49 CFR § 299.443 - Safety appliances.
(a) Couplers.
(1) The leading and trailing ends of each trainset shall be equipped with an automatic rescue coupler that couples on impact.
(i) Uncoupling of the rescue coupler shall be done only at a trainset maintenance facility or other location where personnel can safely get under or between units.
(ii) The leading and the trailing ends of a trainset are not required to be equipped with sill steps or end or side handholds.
(2) The leading and trailing end couplers and uncoupling devices may be stored within a removable shrouded housing.
(3) Leading and trailing automatic couplers of trainsets shall be compatible with the railroad's rescue vehicles. A coupler adaptor can be used to meet this requirement.
(4) The railroad shall develop and implement rescue procedures that assure employee safety during rescue operations and shall be contained in the railroad's operating rules.
(5) Each unit within a trainset shall be semi-permanently coupled and shall only be uncoupled at a trainset maintenance facility or other locations identified by the railroad where the protections afforded in subpart B of part 218 of this chapter can be applied.
(6) The ends of units in a trainset that are semi-permanently coupled are not required to be equipped with automatic couplers, sill steps, end handholds or side handholds.
(b) Crew access.
(1) Each trainset shall provide a minimum of two (2) locations per side, where crew members can board or disembark the trainset safely from ground level.
(2) Each location used for crew access shall be equipped with retractable stairs with handrails designed for safe access to the trainset from ground level.