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ROUNDABOUT
HIGHWAY
RESEARCH
RESEARCH IN PROGRESS
Research about the accessibility is in its infancy. In 1999, a program of research on roundabout accessibility was initiated by Western Michigan University and Vanderbilt University. Conducted at three modern roundabouts in metropolitan Baltimore, Maryland, the study provides information about the ability to use vision and hearing to distinguish ‘crossable’ gaps in traffic from gaps that are too short to afford safe crossing. ‘Crossable gaps’ were defined as those that would have allowed pedestrians sufficient time to cross from a curb to a splitter island before the arrival of the next vehicle at the crosswalk. The results of the study suggest that there are significant differences in the ability of blind and sighted pedestrians to determine whether it is safe to initiate a crossing at some roundabouts, presumably because of differences in the way information is obtained to make decisions about crossings. The Western Michigan/Vanderbilt team also conducted a comparable study at three roundabouts in the greater Tampa, Florida area with similar results. A principal finding of this research was that the ability to judge whether gaps are crossable or not is strongly affected by vehicle volume. For example, the judgements of blind and sighted pedestrians were similar at a single-lane roundabout at mid-day, but blind pedestrians were significantly disadvantaged at rush hour. The team is currently studying the behavior of blind and sighted pedestrians as they cross at roundabouts and the behavior of drivers as they approach blind pedestrians waiting at uncontrolled crosswalks (both at roundabouts and mid-block crosswalks). Preliminary analysis suggests that few drivers yield, although this varies widely from crosswalk to crosswalk. While such research has begun to address several of the key issues cited earlier in this bulletin, it is clear that much more work remains to be done.
The dearth of research addressing the negotiation of roundabouts by blind pedestrians has prompted Federal funding of several projects on this topic. The first, funded by the National Eye Institute of the National Institutes of Health, was awarded in 2000 to a consortium led by Western Michigan University. This project emphasizes the identification of variables affecting blind pedestrians’ safety while crossing streets at roundabouts and treatments to enhance this safety. The second project, funded by the National Institute on Disability and Rehabilitation Research, was awarded in 2001 to a consortium led by the Sendero Group, LLC. This project emphasizes the identification of wayfinding information needed by blind pedestrians at roundabouts (e.g., crosswalk location, intersection geometry) and ways to convey this information to the pedestrian. A third project, focused specifically on the usability of roundabouts and slip lanes by pedestrians who have vision impairments, will be awarded in 2004 by the National Cooperative Highway Research Program (a prior NCHRP study still underway will identify "geometric, traffic, and other characteristics that are expected to affect the safety and operation of all roundabout users, including bicycles, pedestrians, and pedestrians with disabilities" and to "refine geometric and traffic control design criteria used for roundabouts, including….treatments for bicycles and pedestrians (including pedestrians with disabilities and including the impact of accessible pedestrian signals on pedestrian access and vehicle operations)…"). The Turner-Fairbanks Research Center of the Federal Highway Administration/DOT has a human factors study newly underway that will test several potential improvements to roundabout usability by pedestrians who have vision impairments. Collectively, these and other projects should significantly enhance engineers’ and planners’ access to information about how to build roundabouts that can be negotiated safely and efficiently by blind pedestrians. A summary of the Board-sponsored research is posted to the Board's website. Additional resources on public rights-of-way accessibility available from the Board include:
Resources available from the Federal Highway Administration include:
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