Train whistle

Modern diesel and electric locomotives primarily use a powerful air horn instead of a whistle as an audible warning device.

The need for a whistle on a locomotive exists because trains move on fixed rails and thus are uniquely susceptible to collision.

This susceptibility is exacerbated by a train's enormous weight and inertia, which make it difficult to quickly stop when encountering an obstacle.

Steam whistles were almost always actuated with a pull cord (or sometimes a lever) that permitted proportional (tracker) action, so that some form of "expression" could be put into the sound.

This whistle produced a bright G-major 6th chord (GBDEG) and, again, was heavily imitated, copies being made by many different railroads.

But the most beloved of all three-chime train whistles to the public and railroaders alike were the deep-chorded "steamboat minor" long-bells.

It has been documented that a train's whistle, when operating on compressed air, driving an exponential horn, has been measured at a higher decibel levels within the homes of nearby residents than within the cab of a vehicle sitting at the grade crossing.

[2][3] However, one Federal Railroad Administration study has shown that the frequency of grade crossing accidents increases in areas where quiet zones are in effect.

[4] For instance, it was during the same period that locomotives began sporting the now crucially important tri-lamp headlight arrangement ("ditch lights") and reflector strips similar to those commonly found on highway tractor-trailers.

[9][10][11][12][13] Quiet zones are created in municipalities where citizens of the community complain of the noise pollution from the increasing number of trains which decreases their quality of life.