Americans with Disabilities Act History of Detectable Warning Requirement In 1994, the U.S. Access Board temporarily suspended the requirements for detectable warnings except those at boarding platforms in transit stations. The suspension expired on July 26, 2001. Consequently, the requirements for detectable warnings at curb ramps and other areas are now permanently part of ADAAG and DOJ/DOT enforceable standards. Curb Ramp Guidelines This information is from the ADA Accessibility Guidelines for Buildings and Facilities, Federal Register, Volume 56, Number 144, pages 35632-35633 at web address: http://www.access-board.gov/adaag/html/adaag.htm Note: Always consult local building codes for further requirements. ADA Truncated Dome Warnings shall be installed in new and altered curb ramps. ADA Truncated Dome Warnings shall contrast visually with adjoining surfaces, ether light-on-dark or dark-on-light and must extend the full width and depth of the curb ramp. ADA Truncated Dome Warnings shall consist of raised truncated domes with a diameter of nominal .9 inches, a height of nominal .2 inches, and a center to center spacing of nominal 2.35 inches. Curb ramps must be provided wherever an accessible route crosses a curb. An accessible route must have a minimum clear width of 36” except at doors. The smallest possible slope should be used for all ramps and the maximum slope in new construction is 1:12. Transitions from ramps to walks, gutters or streets should be flush without abrupt changes. Maximum slopes of adjoining gutters and road surfaces adjacent to ramp must not exceed 1:20. Ramps must have a minimum width of 36”, exclusive of flared sides. Surfaces must be stable and slip resistant. Changes in surface level up to ¼ inch may be vertical without edge treatment. Changes between ¼ inch and ½ inch must be beveled with a slope of 1:2 or less. Changes in level greater than ½ inches must use a ramp. If a curb ramp is located where pedestrians must walk across the ramp or where the ramp is not shielded by handrails or guardrails, it must have flared sides. The maximum slope of the flare shall be 1:10. Ramps using Returned Curb sides may be used where pedestrians would not normally cross the ramp. Curb ramps shall not project into vehicular lanes. Curb ramps must be located or protected to prevent blockage or obstruction by parked vehicles. Curb ramps (excluding any flared sides) must be completely contained within the markings of marked crossings. If diagonal curb ramps have Returned Curb sides or other well defined edges, these edges must be parallel to the direction of pedestrian flow. The lower end of diagonal curb ramps must have a 48 inch minimum clear space and if marked crossings are used the 48 inch clear space must be completely within the markings. Any raised islands in the crossing must be: a) Contain a street surface level cut the width of the cross walk or; b) Have curb ramps at both sides of the island with a minimum 48 inch long level area between ramps.