Cycling lanes make traffic safer for all road users, study finds

You’d expect roads to be safer for cyclists when there are dedicated cycling lanes, particularly when they are protected by physical barriers. However, researchers of the University of Colorado-Denver found that cycling lanes improve road safety for everyone on the road.

The study was carried out by Wes Marshall, an associate professor of civil engineering at the University of Colorado-Denver and Nicholas Ferenchak, assistant professor at the University of New Mexico, covering more than 17,000 fatalities and 77,000 severe injuries in 12 US cities with populations over 400,000, including Oklahoma City, Seattle, Minneapolis, Dallas, Houstan and Portland.

According to the authors, cities that build protected and separated cycling lanes turned out to be safer for drivers as well.

When they set out to analyse data, the researchers were expecting a safety in numbers phenomenon: surely, the more cyclists on the road, the more likely drivers would slow down and be more aware of what’s going on around them.

Instead, they found that safer cities aren’t due to the increase in the number of cyclists but rather to the infrastructure built for them. They found a strong association between cycling infrastructure and fewer accidents.

The authors also found a strong association between road safety and higher intersection density (so more intersections per square mile). Such conditions typically correspond to more compact streets and lower-speed environments, but the casual observer would expect there to be far more conflicts between riders and drivers and therefore more accidents. That does not appear to be the case.

Of course correlation does not automatically imply causation. Other factors may be at play, too. The researchers also found an association between higher safety levels and gentrification, to name but one.

Image: cycling lane in New York City