49 CFR 37.61: Public transportation programs and activities in existing facilities.

(a) A public entity shall operate a designated public transportation program or activity conducted in an existing facility so that, when viewed in its entirety, the program or activity is readily accessible to and usable by individuals with disabilities.

(b) This section does not require a public entity to make structural changes to existing facilities in order to make the facilities accessible by individuals who use wheelchairs, unless and to the extent required by § 37.43 (with respect to alterations) or §§ 37.47 or 37.51 of this part (with respect to key stations). Entities shall comply with other applicable accessibility requirements for such facilities.

(c) Public entities, with respect to facilities that, as provided in paragraph (b) of this section, are not required to be made accessible to individuals who use wheelchairs, are not required to provide to such individuals services made available to the general public at such facilities when the individuals could not utilize or benefit from the services.