Whether the term detectable warning is new to you, or you could use a refresher, this blog provides a simple, yet effective guide to detectable warnings, including what they are, where they need to be installed and why they are required.
What are Detectable Warnings?
Detectable warnings are defined as being a distinctive surface pattern, noticeably different than the surrounding area, compromised of truncated domes. Truncated domes are detectable underfoot or by guidance cane, and can be installed together as part of an ADA tile, or individually to create a detectable warning surface.
The function of detectable warnings is to alert persons with impaired vision of upcoming street crossing or hazardous drop offs.
Why are Detectable Warnings Required?
Accessible curb ramps became required by the Americans with Disabilities Act (ADA) in 1990, which allowed for persons using wheelchairs or other mobility aids to more easily enter pedestrian crossing. This subtle slope, however, made it difficult for persons with visual impairments to notice the change in grade, removing the tactile clue of the boundary between street and sidewalk.
Detectable warning surfaces were developed to provide a non-visual warning to persons of all abilities of potential upcoming hazards, such as vehicular roadways and the drop offs of transit platforms.
The requirement of detectable warnings is to allow persons with visual impairments can easily, and safely navigate public spaces, unaided.
Where are Detectable Warnings Required?
In order to create a more accessible environment, detectable warnings are required in number of public spaces.
Curb Ramps
The subtle slope of accessible curb ramps poses a potential danger to those with visual impairments, as it removes the tactile clue which warns of oncoming traffic. To address this issue, the ADA requires the installation of detectable warning surfaces on curb ramps.
Transit Platforms
To alert pedestrians of the hazardous drop off, detectable warning plates are required to be installed on the edge of transit platforms, along the entire length of the platform. Additionally, detectable warning surfaces are required on any areas of sidewalk when the path crosses over train tracks.
Stair Landings
Detectable warning tiles are required to be installed on stair landings as a way to alert persons with visual impairments of upcoming stairs and also when the top of stairs has been reached.
What are the Code Compliance Regulations for Detectable Warnings?
Although building codes differ by location, the ADA sets clear requirements, which must be followed, for code compliant detectable warning installations.
The base diameter of truncated domes must be between 23mm and 36mm, with a top diameter of 50% of the base. Center-to-center spacing of truncated domes must be between 41mm and 61mm, with a base-to-base spacing of at least 17mm.
Detectable warning surfaces must provide stark visual contrast with the adjacent surface; dark colored detectable warning plates are installed on light colored substrates and vice versa.
A detectable warning surface must extend a minimum or 610mm in the direction of travel and extend the full width or the curb ramp, stair landing, blended transition, or transit platform.
How Can Detectable Warnings be Implemented?
Detectable warning surfaces can be implemented as a detectable warning plate, compromised of truncated domes, or can be installed as individual truncated domes.
In areas of new construction, it is recommended cast in place ADA tiles are used, which can be set directly into wet concrete. This also helps to ensure easy replacement, when needed. To retrofit existing areas, detectable warning plates can be installed as surface applied ADA tiles, which does not disturb the surrounding concrete.
Additionally, detectable warnings can also be installed as wayfinding bars, which create a tactile guidance pathway to lead persons through open spaces.
Detectable warning surfaces play a vital role in public safety and accessibility, providing a non-visual clue of upcoming hazards.
Access® Tile has been working with industry experts for decades to improve the design of our detectable warnings, resulting in an incredibly durable, slip-resistant, and cost-effective solution for all projects. Our ADA tiles meet the stringent requirements set out by the Americans with Disabilities Act, California Title 24 Requirements, and local building codes.
Our code compliance experts will help you find the right detectable warning plate for all your projects!
