Section 1192.91 - General(a) New, used and remanufactured commuter rail cars, to be considered accessible by regulations issued by the Department of Transportation in 49 CFR part 37 , shall comply with this subpart.(b) If portions of the car are modified in such a way that it affects or could affect accessibility, each such portion shall comply, to the extent practicable, with the applicable provisions of this subpart. This provision does not require that inaccessible cars be retrofitted with lifts, ramps or other boarding devices.(c)(1) Commuter rail cars shall comply with §§ 1192.93(d) and 1192.109 for level boarding wherever structurally and operationally practicable.(2) Where level boarding is not structurally or operationally practicable, commuter rail cars shall comply with § 1192.95 .(d) Existing vehicles retrofitted to comply with the "one-car-per-train rule" at 49 CFR 37.93 shall comply with §§ 1192.93(e) , 1192.95(a) and 1192.107 and shall have, in new and key stations, at least one door on each side from which passengers board which complies with § 1192.93(d) . Vehicles previously designed and manufactured in accordance with the program accessibility requirements of section 504 of the Rehabilitation Act of 1973, or implementing regulations issued by the Department of Transportation that were in effect before October 7, 1991, and which can be entered and used from stations in which they are to be operated, may be used to satisfy the requirements of 49 CFR 37.93 .