Where Do Truncated Domes Need to Be Installed?

One of the requirements set out by the Americans with Disabilities Act (ADA) is that detectable warning surfaces must be installed in specific locations to alert individuals that they are reaching the end of a walkable path and may be entering into a hazard such as moving traffic. These surfaces have truncated domes of a specific size so that they can be felt on the feet and through a wheelchair, cane, or other mobility aid.

Let's look at some of the locations where ADA guidelines say truncated domes must be installed.


Curb ramps allow individuals who rely on mobility aids such as scooters, wheelchairs, and walkers to transition between the sidewalk and the street easily. However, anyone who is visually impaired can find identifying appropriate curb stamps challenging. That is where detectable warning surfaces come in. These should be installed anywhere that the sidewalk meets the street, where a curb indicates a crosswalk, or where a ramp is located. This helps visually impaired people know when they are on a safe walkway and when they may be about to enter moving traffic.


Truncated domes need to be installed on curb ramps located at intersections. Depending on when the street was built, the requirements will vary. Most municipalities will install curb ramps with truncated domes at pedestrian crossings to make reaching accessible buildings or parking garages easier. They may also install tactile surfaces on curb ramps in other locations, depending on nearby facilities. 


It is common in cities for some crossings to cut through a raised island. In order to be ADA compliant, these should have a cut-through path or feature a curb ramp at either side. There should be a level area of a minimum of 48 inches long and 36 inches wide in the direction of the ramp slope. Truncated domes should be installed on islands and cut through medians.


Where transit platforms have no protective screens or guardrails in place, the ADA requires the platform to have a 24-inch wide panel of truncated domes running the entire length of the platform accessible to the public. This is designed to alert visually impaired commuters that they are approaching the platform's edge and prevent them from falling onto the tracks.


In some cities, the sidewalk may cross over a train track. In this situation, truncated domes should be installed on this section of the path. They should start far back enough to give ample warning that the hazard is approaching. As a general rule of thumb, between 6 and 15 feet from the center of the track is acceptable. This allows room for the crossing to close its gates and keep individuals away from the tracks when a train is passing.

If you have any questions, feel free to get in touch to discuss your truncated dome needs.


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