Code of Federal Regulations Title 49. Transportation § 49.230.86 Required illumination

(a) General provisions. Each steam locomotive used between sunset and sunrise shall be equipped with an operable headlight that provides illumination sufficient for a steam locomotive engineer in the cab to see, in a clear atmosphere, a dark object as large as a man of average size standing at least 800 feet ahead and in front of such headlight. If a steam locomotive is regularly required to run backward for any portion of its trip other than to pick up a detached portion of its train or to make terminal movements, it shall also be equipped on its rear end with an operable headlight that is capable of providing the illumination described in this paragraph (a).

(b) Dimming device. Such headlights shall be provided with a device whereby the light from same may be diminished in yards and at stations or when meeting trains.

(c) Where multiple locomotives utilized. When two or more locomotives are used in the same train, the leading locomotive only will be required to display a headlight.