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85 understanding of general traffic performance. The analysis the ambient noise, the level of driver courtesy toward pedes- framework is sensitive to differences between sites and the trians, and probably other variables yet to be identified and impact of pedestrian crossing treatments. studied. A range of treatments is available and discussed in That a measurable concept of accessibility can be quanti- Chapter 2 that have the potential of influencing one of more fied in terms of the availability and utilization of crossing of the dimensions of accessibility defined in the framework opportunities in the form of gaps and yields and that these outlined in Chapter 4. measures can be used to describe the performance measure of delay, although delay is not a measure that can, by itself, Policy Implications be used to measure accessibility to blind pedestrians. That significant variability across study participants was While the U.S. Access Board draft PROWAG specifies a observed for all sites, highlighting individual differences in pedestrian-actuated signal at two-lane roundabout crosswalks terms of travel skills, decision-making, and level of crossing with pedestrian facilities, the ADA allows equivalent facilita- comfort. Significant differences also exist across different tion in all implementations of requirements. Consequently, test sites, including the three tested single-lane roundabouts. other treatments that provide equivalent accessibility are That some CTL crossings are more hazardous than single- acceptable. This is to allow for improvements in technology, lane or two-lane roundabouts for pedestrians who are developments in materials or research, or the implementa- blind, and that the tested CTL treatments--sound strips tion of new ideas and information. It is up to the designer and pedestrian-actuated flashing beacons--did not effec- and/or constructing jurisdiction to provide justification for tively alleviate all accessibility concerns. The sound-strip installation decisions in the case of an ADA complaint. The treatment did show potential, and modified materials and team believes that there is some confusion in the interpreta- installations should be explored further, in addition to tion of these standards in that some may fail to recognize the other potential modifications at CTLs that reduce vehicle inherent difference in civil rights laws and engineering stan- speed and increase yielding. A major concern is the ability dards. While the current draft requirements focus on two- of pedestrians to detect yielding vehicles in the high ambi- lane crossings at roundabouts and CTLs, as well as treatments ent noise environment of most CTLs. Treatments such as that provide information about the crosswalk location such sound strips, lane delineators, and pedestrian-actuated as landscaping or barriers, there is still a responsibility to design flashing beacons cannot be expected to provide adequate and build all facilities to be "accessible to and usable by" pedes- accessibility at two-lane CTLs. trians with disabilities (DOJ 1990). That the three single-lane roundabouts varied considerably An increasing national debate in this area is very positive. in the availability and usability of crossing opportunities, However, a narrow focus in that debate on the signalization delay, and risk for pedestrians. At least one tested single-lane of two-lane crossings is associated with two major concerns: roundabout (PS-RAL) showed a relatively high incidence (1) by focusing on two-lane roundabouts, the accessibility of of interventions (3.9% mean, 15.6% for one individual), single-lane approaches is being largely ignored, and (2) the and another (DAV-CLT) had relatively high pedestrian emphasis on signalization gives a perceived blanket obliga- delays (25.3 s mean, 74.0 s maximum individual average). tion for a one-size-fits-all treatment at all two-lane locations, Therefore, while for one single-lane roundabout crossing regardless of the site specific geometry, traffic volumes, and and some blind pedestrians no treatments appear neces- driver behavioral patterns. sary under tested conditions, at least one high-risk and one There is no real debate over the fact that well-designed high-delay crossing warrant further treatment evaluations. modern roundabouts are generally safer for vehicular traffic That both tested two-lane roundabout treatments, raised than many traditional intersections they replace. There is fur- crosswalk and pedestrian hybrid beacon, appeared to sig- ther no real debate that many sighted pedestrians can safely nificantly enhance the accessibility at the tested site. The negotiate single-lane roundabouts and most two-lane round- improvements were evident in the form of significantly abouts. However, research to date is unclear about the ability reduced pedestrian delays and no posttest interventions of other pedestrian populations, including elderly pedestri- with either of the treatments. However, field observations ans, children, and those with mobility impairments, to cross by a trained observer noted more potentially risky events safely at these locations. Further, it is unclear what challenges at the raised crosswalk and none at the PHB, suggesting are posed by newly emerging three-lane roundabout designs that the latter treatment represents the safest (tested) cross- with potentially high design speeds and high traffic volumes. ing condition for blind pedestrians at this site. The data presented in the present work strongly argues against the belief that all single-lane roundabouts are created The present studies suggest that the accessibility of a site is equally. While one of the studied sites showed generally low a function of the conflicting traffic volume, the speed of traffic, delay and risk, a second site had high pedestrian risk, while