Nonvisual Cues for Aligning to Cross Streets.

Abstract: Accurately aligning to a crosswalk is an important component of safe street crossing for pedestrians who are blind. Six alignment cues were evaluated in a simulated crosswalk environment in which the angle of the crosswalk was not always in line with the slope of the ramp. The effectiveness of each cue is reported and implications are discussed. ********** For individuals who are blind, the tasks required to cross a street include detecting the street, locating the crosswalk or crossing location, aligning (determining the appropriate initial heading), determining an appropriate time to cross, and traveling on an appropriate heading until the crossing is completed (Guth, Rieser, & Ashmead, 2010; Tauchi, Sawai, Takato, Yoshiura, & Takeuchi, 1998). The study reported here is the first of a series that evaluates the effectiveness of various treatments as aids for alignment and for maintaining the correct heading while crossing streets without vision. Orientation and mobility (OM Whipple, 2004). Others involve acoustic cues, such as the sounds of traffic moving parallel or perpendicular to the crosswalk (Barlow, Bentzen, Sauerburger, & Franck, 2010; Guth et al., 2010; Stollof, 2005b). At modern intersections, however, such cues may be unavailable. For example, at a curb ramp, grasslines at the sides of the ramp, if present, are rarely aligned with the crosswalk. Parallel and perpendicular patterns of the movement of traffic often do not occur at some crosswalks, such as crosswalks at roundabouts and channelized turn lanes, and may be unreliable at other crosswalks, such as those where the volume of traffic is low during parts of the day. The installation of curb ramps at many intersections has further complicated the alignment task. In the United States, curb ramps often slope toward the center of the intersection, rather than in the direction of the crosswalk (see Figure 1), which sometimes results in pedestrians who are blind crossing toward the center of the intersection (Hauger, Rigby, Safewright, & McAuley, 1996). Even when separate curb ramps serve the two crosswalks on a corner, the large radius of many corners results in curb ramps at which the slope is out of line with the crosswalk to be perpendicular to the edge of the street and the gutter. Curb ramp slopes are required to be perpendicular to the gutter to minimize the tipping hazard for wheelchair users. Although some curb ramps are aligned with the crosswalks they serve, it is not known whether the slope of the ramp actually provides a useful cue to alignment for pedestrians who are blind. In areas where sidewalks are narrow, parallel ramps are often used, in which the sidewalk itself slopes down to an area that is level with the street (see Figure 2). At a parallel ramp, the sidewalk often curves, and this curvature can affect the direction the pedestrian is facing upon arrival at the street. Previous research evaluated alignment on the basis of traffic sounds, tactile arrows, and bar tiles. Chew (1986) and Guth, Hill, and Rieser (1989) assessed the skill with which experienced pedestrians who were blind aligned themselves parallel and perpendicular to traffic that ranged from a single car to heavy traffic. …