As discussed previously, this prioritization information is to be used in prioritizing existing intersections for retrofit with APS either in response to requests, or in updating an ADA transition plan.
Prioritization schemes should place only limited emphasis on factors related to frequency or likelihood of use by blind pedestrians. The information provided by APS may be necessary at any time, along any route, to residents, occasional travelers, and visitors. Intersections having high pedestrian volumes are likely to have pedestrians whose vision is sufficiently impaired that they have difficulty using conventional pedestrian signals.
Of greater importance are factors related to determining whether sufficient acoustic information exists - at all times - to permit safe crossing at a particular intersection.
Several rating scales have been developed, some of which have been utilized for over 20 years. These rating scales are used in different ways in different cities.
After a request for an APS is made by an individual who is blind or by an organization representing or serving individuals who are blind or visually impaired, the intersection is evaluated using a rating scale.
Systems developed most recently rate each crossing at an intersection rather than the whole intersection.
Systems for determining the priority of APS installations usually involve participation of one or more representatives of three groups of experts: traffic engineers, orientation and mobility specialists, and pedestrians who are blind.
Different persons in different jurisdictions carry out the evaluation.
In San Diego and Portland, the ratings are reviewed by an advisory committee of stakeholders, including blind citizens, that assists the traffic engineering department in prioritizing the installations.
Intersections with the highest number of points are generally considered highest priority, however, date of request, plans for other construction at the intersection in question, and other issues may affect priority of the installation.
Research on a rating scale
As part of NCHRP Project 3-62, a prioritization rating scale will be validated.
After completion of this project, the rating scale will be available for use by jurisdictions involved in prioritization decisions.
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This site was developed under the sponsorship of the National Cooperative Highway Research Program.