Detectable warning surfaces now required in curb ramp installations

Michele Ohmes
ADA Specialist
Public Works Department
City of Kansas City, Missouri

Mary O'Connor
Deputy Public Works Manager
City of Tempe, Arizona

This summer, the U.S. Access Board, the federal agency which develops accessibility guidelines for new and altered facilities under the Americans with Disabilities Act (ADA), will be issuing a Notice of Availability for draft guidelines on public rights-of-way that will supplement its ADA Accessibility Guidelines (ADAAG). These guidelines, which will cover access to sidewalks, street crossings and other related pedestrian and roadway facilities, will be based on recommendations from an advisory committee organized by the Board. The draft will be posted on the Access Board website,

The Public Rights-of-Way Access Advisory Committee (PROWAAC) included representatives from disability organizations, public works departments, transportation and traffic engineering groups, design professionals and civil engineers, government agencies and standard-setting bodies. APWA had two official representatives to this body, and various representatives of local or state governments or other groups were also APWA members. The intent of this broad-based representation was to provide a balanced set of guidelines that reflects a consensus among user needs and knowledgeable input from designers and implementers, resulting in a usable, comprehensive set of design standards.

A detailed article on the recommendations of the PROWAAC, and the Access Board's draft guidelines, is planned for the September issue of the APWA Reporter. APWA's Engineering and Technology Committee has been reviewing the PROWAAC recommendations and received a variety of comments from members. The article will summarize the draft guidelines, and describe comments received from APWA members to date.

Detectable warning surfaces required when constructing or altering curb ramps as of July 2001
Detectable warning surfaces were required in 1991 by the ADAAG for hazardous vehicular ways, transit platform edges, and curb ramps. This requirement was suspended for a time for curb ramps and hazardous vehicular ways (but not for transit platform edges) to conduct further research on the performance of their detectability. The Department of Justice (DOJ) continued the suspension through July 26, 2001, which allowed 10 years for research.

The research, part of PROWAAC's charge, resulted in recommendations based on input from blind and low-vision user groups, wheelchair users, designers, implementing agencies and manufacturers. The group recommended contrasting truncated dome surfaces as the most detectable surface underfoot, with visual contrast for low vision pedestrians. The research determined that other designs used in place of truncated domes such as grooves, striations, and exposed aggregate, were not detectable in the sidewalk and roadway environment because of similarities to other surface textures and defects.

The DOJ, the lead agency that oversees the Americans with Disabilities Act, allowed the suspension to expire on July 26, 2001; consequently, since July 26, 2001 detectable warnings are again required for hazardous vehicular ways and curb ramps. The Federal Highway Administration (FHWA), as the enforcement authority for overseeing pedestrian discrimination issues, is obligated to enforce the requirements. A recent FHWA memo advised transportation agencies of the expiration of the suspension. FHWA noted that state and local governments are required to apply the minimum design standards when constructing and altering pedestrian facilities, and are encouraged to apply higher than minimum standards where possible. Although the original design standard for truncated domes is found in ADAAG (4.29.2), the new design recommendation for the dimension and placement of the domes on curb ramps is recommended by both FHWA and the Access Board.

Where to find more information
To find the regulation on the suspension and requirement: See the DOJ website,, or visit the Access Board website,, click on "publications," go to "facilities," go to "Detectable Warnings: Final Rule."

To find the design and application requirement in ADAAG: Visit the Access Board website,, click on "publications," go to "facilities," go to "ADA Accessibility Guidelines (ADAAG)"; the provision is in 4.7.7 under Curb Ramps.

To find technical information and a list of manufacturers: Visit the Access Board website,, click on "publications," go to "Public Rights-of-Way," go to Detectable Warnings: Synthesis of US and International Practice.

To find the recommended design for curb ramps: Visit the Access Board website,, click on "publications," go to "Public Rights-of-Way," go to Building a True Community: Accessible Public Rights-of-Ways, sections X02.5.6.2 through X02.5.7.3. FHWA's Designing Sidewalks and Trails for Access, Part II, Best Practices Design Guide has comparable information but does not mention that detectable warnings are required.

To reach Michele Ohmes, call (816) 513-2533 or send e-mail to To reach Mary O'Connor, call (480) 350-8819 or send e-mail to Mary_O'