Railroad Torpedo
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A railway detonator, (torpedo in North America) or fog signal is a coin-sized device that is used as a loud warning signal to
train drivers A train driver is a person who operates a train, railcar, or other rail transport vehicle. The driver is in charge of and is responsible for the mechanical operation of the train, train speed, and all of the train handling (also known as bra ...
. It is placed on the top of the
rail Rail or rails may refer to: Rail transport *Rail transport and related matters *Railway track or railway lines, the running surface of a railway Arts and media Film * ''Rails'' (film), a 1929 Italian film by Mario Camerini * ''Rail'' (1967 fil ...
, usually secured with two lead straps, one on each side. When the wheel of the train passes over, it explodes, emitting a loud bang. It was invented in 1841 by English inventor Edward Alfred Cowper.


Uses

Typical uses of detonators include: * A warning, caution or stop signal in dense fog, when
signals A signal is both the process and the result of Signal transmission, transmission of data over some transmission media, media accomplished by embedding some variation. Signals are important in multiple subject fields including signal processin ...
are difficult to see * A warning of a train stopped on the line ahead by an incident or accident—the train crew are usually responsible for placing the detonators * A warning of ongoing engineering works ahead * When a
signaller A signaller, signalman, colloquially referred to as a radioman or signaleer in the armed forces is a specialist soldier, sailor or airman responsible for military communications. Signallers, a.k.a. Combat Signallers or signalmen or women, are ...
or other railway employee requires to stop approaching trains in an emergency On a high-speed line, detonators may need to be placed on both rails. Like all
explosives An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An exp ...
, detonators can become unstable over time and must, therefore, be replaced regularly. They are triggered by pressure, rather than impact. This makes them safe during transport, as they normally cannot detonate in a bag or storage container.


In the United States

Upon hearing the noise of a torpedo exploding, the
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reduces speed to 20 mph or less, not resuming its original speed until at least two miles beyond where it encountered the device. They were traditionally used in pairs to ensure that the sound registered with train crews. Torpedoes are essentially obsolete in the U.S. as soundproof construction of modern locomotive cabs renders them useless. Quoting from the terminology book of the
Brotherhood of Railroad Signalmen The Brotherhood of Railroad Signalmen (BRS) is a labor union in the United States. It represents workers who install, maintain, and repair railroad traffic control systems. These include switching, signaling, and highway-rail crossing warning sys ...
:
A torpedo is a device which is strapped to the top of a rail. When a train drives over the torpedo, it emits a very loud "bang" which can be heard over the noise of the engine, and signals the engineer to stop immediately. Torpedoes are generally placed by the flagman when protecting a train ahead. Torpedoes are about 2" × 2", red in color, about 3/4" high, and have two lead straps attached, which hold it to the rail. The torpedo has discs inside and are filled with detonating powder. The torpedo was invented about 1874.


In the United Kingdom

If a train unexpectedly explodes a detonator, the driver is required to stop immediately and investigate. Detonators are usually deployed in groups of three, spaced 20 metres apart. When being used on electrified lines detonators must be placed on the rail which is furthest from the conductor rail (aka 'third rail'). If a train is about to explode a detonator, personnel are required to stand at least 30 metres away from it and turn away. There are three types of detonator protection in the UK: * Emergency Protection: If a train is involved in an accident or fails ''and it is not possible to contact the signaller,'' then emergency protection must be used. Track circuit operating clips (TCOC) must be placed on all affected lines, and three detonators must be placed at a distance of 2 kilometres in the direction from which a train is most likely to approach. * Assistance Protection: If a train fails and communication can be made with the signaller, then assistance protection must be used. The driver of the failed train must place three detonators at a distance of 300 metres from the failed train in the direction from which the assisting train will approach (unless there is a stop signal within 300 metres of the rear of the failed train). The driver will remain at this ''assistance protection point'' with a red flag (or lamp in darkness) and await the assisting train. * Possession Protection: Possessions (worksites) on the railway are operated separately from the running lines and train movements inside them are not controlled by the signaller. Instead a PICOP (person in charge of possession) controls movement into and out of the possession in co-ordination with the signaller, and an Engineering Manager is responsible for movements of rail vehicles within the possession. Three detonators and a Stop Board are positioned at the entry and exit to the possession to prevent any unauthorised trains from entering accidentally, and also to clearly define the extent of the possession.


In Germany

Detonators were used where hazards had to be secured and there was no time for other signaling or if there was a danger that another signal might not be recognizable in time, for example due to fog or snow. To give the emergency signal, three detonators were placed in short succession, with the explosion of a single detonator being a stop signal. Since 1986 detonators have no longer been used on German railways. Only the
ICE 3 ICE 3 (standing for ''Intercity Express, Intercity-Express'') is a family of high-speed electric multiple unit trains operated by Deutsche Bahn. It currently includes classes 403, 407 and 408 which are additionally specified as ICE 3, New ICE 3 ...
trains and other locomotives that travel to France still have detonators on board, because of French regulations.


In Taiwan

The use of detonators has been superseded by radio communications since the early 1950s. In November 2010, the
Taiwan Railway Administration Taiwan Railways Administration (TRA) was a governmental agency in Taiwan which operated Taiwan Railway from 1948 to 2023. It managed, maintained, and operated conventional passenger and freight railway services on of track. Passenger traffic ...
deployed 800 detonators for destruction on maintenance tracks. It received media attention, emitting sounds similar to the culturally significant
firecracker A firecracker (cracker, noise maker, banger) is a small explosive device primarily designed to produce a large amount of noise, especially in the form of a loud bang, usually for celebration or entertainment; any visual effect is incidental to ...
s.


In Australia

Today known as audible track warning signals, or audible track warning devices, detonators are used to attract the attention of train crews when track repairs or an obstruction are ahead, or when a hand signaller is acting for a signal.


In Tanzania

Detonators are used to attract the attention of train crews in case of: * Visibility of fixed signal restricted by fog, mist or other circumstance * obstruction of line, whether by train or otherwise * protection of push trolleys * protection of shunting movement outside the station limits during total failure of communication


Detonator placer

Many mechanical
signal box A signal is both the process and the result of transmission of data over some media accomplished by embedding some variation. Signals are important in multiple subject fields including signal processing, information theory and biology. In ...
es in the UK were equipped with detonator placers that placed detonators on a running line when a
lever A lever is a simple machine consisting of a beam (structure), beam or rigid rod pivoted at a fixed hinge, or '':wikt:fulcrum, fulcrum''. A lever is a rigid body capable of rotating on a point on itself. On the basis of the locations of fulcrum, l ...
was operated. The levers were painted a striking white and black
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pattern, pointing upwards for the "up" line, downwards for the "down" line. In some cases, the placers were fed from a cartridge holding a number of detonators.


Composition

According to ''Military and Civilian Pyrotechnics'' by Ellern, page 376, FORMULA 155 – Railroad Torpedo, is by mass: *
Potassium chlorate Potassium chlorate is the inorganic compound with the molecular formula KClO3. In its pure form, it is a white solid. After sodium chlorate, it is the second most common chlorate in industrial use. It is a strong oxidizing agent and its most impor ...
– 40% *
Sulfur Sulfur ( American spelling and the preferred IUPAC name) or sulphur ( Commonwealth spelling) is a chemical element; it has symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms ...
– 16% * Sand (—60
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) – 37% * Binder – 5% * Neutralizer – 2%


Garratt locomotives

The length of
Garratt locomotive A Garratt locomotive is a type of articulated steam locomotive invented by the engineer Herbert William Garratt that is articulated into three parts. Its boiler, firebox, and cab are mounted on a centre frame or "bridge". The two other p ...
s made the sound of a detonator hard to hear, so
New South Wales 60 class locomotive The New South Wales AD60 class were Beyer-Garratt patent articulated four-cylinder, simple, non-condensing, coal-fired superheated, 4-8-4+4-8-4 heavy goods steam locomotives built by Beyer, Peacock & Company for the New South Wales Government R ...
had "sound pipes" to bring the noise of the explosion to the crew.


References


External links

* * {{cite web , last1=Clayton Penistone Group , title=Safety Data Sheet - Railway Fog Signal , url=http://www.clayton-penistone.co.uk/SharedFiles/Download.aspx?pageid=25&mid=60&fileid=1430 , accessdate=16 July 2019 , archiveurl=https://web.archive.org/web/20161121231428/http://www.clayton-penistone.co.uk/SharedFiles/Download.aspx?pageid=25&mid=60&fileid=1430 , archivedate=21 November 2016 , language=English , format=English , date=25 April 2016 Explosives Railway safety