Operational Analysis of “Sharrows” on Roadways with Narrow Lane Widths

Sharrows are intended to encourage shared use of a facility for both bicycles and motor vehicles, as well as indentify the appropriate placement for bicyclists within the roadway. This paper analyzes the influence of several site characteristics on the operational and safety effects on bicyclists and motorists at two curbed roadway segments in Florida. Three main site variables were studied: lateral separation between vehicles and bicyclists, vehicle encroachments to the adjacent inside lane, and distance from face of curb that bicyclists track. Results suggest that installation of sharrows can increase the lateral vehicle clearance significantly. It was also observed that less restrictive lane changing conditions greatly increase the lateral separation between vehicles and bicyclists. Also, the percentage of vehicles that passed along side bicyclists with little to no encroachment was notably reduced after sharrows were placed, suggesting positive safety effects for bicyclists. Overall, operational effects for bicyclists and motor vehicles were positive with the implementation of sharrows.