Synthesis of Literature Relevant to Roundabout Signalization to Provide Pedestrian Access - Final Report

BACKGROUND

Implementing regulations under Title II of the Americans with Disabilities Act (1) and other statutes require that new construction and alterations are accessible to, and useable by, people with disabilities. In recent years, with the development of guidelines for the public right-of-way, concerns have been raised about the accessibility of roundabouts to persons with severe visual impairments (2) and subsequent research has tended to support those concerns. For instance, Guth, et al. (3) have shown that blind pedestrians require about 3 more seconds than sighted pedestrians to detect naturally occurring gaps in traffic, and that this requirement markedly reduces the number of gaps available to blind pedestrians at roundabouts with moderate to high traffic volume. Nor can blind pedestrians rely on motorists to yield to them. Inman et al. (4) found that at one double lane roundabout, only 14 percent of motorists yielded to blind pedestrians using a long cane or a guide dog. Furthermore, those investigators found that on 10 percent of trials, the blind pedestrians incorrectly identified that both lanes of a double-lane roundabout were blocked by stopped vehicles, when in fact, only one lane was blocked. Geruschat and Hassan (5) reported on a number of factors that can influence motorists’ yielding rate. They found that drivers are more likely to yield at roundabout entrances than exits and when: (1) speeds are lower, (2) the pedestrian is more aggressive, and (3) when the pedestrian has a long cane or guide dog. At a roundabout entrance where measured speeds were about 10 mi/h, almost all drivers yielded to a pedestrian who had one foot into the street and carried a long cane. At a roundabout exit where measured speeds were about 20 mi/h yielding rates to an apparently blind pedestrian were less than 15 percent.

Thus, it appears that many double lane roundabouts are not accessible to pedestrians who are blind. Vehicles are unlikely to yield to these pedestrians, naturally occurring gaps may be rare, and many roundabouts – in particular multilane roundabouts – with pedestrian facilities, do not provide cues that enable pedestrians who rely on traffic sounds to reliably detect gaps that result when vehicles yield to them. For these reasons, draft guidelines developed by the U.S. Access Board (6), would require some form of signalization at new multi-lane roundabout pedestrian crossings.