49 C.F.R. § 38.99 Floors, steps and thresholds.
Title 49 - Transportation
(a) Floor surfaces on aisles, step treads, places for standees, and areas where wheelchair and mobility aid users are to be accommodated shall be slip-resistant. (b) All thresholds and step edges shall have a band of color(s) running the full width of the step or threshold which contrasts from the step tread and riser or adjacent floor, either light-on-dark or dark-on-light.
Title 49: Transportation
PART 38—AMERICANS WITH DISABILITIES ACT (ADA) ACCESSIBILITY SPECIFICATIONS FOR TRANSPORTATION VEHICLES
Subpart E—Commuter Rail Cars and Systems
§ 38.99 Floors, steps and thresholds.