goes beyond helmet laws. In it, Mr Fishman says only 1% of users of the London and Washington bikeshare schemes “report leaving the car at home.”

It appears the vast majority of public bike users replace walking and/or public transport. While bike share programs in Europe, North America and China are heavily used, their success is limited by the degree to which they can attract people out of their cars.

These findings also bear on the exercise/health benefits which are often cited to justify support for bikeshare schemes. Mr Fishman argues that only new trips and those that substitute for car trips could be regarded as offering an exercise (health) benefit. In the case of Barcelona, for example, that’s 9.6% plus 2.8% i.e. 12.4%.

Moreover, he says any proper assessment of bikeshare schemes must take account of the lower exercise benefit associated with cycling compared to walking. In his British Medical Journal letter, Mr Fishman writes:

One should also factor the health benefit lost from the pedestrians opting for Bicing, given that the literature widely regard walking to have twice the physical activity benefit of cycling on a per kilometre basis.

I don’t think it would be correct to conclude Mr Fishman is opposed to bikeshare – he’s doing his doctorate on the topic. As I read it his concern, quite properly, is that the evidence base should be accurate.

Particular bikeshare schemes (there are 165 currently operational worldwide) might offer other benefits but caution should be exercised in assuming they necessarily provide substantial environmental and health benefits.

Those benefits are far too small to justify general repeal of the helmet law or even a specific exemption for bikeshare. Any public debate over the law needs to have a much wider ambit that takes account of the interests of the entire population.

So far as the outlook for bikeshare is concerned, compulsory helmets aren’t the only or arguably even the main obstacle to greater use in the Australian context. Fear of riding on roads with unfriendly drivers and poor system design are other serious constraints.

Cycling

Oct 24, 2012

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Average distance left by drivers overtaking cyclists in the UK (Source: Walker, 2006)

I came to the debate on the mandatory helmet law last year with an agnostic view. Having seen many references to past studies, I decided to read the key source documents that are consistently cited (e.g. see this article by the Institute of Public Affair’s Luke Turner) in support of the argument to repeal the law .

I started with the before-and-after study done at the time the law was introduced in Victoria in the early 90s. Then I looked at four before-and-after studies undertaken in NSW when the law was introduced at much the same time there.

Next on my list is a UK study which Luke Turner says shows “that some motorists drive closer to helmeted cyclists, than unhelmeted ones.” Although he doesn’t say who did it, he undoubtedly means the frequently quoted 2006 study by Dr Ian Walker from the Department of Psychology, University of Bath.

Like the other ‘foundation’ studies, I suspect this one’s quoted by many more people than’ve actually read it. I’m now one of the apparently select few who has.

Dr Walker’s prime interest was in how closely motorists came to cyclists when they overtook them. He was also interested in how the leeway overtaking motorists gave to cyclists varied by vehicle type, cyclist’s gender and whether or not helmets made any difference.

In order to collect the data, he personally rode 320 km in daytime on a bicycle equipped with an ultrasonic distance sensor and video camera, using a range of street types in Bristol and Salisbury. He rode at a range of fixed distances from the kerb, both with and without a helmet.

In total he recorded 2,355 overtaking events. In roughly half the events he wore a helmet.

Dr Walker also undertook a supplementary exercise to determine the effect of gender. He rode a 1.25 km stretch of road at a fixed 0.75 metres from the kerb, alternating between wearing and not wearing “a long feminine wig.”

His key findings are that overtaking drivers pass closer to cyclists “when the rider wears a helmet, rides away from the edge of the road, is male, or when the vehicle concerned is a bus or heavy goods vehicle.”

Having read the published journal article, I’m not persuaded the study lends convincing support to the argument that cyclists in Australia would be safer if they didn’t wear helmets. That’s for a number of reasons.

This is only one study and, moreover, it applies to a different country. It should be treated with caution until the findings are duplicated in other contexts.

In fact there’s a US researcher who found distance from the kerb made no difference at all to overtaking distances in Los Angeles. Whether either is ‘right’ or not, contrary findings illustrate the dangers of making sweeping generalisations on the basis of a single study in a specific context.

Dr Walker’s study also suffers from the fact the researcher is himself the key participant. That opens up all sorts of opportunities for bias and contravenes a prime rule of serious scientific method.

The idea of wearing a “long female wig” in order to “look plausibly female to motorists approaching from behind” doesn’t give me a lot of confidence in the research either. I’m not at all surprised drivers gave him a wider berth in this get-up – men in drag on bicycles probably aren’t a common daytime sight in Bristol and Salisbury.

Dr Walker’s findings also give some pause for thought.

The exhibit shows the differences are actually quite small. For example, when Dr Walker rode 0.25 metres from the kerb, drivers gave him on average 1.46 metres clearance when he was bare-headed and 1.38 metres when he wore a helmet.

That’s an average difference of 80 mm, or about three inches. It’s a reduction of just 5%. Further, whether with or without a helmet, drivers gave him a considerably wider berth than the one metre minimum overtaking distance cycling organisations in Australia are seeking to have enshrined in law.

Dr Walker reports the distribution of overtaking distances is bell-shaped. It’s strongly clustered around the mean (around 1.5 metres) with much smaller numbers in the tails.

The inner tail, though, is where most accidents are likely to happen. Dr Walker says 23% more vehicles came within one metre of him when he wore a helmet.

His data indicates that figure is right, but the numbers are very small. Only 5% of vehicles came within one metre when he wore a helmet and 4% when he didn’t.

That comes down to 60 overtaking events versus 49. It’s a difference of 11 out of a total of 2,355! That’s hardly a compelling argument.

The convergence of both curves at one metre from the kerb (see exhibit) also suggests that too much shouldn’t be read into the apparent difference. Dr Walker speculates it might be because that’s the distance where motorists have to cross/straddle the white lane to overtake, but why that would so decisively eliminate the helmet effect isn’t explained.

The author suggests the overall difference in overtaking distances could be due to drivers thinking either that helmeted riders are less vulnerable, and/or that they’re more experienced and predictable. The UK differs from Australia however, with only around a fifth of riders on major roads in the UK wearing a helmet, according to a source cited by Dr Walker.

That’s not the case in Australia. Helmets are normalised here – the vast bulk of riders comply with the law. If riding without a helmet were also normalised and popular, it can’t be assumed the two classes of riders would necessarily be treated differently by overtaking drivers.

So I’m not persuaded that this study by itself provides much support for the argument against mandatory helmets in Australia. The other two ‘foundation’ studies I reviewed previously (here and here) didn’t live up to all of the extravagant claims made on their behalf either.

The most interesting findings have nothing to do with helmets. Although they’re also subject to some of the caveats raised above, Dr Walker found buses and trucks pass closest to cyclists and, contrary to popular belief, ‘occupying the road’ encourages drivers to pass nearer. The effects are relatively small though.

Cycling

Oct 7, 2012

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Rates per 100,000 population of bicycle related head and arm hospitalisations. Source: Olivier et al, 2012

There’re two key arguments in the debate on the mandatory helmet law (MHL). On the one hand, it’s argued compulsory helmets deter cycling. On the other, it’s contended they reduce head injuries. Both claim a social benefit in lower health costs – more exercise vs fewer head injuries.

I’ve looked at the deterrent argument before (here and here). Now, a new paper analysing bicycle-related head injuries provides an opportunity to look at the claimed benefits of helmets (you can download the full paper here).

The paper is by three researchers from UNSW, led by Dr Jake Olivier from the School of Mathematics and Statistics. The authors examined hospital admissions data in NSW from 1990, the year before the mandatory helmet law was introduced, until 2010.

To isolate the impact of helmets, they compared hospitalisations for bicycle-related head injuries with those for bicycle-related arm injuries. The logic is that, while there’s no reason they should be the same, they should change over time at the same rate, unless an intervention is directed at one and not the other.

In 1990, just prior to the introduction of the MHL, head injury rates were higher than arm injury rates (see exhibit). However following enactment of the law, they fell 29% relative to the change in arm injuries.

That was a substantial and dramatic benefit. It’s equivalent to around 170 avoided hospitalisations in the first year alone. It’s compelling evidence of the benefits conferred by wearing a helmet.

The authors go further, though, and attribute the social benefit to the mandatory helmet law, because it drastically increased the rate of helmet wearing. Prior to the law, 10% of children and 25% of adults wore helmets, but this jumped to around 80% within two years.

We should expect the helmet law to provide a one-off, permanent lowering of the head injury rate. But what’s very interesting about the exhibit is the two variables didn’t run in parallel over the period from 1991 to 2010 but diverged sharply.

The number of arm injuries increased by 145% over the period while head injuries increased by only 20%. The latter figure is broadly in line with the increase in population, but it’s much, much lower than other indicators of the growth in cycling cited by the authors.

For example, a survey of NSW residents found the number who had cycled within the previous 12 months increased 50% between 2001 and 2010. Bicycle imports grew 145% between 2000 and 2009 and the number of cyclists counted in the Sydney CBD increased 156% between 2002 and 2010.

Thus head injury hospitalisations fell massively in ‘real’ terms over the 20 years from 1990 to 2010.

The exhibit also shows there was a distinct turning point in the trend at 2006. Thereafter the number of both arm and head injury hospitalisations declined, although the reduction in head injuries was even stronger.

The authors attribute the difference between the two variables up to 2006 as entirely due to the protective effect of wearing helmets. Dr Olivier says:

We found that the overall benefit of mandatory helmet legislation in lowering head injuries was larger than previously reported and has been maintained over the past two decades. Before the law commenced in 1991, bicycle-related head injury rates exceeded those of arm injuries. By 2006, head injuries were 46% lower than arm injuries.

On the other hand, they ascribe the post-2006 decline to the combined effect of the mandatory helmet law and the construction of safer cycling infrastructure.

Infrastructure matters because head injuries are strongly correlated with collisions between motorised vehicles and cyclists. These usually occur at higher speeds than other bicycle accidents.

While much cycling infrastructure is only a painted line on the road, it nevertheless increases the separation between bicycles and heavier, faster-moving vehicles.

Why head injuries fell continuously and sharply in ‘real’ terms over the entire 20 year period isn’t clear. It’s possibly helmet-related e.g. improved helmet fitting or fewer ‘risk-takers’ going helmetless.

It might possibly reflect the dramatic decline (mostly for reasons unrelated to helmets) in high school children cycling to school over the last 20 years. Or perhaps the rudimentary cycling infrastructure of the 1990s and early 2000s made a greater contribution to safety than it’s usually given credit for.

We can be pretty confident the big jump in rates of helmet wearing accounted for the initial spectacular reduction in head injuries. Their role in the subsequent equally remarkable further improvement is less clear.

That doesn’t mean however that mandating helmets was necessarily good policy. It’s possible rates of voluntary helmet wearing might’ve improved significantly without the law, perhaps driven by education, better helmet design, and rising concern about the dangers of cycling on roads.

And of course the injury avoidance benefits have to be assessed against the costs. Some cyclists are convinced the cost to the community in foregone exercise due to the deterrent effect of helmets far outweighs the benefits from avoided head injuries.

Cycling

May 16, 2012

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Subterranean London - all things underground, old and new (click to see more)

Fremantle City Council is proposing cyclists over 18 years of age have the option of riding without a helmet within the municipality for a trial period of between two and five years. The proposed trial would apply to segregated cycle paths and streets with a speed limit of 50 km/h. (H/T Michael McPhail).

The rationale for the trial is familiar. Council says the social cost of “lost” exercise deterred by the helmet law exceeds the social benefit from the head injuries that helmets avoid.

Presumably Council has done its due diligence, but the trial probably requires State Government permission – or perhaps even legislation – so I think it’s got very little chance of getting up. The politics just don’t work.

It would be a pity though, because from what I can see (e.g. here, here and here), much of the Australian evidence relied upon in this debate is either too old or too weak. The discussion would really benefit from some contemporary and objective data. Continue reading “Should Freo go helmet-free?”

Number of adult cyclists counted at the same 25 intersections in Sydney between 1990 and 1993. Mandatory helmet law for adults was introduced between the 1990 and 1991 counts (data from Smith & Milthorpe)

As a consequence of the lacklustre performance of bikeshare schemes in Melbourne and Brisbane, there’s been a heated debate over the last couple of years about the wisdom of the country’s mandatory helmet law.

Much of the evidence offered against compulsory helmet wearing relies on a handful of ‘before and after’ studies that were done in Victoria and NSW at the time the law was introduced at the start of the 1990s. These “natural experiments” are cited so many times that I thought it would be an instructive exercise to go back and look at the original sources myself.

I started with a study done in Melbourne by the Monash Accident Research Unit in 1993. You can read my analysis here. In a nutshell, rather than showing the new law devastated cycling across-the-board, I was surprised to discover the level of cycling by adults and primary school children wasn’t seriously affected.

However there was a big fall in the high school-age youth segment (12-17 years). Youth numbers were flat in the years leading up to the law, but declined sharply in the first year after and remained at that lower level in the second year.

Still, that’s only one study. There’s also a group of four related NSW studies that are frequently cited in this debate. They proved so extraordinarily hard to find that I doubt many of the people who reference them have actually read the originals. However thanks to the kindness of a reader I was able to access all four and offer the following thoughts. Continue reading “Did mandatory helmets deter cycling in NSW?”

Cycling

Feb 26, 2012

5 comments

No. cyclists in Melbourne before and after introduction of mandatory helmet law between 90 & 91 (Finch et al)

The effect of the mandatory helmet law on cycling is one of those debates that goes on endlessly because of the absence of hard evidence one way or the other. We simply don’t know how many kilometres of cycling, if any, are foregone because of the helmet laws.

If only a State Government would grant a trial helmet exemption so a proper ‘before and after’ study could be undertaken. But it’s hard to see that happening – there’s no “politics” in it.

However there was an opportunity to undertake a ‘natural experiment’ at the time the mandatory helmet laws were introduced in Australia in the early 1990s. Fortunately, according to an influential paper by D. Robinson, Head injuries and bicycle helmet laws, at least two such studies were undertaken.

These have been cited frequently by opponents of the law to show conclusively that it had a significant negative effect on cycling rates. One was done in NSW by the State’s Roads and Traffic Authority and one by Monash University Accident Research Centre in Victoria.

These studies are frequently cited and re-cited in debates and, as so often happens, succeeding generations of discussants quote others who’ve quoted others who’ve….There’s always the risk of the Chinese Whispers effect – the message gets distorted with each retelling.

My starting view is the deterrent effect of the law (less cycling) probably out-weighs the protective effects it confers (fewer head injuries). Given all the debate about helmets engendered by the disappointing performance of the Brisbane and Melbourne bikeshare schemes, I thought it would be useful to test my view by going direct to the source material: not someone else’s summary of them, but the actual documents themselves.

The first study I sought out is titled An observational survey of law compliance and helmet wearing by bicyclists in NSW – 1993, by N. Smith and F. Milthorpe, published by the NSW Roads and Traffic Authority in 1993.

Astonishingly, I couldn’t find an electronic version of the study anywhere. It’s referenced hundreds of times, but the study itself eluded me. Then I reluctantly looked for a hard copy, searching the catalogues of two major universities, as well as the NSW transport agencies. I know it exists because it’s been cited so many times, but where? So I’ve had to let that pass for the moment – if someone has an electronic copy, could they please make it available?

No such problems with locating the Victorian study, fortunately. It’s got a direct, no-nonsense title: Bicycle use and helmet wearing rates in Melbourne, 1987 to 1992: The influence of the helmet wearing law. It’s by C. Finch, L. Heiman and D. Neiger, and was published in February 1993 by Monash University Accident Research Centre.

Helmets became mandatory in Victoria on 1 July 1990 (the first state in the world). Finch et al counted both the change in the number of cyclists pre and post the law as well as the change in the time spent cycling. They counted cyclists at the same 65 observation sites in Melbourne on four occasions – 1987 and 1990 (the 1990 count was taken five weeks before the new law came into effect), and 1991 and 1992 (after the law).

On each occasion, counting was undertaken over a two-week non-holiday period, seven days a week, between 8am and 6pm. The 1987/88 survey was done in summer, but the others were all done in May/June, a considerably cooler and wetter time of the year in Melbourne.

The exhibit shows that the number of adult cyclists (18 years and over) counted at the observation sites fell in the first year after the law was introduced but returned to almost the pre-law level by the second year. The number of young children (5-11 years) who cycled was declining prior to the new law, but flattened slightly in the first year after and by the second year had returned to the old level.

The big loss was in the high school-age youth segment (12-17 years). Their numbers were flat in the years leading up to the law, but declined sharply in the first year and remained at that lower level in the second year.

So the helmet law didn’t have much effect on the numbers of either adults or primary school-age children who cycled. That’s not a message that’s come through particularly clearly from the frequent references I’ve seen to the Finch et al paper!

Although there were not quite as many of them in absolute terms as adults, the youth segment was a significant group. The age range spans just six years (12-17) but accounted for circa 40% of all cyclists in Melbourne immediately prior to the new law.

However the decline in youth riders has to be evaluated against the main purpose of the law. The improvement in helmet use was spectacular. The adult helmet wearing rate rose from 36% in 1990 to 84% in 1992. The rate for children increased from 65% to 77% over the same period.

And for youth, who clearly didn’t like helmets, the rate rose almost threefold, from a desultory 21% just prior to the new law to 59% of those who were still riding by the second year after the intervention. Of course this won’t cut any ice with those who reckon helmets are pointless (or in some cases positively bad for you!), but it will mean a lot for the much larger group who think helmets have a protective benefit.

I think there are in any event good reasons to question the long-run effect of the new law on youth cycling rates. This cohort was the only one who went from voluntary helmets to compulsory helmets (literally overnight). Subsequent cohorts may not have had as strong an aversion to wearing a helmet since it was always ‘just the way things are’ during their primary school life. Anyone born after 1985 wasn’t even in primary school when helmets were made mandatory (and anyone born after 1978 wasn’t in high school).

It’s also relevant that high school age youth are notoriously fashion and status conscious. This is a fickle business – what was unfashionable in the early 90s might not be unfashionable today, or even five or ten years later. Back in 1990 the Rosebank Stackhat was ugly by any measure. Since then, helmets have become designer items and an Australian won le Tour last year (wearing a helmet). It no longer follows automatically that helmets are as uncool among a majority of today’s 12-17 year olds as they were twenty years ago.

Further, while I haven’t seen any numbers (so I’m not going to die in a ditch over it), I also wonder if cycling has the same allure for youth today that it did in 1983 when Nicole Kidman starred in BMX Bandits. Competing leisure pursuits like game consoles, as well as the increasing propensity of parents to drive their children to school and other destinations, may have reduced their per capita use of bicycles significantly independent of anything to do with helmets. In other words, any aversion to helmets might be very much a second order effect.

But it’s the spectacular growth in adult cycling over the last twenty years that really makes me wonder if the helmet law is a serious constraint on cycling. Bicycle sales have gone gang busters. Rissell and Wen report 18% of Sydneysiders aged 16 and older who were randomly sampled in October 2010 say they had ridden at least once in the last month (and 11% in the last week).

Even if helmets were a serious disincentive twenty years ago (and Finch et al’s work suggests that was only true on average for 12-17 year olds in Melbourne), the alternative interpretation is Australians have adapted to them; we’ve regularised them; we’ve accepted them; we’re simply not bothered any more. Virtually everyone’s forgotten we once had a choice.

Still, that’s only the paper by Finch, Heiman and Neiger. Perhaps the elusive Smith and Milthorpe paper tells a different story, so I’ll reserve judgement until I see a copy of their paper. If someone has an (electronic) copy, could they please provide a link so all can access it?

NOTE: there’s a possibility someone will be tempted to argue that Finch et al mention a cycle rally in 1992 that supposedly “inflated” the numbers at one observation point in 1992, thereby giving a higher adult cycling count than the “true” one.

I don’t think inconvenient results can be ‘cherrypicked’ away. The authors address this question:

From a statistical point of view….an occurrence such as this is a true observation, well within the bounds of “normal” behaviour for that time period, and cannot be excluded from the analysis.

The fact is we don’t know all the myriad other factors that might also have influenced the overall counts – up or down – in all four years or at any of the 65 observation points. It can be argued Finch et al’s sample size was too small to accommodate occurrences like the rally, but in that case the entire study would have to be rejected. I don’t see how that would help the case of those who argue against mandatory helmets.

Cycling

Dec 13, 2011

5 comments

If maps were based on time not distance, this is how big (and small) the Netherlands would look

A new Australian study has thrown more fuel on the fiery debate about whether or not bicycle helmets should continue to be mandatory. Its headline claim is 23% of Sydneysiders say they would cycle more if they weren’t obliged by law to wear a helmet.

This isn’t merely saying that some people would prefer to cycle without a helmet – it’s claiming the law actually suppresses cycling.

I lean toward the school of thought that says mandatory helmets probably do more harm socially than good, but as I’ve said before, it’s not the sort of issue that I would want to die in a ditch over. However if there were reliable evidence that compulsory helmets actually restrain cycling, that would require a rethink.

The research was undertaken by Professor Chris Rissell and his colleague, Li Ming Wen. It is published in the latest edition of the Health Promotion Journal of Australia, under the snappy title, The possible effect on frequency of cycling if mandatory bicycle helmet legislation was repealed in Sydney, Australia: a cross sectional survey.

It’s a brief and easy to read article but a summary by Professor Rissell was published on The Conversation last week, Make helmets optional to double the number of cyclists in Australia. Professor Rissell is a self-confessed cycling advocate and firmly in the activist “repeal” camp on helmets.

He and his colleague surveyed 600 Sydney residents aged 16 years and over. They found one fifth of respondents “said they would cycle more if they did not have to wear a helmet, particularly occasional cyclists”. They conclude that:

While a hypothetical situation, if only half of the 22.6% of respondents who said they would cycle more if they did not have to wear a helmet did ride more, Sydney targets for increasing cycling would be achieved by repealing mandatory bicycle helmet legislation. A significant proportion of the population would continue to wear helmets even if they were not required to do so.

Regrettably, I don’t think this study adds anything to our knowledge of whether Sydneysiders would ride more if helmets weren’t compulsory. They might, but then again they might not. The trouble is the survey relies on a hypothetical situation: “Would you cycle more often if you didn’t have to wear a helmet? Yes or No?”.

Hypothetical survey questions are notoriously unreliable. I’m not picking on the anti-mandatory helmet brigade here – I also took Metlink to task earlier this year for trying to make grandiose predictions about future public transport patronage based on a similarly unreliable methodology.

It’s standard practice to avoid hypothetical questions in surveys. Consider this advice from The World Bank publication, The Power of Survey Design:

Hypothetical questions, especially, should be avoided. People cannot reliably forecast their future behaviour in a hypothetical scenario. Thus, the questionnaire design should make careful use of this style of question.

Hypothetical questions are especially problematic when respondents are asked to predict an activity they’ve had little experience of. The Canada Business Network advises questionnaire designers, if possible, to “avoid hypothetical or future intentions questions:

Hypothetical questions force the respondent to provide an answer to something he or she may never have thought about and, therefore, the respondent may not be able to provide an accurate response.

The authors should’ve been alerted that all might not be right when they found 40% of those who say they’d cycle more if helmets weren’t compulsory, also say they support mandatory helmet legislation. Yes, there’re scenarios where it’s conceivable someone could hold both views simultaneously, but 40%?! Continue reading “Are helmet laws suppressing cycling?”