What is the ADA standard for a sidewalk slope?

According to the 2010 ADA Standards for Accessible Design, the slope of a curb ramp must not be greater than 1:20 when it transitions from the sidewalk to the street. A curb ramp must not increase more than 13 percent in the space of two feet.

According to the U.S. Federal Highway Administration, Chapter 4 of "Designing Sidewalks and Trails for Access" provides sidewalk-design guidelines and practices: Regulations 405.2, 405.10 and 406 address curb ramp and sidewalk specifications.

Sharp slopes are more likely to tip wheelchairs and cause accidents, explains the U.S. Federal Highway Administration. Some wheelchair-users may not be able to maneuver up steep inclines or stop themselves at the bottom after picking up speed. Besides a moderate slope, there must be a flat surface on both the sidewalk and street to facilitate access. Sidewalks must be at least 36-inches wide to accommodate wheelchairs.