On cycle helmets and the importance of the first question

Cycle Helmet

Setting a good example, if you follow the Highway Code

Back when I was 15, in some cold and dank classroom in the middle of a Devon winter my then GCSE Geography teacher was explaining to us about the importance of the practice of research. In amongst all new things about quantitative and qualitative approaches, some rubbish about p values, and doodling on my notepad, one thing did stick with me: “The most important question you’ll ever ask is the first one.”

Its only over time that I’ve really come to understand the importance of that. The first question you ask informs everything that follows. For research, this is the research approach, methods used, statistical analyses undertaken, and ultimately conclusions. In debates it informs whether you learn any new information, how the debate proceeds, and again its conclusions.

For transport professionals, this simple fact is no different. Should we not ask the first question correctly, schemes and policies are delivered with consequences unforeseen (usually I might add) by its promoters. This can literally have life and death consequences in some cases. Therefore, it is essential that our first question when developing or delivering policy ensures that we obtain as much information so that we can come to an informed judgement as to whether or not what we are doing is a good idea.

This approach informed a recent piece of research that I undertook for a Bursary for the Transport Planning Society on the subject of cycle helmets (you can download it and read it if you like). For those of you new to the cycle helmet debate, its one that kicks off every now and then when somebody proposes a law that requires people to wear cycle helmets for their own safety – usually by some dim-witted MP like Alok Sharma or Eric Martlew – or some minor cycling celebrity calls for it. Regardless of the side taken in the debate, the core of the debate surrounds lives prematurely lost through collisions and other things. And it is this debate that I will use to show the pitfalls of not asking the correct question.

Seeing the cycle helmet as a safety intervention

A more traditional – no, that’s not the right word…historic – approach to the debate is to see the cycle helmet as a safety intervention, and thus the approach taken to debating the merits or otherwise of compulsory helmet wearing legislation is its effectiveness as such. Thus the question asked by those favouring this approach is

Do cycle helmets reduce injuries and save lives?

If answering this question, the evidence supporting the cycle helmets role in injury reduction is strong. The Cochrane Collaboration performed a meta analysis concluding that helmets reduce risks of head, brain, and severe brain injuries in all ages of cyclists by between 63% and 88%. The evidence of the effect of compulsory helmet wearing legislation is particularly strong for children, mainly as a result of all such laws that have been enacted covering this group.

Quality evidence on the effects of cycle helmets and compulsory helmet wearing legislation is – surprisingly – somewhat lacking. Studies that have been undertaken into this suffer from a number key flaws, notably being unable to control for other factors that impacts on total fatalities (e.g. quality of cycle infrastructure), and poor quality data as to the likely series of events and kinetic interactions in accidents that will affect a cycle helmets effectiveness in preventing a fatality from a severe blow to the head.

A report often cited in the UK context is a wide-ranging study by TRL into cycle helmets, which used a bio-mechanical assessment to assess what proportion of cyclist fatalities could have been prevented by a cycle helmets (10% to 16%). While its the best – more accurately only – UK estimate, it has a number of significant flaws that undermine its credibility as a usable figure (a more comprehensive critique can be found on the Bicycle Helmet Research Foundation website if you are interested).

Regardless of this need for more quality research into effectiveness of cycle helmets on fatalities, there is good evidence that shows cycle helmets reduce head and brain injuries. Therefore, a compulsory helmet wearing law would be a good thing. There’s our answer, right?


What we should ask is…

What? Where's your helmet, fool? Image from Freedom Treks

What? Where’s your helmet, fool? Image from Freedom Treks

Going back to what I said earlier, in order to come to an informed decision we need to ask a question that gets us as much information for the issue at hand. Clearly its impossible for us to collect every possible bit of every information on every possible impact on every issue associated with a research question or discussion point. But its important that the first question we ask gets us as much relevant information as we need.

What factors and information is relevant is defined by a number of different things: the law, professional best practice endorsed by respected institutions, government guidance, and – yes – even the views of the individual professionals and decision makers are just a few I can think of. Within the context of the compulsory helmet wearing legislation debate, it is taken as a given that transport professionals – indeed any decent human being – accepts measures that save lives and reduces injuries as worthy of consideration. But as of April this year a new legal duty changes the parameters of the debate fundamentally.

From 1st April 2013, under the Health and Social Care Act 2012, many local highways authorities will inherit a general duty to promote public health in their areas from the NHS. I have to say that I am somewhat dismayed that there has been little in the way of debate within transport circles as to the importance of this legislation in how we deliver on public health as part of our work beyond the obvious thing of stopping highway users being killed and injured. A subject for a blog in my drafts folder, certainly.

The importance of this legislation for the way that transport planners do their work is in the question we now need to ask ourselves when considering safety interventions. No longer should we ask “will this safety intervention (in this case the cycle helmet wearing law) reduce accidents/KSIs of road users?” but instead the question we should be asking as part of the cycle helmet legislation debate is:

What are the wider health impacts of this safety intervention?

Failure to do is a failure of not just professional practice, but potentially illegal from April of this year. So what of the wider health impacts of cycle helmet legislation beyond that what we have already shown?

It is well evidenced that increasing levels of physical activity has a number of positive health impacts, and less physical activity has a number of negative impacts. If you don’t accept this, you are flying in the face of well-established medical facts and pretty much most of the medical profession. And if thisthis, and this don’t convince you nothing ever will. Relating to cycling directly, an important study by Anderson et al undertaken in Copenhagen over 30 years showed that those who did not cycle to work experienced a mortality rate 39% than their non-cycling counterparts, even when leisure time physical activity was accounted for.

The act of cycling in itself reduces the risks of many illnesses and ailments, and is also shown to increase live expectancy. Estimates from the excellent World Health Organisation’s Health Economic Assessment Tool for Cycling show even the UK’s paltry cycle modal share of around 2% prevents 2216 premature deaths per annum simply by cycling, to a net economic benefit of £2.718 billion per annum in health impacts alone. Therefore any safety measure, however well-intentioned, that leads to even a small reduction in cycling levels could have a significant impact in terms of premature deaths per annum. This is where the cycle helmet debate gets interesting.

Much better. Clearly the Aussies get it...

Much better. Clearly the Aussies get it…

Data reported by Piet de Jong – largely based upon research undertaken in Australia into the impacts of cycle helmet wearing legislation – reveals a short term impact of a reduction in cycling levels of between 20% and 40%. This evidence is bourne out in further literature reviewed as part of this Bursary, such as an assessment of Australian travel to work statistics and by DL Robinson. Such studies are, of course, not without their issues. Again adequately controlling for other factors is a significant issue facing most studies reviewed, and some focus on cycling for a particular purpose (e.g. to school via cordon counts) as opposed to population-level studies.

The conundrum

As you can see, how we asked the cycle helmet law question has fundamentally changed the answer we have recieved. Looking at it in terms of a pure safety intervention our answer is clear – a helmet law is a good thing. But if we asked what I feel is the correct question about the wider health impacts of such a law, the answer is more complex. On cycle helmet legislation we can conclude that cycle helmets do generally reduce head injuries and possibly fatalities from head injuries, and that compulsory cycle helmets laws do reduce cycling levels which will have much wider health impacts.

This has a profound impact in how we consider transport policy and interventions, and just shows how changing one question can have a profound impact on the sort of policies and interventions that we as professionals deliver. So perhaps we should give as much thought to the questions that we ask to begin with as we do to the methods that we use. After all, we are paid to do this.

For the cycle helmet debate, as part of my Bursary research (if you haven’t got the hint yet: read the thing) I attempted to come up to an answer to the question of whether a cycle helmet law would be a good or bad thing in health terms, using the best data available. Whilst I’m sure it won’t be winning prizes for scientific rigour, the evidence presented is clear: such a law is likely to lead to more premature deaths through reduced cycling levels. Therefore we as professionals should be doing something that will save a hell of a lot of lives – significantly improving the quality of our cycle infrastructure and built environment that will get more people cycling. If we can prevent 2,200 premature deaths every year on a cycle modal split of just 2%, imagine how many we can prevent with even 10% modal split. That is surely more worthy of our attention than one piece of potential legislation, right?

Another aspect to the debate

Don’t worry, I won’t go on about it too much, but a really interesting third aspect to the cycle helmet debate is what effects wearing a cycle helmet has on interactions with other highway users. Research in this area is at an early stage, but i highly recommend reading the works of Dr Ian Walker, and Ross Phillips et al to get a good introduction into this interesting area.


One matter that was raised when I presented my bursary paper, sadly overlooked in the paper itself, was what would be the point of nil effect? In other words, by what level would cycling have to reduce by so that the increase in premature deaths is the same as the number of cyclist fatalities saved by a compulsory helmet law.

Not wanting to leave this question unanswered, I re-opened my spreadsheets of data, fired up the World Heath Organisation’s Health Economic Assessment Tool for Cycling, and got number crunching. I undertook 2 different assessments for this:

  • For an estimate of a reduction of 19 cyclist fatalities from a cycle helmet law per annum as outlined in my bursary paper;
  • For an estimate that all cycle fatalities per annum for the 2006-2011 average (122 fatalities) are saved by a cycle helmet law.

The HEAT Assessment was then undertaken at 5% cycle level reduction intervals, working downwards from 20%. So, what do the results show?

helmet law impacts

Based upon this assessment, we would expect the premature death impacts of cycle helmet legislation to be neutral at around a 5% reduction in total cycling trips. Make of that what you will.

You can download a PDF of the WHO HEAT outputs from here (zip file).

Read the other Bursarians’ papers too

As well as my paper, I strongly urge you to read the papers of this year’s other Bursarians. These are all available for free on the TPS website. Like mine, these were all based around this year’s theme of “A harder edge for softer measures.”

Rebecca Fishburn wrote a paper entitled “Reaching the target audience: how can we encourage increased mode shift if our surveys are biased towards those already using smarter modes?” This looked at optimism bias in surveys we routinely undertake when developing Travel Plans, and is very thought-provoking. For this excellent piece she was awarded the Bursarian of the Year, and highly deserved it was too.

Katie Clarke’s paper asked “Why is it so hard to be soft? How perceptions of effectiveness and acceptance of measures can be improved to encourage smarter travel.” This paper looked at the success of Smarter Choices more generally, and provides food for thought on how we as professionals should not just kick start such measures, but keep them going and keep up interest in them.

Finally, Helen Jones looked at “London 2012: a platform for a successful behaviour change programme?” Building upon the evidence of the largest behaviour change programme ever delivered in the UK, Helen shows how the Olympic and Paralympic Games can leave its legacy for Smarter Choices.


Before I do leave you, I should give a couple of acknowledgements to those who helped out with my TPS Bursary Paper. The first is to John Dales from Urban Movement (@johnstreetdales for the Twitterati among you), who was my Bursary mentor. He provided valuable advice and guidance throughout, particularly at the early stages as I was trying to nail down precisely the research question that needed to be answered.

Thanks also goes to Kate Carpenter of Jacobs (@CarpenterKate). This was for the very useful correspondence and references at the start of the project, that acted as great sign posts towards some good research into cycle helmets.


3 thoughts on “On cycle helmets and the importance of the first question

  1. Hester (@hesterkw)

    I generally agree that it is the wider health implications which make the best case for why we shouldn’t have compulsory cycle helmet laws.

    However I would argue that your second question is still the wrong one. Ask the same thing about helmets in cars ‘What are the wider health impacts of this safety intervention?’ and the answer is rather different. Are we worried that people will abandon their cars under such compulsion and therefore get less exercise? Well, obviously not. So why not have compulsory helmets in cars? It’s one of the biggest sources of head injuries in the UK. Surely some protection is better than none?

    Well, no. Because safety/health is not the only dimension. There are also disadvantages to do with inconvenience, expense, pleasure, which in turn affect likelihood of compliance and general effectiveness of the initiative.

    The question is really ‘does the likelihood of injury/death, coupled with the effectiveness of the safety initiative, outweigh the disadvantages of the safety initiative?’ Which is much harder to answer and will involve a value judgement on some of the disadvantages. But pleasure and convenience do have a value, and should not be dismissed entirely in the effort to preserve life.

    The likelihood of life-changing injury or death due to transport cycling is actually quite low, though there are still concerns and there’s certainly a PR problem here. But some metrics it’s about the same risk as for walking. The number of these for which a cycling helmet would make any difference is lower still. So I think in this context it is reasonable to ask what price we’re willing to pay for what benefit.

    Or you could start arguing for helmets in cars.

    1. jamesgleave2 Post author

      Hi Hester,

      Thanks for your comments, and I do agree with your observation about it not just being about health benefits / disbenefits. I think that it does somewhat prove the point I was making in the article – that we have to question much wider than we currently do in a number of areas (within the bounds of what is reasonable, of course). In that respect, what is covered in the Bursary and this post is still not sufficient to have a fully-rounded debate on the merits or otherwise of cycle helmet compulsion – though I hope it helps.

      There is plenty of evidence covering the effectiveness of such initiatives. The Cochrane Collaboration concluded that legislation does lead to uptake of cycle helmet wearing (not surprising), and some of the work on pyschological impacts of cycle helmet wearing on use of bicycles and interactions with vehicles also explores impacts on convenience, pleasure etc.. But this is an area that has only recently started to be researched in earnest. Perhaps discussing the wider issues for cycle helmets is a matter for a future post!

  2. Kim (@kim_harding)

    Why are you only looking a place where helmet wearing is common, how about looking at head injury rate per billion vehicle kilometres where helmet wearing is rare? Especially as these places also tend to have far higher rates of cycling. Then ask what are the causes of head injury among cyclists and how these are best ameliorate. All too often cyclists in the English speaking world are told that they are solely responsible for their safety and that they the victims should wear personal protection. Oddly we never hear of stab vests being touted as a solution to knife crime, now why is that?


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