This rulemaking would update the Architectural and Transportation Compliance Board's (Access Board or Board) existing accessibility guidelines for transportation vehicles that operate on fixed guideway systems (e.g., rapid rail, light rail, commuter rail, and intercity rail) and are covered by the Americans with Disabilities Act. The existing "rail vehicles" guidelines, which are located at 36 CFR part 1192, subparts C to F and H, were initially promulgated in 1991, and are in need of an update to, among other things, keep pace with newer accessibility-related technologies, harmonize with recently-developed national and international consensus standards, and incorporate recommendations from the Board’s Rail Vehicles Access Advisory Committee’s 2015 Report. Revisions or updates to the rail vehicles guidelines would be intended to ensure that ADA-covered rail vehicles are readily accessible to and usable by individuals with disabilities. Compliance with any revised rail vehicles guidelines would not be required until these guidelines are adopted by the U.S. Department of Transportation in a separate rulemaking.