This report is a before-after evaluation of shared lane markings on Washington Avenue in Miami Beach, FL, which requested and received permission from the Federal Highway Administration (FHWA) to conduct a pilot study of shared lane markings. The markings were placed in the center of the outside lane to encourage bicyclists to take control of the lane. The experimental design was to collect videotape data of bicyclists interacting with motorists before and after the installation of the markings. After the markings were placed, approximately 20 percent of the bicyclists rode over the shared lane marking, and another 10 percent avoided the marking when they approached. Thus, 30 percent tracked over or very near the shared lane marking. Some 44 percent were positioned near the center of the lane when interacting with a motor vehicle after the markings were placed on the street. From an analysis of the spatial data, there was an increase of about 10.5 inches between bicycles and parked motor vehicles after the introduction of the shared lane markings. In addition, more bicyclists were riding out of the door zone. The spacing increased about 4.5 inches between motor vehicles in the travel lane and parked motor vehicles. All of these findings were statistically significant. Approximately 2 to 3 percent of bicyclists were riding in the wrong direction in the street, and there was no change after the shared lane marking. However, the percentage of bicycles using the sidewalk decreased from about 55 to 45 percent, and this reduction was statistically significant. Whereas about 10 percent of bicyclists weaved between motor vehicles in the traffic lane and parked motor vehicles in the before period, some 14 percent did so in the after period. This maneuver greatly increases the risk of a dooring crash. (Author/publisher)
Abstract