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More cyclists on road mean fewer collisions

Ein Fahrrad
© Ralf Winkler

The study focused on Boulder, Colorado, which has one of the highest rates of bicycling in the country at about 12 percent of the population. That makes it one of the few U.S. cities with enough bicycling to achieve the safety benefits already documented by researchers in Europe, said study co-author Wesley Marshall, PhD, PE, assistant professor of civil engineering at CU Denver’s College of Engineering and Applied Science.

The researchers wanted to create safety performance functions (SPFs) for bicycles in Boulder. SPFs model the mathematical relationship between the frequency of crashes and major factors related to them. Yet while there are SPFs for vehicles, there are none for bikes.

The authors created their SPF for Boulder by studying crashes at intersections throughout the city where more than two-thirds of collisions occur. They compared the crash data to bicycle count data.

The researchers found that the chance of collision decreased with more bicyclists. The risk of accident was relatively high at intersections with less than 200 bicyclists per day. The reasons for this remain unknown.

The study was co-authored by CU Denver’s Bruce Janson, PhD, professor of civil engineering and Krista Nordback, PhD, PE. It was published in April in the journal "Accident Analysis & Prevention" veröffentlicht. (Cf. Online-Access via, Krista Nordback, Wesley E. Marshall, Bruce N. Janson: Bicyclist safety performance functions for a U.S. city. In: Accident Analysis & Prevention, Volume 65 (April 2014), p. 114-122.) The study is available upon request. Contact:

Source: University of Colorado Denver (CU Denver)

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26. June 2014
Source / University of Colorado Denver (CU Denver) - // Difu (A.H.)

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