ADA Curb Ramp and Curb Cut Requirements: Slope, Warnings, Landings

ADA curb ramp requirements apply anywhere a pedestrian walkway crosses a curb at an intersection, and they set specific limits on slope, width, landings, and detectable warning surfaces. The 2010 ADA Standards for Accessible Design cap the running slope at 1:12, hold the cross slope to 1:48, and require truncated-dome warning strips at every roadway transition. Government entities and private property owners who control pedestrian walkways carry the duty to build compliant ramps and to keep them working, and that duty reaches existing sidewalks whenever streets are altered or resurfaced.

Who Has to Build and Maintain Curb Ramps

Two parts of the ADA drive the obligation. Title II covers state and local governments, so every city, county, and public transit agency with authority over streets and sidewalks must ensure pedestrian routes include accessible curb ramps.¹ Title III covers private entities that own or operate places of public accommodation, including shopping centers, hotels, and office complexes whose pedestrian walkways connect to public sidewalks.

In 2023, the U.S. Access Board finalized the Public Right-of-Way Accessibility Guidelines (PROWAG), which give more detailed standards for sidewalks, crosswalks, and curb ramps in public streets. PROWAG raises the minimum clear width of curb ramps to 48 inches, up from the 36 inches called for by the general ramp provisions in the 2010 Standards, and adds more specific scoping for when and where ramps must be installed.² Until the Department of Justice and Department of Transportation formally adopt PROWAG through their own rulemaking, the 2010 ADA Standards remain the binding minimum. Courts increasingly look to PROWAG as a benchmark, though, and any municipality planning new construction is better off building to it now than retrofitting later.

When Installation Is Triggered

Two events trigger the obligation: new construction and alterations. Any newly built street or sidewalk must include curb ramps at every intersection where a walkway crosses a curb.¹ The same rule applies when existing streets are altered, and the DOJ and DOT have made clear that street resurfacing counts as an alteration.³ That catches many municipalities off guard. A routine paving project on an existing road pulls in the duty to add or upgrade ramps at every intersection the resurfacing touches.

For entities that have not yet brought their whole sidewalk network into compliance, Title II requires a transition plan that schedules ramp installation. Priority goes to walkways serving government offices, transit stops, places of public accommodation, and major employers, followed by other areas.¹

Slope, Width, and Surface

The running slope, measured in the direction of travel, cannot exceed 1:12. Every inch of vertical rise needs at least 12 inches of ramp length, so a six-inch curb calls for a ramp at least 72 inches long. Steeper slopes make it dangerous or impossible for a manual wheelchair user to climb without tipping backward.⁴

The cross slope, running perpendicular to travel, cannot exceed 1:48. This is far flatter than most people expect. A steeper cross slope pulls a wheelchair sideways, forcing the user to fight the grade with every push and potentially veering into traffic. The ramp surface itself has to be stable, firm, and slip-resistant. Brushed concrete and non-slip coatings are common choices.

Where the ramp meets the gutter, the counter slope of the adjoining road surface cannot be steeper than 1:20, and the two surfaces must be level at the transition point.⁵ A mismatch at this junction is one of the most common compliance failures because it depends on the road grade, which the ramp designer doesn’t always control.

Clear width under the 2010 Standards must be at least 36 inches between handrails or obstructions.⁴ PROWAG raises that to 48 inches for curb ramps in the public right-of-way.⁶ The wider dimension reflects that curb ramps carry bidirectional foot traffic and need to accommodate the larger power wheelchairs and scooters that have become common since the original standards were written.

When Full Compliance Isn’t Possible

Site conditions sometimes make the 1:12 target physically impossible. Under PROWAG, when a ramp would need to exceed 15 feet in length to hit 1:12, it must still extend at least 15 feet but may run steeper.⁶ More broadly, the ADA recognizes “technical infeasibility” when existing structural conditions or physical site constraints prevent full compliance. In those cases the alteration must achieve accessibility to the maximum extent feasible.⁷ That phrase is not a blank check. Every element that can be made accessible must be, and the entity carries the burden of documenting why full compliance was impossible.

Landings and Flared Sides

Every curb ramp needs a level top landing so a user can move between the ramp and the connecting sidewalk without fighting a slope. The landing has to be at least 48 by 48 inches, with a slope no steeper than 1:48 in any direction.⁴ Without that flat area, a wheelchair user arriving at the top has no stable ground to stop, turn, or wait. At the bottom, a clear space of at least 48 by 48 inches must sit entirely outside active traffic lanes so users can pause before entering the roadway.

When the sidewalk layout means pedestrians walk across the sides of the ramp, flared sides prevent a tripping hazard. Flares cannot slope more than 1:10.⁴ If the ramp has returned (vertical) curbs on its sides instead, the top landing is still required. On alteration projects where site constraints make a full top landing impossible, flared sides must be provided with a maximum slope of 1:12.

Types of Curb Ramps

Corners come in different geometries, and the ADA recognizes several ramp configurations.

Perpendicular ramps run straight toward the street at right angles to the curb. This is the preferred design because it aligns the user with the crosswalk and gives a clear directional cue to people with visual impairments.
Parallel ramps run along the curb, dropping the user to street level through a landing between two ramp segments. This works where narrow sidewalks leave no room for a perpendicular ramp to extend back from the curb. A level landing at least 48 inches long, 60 preferred, is needed between the runs.
Diagonal ramps sit at the apex of the corner and point into the intersection. The Access Board discourages this design because it directs users into the middle of the intersection rather than into a crosswalk, and providing the required bottom clear space outside active traffic lanes is difficult.
Built-up ramps rise from the street surface instead of cutting into the curb. They cannot project into parking spaces, access aisles, or vehicle traffic lanes, and they need a top landing at least 36 inches deep.

Wherever possible, each crosswalk at a corner should get its own perpendicular ramp rather than sharing a single diagonal. A diagonal ramp serving two crosswalks gives a wheelchair user no clear directional cue about which crosswalk they’re entering.⁴

Detectable Warning Surfaces

At the bottom of every ramp, a strip of raised truncated domes alerts pedestrians with visual impairments that they are about to step into the roadway. Section 705 of the 2010 Standards sets the dome dimensions tightly:

Base diameter: 0.9 to 1.4 inches
Top diameter: 50 to 65 percent of the base diameter
Height: 0.2 inches
Center-to-center spacing: 1.6 to 2.4 inches, in a square grid

These dimensions make the domes detectable through the sole of a shoe or by a white cane without becoming a tripping hazard themselves.⁸

The warning strip must extend the full width of the ramp and be at least 24 inches deep, measured from the back of curb.⁴ The surface has to contrast visually with the surrounding pavement to help people with low vision. Access Board research found that a luminance contrast of at least 70 percent allowed roughly 95 percent of participants with visual impairments to detect the surface from eight feet away.⁹ Bright yellow domes on gray concrete are the most common pairing. Worn or missing domes are a compliance violation that needs prompt repair.

Placement at the Crosswalk and Gutter

The main ramp run has to sit entirely within the marked crosswalk it serves, though flared sides may extend beyond the markings. That alignment directs users into the safest part of the intersection and keeps them out of the path of turning vehicles.⁴

At the street transition the ramp must be essentially flush with the gutter. The ADA allows a maximum vertical lip of one-quarter inch without treatment. Between one-quarter inch and one-half inch, the edge must be beveled. Anything greater than one-half inch requires a ramp.⁷ Even a half-inch lip can catch the small front caster wheels on a wheelchair and throw the user forward. Contractors who leave a rough transition at the gutter line create one of the most commonly reported accessibility hazards.

At diagonal ramp placements, a segment of curb at least 24 inches long beyond the flares must remain on each side of the ramp within marked crossings. That gives pedestrians a detectable curb edge on either side, which people with visual impairments rely on for orientation.⁴

Ongoing Maintenance

Building a compliant ramp is not a one-time obligation. Under Title II, public entities must keep accessible features in operable working condition. A ramp buried under snow, blocked by a parked car, or overgrown with vegetation is functionally the same as no ramp at all. Municipalities have to make reasonable snow-removal efforts and keep the pedestrian access route clear of obstructions that would drop the width below the required minimum.

Many cities delegate sidewalk maintenance to adjacent property owners through local ordinances, but that delegation does not eliminate the government’s own ADA liability. If a property owner fails to clear snow from a ramp and a person with a disability cannot access the crosswalk, the municipality still bears responsibility under federal law. Temporary interruptions for active construction or repairs are permitted, but only when the entity has a plan to restore access promptly.

How to Report a Non-Compliant Ramp

Anyone who encounters a non-compliant curb ramp can file a complaint with the Department of Justice, Civil Rights Division, online through ADA.gov.¹⁰ After review, the DOJ may investigate, refer the case to mediation, or forward it to another federal agency.

Local governments with 50 or more employees are separately required to designate an ADA Coordinator and maintain a grievance procedure for resolving disability discrimination complaints.¹¹ Filing a local grievance is often faster than a federal complaint and can resolve straightforward issues like a single damaged ramp without years of bureaucratic process. You are not required to exhaust the local grievance procedure before filing a federal complaint or a private lawsuit.

Private lawsuits are also an option. Under Title II, individuals can sue a government entity for injunctive relief, meaning a court order requiring the ramp to be fixed. Under Title III, the DOJ can seek civil penalties in enforcement actions against private businesses. As of mid-2025, the maximum penalty for a first Title III violation is $118,225, and a subsequent violation can reach $236,451.¹² These figures are adjusted annually for inflation.

Tax Incentives for Private Compliance

Federal tax incentives can offset the cost of building or upgrading curb ramps, particularly for small businesses. The Disabled Access Credit under Section 44 of the Internal Revenue Code gives eligible small businesses a credit equal to 50 percent of access-related expenditures that exceed $250 but do not exceed $10,250, for a maximum annual credit of $5,000. To qualify, the business must have had gross receipts of $1 million or less, or no more than 30 full-time employees, in the prior tax year.¹³

Any business, regardless of size, can take a deduction of up to $15,000 per year under Section 190 for expenses related to removing architectural barriers, including curb ramp construction or upgrades.¹⁴ Small businesses that qualify for both can stack the credit and the deduction in the same year, though expenditures claimed under the Section 44 credit cannot also be deducted under Section 190 for the same dollars.

1
ADA.gov. Americans with Disabilities Act Title II Regulations
2
Federal Register. Accessibility Guidelines for Pedestrian Facilities in the Public Right-of-Way
3
ADA.gov. DOJ/DOT Joint Technical Assistance on Title II Curb Ramp Requirements
4
U.S. Access Board. Chapter 4: Ramps and Curb Ramps
5
Corada. 2010 ADA Standards for Accessible Design – 406.2 Counter Slope
6
U.S. Access Board. R3: Technical Requirements
7
ADA.gov. ADA Standards for Accessible Design Title III Regulation 28 CFR Part 36
8
Corada. 2010 ADA Standards for Accessible Design – 705 Detectable Warnings
9
U.S. Access Board. Visual Detection of Detectable Warning Materials by Pedestrians with Visual Impairments
10
ADA.gov. File an ADA Complaint
11
ADA.gov. ADA Best Practices Tool Kit for State and Local Governments – Chapter 2: ADA Coordinator, Notice and Grievance Procedure
12
Federal Register. Civil Monetary Penalties Inflation Adjustments for 2025
13
Office of the Law Revision Counsel. 26 U.S. Code 44 – Expenditures to Provide Access to Disabled Individuals
14
Office of the Law Revision Counsel. 26 U.S. Code 190 – Expenditures to Remove Architectural and Transportation Barriers to the Handicapped and Elderly