406.2 Counter Slope.
Counter slopes of adjoining gutters and road surfaces immediately adjacent to the curb ramp shall not be steeper than 1:20. The adjacent surfaces at transitions at curb ramps to walks, gutters, and streets shall be at the same level.
406.3 Sides of Curb Ramps.
Where provided, curb ramp flares shall not be steeper than 1:10.
Landings shall be provided at the tops of curb ramps. The landing clear length shall be 915 mm (36″) minimum. The landing clear width shall be at least as wide as the curb ramp, excluding flared sides, leading to the landing.
Curb ramps and the flared sides of curb ramps shall be located so that they do not project into vehicular traffic lanes, parking spaces, or parking access aisles. Curb ramps at marked crossings shall be wholly contained within the markings, excluding any flared sides.
406.6 Diagonal Curb Ramps.
Diagonal or corner type curb ramps with returned curbs or other well-defined edges shall have the edges parallel to the direction of pedestrian flow. The bottom of diagonal curb ramps shall have a clear space 1220 mm (48″) minimum outside active traffic lanes of the roadway. Diagonal curb ramps provided at marked crossings shall provide the 1220 mm (48″) minimum clear space within the markings. Diagonal curb ramps with flared sides shall have a segment of curb 610 mm (24″) long minimum located on each side of the curb ramp and within the marked crossing.
Raised islands in crossings shall be cut through level with the street or have curb ramps at both sides. Each curb ramp shall have a level area 1220 mm (48″) long minimum by 915 mm (36″) wide minimum at the top of the curb ramp in the part of the island intersected by the crossings. Each 1220 mm (48″) minimum by 915 mm (36″) minimum area shall be oriented so that the 1220 mm (48″) minimum length is in the direction of the running slope of the curb ramp it serves. The 1220 mm (48″) minimum by 915 mm (36″) minimum areas and the accessible route shall be permitted to overlap.