Important new injury prevention research shows that we cannot achieve a vibrant bicycle friendly city just by painting lines between traffic and parked cars. Yes, a few “strong and fearless” cyclists and a little larger group of “enthused and confident” cyclists will venture into this type of cycling environment, but the largest group of potential cyclists, the so called “interested but concerned” (see Geller), will be slow to take up regular cycling because of the widely held perception that most urban cycling infrastructure is not as safe as it could be. It turns out from recent research that perception is spot on.
In one of the largest studies of its kind, Canadian researchers from the University of British Columbia’s School of Population and Public Health have corroborated and quantified these concerns while pointing the way to overcome them. Their study of cyclist injuries and behavior in Toronto and Vancouver, published in the October 2012 issue of the American Journal of Public Health, was titled Route Infrastructure and the Risk of Injuries to Bicyclists: A Case-Crossover Study. Behind the technical title lies a very significant confirmation of the importance of both the perception and the actual safety of dedicated and traffic separate bike infrastructure for utilitarian and commuter cyclists.
The study team interviewed 690 victims of bike crashes treated in emergency departments and assessed the location where each crash took place with random comparison locations. It focused only on adult (age ≥ 19) utilitarian urban cyclists (25% were involved in on-road recreational activity at the time). This study excluded cycle trips leading to injury while racing or mountain biking.
Both in cyclist preference (vertical axis) and in measured safety (measured by lowered injury risk along the horizontal axis), separated cycle tracks hit the upper right sweet spot (see figure, below).
What this chart says is that bike lanes with vehicle parking, the kind of design most prominent on Dunedin’s busiest cycling byways, such as the one-ways (above photo), are 7 times riskier than fully separated or buffered lanes (N. American photo below). It says fully separated or buffered lanes are 9 times safer than major streets without any designated cycle lanes, the latter also very common around Dunedin and New Zealand.
Detailed Results: What is Safer?
Whereas the most common route type seen in the study was a major street with parked cars and no infrastructure (used as the referent group with an odds ratio of 1), the following other route types had significantly lower injury risks (lower numbers equals less risk):
- Dedicated cycle tracks – one ninth the risk of the reference type (.11)
- Major streets no parked cars and with bike lanes – about half the risk of the reference group (.54)
- Major streets no parked cars and no bike infrastructure – about half the risk of the reference group (.63)
- Local streets with no bike infrastructure – about half the risk of the reference group (.51)
- Local streets designated as bike routes – (.49)
- Major street with parked cars and bike lane – (.69)
Pedestrian and shared space infrastructure had small non-significant risk reductions. The study also identified increased risks associated with downhill slopes, train and streetcar tracks, and construction zones.
Limitations of the Study
The study results were weighted toward bicycle injuries occurring in large city urban cores because that’s where the hospitals the patients were selected from were located. Serious injuries and deaths were excluded from the study because the patients could not be interviewed, but these were only a small proportion of the overall injured population.
Strengths of the Study
- The main analysis looked at the association of injuries with route type.
- This was a case-crossover design that utilized randomly selected control locations. In this way, the findings focus on infrastructure differences, not personal characteristics.
- Infrastructure assessment was assigned by trained observers blinded as to the site status (whether as a control site or where an injury had occurred).
- The study controlled for multiple variables simultaneously.
- The study sample was emergency department-based, not police report-based (the latter often misses many injury cases).
- The study included all crash types, not just those involving motor vehicles (approximately 1/3 were motor vehicle related and 1/4 were surface feature related).
- The study succeeded in obtaining relatively high participation rates (93% of non-eligibles, and about two-thirds of all eligibles).
- The study had a reasonably large sample size and time coverage (690 injured persons over 18 months).
- Dedicated cycle tracks had by far the lowest injury risk.
- Quiet streets are good for cycling.
- Bike specific facilities without parked cars are good.
- Sidewalks and multi-use paths present higher risks then bike only infrastructure.