

As train whistles are inexpensive compared to other warning devices, the use of loud and distinct whistles became the preferred solution for railway operators. Hence a means of warning others of the approach of a train from a distance is necessary.

This susceptibility is exacerbated by a train's enormous weight and inertia, which make it difficult to quickly stop when encountering an obstacle. The need for a whistle on a locomotive exists because trains move on fixed rails and thus are uniquely susceptible to collision.

However, the word whistle continues to be used by railroaders in referring to such signaling practices as "whistling off" (sounding the horn when a train gets underway). Modern diesel and electric locomotives primarily use a powerful air horn instead of a whistle as an audible warning device. One of two (front and rear) whistles on steam locomotive 60163 TornadoĪ train whistle or air whistle (originally referred to as a steam trumpet) is an audible signaling device on a steam locomotive, used to warn that the train is approaching, and to communicate with rail workers.
