Section 221.14 - Marking devices(a) As prescribed in § 221.13 , passenger, commuter and freight trains shall be equipped with at least one marking device, which has been approved by the Federal Railroad Adminstrator in accordance with the procedures included in appendix A of this part, and which has the following characteristics:(1) An intensity of not less than 100 candela nor more than 1000 candela (or an effective intensity of not less than 100 candela nor more than 1000 candela for flashing lights) as measured at the center of the beam width;(2) A horizontal beam with a minimum arc width of fifteen (15) degrees each side of the vertical center line, and a vertical beam with a minimum arc width of five (5) degrees each side of the horizontal center line as defined in terms of the 50 candela intensity points;(3) A color defined by the red-orange-amber color range; and(4) If a flashing light is used, a flash rate of not less than once every 1.3 seconds nor more than once every .7 seconds.(b) Marking devices used on passenger and commuter trains in compliance with paragraph (a) of this section shall be lighted under the conditions prescribed in § 221.13 (b) and (c) .(c) When a locomotive is operated singly, or at the rear of a train, highly visible marking devices may be provided by the use of:(1) At least one marking device that complies with paragraph (a) of this section; or(2) At least one illuminated red or amber classification light on the rear of the locomotive, provided it complies with paragraph (a) of this section; or(3) The rear headlight of the locomotive illuminated on low beam.51 FR 25185, July 10, 1986