4 Trumpet Train Horn - Hm4 4 Trumpet Train Horn

Steam whistles were used until diesel locomotives replaced steam on most railroads. First truck horns were tried but were unsuitable so the air horn was modified for railroad use.

On April 27, 2005 the Federal Railroad Administration (FRA), published the final rule of train horns at highway rail grade crossing. The rule required that locomotive horns be sounded at all public grade crossing at least 15 seconds but not more than 20 seconds before entering a crossing when the train speed is below 45 mph. Above this trains are to sound their horns at the designated location usually marked with a whistle post.

The horn-blowing pattern is two long, one short, and one long, repeated as necessary until the lead locomotive fully occupies the crossing. This pattern can be varied when crossing in close proximity or can be sounded anytime in any emergency situation.