Shared lane markings help convey to motorists and bicyclists that they must share the travel way on which they are operating. The purpose of the markings is to create improved conditions for bicycling by clarifying where bicyclists are expected to ride and to remind motorists to expect bicyclists on the road. The purpose of this study was to evaluate the impact of several uses of shared lane pavement markings, specifically the sharrow design, on operational and safety measures for bicyclists and motorists. Experiments were conducted in three cities. In Cambridge, MA, there was interest in experimenting with the placement of sharrows at a 10-ft spacing from the curb to prevent dooring from parked vehicles. In Chapel Hill, NC, sharrows were placed on a busy five-lane corridor with wide outside lanes and no parking. In Seattle, WA, sharrows were placed in the center of the lane on a downhill portion of a busy bicycle commuting street. Prior to the sharrows, a 5-ft bicycle lane was added to the uphill portion of the street in conjunction with shifting the center line. A variety of hypotheses were examined, and results were generally positive. Sharrows can be used in a variety of situations, and increased use should serve to raise motorist awareness of bicyclists or the possibility of bicyclists in the traffic stream. It is recommended that trials similar to those performed in this study be continued in other locations and traffic settings to improve guidance for users. (Author/publisher)
Abstract