Train whistle
From Wikipedia, the free encyclopedia
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.
The older 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. Many train operators would have their own style of blowing the whistle, and it was often apparent who was operating the locomotive by the sound. Modern locomotives, often make use of a pushbutton switch, which takes away the fine control over the way the whistle is sounded.
Because trains generally have extremely high mass and relatively low braking friction, they are inherently difficult to stop at normal speeds. Since train whistles were extremely inexpensive to institute compared to other more effective warning devices, the use of loud and distinct train whistles had become the preferred safety fallback for railroad operators.
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[edit] History of train whistles
John Holliday describes the history of train whistles as originating in 1832, by way of a stationmaster at the Leicester and Swannington Railway opening, that the trains should have an audible signaling device. A local musical instrument builder was commissioned to provide a steam-powered whistle, then known as a "steam trumpet".
The article describes also a train-bus collision arising from a train that used truck horns instead of the standard whistle. Although the bus driver heard the horn, he thought it was a truck rather than a train.
American train whistles usually had anywhere from one to six frequencies which were sounded together. As compared with automobile horns, for example, which form a major third, usually with the notes "F" and "A", the train whistle usually forms a non-major chord which is full of dissonance, allowing it to have a distinct, frightening, and serious sound, rather than a happy one.
A train whistle is usually low in pitch, compared to similar mobile signaling devices on automobiles, trucks, bicycles, etc. The low pitch helps people mentally connect with the fact that the source of the sound is large in size and weight.
[edit] Noise complaints from train whistles
It is not uncommon for the sound of a train's whistle to resonate for miles; yet operators of the vehicles still have a difficult time hearing the warning signal due to the vehicle's soundproofing and ambient noise within the cab (such as engine, road, radio, and conversation noises).
The need to blare a train's whistle excessively loud to be heard by the driver of a vehicle approaching a grade crossing has become a major disadvantage to the use of train whistles as a safety device and has caused much controversy to those living within earshot of the train's whistle. 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[citation needed]
Given the tonal design of the train whistle, the sound level, how often trains pass through given community, the number of grade crossings in proximity, and the time of day (night) of occurrence, some feel that train whistles have a serious detrimental effect on the quality of life of community residents in a given area despite the gain in safety that sounding the horn provides to motorists. However, studies have shown that the frequency of grade crossing accidents increase in areas where quiet zones are in effect.
Conversely there are those who do not object to the train whistle, as they believe it provides an important safety feature. Some people even like the sound of the whistle, as it calls to mind a nostalgic era, as with the riverboats and their steam whistles and calliopes.
[edit] History of the Doppler effect
It is train whistles that led to the discovery of the Doppler effect. At the time, trains were one of the few objects that would move quickly while playing a relatively constant (though not single-note) sound.
[edit] Whistle code
Train whistles are used to communicate to other railroad workers on a train or to railroad workers in the yard. Different combinations of long and short whistles each have their own meaning. They are used to pass instructions, as a safety signal, and to warn of impending movements of a train. Despite the advent of modern radio communication, many of these whistle signals are still used today. (See also Train horn (Common Horn Signals).)
Signals are illustrated by an "o" for short sounds, and "-" for longer sounds.
| Sequence | What it means |
|---|---|
| Succession of short sounds | Used when an emergency exists, or if persons or livestock are on the track. |
| - | 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 | Request for a signal to be given or repeated if not understood. |
| - o o o | Instruction for flagman to protect rear of train. |
| - - - - | Flagman return from the west or south. |
| - - - - - | Flagman return from the east or north. |
| - - o - | Train is approaching public grade crossing(s). This is known as Rule 14L in almost all railroad operating rules. |
| - o | Inspect the brake system for leaks or sticking brakes. |
[edit] Other whistle code
Not all railroads use the exact same whistle signals or assign the same meanings. Some railroads will use their own variations of the above. A few of the signals are obsolete because the workers they were used to communicate with (such as flagman) are now obsolete.
In Norway, for example, the following whistle signals are used:
- One short: Stand by or general acknowledgment.
- Two short: Apply/increase manual brakes.
- Three short: Apply manual brakes to stop the train as soon as possible.
- One long: Approaching railroad station or blind curve.
- One long, one short: Decrease manual brakes. When repeated, decrease brakes fully.
- One long, two short: Prepared for change of tracks, crossing and/or other situations that necessitates a gentle approach.
- Multiple short: Danger.
In Finland, the following are some of the signals used:
- One short: Engine is starting forward.
- Two short: Engine about to run backwards.
- One long, one short: Warning, used before arriving to a crossing.
- Three long: Danger.
[edit] Train whistles in folk culture
The well-known song "Five Hundred Miles" makes frequent reference to the sound of the train whistle, as being audible over a great distance.
Excerpt: If you miss the train I'm on, You will know that I am gone. You can hear the whistle blow a hundred miles, A hundred miles, two hundred miles, three hundred miles, four hundred miles, You can hear the whistle blow five hundred miles.
[edit] The melancholy nature of train whistles
In popular and folk culture, train whistles are often associated with loneliness or hard luck, because of the association of trains with transients and hobos who often wait outside the train station and run and jump on to ride the railcars as they just begin moving out of the station. The book "Hear That Lonesome Whistle Blow" is an example.
Furthermore, minor chords (like that of a train whistle) are said to have a melancholy sound. Additionally, steam whistles (the traditional sounding mechanism of train whistles) tend to waver in pitch, and thus make more of a crying or wailing sound, that further adds to the lonesome nature of the whistle. Even the modern compressed-air whistle wavers in pitch much more than does a car horn, and the sound of the whistle is more "throaty" and windy (more like a pan flute or calliope) than other signalling devices like automobile horns.
Lastly, train stations were (and, to some degree still are) associated with the departure of loved ones, and the sadness of saying goodbye. To the extent that the sound of a train whistle is unique, and somewhat symbolic of long distance travel, it has come to contextualize itself as mournful and melancholy.
