The Ramp That Ends at a Curb
A community center adds an exterior ramp to its main entrance. The ramp runs 30 feet along a wall, rises 30 inches from the sidewalk to the landing, and is 44 inches wide between handrails. There is a level landing at the top and at the bottom. The bottom landing is 48 inches long in the direction of travel and ends at a curb where a 6-inch drop meets the parking lot. The handrails are mounted at 34 inches above the ramp surface and extend the full length of the ramp but stop flush at the top landing's edge. There is no intermediate landing. The designer argues the ramp is fine because the slope is exactly 1:12 and the width exceeds 36 inches.
1. Check the ramp's slope, landings, and handrail extensions. What complies and what does not?
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Slope: a 30-inch rise over a 30-foot (360-inch) run is 1:12 - the maximum permitted for a ramp, so slope is acceptable, but only just; any construction tolerance that steepens it would fail. Intermediate landing: a ramp with a rise greater than 30 inches must have intermediate landings; at exactly 30 inches it is at the threshold, so no intermediate landing is strictly required - but the 30-foot run with a single continuous slope is at the limit, and any added rise would require one. Bottom landing: the landing must be at least as wide as the ramp and at least 60 inches long in the direction of travel where the ramp changes direction or where doors swing onto it; a 48-inch landing at the foot of the ramp is short of the 60-inch dimension required for a landing at the bottom of a run. Handrail extensions: handrails must extend at least 12 inches beyond the top and bottom of the ramp run, parallel to the floor or landing, so a person can grasp the rail before stepping onto the sloped surface. Flush termination at the landing edge fails. Height: 34 inches is within the 34–38 inch range, so that is acceptable.
2. The curb at the bottom landing creates a 6-inch drop. How should this be resolved, and what does it mean for the route?
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A 6-inch vertical drop at the end of an accessible route is an abrupt level change that blocks wheelchair users and is a trip hazard for ambulatory users with low vision. Because the drop exceeds 1/2 inch, it cannot be treated as a minor change in level; a curb ramp, flush transition, or regraded landing is required so the route connects continuously to the parking lot. The landing must be reconfigured to provide the required length and to meet the parking-lot surface without a vertical discontinuity. This also implicates the accessible route as a whole: the route from accessible parking to the entrance must be continuous, stable, firm, and slip-resistant, and it must not require a person to traverse the vehicular way where a pedestrian route is provided. The designer's "the slope is fine" argument misses that a ramp is only one segment of a route; a compliant ramp that dumps users onto a 6-inch curb does not deliver an accessible entrance.
3. If the ramp were instead 36 inches of rise over the same 30-foot run, what changes?
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At 36 inches of rise over 360 inches of run, the slope becomes 1:10, which exceeds the 1:12 maximum for a ramp in new construction. A 1:10 slope is permitted only in very limited circumstances (for example, certain alterations where space is constrained) and generally requires a variance or a documented technical-infeasibility determination; it is not a design choice. The steeper slope also triggers intermediate landing requirements because the rise exceeds 30 inches, and it changes the handrail and edge-protection considerations - a ramp this steep should have edge protection (curbs or raised barriers) to keep wheels and canes from slipping off the side. The practical answer for the designer: lengthen the run to keep the slope at or below 1:12, add the intermediate landing, extend the handrails, and fix the bottom landing and curb transition. If site constraints make that impossible, the correct path is a documented technical-infeasibility analysis with the maximum extent feasible, not a silent 1:10 design.