Did you know that the rules for big railroads still specify “whistle signals”, even though modern diesel engines only have air horns? People often comment about how and when we blow the whistle, so we thought you might like to know about what all the signals mean.

In this example, a “o” means a short toot, and — means a long toot.

Meaning Sound
Go Forward o o
Back up o o o
Crossing Trestle — —
Yard Limit — o o o
Grade Crossing — — o —

The grade crossing is probably the one signal everyone recognizes. It sort of sounds like “here comes the bride”, and it’s also the International Morse Code sound for Q. Who knew that whistle signals could be so much fun?