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ADA 2010 Standards

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406 Curb Ramps

406.1 General. Curb ramps on accessible routes shall comply with 406, 405.2 through 405.5, and 405.10.

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.
 

In cross section, a curb ramp with a maximum slope of 1:12 adjoins a surface at the bottom that has a maximum counter slope of 1:20.  

Figure 406.2 Counter Slope of Surfaces Adjacent to Curb Ramps

406.3 Sides of Curb Ramps. Where provided, curb ramp flares shall not be steeper than 1:10.

A curb ramp with triangular flared sides is shown.  The flared sides have a maximum 1:10 slope, measured at the curb face.  

Figure 406.3 Sides of Curb Ramps

406.4 Landings. Landings shall be provided at the tops of curb ramps. The landing clear length shall be 36 inches (915 mm) minimum. The landing clear width shall be at least as wide as the curb ramp, excluding flared sides, leading to the landing.

EXCEPTION: In alterations, where there is no landing at the top of curb ramps, curb ramp flares shall be provided and shall not be steeper than 1:12.

A plan view of a curb ramp shows the required top landing which has a length of 36 inches (915 mm) minimum in the direction of the ramp run and is at least as wide as the ramp.  

Figure 406.4 Landings at the Top of Curb Ramps

406.5 Location. 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 48 inches (1220 mm) minimum outside active traffic lanes of the roadway. Diagonal curb ramps provided at marked crossings shall provide the 48 inches (1220 mm) minimum clear space within the markings. Diagonal curb ramps with flared sides shall have a segment of curb 24 inches (610 mm) long minimum located on each side of the curb ramp and within the marked crossing.
 

A plan view of a diagonal curb ramp is shown at a marked crossing.  A space 48 inches (220 mm) minimum, measured in the direction of the ramp run, is provided at the bottom of the ramp outside active traffic lanes and within the boundary of the marked pedestrian crossing.  Sections of curb 24 inches (610 mm) minimum in length are shown beyond the flared sides and within the marked crossing.  

Figure 406.6 Diagonal or Corner Type Curb Ramps

406.7 Islands. 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 48 inches (1220 mm) long minimum by 36 inches (915 mm) wide minimum at the top of the curb ramp in the part of the island intersected by the crossings. Each 48 inch (1220 mm) minimum by 36 inch (915 mm) minimum area shall be oriented so that the 48 inch (1220 mm) minimum length is in the direction of the running slope of the curb ramp it serves. The 48 inch (1220 mm) minimum by 36 inch (915 mm) minimum areas and the accessible route shall be permitted to overlap.
 

Figure (a) is a plan view of a raised pedestrian island with a walkway cut through at the same level as the street crossing.  Figure (b) is a plan view of a raised pedestrian island between two traffic lanes.  Aligned curb ramps with side flares slope down on each side.  The level space between the top of both ramps is 48 inches (1220 mm) long minimum.  The width of both ramp runs is 36 inches (915 mm).  

Figure 406.7 Islands in Crossings