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PROWAG Curb Ramp & Sidewalk Requirements

PROWAG, the U.S. Access Board’s Public Right-of-Way Accessibility Guidelines, covers sidewalks, crossings and curb ramps. Most of what designers and inspectors check comes from a few numbers: 48 inches of clear width, 2.1 percent cross slope, 1:12 ramp slope, and truncated-dome warnings at the street edge. The full text of the guidelines is in the BuildSpec PROWAG library.

Requirement	Model Code Standard	Section
Clear width of the walking route	48 in. minimum, not counting the curb; 60 in. across medians and refuge islands	PROWAG R302.2, R302.2.1
Passing spaces	Where the clear width is under 60 in., provide 60 by 60 in. passing spaces at least every 200 ft	PROWAG R302.3
Running slope of the route	1:20 (5%) maximum, or the street grade where the adjacent street is steeper	PROWAG R302.4.1
Cross slope	1:48 (2.1%) maximum on sidewalks; crosswalks controlled by a signal or at an uncontrolled approach may go to 1:20 (5%), and stop- or yield-controlled crossings stay at 1:48	PROWAG R302.5.1, R302.5.2
Surface changes	Vertical changes up to 1/4 in.; beveled between 1/4 and 1/2 in.; grating openings may not pass a sphere over 1/2 in.	PROWAG R302.6.2, R302.6.3
Curb ramp running slope	1:12 (8.3%) maximum, but a ramp never needs to be longer than 15 ft to get there	PROWAG R304.2.1
Curb ramp width and cross slope	48 in. minimum clear width (excluding flares) and 1:48 (2.1%) maximum cross slope	PROWAG R304.5.1.1, R304.2.2
Landings and clear area	48 by 48 in. landing at the top when the route turns, and a 48 by 48 in. clear area at the bottom within the crosswalk, sloped 1:20 (5%) maximum	PROWAG R304.2.5, R304.2.4
Flared sides	Where people cross the side of a ramp, the flare may be no steeper than 1:10 (10%)	PROWAG R304.2.6
Detectable warning surface	Truncated domes in a grid, base diameter 0.9 to 1.4 in., height 0.2 in., 24 in. deep in the direction of travel and the full width of the ramp run, contrasting with the surface next to it	PROWAG R305.1.1, R305.1.3, R305.1.4
Detectable warning location	At the back of curb or within 6 in. of the pavement edge on perpendicular ramps; on the landing for parallel ramps; on the transition for blended transitions	PROWAG R305.2

Worth knowing

PROWAG is a set of guidelines. It becomes an enforceable standard only where a federal or state agency adopts it for covered facilities, and many agencies still use their own standard drawings or the ADA Standards. Confirm what your project is actually held to before designing to these numbers.
Many agencies publish standard curb ramp drawings that already fold these dimensions in. The DOT standard drawings for your state usually answer the detail question and the agency, not this page, is the authority on a state-funded job.
The 2.1 percent cross slope is a maximum, so a design at exactly 2.0 percent leaves almost no construction tolerance. Many designers aim for 1.5 percent.
The detectable warning rules apply to curb ramps, blended transitions, cut-through islands and some rail crossings, each with its own placement rule in R305.2.
The complete PROWAG text is searchable in the Code Library; this page summarizes the sections most often cited and does not replace them.

Common questions

What does the code say about clear width of the walking route for Sidewalks & Curb Ramps (PROWAG)?

48 in. minimum, not counting the curb; 60 in. across medians and refuge islands. (PROWAG R302.2, R302.2.1)

What does the code say about passing spaces for Sidewalks & Curb Ramps (PROWAG)?

Where the clear width is under 60 in., provide 60 by 60 in. passing spaces at least every 200 ft. (PROWAG R302.3)

What does the code say about running slope of the route for Sidewalks & Curb Ramps (PROWAG)?

1:20 (5%) maximum, or the street grade where the adjacent street is steeper. (PROWAG R302.4.1)

This guide is BuildSpec’s own plain-English summary of the U.S. Access Board’s Public Right-of-Way Accessibility Guidelines. The full text is free in the PROWAG library. It is not an adoption record: confirm which standard your agency applies to the project.

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