An Accessible Route That Wants to Be a Ramp
The only accessible route from a new parking lot to a building's main entrance follows a 150-ft walk from the last accessible stall (elev. 102.0) to the entry landing (elev. 110.5). The lot drains as sheet flow across the walk at its midpoint, where the walk crosses a shallow swale. The driveway apron at the lot entrance has a 4 percent cross slope. The building's finished floor is at 111.0, 6 in. above the exterior landing. The architect proposes to "just add a handrail so it qualifies as a ramp," and the civil engineer proposes lowering the walk to 1 percent "to keep the water off."
1. Evaluate the route against accessibility criteria. Is the architect's handrail proposal sufficient?
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Check the running slope. 8.5 ft of rise over 150 ft = 8.5 / 150 = 5.67 percent. Anything steeper than 1:20 (5.0 percent) on an accessible route is a ramp, not a walking surface. At 5.67 percent, the route is a ramp - and ramp requirements apply to the whole run.
What ramp compliance actually requires:
- Maximum running slope 1:12 (8.33 percent) - satisfied here.
- Landings at the top and bottom and at intervals of no more than 30 in. of rise. 8.5 ft = 102 in. of rise, so at least four runs with three intermediate landings, plus top and bottom landings. Landings must be level (1:48 max in any direction) and at least as wide as the ramp run.
- Handrails on both sides where the rise exceeds 6 in., continuous, at compliant height.
- Edge protection and, where the drop exceeds a threshold, guards.
Handrail alone does not make a ramp. The landings are what create the compliant ramp. Without them, the 5.67 percent route is a noncompliant sloped walking surface: too steep for a walking surface, missing the landings required of a ramp.
Better option than a ramp: lengthen the route to 170 ft (8.5 / 0.05 = 170 ft). That reaches 5.0 percent or less, and the ramp requirements - landings and handrails - no longer apply. Twenty extra feet of walk is usually cheaper than three landings and continuous handrails.
Also flagged: the 4 percent cross slope at the driveway apron exceeds the 2.08 percent maximum cross slope. Warp the apron to 2 percent or less across the route width, or relocate the crossing.
2. Resolve the drainage conflict. The engineer's 1 percent walk: does it solve the problem?
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No - it moves the problem and creates a worse one. At 1 percent, the walk is nearly flat; sheet flow crossing it will spread and pond on the walk rather than pass over, and in freezing climates it becomes an ice sheet on the accessible route. Low-slope pavement that carries water is the classic formula for a winter liability claim.
Design the water to be intercepted, not crossed.
- Add an uphill interception swale or a trench drain above the walk at the crossing, and carry it to a positive outfall. Keep it outside the accessible route's cross slope envelope.
- Cross-slope the walk at 1.5-2.0 percent - within the 2.08 percent accessible maximum and enough to shed water - and drain it to the landscape, not to the walk's own centerline.
- Never let the lot's sheet flow cross an accessible route at grade. If a flush crossing is unavoidable at the accessible stall, use a slotted trench drain on the uphill side, sized for the developed flow, with a level walk surface and a compliant transition.
- Keep the 4 percent apron warped down only outside the accessible route; at the crossing, hold 2 percent maximum in both directions.
Check the vertical geometry. The walk has to sit above the swale invert with enough cover that the swale does not undercut it, and the swale must have 1 percent minimum fall. If the swale is shallow, the walk may need to be a filled section - which changes the grading and the drainage.
Say it in one sentence: the 1 percent walk solves a drainage complaint by creating an accessibility and icing problem; interception upstream solves both.
3. What needs to happen at the entry landing and the building face, given the 6-in. step-down from finished floor?
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Confirm the landing. A level landing at least 60 in. long and the width of the route, with slopes no steeper than 1:48 in any direction. At 110.5 with a finished floor at 111.0, the landing has 6 in. of headroom to the door - fine, but verify:
- The door swing does not conflict with the required maneuvering clearance, and the landing extends on the latch side.
- The 6-in. difference must be a threshold detail, not a step. If any change in level exceeds 1/4 in., it must be beveled at 1:2 up to 1/2 in. and cannot be a vertical face beyond that.
Drain away from the building. Provide at least 2 percent slope away from the building face for the first 10 ft. With 6 in. of fall available, 2 percent for 10 ft needs 2.4 in. - feasible, but it has to be designed explicitly at the entry rather than inherited from the walk's 5.67 percent slope.
Watch the conflict between the two requirements. The walk arriving at 5.67 percent needs a level landing; the level landing then needs to shed water away from the door without ponding against the threshold. That usually means an area drain or a shallow swale flanking the landing, and the walk's cross slope flipping away from the building at the last few feet.
Sequence the elevations before the walk alignment. Set the landing elevation, set the fall away from the building, then solve the route to reach the landing at 5 percent or less. Designing the route first and shoehorning the landing afterward is how the 5.67 percent happened in the first place.