Location
Curbs must be provided wherever an accessible route crosses a curb. An accessible route
has a minimum clear width of 36" except at doors.
Slope
The smallest possible slope should be used for all curbs. The maximum slope of a curb in
new construction is 1:12. Transistions
from ramps to walks, gutters, or streets should be flush and free of abrupt changes.
Maximum slopes of adjoining gutters and road surfaces immediately adjacent to the curb
ramp or accessible route must not exceed 1:20.
Width
A curb must have a minimum width of 36", exclusive of flared sides.
Surface
Surfaces must be stable, firm, and slip resistant. Changes in level up to 0.25"
may be vertical without edge treatment. Changes in level between 0.25" and 0.5" must be
beveled with a slope no greater than 1:2. Changes in level above 0.5" must be accomodated
using a ramp.
Sides of Curb Ramps
If a curb ramp is located where pedestrians must walk across the ramp, or where it is not
protected by handrails or guardrails, it must have flared sides. The maximum slope of
the flare shall be 1:10. Curb ramps with returned curbs may be used where pedestrians
would not normally walk across the ramp.
Built-up Curb Ramps
Built up curb ramps shall be located so that they do not project into vehicular lanes
of traffic.
Detectable Warnings
Detectable warnings consist of raised truncated domes with a diameter of nominal 0.9",
a height of nominal 0.2", and a center-to-center spacing of nominal 2.35". They must
contrast visually with adjoining surfaces, either light-on-dark or dark-on-light.
The detectable warning extends the full width and depth of the curb ramp.
Obstructions
Curb ramps must be located or protected to prevent obstructions by parked vehicles.
Locations of Marked Crossing
Curb ramps at marked crossings must be completely contained within the markings, excluding
any flared sides.
Diagonal Curb Ramps
If diagonal (or corner type) curb ramps have returned curbs or other well-defined edges, such
edges are parallel to the direction of pedestrian flow. The bottom of diagonal curb
ramps have 48" minimum clear space. If diagonal curb
ramps are provided at marked crossings, the 48" of clear space must be within the
markings. If diagonal curb ramps have flared sides, they must have at least a 24"
long segment of straight curb located on each side of the curb ramp and within the marked
crossing.
Islands
Any raised islands in crossing must be cut through level with the street or have curb
ramps at both sides and a level area at least 48" long between the curb ramps in
the part of the island instersected by the crossings.