APS Design at an Existing Intersection
Application of new construction guidelines
In retrofit situations, the ADA requires that new construction guidelines be followed to the maximum extent feasible if compliance with the new construction guidelines is technically infeasible. The determination of technical infeasibility will vary depending on the scope of the project and the existing situation.
The new construction guidelines, as described in the previous section, should be applied as much as possible given the constraints of the project and the site.
The following sections provide guidance to assist the engineer/designer in understanding the effect of varying locations and different actuation on the usability of the information provided by APS.
The goal of the new construction location requirements and guidelines is to provide unambiguous information about which crosswalk has the WALK indication, and to make pushbuttons accessible to and usable by all pedestrians, including those with visual and mobility impairments. Poor location and installation can render APS unusable by a pedestrian who is blind or mobility impaired or can provide dangerously incorrect information.
Pedhead-mounted and pushbutton-integrated APS in the U.S. have typically been mounted on the same pole as the pedestrian signals for that crosswalk, regardless of whether the pedhead is the one closest to that crosswalk. This does not always provide unambiguous audible WALK indications.
In Australia and some European countries, it is common to install a separate stub pole to mount APS in a consistent location in relation to crosswalks. This consistent location makes it easy to determine which device the WALK indication is coming from, and, therefore, provides unambiguous information regarding which crosswalk has the WALK interval. The MUTCD, proposed PROWAG, and Draft PROWAG implement this strategy in new construction in the U.S.
Issues to consider
In designing retrofit installations, an understanding of the effect of certain intersection features on APS use will be helpful in making decisions. Another factor that becomes critical when adding APS to an existing intersection is the location of existing poles and the possible need for new poles to position the APS close to the crosswalk. Details on these issues and recommended solutions are given in the following sections.
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