Accessible Pedestrian Signals at Complex Intersections

Abstract

Pedestrians with vision impairments often have to cross streets at unfamiliar signalized intersections. The results are reported of research on crossings by blind pedestrians at complex intersections before and after the installation of accessible pedestrian signals (APS) and again following the installation of innovative device features. Objective data on measures of street crossing performance by 56 participants were obtained at four intersections, two each in Charlotte, North Carolina, and Portland, Oregon. The analysis includes broad measures of crossing timing, wayfinding, and independence. After APS installation, delay in starting to cross was reduced by approximately 2 s, and there was significant improvement in independently determining a safe time to cross, beginning to cross during the “Walk” signal, and completing crossings before the onset of perpendicular traffic. Some measures of wayfinding and related measures of independence also improved in Portland. Additional device features introduced after the first postinstallation testing session led to additional improvements in wayfinding during a second postinstallation test in Charlotte.

Wayfinding Problems for Blind Pedestrians at Noncorner Crosswalks: Novel Solution

“…Without it, participants were well aligned on approxi mately half of their trials, while with the guidance surface present and used for alignment, they were on average well aligned on more than threefourths of their individual trials. When pedestrians who are visually impaired are not well aligned when they begin crossing a street, they are quite likely to be outside the crosswalk by the time they reach the opposite end (1,9,10). This misalignment sometimes results in encountering landscaping or some kind of barrier on an island that prevents them from getting out of the street promptly, thus leading to greater exposure to moving traffic, or entirely missing a splitter island at a roundabout or channelized turn lane and walking into traffic lanes on either side of the island (1).…”

“…Participants typically used either or both the location of the curb ramp and the detectable warning, which were always approximately in the center of the crosswalk width, or the guidance surface, which was beside the detectable warning, also within the width of the crosswalk. In locations having poorly located curb ramps, or lacking detectable warnings, or having curb ramps or blended curbs that are much wider than the crosswalk, aligning to cross from a location within the crosswalk width has been found to be more of a problem (9).…”

Nonvisual Cues for Aligning to Cross Streets

“…Their findings suggest that under geometrically ideal conditions, traffic sounds can be used to align to within about 10 degrees of the desired direction. At complex intersections without special alignment cues, blind pedestrians have been found to be misaligned prior to crossing between 24% and 50% of the time (Barlow, Bentzen, & Bond, 2005; Scott, Barlow, Bentzen, Bond, & Gubbe, 2008; Crandall, Brabyn, Bentzen, & Myers, 1999). …”

Psychoacoustical Estimation of Selected Acoustic Signals Which Can Be Applied at Pedestrian Crosswalks

“…A lot of studies have shown a significant improvement in safety of vision impaired persons at the pedestrian crosswalks after introduction of audible pedestrian traffic signals [1,2]. The study carried out in California in 1991 [1] has shown that after installation of acoustic signalling devices generating audible traffic signals at the pedestrian crosswalks, the number of accidents involving vision impaired persons was reduced.…”