Research — Illustrative (draft, unvalidated)
Curb ramp slope, width and landing
Choose perpendicular, parallel or blended transition, then drag the running slope, cross slope, run length, clear width and landing. The limits come from PROWAG R304 and are derived from the ratios (1:12, 1:20, 1:48), never from rounded percents.
To-scale profile and plan · fixed illustrative layout with a derived rise
Ramp type
Running slope
Cross slope
Ramp run length
Clear width
Landing (width x length)
Not part of a blended transition: the function has no landing check for this type.
Curb ramp status
Actual
Required
Margin
How the check read it
Client-side port:the logic and table in this page are a TypeScript port of the harness function, checked against values exported from the Python tests. Not a live API call. Domain maturity, quoted from the harness README: “No domain expert (ADA/accessibility consultant or city ADA coordinator) has reviewed this code yet.” It is a v1 draft; nothing here is authoritative compliance guidance, and PROWAG is only enforceable where DOJ or USDOT have adopted it. The 15 ft length exception is implemented as an unbounded exemption of the running-slope check, which the harness's own validation sheet flags as an open question. The amber “tight” band is a display choice, not a PROWAG tolerance. Dimensions the sliders do not expose (landing slope, clear area, flares, gutter grade break) are fixed illustrative values, and switching “secondary dimensions” off omits them so the check reports not enough input.Real function this maps to:
check_curb_ramp.Not modeled: alterations and technical-infeasibility exceptions (this function does not cover them), shared use paths (the function checks them; this demo does not expose them), crosswalk-context cross slopes (the check always applies 1:48), grade-break flushness, surfaces, crosswalk containment, the blended-transition bypass, the second half of the landing-slope rule and the two-ramp landing rule, and the transitional-space cross-slope clause of the change-of-grade rule. The drawing is a fixed illustrative layout with a derived rise, not a survey.See also:Curb ramp, auto sweep · Detectable warning surface, interactive