Tuesday, October 23, 2012

New Study Finds Bicycle Infrastructure Makes Bicyclists Safer

A new study from the University of British Columbia found that better bicycle infrastructure dramatically decreases the injury risk for people riding bicycles.

From today's Streetsblog article about the story:

Click for larger view of their kind of weird chart
The study, published in the American Journal of Public Health, examined the circumstances around the injuries of 690 cyclists who wound up in emergency rooms in Vancouver and Toronto during a six month span in 2008 and 2009. Based on interviews with the cyclists, the authors plotted where the injuries occurred on each cyclist’s route. Then for each route, the injury site and a randomly-selected control site were categorized in one of 14 different street types. The authors used this method to measure the safety of each street type while controlling for other factors.
From the study overview:

Of the 690 injured cyclists in the study, 59% were male. The injury trips were mainly on weekdays (77%), less than 5 km long (68%), and for utilitarian purposes (74%). Of the injury events, 72% were collisions (with motor vehicles, route features, people, or animals) and 28% were falls.
We found that route infrastructure does affect the risk of cycling injuries. The most commonly observed route type was major streets with parked cars and no bike infrastructure. It had the highest risk. In comparison, the following route types had lower risks (starting with the safest route type):

  • cycle tracks (bike lanes physically separated from motor vehicle traffic) alongside major streets (about 1/10 the risk)
  • residential street bike routes (about 1/2 the risk)
  • major streets with bike lanes and no parked cars (about 1/2 the risk)
  • off-street bike paths (about 6/10 the risk)

The following infrastructure features had increased risk:

  • streetcar or train tracks (about 3 times higher than no tracks)
  • downhill grades (about 2 times higher than flat routes)
  • construction (about 2 times higher than no construction)
You can read the full study here. So what applications to bicycling in Philly can we draw from this study? Well, some that probably fit conclusions many of us have come to already on our own.
Broad Street is neither an enjoyable nor a safe street for bicycling:
Major street with parked cars and no bike infrastructure
And improving Philadelphia's network of buffered bike lanes will not only help people get where they need to go on bicycles, but will make them get there safer.
Moving people, safely


Andrew J. Besold said...

This is an fascinating study. The study methodology was very interesting as it looked at the route the cyclist took when he/she crashed and then compared the crash site to the 2 other random control points prior to the crash. The way the study organizers got the data was by interviewing cyclists who required hospitalization. This both acted as a severity threshold and it also likely provided more detailed information than they would have gotten be police crash reports.

But here is something that I just thought of that might just bias the results. This data comes from people who crashed their bikes. Maybe they were just bad cyclists or bad at choosing the safest routes? From the study methodology that I've been able to access there is no mention of the cyclist's skill level. I'm not saying that this caveat ruins the results, far from it, but it just might not be giving the best or most accurate numbers regarding the safety of the facility type.

This is still one of the best studies looking at bicycle facility safety that I've seen and I'll admit that the question I bring up might not have any effect on the results at all. I'm just asking.

Peter said...

my take away from the study is if you throw out the outliers ( MUPS, which were much more dangerous than streets) and cyclepaths (which were much safer), everything except major streets with parked cars were about the same. Whether there were bike lanes or not made little difference. The nain factor was whether there were parked cars. All roads without parked cars, whether major or minor, bike laned or bike routed, were roughtly the same.

So my take away was that bicycle infrastructure made little difference.

I find it interesting that "bicycle only paths" were half as safe as "cycle tracks". I'm assuming a "bicycle only path" is liek a MUP but retricted to bikes, while a "cycle track" parallels a road but with some sort of separation. Why would the path be so much less safe than a "cycle track"?