S-3.3, r. 2 - Regulation respecting rail safety

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22. The use of the locomotive whistle or horn by an engineer is authorized only for the purposes of rail communication.
Locomotive whistles or horn signals must be given by an engineer in accordance with the standards described in Schedule II.
Under no circumstances may an engineer use a locomotive that does not have an operational whistle or horn.
O.C. 1401-2000, s. 22.