49 C.F.R. § 37.107 – Acquisition of passenger rail cars by private entities primarily engaged in the business of transporting people.

(a) A private entity which is primarily engaged in the business of transporting people and whose operations affect commerce, which makes a solicitation after February 25, 1992, to purchase or lease a new rail passenger car to be used in providing specified public transportation, shall ensure that the car is readily accessible to, and usable by, individuals with disabilities, including individuals who use wheelchairs. The accessibility standards in part 38 of this title which apply depend upon the type of service in which the car will be used.
(b) Except as provided in paragraph (c) of this section, a private entity which is primarily engaged in transporting people and whose operations affect commerce, which remanufactures a rail passenger car to be used in providing specified public transportation to extend its useful life for ten years or more, or purchases or leases such a remanufactured rail car, shall ensure that the rail car, to the maximum extent feasible, is made readily accessible to and usable by individuals with disabilities, including individuals who use wheelchairs. For purposes of this paragraph, it shall be considered feasible to remanufacture a rail passenger car to be readily accessible to and usable by individuals with disabilities, including individuals who use wheelchairs, unless an engineering analysis demonstrates that doing so would have a significant adverse effect on the structural integrity of the car.
(c) Compliance with paragraph (b) of this section is not required to the extent that it would significantly alter the historic or antiquated character of a historic or antiquated rail passenger car, or a rail station served exclusively by such cars, or would result in the violation of any rule, regulation, standard or order issued by the Secretary under the Federal Railroad Safety Act of 1970. For purposes of this section, a historic or antiquated rail passenger car means a rail passenger car—
1. (1) Which is not less than 30 years old at the time of its use for transporting individuals;
2. (2) The manufacturer of which is no longer in the business of manufacturing rail passenger cars; and
3. (3) Which—
  1. (i) Has a consequential association with events or persons significant to the past; or
  2. (ii) Embodies, or is being restored to embody, the distinctive characteristics of a type of rail passenger car used in the past, or to represent a time period which has passed.