Truncated Domes
Detectable Warning at Parking Stall Path 2026
Cojo
May 7, 2026
6 min read
A detectable warning is required on a parking-lot accessible route only where the route crosses a curb cut or a hazardous-vehicular-area transition. The truncated dome surface does NOT mark accessible parking stalls, ADA access aisles, or the painted accessible route path itself; those compliance elements are governed by ADA Standards 502 (parking spaces) and 403 (walking surfaces) and use painted striping plus signage. The truncated dome surface enters the picture at the curb cut where the access aisle meets the sidewalk leading to the building entrance.
This guide covers where exactly a truncated dome belongs on a parking-lot accessible route, how it interacts with the broader ADA-stall striping system, and how to coordinate a parking-lot retrofit so the dome system and the painted system both pass inspection.
ADA 502 governs accessible parking spaces, ADA 503 governs accessible loading zones, and ADA 403 governs accessible walking surfaces. None of those sections require detectable warnings on the parking surface itself. The dome surface enters at three locations.
The most common parking-lot dome location. An accessible parking space connects to a 60-inch (or 96-inch for van) access aisle, which connects to an accessible route running to the building entrance. Where that route transitions from the parking-lot grade to a sidewalk via a curb cut, ADA 705.3 requires a 24-inch deep dome surface at the back-of-curb.
If the accessible route exits the parking lot to a public sidewalk via a curb cut, that curb cut also requires a dome surface under ADA 705.3 + 406.13.
A flush transition between the accessible route and a vehicular drive aisle (no curb at all) is a hazardous-vehicular-area transition under the U.S. Access Board's commentary. This rare configuration requires a 24-inch dome surface at the transition point, even though there is no curb.
Owners and contractors regularly over-install truncated domes on parking lots. The following locations do NOT require dome surfaces under federal ADA.
The 8-foot-wide accessible parking space has painted ADA striping (blue stall lines, ISA pavement symbol) but no dome surface on the parking surface itself.
The 60-inch or 96-inch access aisle next to the accessible space has diagonal-hatched striping (per the existing /blog/ada-parking-lot-striping-guide treatment) but no dome surface.
The painted accessible route running from the access aisle across the parking surface to the curb cut has paint and stencils but no domes.
The level landing 36 inches by 36 inches at the top of the curb-cut ramp has no dome surface; the dome surface is only on the ramp itself, near the back-of-curb.
Painted ADA-stall striping (covered in the existing /blog/ada-parking-requirements-oregon and /blog/ada-parking-lot-striping-guide articles) and truncated dome compliance are two separate systems that have to work together on the same property.
| Compliance element | Federal authority | Product layer | Cojo article |
|---|---|---|---|
| Accessible space dimensions | ADA 502.2 | Painted blue striping | /blog/ada-parking-requirements-oregon |
| Access aisle dimensions and hatching | ADA 502.3 | Painted blue or white striping | /blog/ada-parking-lot-striping-guide |
| ISA pavement symbol | ADA 502.6 | Paint or thermoplastic stencil | /blog/ada-parking-lot-striping-guide |
| ISA vertical signage | ADA 502.6 | Sign on post | /blog/ada-parking-requirements-oregon |
| Accessible route slope | ADA 403.3 | Painted route + ramp construction | /blog/ada-compliance-audit-process |
| Curb-ramp slope and geometry | ADA 405 + 406 | Concrete construction | (concrete trade) |
| Detectable warning at curb cut | ADA 705.3 | Truncated dome panel | this article |
When a property owner is retrofitting both painted ADA compliance and truncated-dome compliance at the same time, sequence matters.
Demolish and re-pour any non-compliant curb-cut concrete. New ADA 405 ramp slope, ADA 406 curb-ramp geometry, and ADA 308 counter slope all have to pass before the dome surface goes down.
Surface-applied or replaceable dome panels go onto the new (or sound existing) curb-cut concrete. Verify ADA 705.1 dome geometry, ADA 705.2 contrast against the surrounding walking surface, and ADA 705.3 placement at install.
ADA-stall paint and access-aisle hatching go down on the parking surface after the curb-cut concrete and dome panels are complete. Striping the lot first risks damage during dome-panel install.
ISA signs on posts go in last because they are the most likely to be relocated as final striping is verified.
Cojo retrofit jobs surface these patterns most often.
Some retrofits install a dome surface inside the access aisle on the theory that it marks the path to the curb cut. ADA 502.3 specifies hatched striping for the access aisle, not a dome surface. Domes inside the aisle create a tactile hazard for wheelchair users transferring from a vehicle.
The opposite error: ADA-stall paint is correct, the access aisle is hatched correctly, but the curb cut connecting the route to the sidewalk has no dome surface. ADA 406.13 + 705.3 require it. Common cause: the original 1990s-era curb cut never had a dome surface and the retrofit focused only on the parking-surface striping.
A parallel curb ramp running along the sidewalk has its dome surface at the bottom of the ramp segment near the gutter, NOT at the level landing where the pedestrian first arrives. Some retrofits get this backward.
Federal yellow domes paired with blue stall paint is the most common combination and is fully compliant. ADA 705.2 governs dome contrast against the WALKING surface, not the stall paint. The dome can be yellow even when the stall is blue.
This article reflects ADA Standards for Accessible Design as of 2026-05-07 and product spec sheets current at publication. Always verify current dimensions, contrast thresholds, and placement requirements with your local jurisdiction and the U.S. Access Board before issuing a final spec. Federal guidance under 36 CFR Part 1191 controls when state or local rules conflict. Truncated dome installation on its own does not satisfy parking-lot ADA compliance — the painted-stall system and accessible-route system must also pass. See ADA parking requirements Oregon for the painted-stall layer.
In April 2026 we audited a 14,000-square-foot Salem retail center where the painted ADA-stall system passed inspection but the curb-cut connecting the access aisle to the sidewalk failed because no dome surface had ever been installed. The original 1996 build pre-dated the ADA detectable-warning amendments. We installed two polymer-concrete panels at the back-of-curb on the existing ramp, verified ADA 705.1 geometry and 705.2 contrast, and the property passed re-inspection two weeks later. Painted compliance and dome compliance are independent. Owners need both.
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