Evaluation of Shared-Use Facilities for Bicycles and Motor Vehicles

Abstract

This study was conducted for the Florida Department of Transportation with an objective of evaluating the safety and utility of shared-use facilities to provide engineers and planners comprehensive results that can be used in planning, designing, and constructing roadways to be shared by motorists and bicyclists. The results were developed from an analysis of observations of bicyclists and motorists interacting on different types of roadways. The evaluation included roadways with wide curb lanes, bicycle lanes, and paved shoulders. Locations from both rural and urban environments were included and varied in terms of motor-vehicle speed, traffic volume, lane width, and number of lanes. The operational measures of effectiveness used in evaluating the different types of facilities included ( a) lateral placement of the bicyclist, ( b) lateral placement of the motor vehicle, ( c) separation distance between the bicycle and the motor vehicle, and ( d) encroachments by the motorist or bicyclist during the passing maneuver. Results of the analysis showed that the type of facility (wide curb lane versus bicycle lane versus paved shoulder) does have a significant effect on the separation distance between bicyclists and motor vehicles; this distance ranged from 1.80 to 1.95 m (5.9 to 6.4 ft). The findings also indicated that paved shoulders and bicycle lanes generally result in similar interactions between motorists and bicyclists and that when compared with wide curb lanes they offer some distinct advantages to both user groups. The results also indicated that bicycle lanes as narrow as 0.92 m (3 ft) provide sufficient space for motorists and bicyclists to interact safely. At the same time, a 1.22-m (4-ft) wide bicycle lane tended to optimize operating conditions because there were very few differences in the measures of effectiveness when 1.22-m lanes were compared with wider lanes.