Tactile paving, also known as truncated domes or detectable warning surfaces, refers to ground surface indicators to guide and warn visually impaired pedestrians. Truncated domes are characterized by unique patterned cones that are detectable by a cane or foot, which warns or informs pedestrians about the presence of a street or an immediate drop-off. Tactile paving first came to being in 1960, developed by the Japanese, and quickly expanded to the UK and Australia. It would later be adopted in the United States in the 1990s, followed closely by Canada. More than 18countries have now installed truncated domes in front of rail lines, city crosswalks, government buildings, schools, etc.
The importance of truncated domes
Recently, the sidewalk design required by the ADA (Americans with Disability Act) has transformed to integrate the idea of universal design so that people with disabilities can access public pedestrian environments. Instances of this significant change have been introducing curb ramps or curb cuts, which allow wheelchair users to leave a pedestrian way, cross a hazard such as a street, and reaccess the pedestrian street without any barrier. While that change successfully accommodated and enhanced the mobility of wheelchair users, the visually impaired population was left out with no indicator that they were entering a vehicular passageway.
Following that, the industry implemented several solutions, including makeshift warning signs as an alternative to replace the curb. Out of all the solutions implemented, or tactile paving has proven to be the most effective solution. Truncated domes are designed as consistent surfaces that rise 0.2 inches above the sidewalk’s base and alerts the visually impaired when they reach the entrance of a crossing. They can be comfortably felt on the footwear and can be audibly heard when you tap them with a guidance cane. What happens is, they make a unique sound that makes them distinguishable from the path or walkway.
Today, truncated domes are categorized as an ADA-compliant tile known as a detectable warning tile or tactile paving. The detectable warning surfaces are lengthy tactile panes featuring series of truncated domes. They are useful as tactile warning systems for many projects, including walkways, curbs, and transit platforms.
Truncated domes ADA guidelines
Truncated domes must have a distinct color from the walkway next to them. ADA has established guidelines that state the color contrast must be at least 70% to maximize the advantage to the visually impaired population. That is so that people with limited vision can be able to see the tactile pavings. Many jurisdictions choose the federal yellow, although many colors are available such as brick red, blue, dark grey, safety red, Seattle yellow, bright white, black, and clay red. In cases where the surrounding pathway is of a light color, black or dark gray colored surfaces are used.
A further benefit
An additional benefit of truncated domes to all people, including visually impaired persons, is the antislip surface of truncated domes. It maximizes the slip resistance in the detectable warning signs. Some have unique incorporated designs to minimize wear and tear.
Note that curb ramps are beneficial to wheelchair users, but truncated domes help visually impaired people. Truncated domes are a detectable warning surface that fully complies with ADA accessibility guidelines.