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Designing Sidewalks and Trails for Access

Part II of II: Best Practices Design Guide

Updated June 26, 2009

Detectable Warnings

Detectable warnings are an Americans with Disabilities Act (ADA) requirement in the current Americans with Disabilities Act Accessibility Guidelines (ADAAG) for the use of detecting the boundary between the sidewalk and the street. The original requirement in ADAAG was suspended for a time to conduct further research. Research was conducted and the suspension of the requirement was lifted on July 26, 2001. At the time Designing Sidewalks and Trails for Access went to print, the suspension had not been lifted, so the text in Chapter 6 did not mention that detectable warnings are required.

Detectable warnings are now required when constructing and altering curb ramps. Truncated domes are the only detectable warnings allowed by ADAAG. The Access Board has detectable warning design information at; scroll to Public Rights of Way, Guidance Material. The Building a True Community report has information on the new recommended detectable warning/truncated dome design based on the current research. FHWA concurs with this design. Chapter 6 has dome patterns that were acceptable at the time Designing Sidewalks and Trails for Access went to print, but are no longer considered acceptable. For information on the detectable warning requirement, see the US Department of Justice website, FHWA policy on detectable warnings, released May 6, 2002, is posted at


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Notes for Reprint

Updated: 12/9/2016
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