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Go to Front page Background section Travel by Blind
Other Effects of APS
Blind Pedestrians' Access to Complex Intersections
Project 3-62 Guidelines for Accessible Pedestrian Signals
Comparison of two types of APS
Interfacing Accessible Pedestrian Signals (APS) and Traffic Signal Controllers
Wayfinding Technologies for People with Visual Impairments
Comparison of APS signal technologies
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Technologies and Features section Types
Walk Indications
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Field Adjustments

Crossing problems that may be ameliorated by APS

Key research
Survey of blind pedestrians and orientation and mobility specialists
In 1998, the American Council of the Blind (ACB) and the Association for Education and Rehabilitation of the Blind and Visually Impaired (AER) conducted surveys having similar questions to determine problems experienced by blind pedestrians during street crossings.
  • ACB survey (Carroll, J. & Bentzen, B.L. 1999) - surveys administered orally, in groups, to 158 pedestrians who are visually impaired
  • AER survey (Bentzen, B.L., Barlow, J.M. & Franck, L. 2000) - mailed to 1000 orientation and mobility specialists. 349 surveys returned.

Crossing with and without APS (Talking Signs®)
In research by The Smith-Kettlewell Eye Research Institute (SKERI) in 1997, (Crandall, W.F., Bentzen, B.L., & Myers, L. 1998; and Crandall, W.F., Bentzen, B.L., Myers, L. & Brabyn, J. 2001), 20 blind participants made a total of 80 crossings at 4 fixed-time signalized intersections in downtown San Francisco, both with and without Talking Signs. The data on crossings without Talking Signs indicate problems experienced in the absence of APS.

Pedestrian crashes
In the survey conducted by the American Council of the Blind (ACB), 12 of 158 respondents had been struck by a car at an intersection, and 45 had had their long canes run over.

Locating the crosswalk
On 19% of street crossings in SKERI research, participants requested assistance in locating the crosswalk. Participants were permitted to begin a crossing from any location that satisfied them, whether or not it was actually within the crosswalk lines. It is common for pedestrians who are blind, if they do not need to locate and push a button, to cross from the position at which they have first encountered the curb line.

Identifying the crossing interval
In the surveys conducted by ACB and AER, many respondents indicated that they or their students sometimes had difficulty knowing when to begin crossing: ACB - 91%; AER - 98%

Reasons were:

  • Surge of traffic was masked by right turning traffic;
  • Traffic flow was intermittent;
  • Intersection was too noisy; and
  • Surge of traffic was too far away.
In the AER survey, 79% of respondents indicated that blind students sometimes had difficulty determining the onset of the Walk interval at intersections having exclusive pedestrian phasing. On 24% of trials in SKERI research, where APS information was not available, blind pedestrians requested assistance in knowing when to start crossing. On 34% of trials on which they independently initiated crossings, they began crossing during the flashing or steady DON'T WALK.

Establishing correct heading
In the AER survey, 66% of O&M; specialists who responded indicated that their students sometimes had difficulty establishing a heading toward the destination corner, the most important reasons being that traffic was intermittent or the intersection was offset. In the ACB survey, 79% of respondents indicated that they sometimes have difficulty figuring out where the destination corner is.

On 52% of crossings in SKERI research, where APS information was not available, blind pedestrians were not facing directly toward the opposite corner when they started their crossing; they were facing somewhat toward or away from the center of the intersection.

Understanding intersection geometry
In the ACB survey, 85% of respondents indicated that they were sometimes confused by unexpected features such as medians or islands.

On 54% of crossings in SKERI research, where APS information was not available, blind pedestrians did not know whether the intersection they had just crossed was a 4-way intersection or a "T"-shaped intersection.

Pedestrians who are blind need to understand the shapes of intersections they are crossing because intersection geometry is a good predictor of the probability of the timing, volume and direction of turning traffic.

Understanding intersection signalization
On 50% of trials in the SKERI research, where APS information was not available, participants were not able to obtain sufficient information from traffic sounds and other clues to identify whether an intersection was signalized or had stop signs.

Understanding the type of traffic control is necessary for pedestrians who are blind or visually impaired to make good judgments about what timing strategy they will use when crossing a street.

Problems with pushbuttons
Blind pedestrians experience a number of problems with pushbuttons.

In the ACB and AER surveys, many respondents indicated that they or their students had difficulty with pushbuttons: ACB - 90%; AER - 94%.

Reasons were:
  • They couldn't tell whether they needed to push a button;
  • They had difficulty locating the button;
  • They couldn't tell which crosswalk was actuated by the button; and
  • The pushbutton was so far from the crosswalk that they couldn't push the button and then return to the crosswalk and establish a heading before the Walk interval began.
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