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turning radius does not follow the pattern of a typical inter- by perpendicular crosswalk geometry. This fourth component
section. Making the locating task even more difficult is the depends on the provision of proper aligning geometry (the
placement of the crosswalk, which requires crossing an uncon- second component, discussed above) and assistive devices so
trolled movement at the turn lane. With non-standardized that the appropriate heading can be properly determined and
placement of the crosswalk at the upstream end, midpoint, maintained. In other words, maintaining alignment is highly
or downstream end, it is difficult to provide blind travelers unlikely if a pedestrian starts the crossing in the unintended
consistent guidance. direction. Far-side locator beacons or other treatments can
be extremely helpful in properly aligning and maintaining
alignment. Under a separate grant (NIH 2010), research is
Aligning to Cross
underway to test alternative alignment devices such as raised
Once the crosswalk has been found, the proper alignment guiding surfaces in the pavement area, far-side audible bea-
should be determined so that the pedestrian does not start the cons, and remote infrared audible signals. No definitive analy-
crossing with an unsuccessful alignment. For instance, many sis of such treatments has been completed at this time on the
times curb cuts at signalized intersections are installed as a ability of these devices to successfully aid pedestrians in main-
single curb cut in the middle of the curb radius to eliminate taining alignment.
the (perceived) need for two perpendicular curb cuts, saving
time and costs. This single curb-cut installation method sig-
The U.S. Access Board and ADA
nificantly hinders the ability of a blind pedestrian to align
correctly. Alignment is an important task that if not done One of the responsibilities of the U.S. Access Board is to
correctly, could lead to problems when maintaining that align- develop design guidelines for transportation facilities, ensuring
ment during crossing. For blind pedestrians, typical aids used that public rights-of-way are accessible to and usable by all
for aligning are specialized tactile surfaces or the edge of curb people and are thereby in compliance with the ADA. The
cuts (Barlow et al. 2005). Other research efforts underway at Access Board published the draft Public Rights-of-Way Acces-
the time of this report [National Institutes of Health (NIH) sibility Guidelines (PROWAG, U.S. Access Board 2005), out-
2010] are looking at alternative treatments to further aid pedes- lining requirements for making crosswalks and intersections
trians in aligning under various conditions, primarily focused in the public rights-of-way compliant with the ADA. Even
on improving detectable warning surfaces using parallel and before the draft PROWAG was published, the requirements
perpendicular bar tiles and far-side beacons. At the time of this for accessibility were outlined in the implementing regula-
report, no findings were available on the success or failure of tions of Title II of the ADA, which specifies that any newly
such devices in aligning to cross. constructed or altered public facility shall be "readily accessi-
ble to and usable by individuals with disabilities" (DOJ 1990),
including those with vision loss, mobility impairments, or
Identifying a Crossing Opportunity
other disabilities. The draft PROWAG provides more specific
The focal point of this research effort was on measures guidance, outlining features that make a site compliant with
describing the third component, the task of deciding when it is the ADA. Specifically, the provision of a pedestrian-actuated
actually safe to cross conflicting traffic. At unsignalized cross- signal with APS at two-lane roundabout approaches is dis-
ings, which constitute the large majority of roundabouts and cussed as making the site usable by pedestrians who are blind.
CTLs, the two crossing opportunities available to the pedes- A pedestrian-actuated and APS-equipped signal thereby
trian are yielding drivers or large gaps in traffic. At signalized satisfies the accessibility requirement for two-lane round-
crossings, the pedestrian walk phase presents a planned cross- about approaches (PROWAG R305.6.2). However, the draft
ing opportunity that is a function of signal phasing, which can PROWAG continues to allow the use of alternative treatments
be very useful to a blind pedestrian when negotiating very dif- if justified. The draft PROWAG language for two-lane CTL
ficult geometries and traffic conditions such as those posed by crosswalks is very similar to two-lane roundabouts in that
large two-lane roundabouts or CTL facilities. However, the a pedestrian signal with APS satisfies the accessibility require-
walk phase does not ensure that traffic is stopped due to right ment. In addition, the draft PROWAG also specifies the pro-
turns and permissive left-turning movements. Therefore, the vision of landscaping or barriers to delineate the crossing
walk phase by itself does not identify a safe time to cross. locations at roundabouts and CTLs, the use of APS devices
at all signalized pedestrian crossings, and the provision of
detectable warning surfaces on the curb ramp to demark the
Maintaining Alignment During Crossing
streetsidewalk boundary (PROWAG R305.6.1). The draft
Finally, the fourth component is the task of maintaining PROWAG does not discuss signalization at single-lane round-
alignment during the crossing, which is greatly facilitated abouts or single-lane CTLs.
