The National Academies

NCHRP 03-78 [Completed]

Crossing Solutions at Roundabouts and Channelized Turn Lanes for Pedestrians with Vision Disabilities

  Project Data
Funds: $30,328
Research Agency: The University of North Carolina at Chapel Hill
Principal Investigator: Ron Hughes
Effective Date: 2/1/2005
Completion Date: 6/30/2005


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 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 AASHTO Policy on Geometric Design of Highways and Streets and the 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. Accomplishment of the project objective will include at least the following tasks.

Phase I Tasks (1.) Review the existing geometric design, traffic control, and other relevant literature (both domestic and international) to (a) Document the current state of practice with respect to pedestrian and vehicular control at roundabouts and channelized turn lanes and the subsequent impact on pedestrian safety and access, (b) Identify changes in the design or operation of roundabouts and channelized turn lanes as well as new technologies that have potential for improving usability and safety for pedestrians with vision impairment, and (c) Determine engineering policies and practices that may need to be revised as a result of the anticipated recommendations from this research effort.

Augment the literature review by consulting with transportation professionals, orientation and mobility professionals, pedestrians with vision disabilities, and others with experience on this topic.

(2.) Define the information needs and functional requirements for pedestrians with vision disabilities at intersections. Two critical aspects are the ability of a visually impaired person to determine (a) where to cross and (b) when it is safe to cross. Based on those needs and requirements, establish a facility-performance specification. Develop draft criteria to be used to evaluate potential solutions. Describe how to apply the facility-performance specifications and the metrics to be used. (3.) Identify and examine changes to geometric design elements, traffic control devices, and other physical treatments that could be implemented to meet the facility-performance specification established in Task 2. The identification of potential solutions should attempt to address the full range of operational and geometric types of roundabouts and channelized turn lanes that are now in existence or anticipated to be built in the United States. (4.) Examine the application of a range of advanced technology (e.g., Intelligent Transportation Systems devices and wayfinding products) that could be used to meet the facility-performance specification established in Task 2. The immediate focus for this research effort will be on publicly provided infrastructure ITS solutions as opposed, for example, to hand-held products that might be carried by a pedestrian. (5.) Based on the results of Tasks 1 through 4, identify the most promising potential solutions. Refine the Phase II work plan to further evaluate potential solutions. At a minimum, the work plan should include the geometric and operational conditions under which each potential solution selected is expected to be appropriate, the number of field sites required for testing, a list of potential sites, the research methodology, and the evaluation criteria. (6.) Submit an interim report presenting the results of Tasks 1 through 5 in an accessible format. The interim report shall include the products of Tasks 1 through 4 as separate chapters and the updated work plan developed in Task 5. Document the results of Tasks 1 through 5 in an accessible format suitable for publication on the NCHRP website.

Phase II Tasks (7.) Execute the work plan approved for Phase II. (8.) Develop cost estimates for the solutions that are recommended based on the Task 7 evaluation. The costs include initial implementation costs as well as operation and maintenance costs over the life-cycle of the solutions. These cost estimates apply only to solutions at newly constructed roundabouts and channelized right turn lanes, not to retrofits. (9.) Submit a final report that documents the entire research effort, recommends the most promising solutions, and includes the products of Tasks 1 through 4 as separate chapters. Where appropriate, the report should include appendices with recommended language for the AASHTO Policy on Geometric Design of Highways and Streets; the AASHTO Guide for the Planning, Design, and Operation of Pedestrian Facilities; the AASHTO Guide for the Development of Bicycle Facilities; the FHWA Manual on Uniform Traffic Control Devices; the Traffic Control Devices Handbook; and other documents as appropriate.

Status: The panel met informally with the contractor at the TRB Annual Meeting in January 2005. Research was conducted through the University of North Carolina from February 1 through June 30, 2005, at which time the contract was terminated for convenience due to the principal investigator's move to North Carolina State University. The contract has moved with the principal investigator to North Carolina State University, where the project scope and tasks remain the same. See 3-78A for further developments.

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