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Open Access Highly Accessed Review

The impact of transportation infrastructure on bicycling injuries and crashes: a review of the literature

Conor CO Reynolds*, M Anne Harris, Kay Teschke, Peter A Cripton and Meghan Winters

Environmental Health 2009, 8:47  doi:10.1186/1476-069X-8-47

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Authors' response

Conor Reynolds   (2010-02-09 13:29)  Institute of Resources, Environment and Sustainability email

It could be said that a gauge of an issue's importance is the passion it inspires, and the safety of cyclists is certainly an issue that people are passionate about. However, passions can be obstacles to collegial discourse. Our review was an attempt to conduct an objective review of the scientific, evidence-based literature on the influence of infrastructure on cycling safety. An important function of a review paper is to compile the relevant literature, so that everyone can use the list to locate and examine original sources. Readers can then evaluate the conclusions of the review paper, based on their own interpretation of the empirical evidence. We trust that interested readers will do just that, as Forester has done.

We have done our best to ensure that this literature review is as complete as possible, within the scope that we have outlined. We restricted ourselves to the peer-reviewed English language literature. The commenter mentions that we missed "the Copenhagen studies". This comment refers to a report [1] that in fact illustrates some of the difficulties with including non-peer-reviewed literature. The methods and results are not described sufficiently for us to be able to abstract and interpret the data. It would be a wonderful contribution for this research to be completely described in the peer-reviewed literature in the future. When and if any additional literature is considered, it will be important to put it in the context of the weight of evidence from existing studies, as we have attempted to do in our review.

C. Reynolds, M. Harris, K. Teschke, P. Cripton and M. Winters

Reference

1. Jensen, SU, Rosenkilde, C, Jensen, N: Road safety and perceived risk of cycle facilities in Copenhagen. Copenhagen, Denmark: Trafitec, Inc. [English-language report, no date] Available at: http://www.trafitec.dk/pub/Road%20safety%20and%20percieved%20risk%20of%20cycle%20tracks%20and%20lanes%20in%20Copenhagen.pdf

Competing interests

The authors are part of a research team that is studying the association between bicyclists' injuries and the cycling environment in Vancouver and Toronto. The Heart and Stroke Foundation of Canada and the Canadian Institutes of Health Research have funded this three-year study. See http://www.cher.ubc.ca/cyclingincities/injury.html for more information.

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But isn't the survey rather incomplete?

J Thorne   (2010-02-09 13:29)  none email

Perhaps we could have a response to the most obvious source of a negative review of the column.

I tend to agree that the omission of the Copenhagen studies of before-and-after infrastructure installation tends to reduce the credibility of the paper and that there is some confusion regarding just what is considered "vehicular cycling."

Competing interests

None declared

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Authors' response to Morten Lange's comments

Conor Reynolds   (2009-12-01 15:00)  University of British Columbia, Vancouver, Canada email

We thank Morten Lange for his comprehensive and thoughtful comments about our literature review. We are pleased that the article is of interest to the wider community of cycling advocates as well as academics who study cycling safety. The points made by Mr. Lange offer valuable insights into the challenges of increasing cycling rates, and the need to promote bicycling because it has a low-impact on the environment and is a sustainable mode of transportation. In general, and as the title so-alludes, we chose to constrain the scope of our literature review to topics directly related to the influence of physical infrastructure in the built environment, rather than expand it to include detailed discussion about regulation (e.g. pros and cons of helmet legislation), or cyclist education (e.g. cyclist skills courses and vehicular cycling).

However, we would like to respond to three of the issues raised: first, whether we have overemphasized the risk of crashes and injury to the detriment of the health benefits of cycling; second, whether helmets reduce injury rates; and third, vehicular cycling.

First of all, we agree that there are many health benefits of cycling and have outlined them at the beginning of the article. Mr. Lange suggests that our article may be interpreted as blaming and worrying the victim by focusing on cycling safety. This is certainly not our intent. The injury rate data in different jurisdictions clearly illustrate that cyclists in North America face a risk of injury that is several times higher than in many European countries. Our motivation for performing this review and encouraging further study is the belief – supported by the evidence – that through concerted action by various stakeholders, cycling can be made safer in all jurisdictions.

Secondly, we agree that D. Robinson’s statistical analyses of helmet use and injury reveal that regulation of helmet use does not necessarily result in a significant reduction in serious head injury on a population basis [1]. She highlighted that the number of people cycling in the region studied decreased after introduction of such laws. We cited her article in our review specifically to illustrate that helmet legislation can discourage cycling. In contrast, improvements to infrastructure could both improve safety and make cycling more attractive. However, we could not support any assertion that helmets do not protect individuals from serious injury: they do. Modern cycling helmets are effective at preventing head injuries including skull and brain injury in head impacts against a vehicle or against the ground. Biomechanical testing using artificial head forms in matched drop tower impacts has clearly established the efficacy of helmets on an individual basis. Indeed, based on the reduction in head accelerations, these tests have shown that a head impact that would result in permanent debilitating brain injury (such as a person living their life out in a vegetative state) in a cyclist not wearing a helmet can be reduced in severity to an impact that would cause only a mild concussion or no concussion at all in a cyclist who is wearing a helmet [2, 3]. Case-control studies have also definitely established that helmets are effective at preventing head injury in real-world head impacts [4]. We encourage all cyclists to wear bicycle helmets while cycling for the clear and obvious benefits outlined above. Our focus on infrastructure was intended to address the issue of primary prevention, rather than to discourage measures to reduce injury severity.

Third, we are indeed aware that there is an outspoken group that advocates for vehicular cycling. As we understand it, they advocate that cyclists should have the same access to the road network as motorized vehicles, in part because they believe that cycling on roads is safer than on other transportation infrastructure. Policies about access to the road network were not a subject of our review. Laws in most North American jurisdictions specify roads as the location for cyclists, and often forbid cyclists on sidewalks. Safety related to various types of transportation infrastructure was the focus of our review. In comparison to cycling on sidewalks and on multiuse paths, on-road cycling appears to be safer. In comparison to cycling on bicycle-specific infrastructure (paths, lanes, routes), on-road cycling appears to be less safe.

Finally, we would like to mention that all of the authors have been enthusiastic cyclists for many years, and have cycled in many countries around the world. We are optimistic that with continued efforts by cycling advocates and academics, cycling rates will increase in the coming years while their risk of injury is further reduced.

C. Reynolds, M. Harris, K. Teschke, P. Cripton and M. Winters


References

1. Robinson DL: No clear evidence from countries that have enforced the wearing of helmets. BMJ 2006, 332:722-725.

2. Benz G, McIntosh A, Kallieris D, Daum R: A biomechanical study of bicycle helmets' effectiveness in childhood. Eur J Pediatr Surg 1993, 3:259-263

3. Scher I, Harley E, Richards D, Thomas R: Likelihood of brain injury in motorcycle accidents: A comparison of novelty and DOT-approved helmets. SAE World Congress 2009, 2009-01-0248

4. Thompson DC, Rivara FP, Thompson R: Helmets for preventing head and facial injuries in bicyclists. Cochrane Database Syst Rev. 2000, (2):CD001855.

Competing interests

The authors are part of a research team that is studying the association between bicyclists' injuries and the cycling environment in Vancouver and Toronto. The Heart and Stroke Foundation of Canada and the Canadian Institutes of Health Research have funded this three-year study. See http://www.cher.ubc.ca/cyclingincities/injury.html for more information.

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Some caveats: Relative risk, Perceived risk,Helmet efficiency, Training

Morten Lange   (2009-12-01 14:59)  Landssamtök hjólreiðamanna email

Thanks to the authors for carrying out such a large review of the research literature on roads/facilities and cycling safety, and bringing forth some of the multitude of arguments for increased cycling for transport.

I have several caveats though, many of which are shared with many that have put some long-term effort into understanding the issues and myths around cycling for transport. As such they should be known to the authors, as this is mostly readily available to those interested. This time around I'll mention them rather summarily :

A. This article is not primarily of academic interest, rather the connection to key concerns in society is spelled out in the article, and the authors seem to hope to bring an important piece to a puzzle helping society to provide better for cyclists to improve their safety. So the preconceptions that the authors build on and the mindset in which the article will be read are important.

B. Reading the introductory paragraphs it seems that the preconception of cycling being "inherently" dangerous is shared by the authors, as it will probably be by most readers. But to what extent does this preconception hold true ? The prime statistic that has been used to underpin the unsafe nature of cycling is to compare injuries pr. kilometre or mile with that of travelling in an car. But, as detailed in the 1999 EU booklet, "Cycling the way ahead for towns and cities", referring to various studies, this is misleading. As an example pedestrians have more deaths pr. kilometre than cyclists, and cyclists have a comparable number of deaths as do car occupants. Also on a per-trip basis. For certain age-groups, risk is much lower on bicycles than in cars.
Another thing is this all "conveniently" excludes the question of the counterpart. Saying cycling is dangerous because cars drive fast and are large and heavy is like... ( Insert favourite victim-blaming phrase here ).

Besides cyclists live longer than non-cyclists, according to several studies. That does not diminish the importance of improving safety for cyclists, but should put cause-and-effect pondering into perspective. Cyclists do not die because of cycling, or because of being vulnerable, they die because of excessive speeds of cars, taking size, weight manoeuvrability and lack of criminalisation of dangerous behaviour into account. Instead of takling of vulnerable road users, which sets them out as 2the others" we should talk of them as users of healthy means of transport. "Sound road users" ?


C. The article gives the impressions that safety needs to be improved to increase cycling. The above should make the point that safety is not so bad. The difference is who is to blame for lack of safety. Unlike car users the threat comes from another group of users, that by the way also pollute, restrict access, and crave vast resources and areas of land.
But clearly there is a problem of perceived risk. And clearly for many cyclists, especially novice ones, the feeling of being unsafe is a serious impediment.

D. when talking of safety it is important to bear in mind that traing for cyclists, as well as years of experience both builds,trust, improves safety and inspires to growth in cycling which can bring about increased safety, not least through heightened awareness amongst motorists.

E. The article seems to seek to shift focus in cycling safety from helmets etc to facilities. To shift focus from helmets is laudable, as their efficiencies have been much overstated, and are a hassle to many new and seasoned cyclists. And focus on helmets for cyclists generally constitute victim blaming in the case of collisions with cars.
But in quote ii below the authors misrepresent the facts on helmet efficiency in the eyes of many experts. Anyone with god quality studies not mentioned in the Wikipedia article on bicycle helmets is encouraged to add references and a two-sentence synopsis in the appropriate paragraph. Probably unwittingly the authors of the present article (indirectly) misrepresent the main conclusion of one of the authors they cite. The conclusion of Dorothy Robinson, senior statistician, is not that helmets work, but that compulsion can reduce cycling. Her conclusion from several studies, are that helmet compulsion that brought about a very significant change in helmet usage in several jurisdictions, was not accompanied by any detectable improvement in the risk of serious head injuries. The reduction in cycling, following the enforcement of the helmet compulsion laws was however clear and significant.

E. Finally I miss at least a short reference to the contrarian arguments to Pucher et al, that is the concept and the arguments for "Vehicular cycling", which appears as a word in the tables, but is not explained nor countered. See e.g John Franklin (Cyclecarft.co.uk) that wrote the book used for the national cycle training standard in the UK, John Forester etc.


Best Regards,
Morten Lange, MSc in Physics, Reykjavík, Iceland


Relevant quotes from the article:
i) "Bicyclists are vulnerable because they must frequently share the same infrastructure with motorized vehicles, and yet bicycles offer their users no physical protection in the event of a crash. In addition, the mass of a typical automobile is at least an order of magnitude greater than a bicycle plus its rider, and motorized vehicles have top speeds that are considerably faster than bicycles. As a result, bicycle riders who are
involved in a crash are exposed to a much higher risk of injury compared to motor vehicle users (with the exception of motorcycle riders)."

ii)
"While helmets are effective in reducing the severity of head injuries, they do not address impacts to other parts of the body [16, 17]. More importantly, they do not prevent incidents from occurring in the first place [18], and legislating their use may even
discourage cycling [19]."

Competing interests

None that fall into the traditional usage of this term.
Some might consider cycling advocates to have competing interests, but I have seldom encountered a more honest, academically unbiased or altruistic group. They do however hold certain insights into the myths on cycling and the validity of some of the replies.

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