What Are the Requirements for Detectable Warnings?

Subject: The ADA Accessibility Guidelines (ADAAG) written by the U.S. Architectural and Transportation Barriers Compliance Board (Access Board) and published July 26, 1991, includes the following:

4.29 Detectable Warnings.
4.29.2* Detectable Warnings on Walking Surfaces.
“Detectable warnings shall consist of raised truncated domes with a diameter of nominal 0.9 inch, a height of nominal 0.2 in and a center-to-center spacing of nominal 2.35 inches and shall contrast visually with adjoining surfaces, wither light-on-dark or dark-on-light.  The material used to provide contrast shall be an integral part of the walking surface.  Detectable warnings used on interior surfaces shall differ from adjoining walking surfaces in resiliency or sound-on-cane contact.”

4.29.5 Detectable Warnings at Hazardous Vehicular Areas.
“If a walk crosses or adjoins a vehicular way, and the walking surfaces are not separated by curbs, railings, or other elements between the pedestrian areas and vehicular areas, the boundary between the areas shall be defined by a continuous detectable warning which is 36 inches wide, complying with 4.29.2.”

In the ADAAG of 1991, Section 3.5 Definitions does not define hazardous vehicular area, but it does define vehicular way:  “A route intended for vehicular traffic, such as a street, driveway, or parking lot.”  It is the opinion of ACCESS that because all walk crossings of a vehicular way are not hazardous, detectable warnings are only required on some walk crossings of a vehicular way.  Therefore, design professionals and contractors must have a list of criteria for determining when a walk that crosses a vehicular way is hazardous, such as:

·         Posted speed in vehicular way – above 35 MPH.
·         Number of traffic lanes being crossed – above 2.
·         Location, such as business or residential – not residential.
·         Intersection with traffic controls – lights or stop signs.
·         Any special condition deemed hazardous by a registered professional architect or engineer.

The above are opinions of Hank Falstad, AIA, Managing Senior Associate of Access Technologies Services, Inc. (ACCESS).  See our web site for additional information:  www.accessts.net.