Cal. Pub. Util. Code § 7678

Except as provided in paragraphs (1) to (3), inclusive, of subdivision (a) of Section 7604, every person in charge of a locomotive engine who, before crossing any traveled public way, omits to cause a bell to ring or steam whistle, air siren, or air whistle to sound at the distance of at least 1,320 feet from the crossing, and until the lead locomotive has passed through the crossing, is guilty of a misdemeanor.