CFR › Title 30 › Part 57 › §57.1421430 CFR §57.14214Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗Copy linkA warning that is audible above the surrounding noise level shall be sounded—(a)Immediately prior to moving trains;(b)When trains approach persons, crossing, other trains on adjacent tracks; and(c)Any place where the train operator's vision is obscured.