How does cycling volume impact crash statistics?

As a bike commuter I really appreciate a lot of cycling infrastructure. Marked bike lanes are great, and separated paths are typically better, except for one giant caveat: intersections. I am always extra vigilant at intersections, but especially ones where I’m moving from a separated path across the intersection. It definitely feels like drivers don’t even register that there could be a cyclist coming.

My perception of safety matches what von Stülpnagel, Petinaud, an Lißner (2022) found for objective risks when adjusted for volume. So what does that mean exactly? Research often shows that there are more crashes and near misses reported on cycling infrastructure than in areas without the infrastructure. But, as the researchers found, this doesn’t account for the number of cyclists in each area.

Not surprisingly, there are more cyclists who ride in areas with dedicated infrastructure. More volume means more opportunities for incidents. Therefore, if you only look at crash statistics, it can look as though cycling infrastructure is, at best, no better than areas without infrastructure. But, when you adjust for the numbers of cyclists moving through an area, the picture changes. Per cyclist, dedicated infrastructure and lower traffic speed limits both decrease the crash risk. But there is an exception where infrastructure doesn’t help: the afore mentioned intersections. The risk there is higher regardless of whether infrastructure is present or not.

There are a few takeaways from this research. First, it does indicate that cycling infrastructure is helpful for reducing risks for cyclists. This is important as more communities are looking at investing in this mode of transportation. Second, it shows that we have a communication challenge when it comes to looking at the benefits of the infrastructure. The absolute crash data won’t help advocate. We need to show how the proportion of individuals involved in crashes improves. Third, it confirms, for the most part, what cyclists feel to be true. As a cyclist, I find this reassuring because it leads me to “trust my gut” more, so to speak. If it doesn’t feel safe, it probably isn’t. Finally, there are a couple spots where I shouldn’t “trust my gut” that I need to watch for. One is when bike infrastructure is in the opposite direction to the direction cars are travelling (I admit, I don’t find this one safe, thanks to how they cross through intersections). The other is when streets with slower speed limits intersect with streets with higher speed limits. To me, that last one just falls under intersections are risky, but I can see where it would create some mental discrepancies.

I think this was an important question for researchers to explore. I hope that it will be carried out in more locations; this study was done in Germany. And I hope that these results get communicated both to the communities and the governments who are making decisions about where to invest budgets.