Detonator (railway)
Encyclopedia
Railroad engineer
A railroad engineer, locomotive engineer, train operator, train driver or engine driver is a person who drives a train on a railroad...
. The detonator is the size of a large coin with two lead straps, one on each side. The detonator is placed on the top of the rail
Rail tracks
The track on a railway or railroad, also known as the permanent way, is the structure consisting of the rails, fasteners, sleepers and ballast , plus the underlying subgrade...
and the straps are used to secure it. 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
Edward Alfred Cowper
Edward Alfred Cowper was a British mechanical engineer.He was the son of Professor Edward Shickle Cowper , head of the department of engineering at King's College London and Ann Applegath.In 1833, he was apprenticed to John Braithwaite, a railway engineer in London.In 1837, he invented the...
.
Uses
Typical uses of detonators include- a warning, caution or stop signal in dense fog, when signalsRailway signalA signal is a mechanical or electrical device erected beside a railway line to pass information relating to the state of the line ahead to train/engine drivers. The driver interprets the signal's indication and acts accordingly...
are difficult to see; - a warning of a train stopped on the line ahead by an incident or accident — the train's personnel are usually responsible for placing the detonators;
- a warning of ongoing way works ahead; or,
- when a signaller 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.
As with all explosives
Explosive material
An explosive material, also called an explosive, 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...
, detonators can become unstable after a period of time and, therefore, must be replaced regularly.
Contrary to popular belief, they are triggered by pressure, rather than impact. This makes them safe during transport, as they cannot detonate in a bag or storage container. Attempting to detonate them by striking with a hammer will not work.
In the United States
Upon hearing the noise of a torpedo exploding, the engineerRailroad engineer
A railroad engineer, locomotive engineer, train operator, train driver or engine driver is a person who drives a train on a railroad...
would reduce speed to 20 mph or less; the train could not resume its original speed until it had travelled at least two miles beyond where it encountered the device. Traditionally, used in pairs to ensure that the sound registered with train crews. Torpedoes are essentially obsolete in the U.S. today, as soundproof construction of modern locomotive cabs renders the devices useless.
Quoting from the terminology book of the Brotherhood of Railroad Signalmen
Brotherhood of Railroad Signalmen
The Brotherhood of Railroad Signalmen is a labor union in the United States and Canada. It represents workers who install and maintain signal systems on rail transport networks...
:
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" x 2", red in color, about 3/4" high, and have two lead straps attached, which hold it to a rail. The torpedo has discs inside and are filled with detonating powder. The torpedo was invented about 1874.
In the United Kingdom
Defined by the Rule Book, when protecting a line — for whatever reason (failed train, obstruction fouling the running lines) — three detonators must be placed 20 yards apart. This signals an emergency stop to the driver. Detonators are also used to protect engineering works, where the line remains open. The controller of the possession will communicate with the operative with the detonators as to when to place them on the track, or lift them to allow an engineering, freight, or passenger train through.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 is not recognizable in time, for example due to fog or snow. To give the emergency signal, three detonators were placed in short succession. Even the explosion of a single detonator was seen as stop signal. Since 1986 detonators are no longer used on German railways. Only the ICE 3ICE 3
ICE 3 is a family of high-speed EMUs of Deutsche Bahn. It includes classes 403 and 406, which are known as ICE 3 and ICE 3M respectively...
trains that travel to France still have detonators on board because of French regulations.
In Taiwan
The use of detonator signals have been superseded by radio communications since the early 1950s. In November 2010, the Taiwan Railway AdministrationTaiwan Railway Administration
The Taiwan Railway Administration is an agency of the Ministry of Transportation and Communications of the Republic of China responsible for managing, maintaining, and running passenger and freight service on 1097 km of conventional railroad lines in Taiwan...
deployed 800 of these obsolete signals for destruction on maintenance tracks. It received media attention, emitting sounds similar to the culturally significant firecracker
Firecracker
A firecracker is a small explosive device primarily designed to produce a large amount of noise, especially in the form of a loud bang; any visual effect is incidental to this goal. They have fuses, and are wrapped in a heavy paper casing to contain the explosive compound...
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.Detonator placer
Many mechanical signal boxSignal box
On a rail transport system, signalling control is the process by which control is exercised over train movements by way of railway signals and block systems to ensure that trains operate safely, over the correct route and to the proper timetable...
es in the UK were fitted with detonator placers, which automatically placed a number of detonators on a running line when a lever
Lever frame
Mechanical railway signalling installations rely on lever frames for their operation to interlock the signals and points to allow the safe operation of trains in the area the signals control...
was operated in the signal box. The levers were painted a striking white and black chevron
Chevron (insigne)
A chevron is an inverted V-shaped pattern. The word is usually used in reference to a kind of fret in architecture, or to a badge or insignia used in military or police uniforms to indicate rank or length of service, or in heraldry and the designs of flags .-Ancient history:The chevron occurs in...
pattern – pointing upwards for the "Up" line or pointing downwards for the "Down" line. In some cases, the placers were fed from a cartridge holding a number of detonators.
According to Military and Civilian Pyrotechnics by Ellern on pg 368 the formula for Railroad torpedoes are by mass:
KClO3-40%
S-16%
Sand(-60 mesh)-37%
Binder-5%
Neutralizer-2%
Garratt locomotives
Because of the length of GarrattGarratt
A Garratt is a type of steam locomotive that is articulated in three parts. Its boiler is mounted on the centre frame, and two steam engines are mounted on separate frames, one on each end of the boiler. Articulation permits larger locomotives to negotiate curves and lighter rails that might...
locomotives, which made the sound of a detonator hard to hear, the New South Wales 60 class locomotive were fitted with "sound pipe" to bring the noise of the explosion closer to the crew.