|Succession of short sounds||The whistle is sounded in an attempt to attract attention to the train. It is used when persons or livestock are on the track at other-than-road crossings at grade.|
|=||When train is stopped. The air brakes are applied and pressure is equalized.|
|= =||Train releases brakes and proceeds.|
|o o||Acknowledgment of any signal not otherwise provided for.|
|o o o||When train is stopped: means backing up, or acknowledgment of a hand signal to back up.|
|o o o o||A request for a signal to be given or repeated if not understood.|
|= o o o||Instruction for flagman to protect rear of train.|
|= = = =||The flagman may return from west or south.|
|= = = = =||The flagman may return from east or north.|
|= = o =|
Train is approaching public crossings at grade with engine in front. Signal starts not less than 15 seconds but not more than 20 seconds before reaching the crossing. If movement is 45 mph or greater, signal starts at or about the crossing sign, but not more than 1/4 mile before the crossing if there is no sign. Signal is prolonged or repeated until the engine completely occupies the crossing(s).
In addition, this signal is used when approaching private crossings if pedestrians or motor vehicles are at or near the crossing. (In the states of California, Idaho and Montana, the whistle is sounded at all crossings, public and private.)
|o =||Inspect the brake system for leaks or sticking brakes.|
Train is approaching men or equipment on or near the track, regardless of any whistle prohibitions.
After this initial warning, "o o" sounds intermittently until the head end of train has passed the men or equipment.
On April 27, 2005, the Federal Railroad Administration (FRA), which enforces rail safety regulations, published the Final Rule on the Use of Locomotive Horns at Highway-Rail Grade Crossings. Effective June 24, 2005, the Final Rule requires that locomotive horns be sounded at all public grade crossings 15-20 seconds before entering a crossing, but not more than one-quarter mile in advance.
The pattern for blowing the horn remains two long, one short, and one long sounding to be repeated as necessary until the locomotive clears the crossing. Locomotive engineers will retain the authority to vary this pattern as necessary for crossings in close proximity and will be allowed to sound the horn in emergency situations.
A ban on locomotive horns in Florida was ordered removed by the FRA after it was shown that the accident rate doubled during the ban. The new Final Rule preempts any state or local laws regarding the use of the train horn at public crossings. The Final Rule also provides public authorities the option to maintain and/or establish quiet zones provided certain supplemental or alternative safety measures are in place and the crossing accident rate meets FRA standards. Read more about the FRA Rule on the Use of Locomotive Horns