running and bicycling on the lakefront trail

Some parts of the Chicago Lakefront Trail have a 2-foot wide side path designed for pedestrians but the study reviewed very cases where bicyclists crashed with pedestrians. It’s unknown if this side path results in fewer crashes than the parts of the Lakefront Trail without it. Photo: Eric Allix Rogers

The Active Transportation Alliance posted a link on Facebook to a new study [PDF] in the Open BMJ from December 2014, a free peer-reviewed “version” of the British Medical Journal, and said it “conclusively shows separated space reduces crashes and the severity of injuries when crashes occur”.

The posting was in the context that bicyclists and pedestrians using the Lakefront Trail should have separate paths. I agree, but there’s a problem in how they stated the study’s support for separation.

I wouldn’t say that the study “conclusively” shows that bicyclists would fare better on paths without pedestrians. The study reviewed fewer than 700 crashes in two Canadian cities. Only 11% of those crashes occurred on multi-use trails and only 5.9% of the crashes were with a pedestrian or animal (the two were grouped) – this sample size is too low from which to draw that kind of conclusion.

The study didn’t report the association (correlation) between crash severity and pedestrians. The authors didn’t even recommend that bicyclists and pedestrians have separate paths, but instead wrote “These results suggest an urgent need to provide bike facilities…that are designed [emphasis added] specifically for bicycling rather than for sharing with pedestrians”.

While I don’t discount the possibility that separating bicyclists and pedestrians in off-street corridors will reduce the number of crashes and injuries when those two user groups collide, it’s imprudent to call this study “conclusive” when linking it to the measure of crashes between bicyclists and pedestrians.

The study’s primary conclusion was that bicyclists crash more often when there are high slopes, fast moving cars, or no bike lanes and the authors recommended that bike infrastructure be built for bicycling. That’s a solid recommendation and I recommended that you sign Active Trans’s petition advocating for separate facilities in the North Lake Shore Drive reconstruction project.