Publication Year: 2024

The Traffic Calming Effect of Delineated Bicycle Lanes


Hannah Younes, Clinton Andrews, Robert B. Noland, Jiahao Xia, Song Wen, Wenwen Zhang, Dimitri Metaxas, Leigh Ann Von Hagen, and Jie Gong. 2024. “The Traffic Calming Effect of Delineated Bicycle Lanes” Journal of Urban Mobility, June.


We analyze the effect of a bicycle lane on traffic speeds. Computer vision techniques are used to detect and classify the speed and trajectory of over 9,000 motor-vehicles at an intersection that was part of a pilot demonstration in which a bicycle lane was temporarily implemented. After controlling for direction, hourly traffic flow, and the behavior of the vehicle (i.e., free-flowing or stopped at a red light), we found that the effect of the delineator-protected bicycle lane (marked with traffic cones and plastic delineators) was associated with a 28 % reduction in average maximum speeds and a 21 % decrease in average speeds for vehicles turning right. For those going straight, a smaller reduction of up to 8 % was observed. Traffic moving perpendicular to the bicycle lane experienced no decrease in speeds. Painted-only bike lanes were also associated with a small speed reduction of 11–15 %, but solely for vehicles turning right. These findings suggest an important secondary benefit of bicycle lanes: by having a traffic calming effect, delineated bicycle lanes may decrease the risk and severity of crashes for pedestrians and other road users.