摘要: |
The Americans with Disabilities Act (ADA) requires that public rights-of way, including sidewalks and crosswalks, be accessible to pedestrians with disabilities. The U.S. Access Board's ADA accessibility guidelines specify the minimum level of accessibility in new construction and alteration projects and serve as the basis for enforceable standards maintained by other agencies. On June 17, 2002, the U.S. Access Board published draft rights-of-way guidelines (Docket No. 02-1) proposing to require pedestrian signals at roundabouts and channelized turn lanes that would create and identify gaps in the vehicle stream adequate for pedestrians who are crossing without vision cues. Many transportation agencies are looking for guidance on working with these proposed provisions. Modern roundabouts are unsignalized circular intersections that are common in many parts of the world. Although relatively new in the United States, they are being implemented at an increasing rate. Studies conducted in Europe, Australia, and in the United States have generally found that roundabouts result in significantly fewer and less severe vehicular crashes than do more traditional intersection treatments. This safety benefit has been the most compelling reason cited by transportation engineers for the installation of roundabouts. Roundabouts and channelized turn lanes present challenges different from other intersections for individuals with blindness and visual impairments, because the traffic is most often under yield control as opposed to stop control. Anecdotal evidence indicates that pedestrians with vision impairment sometimes avoid roundabouts and channelized turn lanes by taking a more circuitous route. In addition to determining when to cross the road, pedestrians with vision impairment must identify where to cross, which way to walk during the crossing, and when they have arrived at their destination curb or island. All of these tasks become more difficult for pedestrians with vision impairment at roundabouts and channelized turn lanes. This effort will build on research being conducted in National Cooperative Highway Research Program (NCHRP) Project 3-65, "Applying Roundabouts in the United States," and the research to be conducted in NCHRP Project 3-72, "Lane Widths, Channelized Right Turns, and Right-Turn Deceleration Lanes in Urban and Suburban Areas." Other relevant resources that should be considered in the performance of this research are results from a National Institutes of Health study and the proceedings from the ITE/FHWA Roundabout Accessibility Summit; specifics are provided in Special Note F. The objective of this research is to recommend a range of geometric designs, traffic control devices, and other treatments that will make pedestrian crossings at roundabouts and channelized turn lanes useable by pedestrians with vision impairment. These recommendations should be suitable for inclusion in transportation-industry practice and policies, including the American Association of State Highway and Transportation Officials (AASHTO) Policy on Geometric Design of Highways and Streets and the Federal Highway Administration (FHWA) Manual on Uniform Traffic Control Devices. Exploration of the proper balance among the needs of passenger cars, trucks, pedestrians (including pedestrians with vision impairments), and bicycles is central to achieving the objectives of the research. |