Effects of roadside parking on bicyclist and motorist lateral positions

Because many bike facilities in America must be fit within constrained roadway right-of-way, bicyclists will continue to have to interact with motorists, and the details of these cyclist/motorist interactions are crucial to the understanding of bicycle and motorist comfort and safety. Previous studies have analyzed these interactions along roadways without road-side parking; however, the presence of parked cars has many possible implications on motorist and cyclist behavior. This study hopes to help fill this gap in knowledge by studying the effects of different parking arrangements on these behaviors. Cyclists were hired to ride laps along sites with bike lanes and roadside parking, and the positions of both cyclists and passing motorists were captured on video. The data indicates that cyclists pay attention to the type of parked vehicles they are passing; vehicles parked close to the bike lane tend to pose a threat to cyclists, who then pass closer to the motor vehicle lane. When vehicles are parked farther away, cyclists have more of a safety buffer and therefore tend to move away from the motor vehicle lane. Passing motorists generally do not pay attention to details of parking, probably because they have a sufficient buffer because of the bike lane. However, when they are passing a cyclist, motorists do tend to provide the cyclist with more room if vehicles are parked close to the bike lane.