ADA Guidelines

• If the slope of a ramp is between 1:12 and 1:16, the maximum rise shall be 30 inches (760 mm) and the maximum horizontal run shall be 30 feet (9 m). If the slope of the ramp is between 1:16 and 1:20, the maximum rise shall be 30 inches (760 mm) and the maximum horizontal run shall be 40 feet (12 m).
  
• Clear Width. The minimum clear width of a ramp shall be 36 in (915 mm).
  
• Landings. Ramps shall have level landings at bottom and top of each ramp and each ramp run. Landings shall have the following features:
  (1) The landing shall be at least as wide as the ramp run leading to it.
  (2) The landing length shall be a minimum of 60 in (1525 mm) clear.
  (3) If ramps change direction at landings, the minimum landing size shall be 60 in by 60 in.

• Wheelchair Turning Space. The space required for a wheelchair to make a 180-degree turn is a clear space of 60 in (1525 mm) diameter (see Fig. 3(a)) or a T-shaped space (see Fig. 3(b)).
  

• A 90 degree turn can be made from a 36 inch (915 mm) wide passage into another 36 inch (915 mm) passage if the depth of each leg is a minimum of 48 inches (1220 mm) on the inside dimensions of the turn.