Truncated Domes

What Are Truncated Domes?

There are many different terms used to describe Truncated Domes:

• Detectable Warnings

• Tactile Paving

• ADA Dome Mats

• Those Yellow Bumpy Things

Whatever you choose to call it, Truncated Domes are the textured ground surfaces commonly found on curb ramps, transit stations and commercial shopping center parking lots. Truncated Domes are one form of detectable warning using in the built environment. They serve as physical warnings for people with vision impairments to avoid hazards.

While navigating throughout the built environment, those with healthy vision can easily distinguish the boundary between a safe pedestrian walk or sidewalk and a hazardous vehicular way. In many cases, even people with vision impairments can distinguish the boundary when a curb separates safety from hazard. There are some conditions however, where there is no detectable separation between walks and vehicular areas. Curb ramps and blended transitions (AKA flush transitions with no curb) offer no caution that people with vision disabilities can detect. In these instances, the presence of truncated domes can provide a clear detectable warning system to distinguish the boundary between safety and danger.

Does the ADA Require Truncated Domes?

Yes, in some cases Truncated Domes are required to be provided in the built environment. Specifically, the 2010 ADAS requires truncated domes to be provided at platform boarding edges where not protected by guards or platform screens. That’s it. Rail platform edges are the only place that truncated domes are specifically required in the current ADAS. However if you found your way to this blog post, it is likely because you are responsible for a property in California.

California requires Truncated Domes to be provided at the following locations where other forms of detectable warning are not present:

• Platform Edges

• Curb Ramps

• Islands and Cut-through Medians

• Bus Stops

• Blended Transitions

• Reflecting Pools

• & Track Crossings

Before taking any action to install Truncated Domes or construct any of the elements above, we recommend consulting with a Certified Access Specialist (CASp) that understands the application of Detectable Warnings. In some case, a CASp may suggest a better alternative to providing Truncated Domes as a detectable warning.

Are Truncated Domes Required to be Yellow?

Maybe. It depends where they are located. In California, new Detectable Warning surfaces shall be yellow and approximate FS 33538 of SAE AMS-STD-595A. Existing California Detectable Warnings at curb ramps, islands, or cut-through medians have the option to provide Truncated Domes with a 70 percent minimum visual contrast with adjacent walking surfaces as required by 11B-705.1.1.3.2.

Are There Areas Where Truncated Domes Are Prohibited?

YES! Failure to understand that there are locations that where Truncated Domes are specifically prohibited is the biggest mistake that architects, contractors and property owners make. Detectable Warning are NOT permitted in the following areas:

• Parking Spaces & Access Aisles

• EV Spaces and Access Aisles

• Passenger Drop-Off and Loading Zones & Access Aisles

• Door Landings

• Ramps & Ramp Landings

• Clear Floor Spaces

• Wheelchair Spaces

• Turning Spaces

• Stair Treads

Certified Access Specialist

If you are installing detectable warnings to be proactive or because are being required as a result of new construction or a Path of Travel requirement, it is highly recommended that you consult with a Certified Access Specialist. A CASp Inspector will not only advise where to install Truncated Domes but also where NOT to install them. Misplacement of truncated domes are one of the most common barriers that we find at new and existing facilities. Improper installation of truncated domes not only make it harder for people with vision disability to navigate throughout a property but they can create a serious safety hazard. Schedule a free consultation with an experienced disability access experts today.