Special Report: Cycling

Cycling Infrastructure Strongly Influences Injury Risk

A new study published in the American Journal of Public Health using injury data from Toronto and Vancouver finds that street infrastructure has a big impact on risk of injury for cyclists.

By Ryan McGreal
Published October 22, 2012

this article has been updated

A new study, titled, "Route Infrastructure and the Risk of Injuries to Bicyclists: A Case-Crossover Study" and published in the American Journal of Public Health, finds that street infrastructure has a big impact on risk of injury for cyclists.

Noting that Canada, Australia, The USA and the UK have much higher cycling injury rates and much lower cycling participation rates than Denmark, Germany, Finland, the Netherlands and Sweden, authors Kay Teschke et al. point out, "helmet use cannot explain the risk difference because helmets are rarely used in the European countries with lower injury rates."

Hypothesizing that the difference in injury risk is related to the design of the bike routes - the European countries with much lower injury rates have a lot more dedicated bicycle infrastructure - the authors developed a study to isolate the effects of the route design from other confounding factors.

Using cycling injury data from Toronto and Vancouver where the injury was serious enough to warrant a trip to the hospital, the researchers conducted a case crossover study to identify the role of the street design where the injury occurred.

The control was clever: the researchers compared the location where each cyclist was injured to a randomly selected section of their route where an injury did not occur. The selection of the control section was weighted according to its length relative to the entire route.

The benefit of this approach is that by using the same population and the same trip for the study group and the control group, the study automatically controls for the personal characteristics of the population and their exposure to various types of route infrastructure.

Routes Compared

The researchers presented each injured cyclist with a questionnaire [PDF] to determine the route they had been taking. They also defined 14 specific types of route:

Definitions of the 14 Route Types
Route Type Definition
Major street, with parked cars Paved city street with at least 2 demarcated moving lanes of motor vehicle traffic, with parked cars on the cyclist's side of the street
     No bike infrastructure No bicycle markings on street surface, bike signage on posts may be present
     Shared lane Markings on street surface indicating shared bike-HOV lane, shared bike-bus lane, or sharrows indicating bikes and motor vehicles share space
     Bike lane Bike-only lane marked with solid or dotted lines on street surface
Major street, no parked cars Paved city street with at least 2 demarcated moving lanes of motor vehicle traffic, no parked cars
No bike infrastructure No bicycle markings on the street surface, bike signage on posts may be present
Shared lane Markings on street surface indicating shared bike-HOV lane, shared bike-bus lane or sharrows indicating bikes and motor vehicles share space
Bike lane Bike-only lane marked with solid or dotted lines on street surface
Local street Paved city street with no demarcated lanes of motor vehicle traffic; car parking may be allowed or not
     No bike infrastructure No bike signage or markings on the street surface
     Designated bike route Bike signage on the street surface or on posts, indicating designated bike route; may have bicyclist operated traffic signals at intersections with major streets
     Designated bike route with traffic calming Bike signage on the street surface or on posts, indicating designated bike route; may have bicyclist operated traffic signals at intersections with major streets; traffic calming measures may include speed humps or bumps, traffic circles, traffic diverters, medians, or street width restrictions via corner bulges or planters
Off-street route Route that is physically separated from traffic, at least on straightaways between intersections
     Sidewalk or other pedestrian path Paved path meant for pedestrian use, either alongside city streets or away from streets (e.g., in parks)
     Multiuse path, paved Paved path meant for nonmotorized use by pedestrians, cyclists, skaters and others, either alongside city streets or away from streets (e.g., in parks)
     Multiuse path, unpaved Unpaved path meant for nonmotorized use by pedestrians, cyclists, skaters and others, either alongside city streets or away from streets (e.g., in parks)
     Bike path Paved path meant for cyclist use away from streets, (e.g., in parks)
     Cycle track Paved path meant for cyclist use alongside major streets, separated by a physical barrier (e.g., a curb or bollards)

Of the 2335 cyclists who were admitted to one of the five hospitals during the study period, 741 were known to be eligible for the study and 690, or 93.1%, agreed to be interviewed. Using a major street with parked cars and no bike infrastructure as a baseline, the researchers calculated the adjusted odds ratio for the other 13 types of bike route and found that all other types of route had lower odds ratios.

The most dramatic was an off-street cycle track, which had an adjusted odds ratio of only 0.11 compared to 1.0 for the baseline. But even adding a bike lane to a major street with parked cars reduced the adjusted odds ratio to 0.69. The odds ratios on multi-use paths (0.79) and sidewalks (0.87) were slightly lower than the baseline but the reduction was not statistically significant.

The results indicate that the presence or absence of parked cars had a significant effect on risk. A major street with no bike infrastructure but no parked cars had an adjusted odds ratio of 0.63, dropping to 0.54 with a bike lane.

There was also a significant risk reduction between major streets and local streets. A local street with no bike infrastructure had an odds ratio of 0.51 compared to a major street with no bike infrastructure.

Conclusions

The authors write, "These findings reinforce some conclusions of our recent review: that busy streets are associated with higher risks than quiet streets; and that bicycle-specific facilities are associated with lower risks." They also noted that cyclists tend to prefer bike routes that are also safer, when those routes are available.

Many route types with positive preference ratings were also among the safest: cycle tracks; local streets; bike only paths; and major streets with bikes lanes and no parked cars. These provide a range of options with potential to both lower injury rates and increase cycling. This in turn may create a positive feedback cycle because increased ridership has been associated with increased safety.

The authors close with the following conclusion, which will be familiar to RTH readers:

As a public health approach, safer route infrastructure offers many advantages: it is population-based and therefore benefits everyone, it does not require active initiatives by individual cyclists, it does not require repeated reinforcement, and it prevents crashes from occurring rather than preventing injuries after a crash has occurred.

Interesting sidenote: Toronto 11 kilometres of bike lanes per 100,000 people, and 1.7% of trips are by bicycle. Vancouver has 26 kilometres of bike lanes per 100,000 people and 3.7% of trips are by bicycle. Vancouver has 2.4 times as many bike lane kilometres per capita and 2.2 times as many bike trips per capita - a very strong correlation between the extent of bike infrastructure and its use.

(h/t to the Atlantic Cities for finding this study)


Update: Updated to add a table of results by route type from the study.

Results by Route Type
Variable No. Injury Sites/No. Control Sites Unadjusted OR (95% CI) Adjusted OR (95% CI)
Major street route, parked cars
No bike infrastructure 155/114 1.00 (Ref) 1.00 (Ref)
Shared lane 9/7 0.78 (0.25, 2.41) 0.71 (0.21, 2.45)
Bike lane 25/28 0.53 (0.26, 1.07) 0.69 (0.32, 1.48)
Major street route, no parked cars
No bike infrastructure 112/118 0.65* (0.44, 0.97) 0.63* (0.41, 0.96)
Shared lane 13/12 0.66 (0.24, 1.82) 0.60 (0.21, 1.72)
Bike lane 35/46 0.47* (0.26, 0.83) 0.54 (0.29, 1.01)
Local street route
No bike infrastructure 89/116 0.44* (0.28, 0.70) 0.51* (0.31, 0.84)
Designated bike route 52/57 0.53* (0.30, 0.94) 0.49* (0.26, 0.90)
Designated bike route with traffic calming 49/47 0.59 (0.32, 1.07) 0.66 (0.35, 1.26)
Sidewalk or other pedestrian path 52/47 0.73 (0.42, 1.28) 0.87 (0.47, 1.58)
Multiuse path, paved 64/56 0.75 (0.42, 1.34) 0.79 (0.43, 1.48)
Multiuse path, unpaved 12/11 0.63 (0.21, 1.85) 0.73 (0.23, 2.28)
Bike path 21/21 0.54 (0.20, 1.45) 0.59 (0.20, 1.76)
Cycle track 2/10 0.12* (0.03, 0.60) 0.11* (0.02, 0.54)

Ryan McGreal, the editor of Raise the Hammer, lives in Hamilton with his family and works as a programmer, writer and consultant. Ryan volunteers with Hamilton Light Rail, a citizen group dedicated to bringing light rail transit to Hamilton. Several of his articles have been published in the Hamilton Spectator. Ryan also maintains a personal website and has been known to post passing thoughts on Twitter @RyanMcGreal.

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By SpaceMonkey (registered) | Posted October 22, 2012 at 15:30:55

I'm having trouble making sense of the results. Can someone clarify if I have the results correct?

In order of most dangerous to least dangerous...
1)Sidewalks
2)Multi Use Paths
3)Major street with bike lane and parked cars
4)Major street with no bike lane and no parked cars
5)Major street with bike lane and no parked cars

Is that correct?

Comment edited by SpaceMonkey on 2012-10-22 15:33:46

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By Ryan (registered) - website | Posted October 22, 2012 at 20:05:51 in reply to Comment 82047

I updated the article to add a table of results by route type. The important value is the last column, the adjusted odds ratio. Lower is better.

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By SpaceMonkey (registered) | Posted October 22, 2012 at 21:03:03 in reply to Comment 82060

Thanks Ryan,

That helps me (and likely others) understand the results better.

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By Pxtl (registered) - website | Posted October 22, 2012 at 17:11:13 in reply to Comment 82047

I think so. Every hardcore cyclist knows that sidewalks are dangerous, but "almost as dangerous as a major street with parked cars" is more than I expected.

It goes to show how dangerous parked cars are for cyclists, and how cyclists might not realize the care needed on multi-use paths. As a cyclist it's easy to obsess over the big fast-moving cars travelling in the live lanes of traffic, when this shows how it's the slow-moving but uncontrolled things you really need to worry about - I wonder how those multi-use-path injuries generally occur?

This may support the move towards left-side bike lanes on one-way streets (far away from the parked cars), but it seems like turning is messy and complicated in those.

Of course, fatalities can't fill out the survey so that might be why the more severe accidents that generally involve fast-moving cars didn't appear.

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By SpaceMonkey (registered) | Posted October 22, 2012 at 17:21:28 in reply to Comment 82049

From my experience, multi use pathways are more dangerous than the road by a huge factor. Not more dangerous in potential to be killed, but more dangerous in terms of chances of being injured.

There are many ways which they can occur. The most frequent that I come across are people walking and then suddenly, without warning drastically changing their direction. Children seem to be the most likely to do this. The next most common thing, for me, are dogs either not on a leash or on a leash, but the owner isn't paying close attention to the dog. The worst one that happened to me was a girl walking her dog along a path. She was about to enter/cross the path. I could see her well ahead of me and was slowing down, prepared to stop if needed. She made direct eye contact with me, stopped and was seemingly waiting for me. I gave the pedals some juice and at the absolute worst time, she ran into my path. I don't know if me, her, or her dog were more scared, but thankfully no contact occurred. I have no idea what made her do that. The only thing I can come up with is that she blatantly misjudged how fast I was approaching... lesson learned for me.

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By jason (registered) | Posted October 22, 2012 at 19:14:55

this jives well with my idea for a separated, two-way bikeway on Cannon St on the opposite side of the parked cars and buses. http://raisethehammer.org/article/1684/t...

Can anyone help me out with the above data...where does 'designated street cycling route with traffic calming' rank??

Thx

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By Today (anonymous) | Posted October 22, 2012 at 19:42:31

These are the type of articles I actually read and enjoy thinking about at RTH. Move on from the stadium Ryan, I know many people think it's "huge" but you're strength and the strength of this site now that the stadium issue is resolved, is this type of excellent journalism, rather than "run around the bushes" stadium stuff.

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By lance armstrong (anonymous) | Posted October 23, 2012 at 06:35:07

Interesting fact that simply removing parking is more effective in reducing injury risk than creating a bike lane.

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By -Hammer- (registered) | Posted October 23, 2012 at 23:38:25

The presence of parked cars in no way surprises me. I can't recall how many times I've seen cyclists move into the left lane to pass a parked car, then incorrectly change lanes back into the right lane, ride for a couple of meters and then change back into the left lane because of another parked car, all without any hand signals.

Even worse, when I see cyclists squeeze between the parked car and the border of the right and left lane. That's one open door, or one brief moment of lost balance due to a bump in the road, a quick car passing by or even a brief lapse in concentration away from a serious accident.

I'm a little surprised though that it seems that an unpaved multi-use path is safer then a paved one though. I've never once wiped or felt unsafe on a paved path at the bayfront, the rail trail or the radial trail although I've wiped out many times on unpaved ones, and have had to dodge mountain bikers/avoid pedestrians while walking/biking along the escarpment paths between Dundurn and West 5th and in the paths around Iroquois Heights.

Comment edited by -Hammer- on 2012-10-23 23:52:51

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By Noted (anonymous) | Posted February 19, 2013 at 13:51:42

"...odds of dying in any given year from choking, cycling, being struck by lightning or stung by a bee."

http://www.economist.com/blogs/graphicdetail/2013/02/daily-chart-7

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By Helmut (anonymous) | Posted February 19, 2013 at 14:04:27 in reply to Comment 86480

Since we're 6.2 times as likely to die walking as cycling, I eagerly await the safety helmet brigade to demand new laws mandating walk helmets for pedestrians to keep them safe from harm.

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