Detectable Warnings

Detectable warnings are standardised tactile surface features installed on walking surfaces to alert people with visual impairments to hazards or transitions — most commonly the edge of a transit platform, the bottom of a curb ramp, or the junction between pedestrian and vehicular areas. The most familiar form in the United States is the truncated-dome pattern mandated by the ADA Accessibility Guidelines, typically cast in a bright contrasting colour (often safety yellow) so that it also provides a visual cue for people with low vision. Other detectable-warning patterns used internationally include grooves and bars. Because they are detected through foot or cane contact, they work without batteries, electronics, or user training and are therefore one of the most robust pieces of accessibility infrastructure in the built environment.