Think Bikes Create Traffic Hazards? Think Again

Boulder Bike Story from Bikes Belong on Vimeo.

As biking continues to grow in popularity, a new report is adding to the list of reasons why cities should step up their efforts to accommodate cyclists. Researchers at the University of Colorado Denver found that as more bikes hit the streets the number of collisions goes down.

The study focused on Boulder, Colo., because of its high biking population and because the city has been performing bike counts for more than a decade. Wesley Marshall, an assistant professor of civil engineer at CU Denver, told Curbing Cars that once intersections began seeing upwards of 200 bicyclists a day, the number of collisions began to drop.

“It’s interesting because you see the same affect with other modes of transportation too,” said Marshall, a co-author of the study. “If you have more cars going through, it is sort of safer per car.”

It may seem counter intuitive that as an intersection has more moving parts, the number of incidents would go down. While the CU Denver study did not look into the reasons why incidents were reduced, Marshall provided some possible explanations.

“If you’re in a city that has bikers everywhere, as a driver you expect to see them,” he said.

Increasing the number of bikes on the road could create a traffic-calming effect Marshall said, or it could be a case of the chicken or the egg.

“On the other hand, you could say maybe a city like Boulder built these safer facilities, and the safer facilities are what attracted more bicyclists,” he said. “So, maybe it’s not the number of bicyclists that’s creating the safety, maybe it’s the facilities in the first place.”

Either way, Marshall said that when a city has an increase in bicyclists on streets, there is a broader affect on safety. In a previous study, he found that increasing the number of bicyclists had the greatest impact on increasing safety across all platforms.

“We looked at not just safety for bicyclists, but safety for all road users, and I was finding that cities that have high bicycling mode share tend to be safer for everybody, not just the bicyclists,” he said.

Marshall said places such as Boulder, Davis, Calif. and Portland have some of the highest biking populations and are some of the safest cities across all transportation platforms.

The results of the CU Denver study have also been seen in other communities around the country as well. In a national bike and pedestrian study from the Nonmotorized Transportation Pilot Program released this month, research also found that more bikes results in fewer accidents.

“The pilot communities collectively observed a 20 percent decline in the number of pedestrian fatalities and a 28.6 percent decline in the number of bicycle fatalities from 2002 to 2012,” according to the study, which looked at four communities in the U.S., Columbia, Mo., Marin County, Calif., Minneapolis, Minn., and Sheboygan County, Wis.

Marshall said he hopes as more studies continue to show the safety benefits of biking that public policy will continue to focus more on cultivating bike friendly infrastructure.

“It makes sense policy wise to push for low-stress bicycle facilities, like the kinds that kids that are 7 or 8, up to people that are 70 years old can use  and not just the young urban cyclists,” he said. “If you have a lot of those facilities, then you encourage not just those fearless bikers to get out there but a greater percentage of the population.”


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