A train whistle
or air whistle
, (originally referred to as a steam trumpet
), is an audible signaling device on a steam locomotive
A steam locomotive is a railway locomotive that produces its power through a steam engine. These locomotives are fueled by burning some combustible material, usually coal, wood or oil, to produce steam in a boiler, which drives the steam engine...
used to warn that the train is approaching, and to communicate with rail workers.
The older steam whistle
A steam whistle is a device used to produce sound with the aid of live steam, which acts as a vibrating system .- Operation :...
s were almost always actuated with a pull cord (or sometimes a lever) that permitted proportional (tracker
Tracker action is a term used in reference to pipe organs and steam calliopes to indicate a mechanical linkage between keys or pedals pressed by the organist and the valve that allows air to flow into pipe of the corresponding note...
) action, so that some form of "expression" could be put into the sound. Many locomotive 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 railway operators.
John Holliday describes the history of train whistles as originating in 1832, by way of a stationmaster at the Leicester and Swannington Railway
The Leicester and Swannington Railway was one of England's first railways, being opened on 17 July 1832 to bring coal from collieries in west Leicestershire to Leicester.-Overview:...
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 also describes a train-cart collision arising from a train that used a horn blown by the driver as whistles had not been invented. Although the cart driver heard the horn some sources say he did not hear the horn. Although no-one was injured, the accident was deemed serious enough to warrant George Stephenson’s personal intervention. One account states that Weatherburn the engine driver had `mouthblown his horn' at the crossing in an attempt to prevent the accident, but that no attention had been paid to this audible warning, perhaps because it had not been heard.
Stephenson subsequently called a meeting of directors and accepted the suggestion of the company manager, Ashlin Bagster, that a horn or whistle which could be activated by steam should be constructed and fixed to the locomotives. Stephenson later visited a musical instrument maker in Duke Street in Leicester, who on Stephenson's instructions constructed a ‘Steam Trumpet’ which was tried out in the presence of the board of Directors ten days later.
Stephenson mounted the whistle on the top of the boiler's steam dome which delivers dry steam to the cylinders. The device was apparently about 18 inches (457.2 mm) high and had an ever-widening trumpet shape with a 6 inches (152.4 mm) diameter at its top or mouth. The company went on to mount the device on its other locomotives.
There is another account that sets the invention of the steam whistle against the actual opening of the line in 1832, rather than associating it with a specific incident.  Source http://leicesterchronicler.com/whistle.htm
North American steam locomotive whistles have different sounds from one another. They came in many forms, from tiny little single-note shriekers (called banshees on the Pennsylvania Railroad
The Pennsylvania Railroad was an American Class I railroad, founded in 1846. Commonly referred to as the "Pennsy", the PRR was headquartered in Philadelphia, Pennsylvania....
) to larger plain whistles with deeper tones (a deep, plain train whistle is the "hooter" of the Norfolk & Western, used on their A- and Y-class Mallet locomotive
The Mallet Locomotive is a type of articulated locomotive, invented by a Swiss engineer named Anatole Mallet ....
s). Even more well known were the multi-chime train whistles. Nathan of New York copied and improved Casey Jones
John Luther Jones was an American railroad engineer from Jackson, Tennessee, who worked for the Illinois Central Railroad...
's boiler-tube chime whistle by casting the six chambers into a single bell, with open "steps" on top to save on casting. This whistle is still considered the "king of train whistles". This whistle is the most copied train whistle in the United States, and many railroads' shops cast their own version of it. Another very popular American train whistle was, again, a Nathan product. This was a five-note whistle, with much shorter bell, and therefore, much higher in pitch. This whistle sang a bright G-major 6th chord (GBDEG) and, again, was heavily imitated, copies being made by many different railroads. Even the Chinese copied American five-chime whistles for their own locomotives. The final most popular American chime train whistle was the three-note version. These were either commercially made (Crosby, Lunkenheimer, Star Brass, Hancock Inspirator Co. among others) or shop-made by the railroads themselves. Some famous and very melodious shop-made train whistles were Pennsy's passenger chimes and the Baltimore and Ohio's step-top three chimes. But the most beloved of all three-chime train whistles to the public and railroaders alike were the deep-chorded "steamboat minor" long-bells. A well known commercially made chime was Hancock Inspirator Company's three-note step top. These found use on almost every American railroad. Some railroads copied these also, examples being found on the old St. Louis–San Francisco Railway and Illinois Central.
The Southern Railway made three-chime train whistles. These were all distinctive, having top-mounted levers. They had short-bell three-chimes as well as their (highly copied) long-bell three-chimes on passenger engines, especially their PS4 engines, one of which resides today in the Smithsonian Institution
The Smithsonian Institution is an educational and research institute and associated museum complex, administered and funded by the government of the United States and by funds from its endowment, contributions, and profits from its retail operations, concessions, licensing activities, and magazines...
Two-note and four-note train whistles never caught on with North American railroads, with one exception: Canadian National Railway
The Canadian National Railway Company is a Canadian Class I railway headquartered in Montreal, Quebec. CN's slogan is "North America's Railroad"....
created a large four-chime step-top whistle for limited use on some of their locomotives. These were not common and only a few survive today in the hands of collectors. Otherwise North American train whistles were in single-note, three-note, five-note and six-note combinations.
A few American railroads with whistles valued by collectors:
- Southern Pacific for their six-chimes.
- Union Pacific for their Hancock "steamboat" chimes.
- Reading Railroad for their high-pitched passenger six-chimes.
- Chicago, Burlington and Quincy Railroad
The Chicago, Burlington and Quincy Railroad was a railroad that operated in the Midwestern United States. Commonly referred to as the Burlington or as the Q, the Burlington Route served a large area, including extensive trackage in the states of Colorado, Illinois, Iowa, Kentucky, Missouri,...
for their five-chimes and three-chimes.
- Baltimore and Ohio for their three-chime step-tops and six-chimes.
- Grand Trunk
Grand Trunk can refer to:*The Grand Trunk Company in Terry Pratchett's Discworld novels*The Grand Trunk Pacific Railway in Canada*The Grand Trunk Railway in North America*The Grand Trunk Road in South Asia...
for their shop-made six-chimes (Nathan copies).
- New York Central for their shop-made six-chimes.
- Norfolk and Western for their low pitched, distinctive sounding 'hooter' whistles.
In the United Kingdom, it is normal for diesel and electric multiple-units and locomotives to have two horns, of different pitches (rather like two-tone emergency road vehicles—police cars, etc.). This has given rise to drivers "playing" unofficial combinations of low and high notes. When passing through the local station in the Yorkshire town of Ilkley
Ilkley is a spa town and civil parish in West Yorkshire, in the north of England. Ilkley civil parish includes the adjacent village of Ben Rhydding and is a ward within the metropolitan borough of Bradford. Approximately north of Bradford, the town lies mainly on the south bank of the River Wharfe...
, drivers soon began to play the first line of the folk song, "On Ilkla Moor Baht 'at" on their loco/DMU horns, using a series of short blasts: LOW, h-i-g-h high high, LOW, high, until the practice was stopped by authorities.
The first four notes of Beethoven's Fifth Symphony—played during World War II as the Morse code
Morse code is a method of transmitting textual information as a series of on-off tones, lights, or clicks that can be directly understood by a skilled listener or observer without special equipment...
(for Victory)—can be sounded on a train horn as three short notes and a longer one, often the last note on the lower-tone horn.
Early railways, before continuous brakes, had the communication chain or cord from the carriages connected to a "brake whistle" on the engine. This was usually of a lower note than the normal whistle used by the driver.
Engines of Britain's Great Western Railway
The Great Western Railway was a British railway company that linked London with the south-west and west of England and most of Wales. It was founded in 1833, received its enabling Act of Parliament in 1835 and ran its first trains in 1838...
carried two whistles. Some Great Western "autocoaches
The GWR Autocoach is a type of coach that was used by the Great Western Railway for push-pull trains powered by a steam locomotive. The distinguishing design feature of an autocoach is the driving cab at one end, allowing the driver to control the train without needing to be located in the cab of...
"—from where the driver operated the steam engine's regulator and brakes, when the engine was propelling one or more autocoaches—still had a whistle connection with the engine's brake whistle, although a gong (much like a tram gong) was fitted at the front of each autocoach and was operated by the driver using a foot treadle.
Back in the days of steam, when assisting engine
An assisting engine is an additional locomotive attached to a train to assist the train engine – the locomotive assigned to haul the train...
s pushed long goods trains up steep gradients (or "banks"), the train would come to a halt at the bottom of the bank. The assisting engine—or "banker
A bank engine or helper engine or pusher engine is a railway locomotive that temporarily assists a train that requires additional power or traction to climb a grade...
"—would either be attached to the rear of the train, or just come up against the guard's brake van's buffers. Then the banker's driver would whistle—using a series of long blasts and shorts. This told both the signalman and the driver of the train engine that he was ready. The train engine's driver would reply in similar fashion and, with signals at clear, they would set off in unison. If the banker was coupled to the train then, when it reached the top of the bank, the train would stop or come to a crawl for the banker to be uncoupled; if not, then the banker's driver would just ease off the regulator, allowing the train to continue on its way, with, of course, a whistled "goodbye".
Noise complaints from train whistles
It is not uncommon for the sound of a train's whistle to propagate for miles; yet vehicle operators still have a difficult time hearing the warning signal due to the vehicle's soundproofing
Soundproofing is any means of reducing the sound pressure with respect to a specified sound source and receptor. There are several basic approaches to reducing sound: increasing the distance between source and receiver, using noise barriers to reflect or absorb the energy of the sound waves, using...
and ambient noise within the cab (such as engine, road, radio, and conversation noises).
The need to blare a train's whistle loudly 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 among those living within earshot of the train's whistle. It has been documented that a train's whistle, when operating on compressed air
Compressed air is air which is kept under a certain pressure, usually greater than that of the atmosphere. In Europe, 10 percent of all electricity used by industry is used to produce compressed air, amounting to 80 terawatt hours consumption per year....
, driving an exponential horn, has been measured at a higher decibel
The decibel is a logarithmic unit that indicates the ratio of a physical quantity relative to a specified or implied reference level. A ratio in decibels is ten times the logarithm to base 10 of the ratio of two power quantities...
levels within the homes of nearby residents than within the cab of a vehicle sitting at the grade crossing.
Given the tonal design of the train whistle, the sound level, how often trains pass through a given community, the number of grade crossings in proximity, and the time of day (night) of occurrence, community residents residing near crossing sometimes feel that train whistles have a serious detrimental effect on the quality of life
The term quality of life is used to evaluate the general well-being of individuals and societies. The term is used in a wide range of contexts, including the fields of international development, healthcare, and politics. Quality of life should not be confused with the concept of standard of...
despite the gain in safety that sounding the horn provides to motorists. However, one Federal Railroad Administration
The Federal Railroad Administration is an agency in the United States Department of Transportation. The agency was created by the Department of Transportation Act of 1966...
study has shown that the frequency of grade crossing accidents increases in areas where quiet zones
are in effect. The study fails to account for other factors that were also introduced at the same time which may have also accounted for the reduction in accidents during the same period the study measured. Additionally, the measurements were based on accidents at grade-crossings, which are very low numbers overall to begin with. A grade-crossing that had two accidents during the comparison years, that were contrasted with only one accident during the control period would statistically yield a high percentage-wise improvement in safety, when in reality, it was the difference in only one accident for that grade-crossing.
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
A calliope is a musical instrument that produces sound by sending a gas, originally steam or more recently compressed air, through large whistles, originally locomotive whistles....
. However, no real studies have been performed by unbiased official entities to measure the real effects such noise has on a community.
History of the Doppler effect
It is train whistles that led to the discovery of the Doppler effect
The Doppler effect , named after Austrian physicist Christian Doppler who proposed it in 1842 in Prague, is the change in frequency of a wave for an observer moving relative to the source of the wave. It is commonly heard when a vehicle sounding a siren or horn approaches, passes, and recedes from...
. At the time, trains were one of the few objects that would move quickly while playing a relatively constant (though not single-note) sound.
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 illustrated below are for North American railroads, an "o
" for short sounds, and "-
" for longer sounds.
|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.
||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
||Warning that a second section of a timetabled train is following.
|– 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.
||Inspect the brake system for leaks or sticking brakes.
Other whistle codes
Not all railroads use exactly the 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.
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...
, 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.
Finland , officially the Republic of Finland, is a Nordic country situated in the Fennoscandian region of Northern Europe. It is bordered by Sweden in the west, Norway in the north and Russia in the east, while Estonia lies to its south across the Gulf of Finland.Around 5.4 million people reside...
, 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.
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.
- 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.
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 hobo
A hobo is a term which is often applied to a migratory worker or homeless vagabond, often penniless. The term originated in the Western—probably Northwestern—United States during the last decade of the 19th century. Unlike 'tramps', who work only when they are forced to, and 'bums', who do not...
s 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 of this diesel horn.Minor(.wav)
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 shrill steam whistle.Waver(.wav)
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 or this diesel train horn.Throaty(.wav)
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 steam train whistle is unique, and somewhat symbolic of long distance travel, it has come to contextualize itself as mournful and melancholy as this three-chime steam train whistle.Sad(.wav)