49 C.F.R. § 38.25 Doors, steps and thresholds.
Title 49 - Transportation
(a) Slip resistance. All aisles, steps, floor areas where people walk and floors in securement locations shall have slip-resistant surfaces. (b) Contrast. All step edges, thresholds and the boarding edge of ramps or lift platforms shall have a band of color(s) running the full width of the step or edge which contrasts from the step tread and riser, or lift or ramp surface, either light-on-dark or dark-on-light. (c) Door height. For vehicles in excess of 22 feet in length, the overhead clearance between the top of the door opening and the raised lift platform, or highest point of a ramp, shall be a minimum of 68 inches. For vehicles of 22 feet in length or less, the overhead clearance between the top of the door opening and the raised lift platform, or highest point of a ramp, shall be a minimum of 56 inches.
Title 49: Transportation
PART 38—AMERICANS WITH DISABILITIES ACT (ADA) ACCESSIBILITY SPECIFICATIONS FOR TRANSPORTATION VEHICLES
Subpart B—Buses, Vans and Systems
§ 38.25 Doors, steps and thresholds.
