The U.S. Department of Transportation’s (DOT) Americans with Disabilities Act (ADA) regulation at 49 CFR § 37.43(a)(1), provides that when a public entity "alters an existing facility or a part of an existing facility used in providing designated public transportation services in a way that affects or could affect the usability of the facility or part of the facility, the entity shall make the alterations (or ensure that the alterations are made) in such a manner, and to the maximum extent feasible, that the altered portions of the facility are readily accessible to and usable by individuals with disabilities, including individuals who use wheelchairs, upon the completion of such alterations."