Design Considerations
The draft Americans with Disabilities Act include specific requirements for pedestrian signals and a comprehensive list that the designer should review.
The TMUTCD, Section 4E. “Pedestrian Control Features” also covers many of the design requirements of APS systems. As with any traffic control device, the TMUTCD should be reviewed when designing accessible pedestrian signals. For example, the TMUTCD indicates that the push buttons should be separated by 10 feet and located near the curb ramp they serve, preferably at the landing for the curb ramp.
The APS units require mounting with proper orientation to direct pedestrians across the street.
The , which was developed by the NCHRP, is very comprehensive in regard to all aspects of APS. It goes into extensive detail regarding all aspects of APS and is recommended as a reference for APS design considerations.
APS have undergone several advancements throughout the years. The most current devices are the push button integrated systems. With these systems, the speaker, push button, and vibro-tactile arrow are all contained in the push button housing. Placement of the push button/APS is critical to the proper operation of the system. The pedestrian uses the arrow on the APS for orientation in crossing the street. The button stations serving adjacent crosswalks at the same corner require separation so that the user can tell which crossing is being served with a walk indication. The APS provides a locater tone and “walk” tone; the cuckoo and chirp tones are no longer considered effective. These systems have the capability to adjust to ambient noise levels and can be configured so that they are only discernible from a specific distance from the intersection, posing less of a noise issue for the surrounding environment. In consideration of the above, it is critical in design to locate the pushbuttons and crosswalks such that the installation of APS will be effective.