Detectable Warnings on Ramps

Research

• Warnings on ramps have been a part of the American with Disabilities Act since it was passed. Detectable warnings on ramps were found to be effective for warning the visually impaired of their approach to a street or vehicular pathway. Ramps with detectable warnings were found to be safer, more slip-resistant, more stable and easier to navigate then those ramps without a detectable warning. Detectable warnings on ramps have been found to have safer street crossings.

Need

• ADA detectable warnings are needed for those who are visually impaired. Before the advent of detectable warnings, the visually impaired had a hard time navigating across a street or from a store's entrance to the parking lot without assistance. The difficulty became even more apparent when the American with Disabilities Act was passed. By requiring curb ramps at intersections, it became virtually impossible for the visually impaired to determine the start of the street and the end of the sidewalk.

Definition

• A detectable warning is a feature built into or applied to the walking surface to warn of a hazard in the circulation path. It serves as a warning or stop sign for visually impaired people to warn them that they are entering an area in their path of travel that allows for vehicular circulation. Curb ramps are located at pedestrian corners to allow the physically disabled the ability to transition from a sidewalk elevation height to the street elevation height. Both are required by the ADA.

Specifications

• Detectable warnings are truncated domes aligned in a grid pattern. The truncated domes are a minimum of .9 inches to a maximum of 1.4 inches. They are spaced from 1.6 to 2.4 inches from the center of each dome. The detectable warnings are required to be of contrasting color from the adjacent finished surface of the surrounding walkway. It can be a visually contrasting color of light to dark or dark to light.