What are the laws for trains on blowing horns

I got a question this morning I got stopped by a train on the CP and he did not blow his horn then again it was at 5:30AM but in this area where the tracks are it is all of bussiness and no homes. But my question what are the times trains can and can not blow there horns is it like fire trucks and police cars at certin times of the night they can’t use their sirens or is it. Diffrent [:)][:)]

Gobs and gobs of current regulations on locomotive horns.

http://www.fra.dot.gov/us/content/1318

More than you’d ever want to know.

Really.