The Americans with Disabilities Act (ADA) includes requirements to make public areas accessible to wheelchairs, walkers, and motorized scooters through the use of ramps.1 These include ADA curb ramp requirements based on specific guidelines, depending on the type of ramp in use, its location, and other such factors.

Without ADA curb ramps, curb edges and a lack of accessibility would create hazards for those people with disabilities. These include increased risks of falling out of a wheelchair or scooter or tripping while using a walker when going over an elevated curb. In addition, restricting access in public areas under current federal laws could be construed a form of discrimination against such individuals.2

ADA Wheelchair ramp sign


To help you have a better understanding of the ADA ramp specifications and requirements, we will look at some of the more commonly asked questions by business owners, building managers, and construction companies.

Where are curb ramps and ramps required by the ADA?

A facility must install curb ramps or ramps in public areas along accessible routes with a change in height greater than ½ inch. However, in lieu of installing curb ramps and ramps, a facility may provide accessibility using elevators or platform/chair lifts.1 Furthermore, any accessibility routes which have a slope steeper than 5% have to be treated under the ADA ramp guidelines.

The general ADA curb cut dimensions per the latest requirements under section §405 of the ADA curb ramp requirements for 2020 include:

  • Clear Width: A minimum of 36 inches wide between the leading edge of a ramp’s handrails.
  • Rise: A maximum of 30 inches per run.
  • Running Slope: 1:12 maximum slope, or one foot in elevation change for every 12 feet.
  • Cross Slope: A maximum ratio of 1:48 is permitted.
  • Alterations: Are permitted on running slopes with limited space, such as:
    • 1:10 maximum with 6 inches maximum rise
    • 1:8 maximum with 3 inches maximum rise

What are some additional requirements for curb ramp dimensions?

The available space of a curb ramp must be 36 inches wide, not including handrails, which must be installed on both sides if the ramp has a rise of greater than 6 inches. Indentations, flared sides, or other features incorporated into the ramp’s design must not reduce the width below the minimum requirements. The only exception is where work area equipment that’s essential to the work being performed is used.1

If the height of a ramp at its highest point exceeds 30 inches, it can be installed as several smaller ramps. Landings must be placed between each individual ramp. As long as a curb ramp or ramp doesn’t exceed 30 inches in height, there are no restrictions on length. However, if a ramp run is excessively long, it can be difficult to navigate for those using a wheelchair or walker—a chair or platform lift might be used to mitigate this issue.

handicapped curb ramp

What do the slope requirements for curb ramps and ramps mean?

The slope is directly related to the rise (height) and length of the ramp. The ADA curb ramp slope standards require the slope to be no more than a maximum of a 1:12 ratio or 8.33%. The slope must be uniform from one end of the ramp to the other, with a few exceptions for slight variations in the materials used to create the ramp.

The only other exception is in regards to cross-sloped ramps, where the cross slope maximum is a ratio of 1:48. Furthermore, side flares used with certain curb ramp designs can only have a maximum of a 1:10 ratio.1

For landings, what are the specific requirements under the latest ADA guidelines?

Landings are required at the top and bottom of ramps, in between separate sections of ramp, and must be at least 60 inches long and at least 36 inches wide for single ramps.1 They must not have a change in level of more than 1:48.1 Intermediate landings between runs must have a clear width of at least 60 inches and a minimum length of 60 inches, without being obstructed by handrails, vertical posts, edge protectors, or any other elements.

Handrail extensions must be at least 12 inches long. They must be linear but can turn or wrap with the handrail where it is continuous at an inside turn of a dogleg or switchback type ramp. Extensions must be in the same direction as the run. In addition, curb ramps and ramps, landings, and the bottom of curb transitions must be designed to prevent the accumulation of water.

A ramp can also overlap with a door opening clearance if the door does not open into the landing area. In case of an overlap, it’s highly recommended for the door to swing open in the direction opposite the landing.

Is a top landing required if there are side flares?

Side flares are included to reduce the risk of tripping. However, they are generally not suited to accommodate wheelchairs, unless the curb ramp must be altered to account for space constraints. If the landing is at least 36 inches long, it has enough room for a person using a wheelchair to approach the ramp, exit, or turn without crossing over to the flared side’s compound slope.

Are side flares required?

Side flares are not required on curb ramps but are essential when there’s not enough space for a top landing. A wheelchair user might use a side flare for maneuvering where there’s not enough landing space on top. However, a parallel-type curb ramp can be used to avoid this.

Benefits of Handicap Ramps

Where can built-up curb ramps be used?

Built-up curb ramps are ramps that are added off a curb to allow for access. They can be cut through or built up to the curb. These are perfectly acceptable alternatives in locations such as parking lots. However, they cannot project into vehicle traffic lanes, bus lanes, or bike paths. Nor can they project into parking spaces or restrict access to aisles.

If a built-up curb ramp is not feasible and there is limited space to install parallel curb ramps, a different design can be used. The curb ramp requirements call for ramps that run parallel to the sidewalk and have landings which are a minimum of 48 inches wide at the base of each ramp.3

Can a curb ramp or ramp be curved or circular?

This is not considered a convenient or safe design for wheelchair use. If a ramp does not have a level landing at changes in direction, its compounding slopes will not meet ADA curb ramp requirements unless the radius supports a compliant cross slope. Otherwise, the surfaces will be uneven due to the resulting slope and curvature.

Can a ramp be portable or added later?

All curb ramps and ramps must be installed during initial construction or alterations and be permanent fixtures. A ramp can be temporary or portable only if it serves a temporary structure. The only instances why one can be added after construction is to access a raised workstation or courtroom.

Can raised crossings be used instead of curb ramps?

Raised crossings are allowed under the ADA guidelines in locations where the entire crossing is raised to the elevation of the curb. This eliminates an ADA curb cut and can be used to reduce the speed of traffic. For specific requirements, you need to review your local requirements in regard to the width, height, appropriate markings, and so on.

What are the requirements for curb ramps at islands?

The curb ramps at either side of the island must be separated by at least 48 inches. This enables people using wheelchairs to pass one ramp before they need to descend the other. If the island is too narrow for this, a level cut-through is permitted.

intersection curb ramp

What are the requirements for curb ramps used at intersections?

The ramp section, excluding flared sides, must be within the allowed space for the crosswalk, regardless of the markings used in the intersection. Crossings do not have to be marked, and there are no standards for how they should be marked. However, the ADA curb cut requirements dictate that curved curbs should have ramps placed so they are perpendicular around corners while still within the crosswalk space.1 The opening of perpendicular curb ramps can be aligned with the curb line or oriented with the crosswalk.

Diagonal curb ramps can be used in place of two separate ramps for each crosswalk. They must be at least 48 inches long with 24-inch-long segments on either side beyond the flares. However, the ramp must still transition at the bottom into the street inside the marked crossings for both crosswalks.

Please keep in mind that it is your responsibility to fully review the latest state, local, and federal requirements, as there are regular updates made to the ADA. The most recent ones were made in 2016.

detectable tactile warming systems

Detectable Warning Systems and Ramps and Curb Ramps

Aside from specific requirements for ramps and curb ramps, the ADA also includes a section regarding the use of detectable warning systems on accessible routes. The use of tactile raised domes at the top and bottom of ramps is not always required, except when used in public transportation areas, such as subways, train stations, and bus stations.

Where are detectable warnings required on curb ramps?

The ADA curb ramp design standards for tactile warnings apply to areas that are designated for public transportation. These include bus, rail, and other facilities operated by federal agencies. Intercity and commuter rail stations fall under this designation as well. Rail facilities where detectable warnings are always required include where boarding platforms have an open drop-off (private sector facilities included).

It is worth noting, both the Department of Justice (DOJ) and Department of Transportation (DOT) have their own requirements regarding the use of detectable tactile warning systems. These requirements can be in addition to those contained within the ADA.

For curb ramps, the DOJ and DOT require that raised domes are used in areas that receive funding from the Federal Highway Administration, as well as in federal, state, and local government facilities.

However, since visually impaired individuals tend to use ramps and curb ramps for access, it is highly recommended that, even when there is no federal, state, or local requirement, facilities should still install truncated dome panels at the top and bottom of ramps to indicate a change in surface.

Why are tactile warnings not required for all curb ramps?

The latest guidelines specify facilities at sites meeting the Access Board’s criteria for public rights-of-ways, specifically public streets and sidewalks used by people with vision impairments. Not all hazardous vehicle areas need tactile warning surfaces either. Some facilities may benefit from other measures such as speed bumps, reduced traffic speeds, marked crossings, and other options.

However, when the use of tactile warning curb ramps is required by federal, state, or local laws, they must comply with specific guidelines in regard to spacing, size, and contrast with the regular pavement surface. For instance, California laws have adopted the use of yellow as the only allowed color, with a few exceptions. Overall, the ADA requires that a truncated dome has specific dimensions: