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Railway signalling
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This article is about the principle of railway signalling. For the physical signals
themselves, see railway signal.
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A Class 66 locomotive (right) is waiting at a red signal
while a First Great Western passenger train (left) crosses its path at a junction.
Railway signalling (BE), or railroad signaling (AE), is a system used to control the
movement of railway traffic. Trains move on fixed rails, making them uniquely
susceptible to collision. This susceptibility is exacerbated by the enormous weight
and inertia of a train, which makes it difficult to quickly stop when encountering an
obstacle. In the UK, the Regulation of Railways Act 1889 introduced a series of
requirements on matters such as the implementation of interlocked block signalling
and other safety measures as a direct result of the Armagh rail disaster in that year.
Most forms of train control involve movement authority being passed from those
responsible for each section of a rail network (e.g. a signalman or stationmaster) to
the train crew. The set of rules and the physical equipment used to accomplish this
determine what is known as the method of working (UK), method of operation (US)
or safe-working (Aus.). Not all these methods require the use of physical signals, and
some systems are specific to single-track railways.
The earliest rail cars were hauled by horses or mules. A mounted flagman on a
horse preceded some early trains. Hand and arm signals were used to direct the
"train drivers". Foggy and poor-visibility conditions later gave rise to flags and
lanterns. Wayside signalling dates back as far as 1832, and used elevated flags or
balls that could be seen from afar.
Timetable operation[edit]
The simplest form of operation, at least in terms of equipment, is to run the system
according to a timetable. Every train crew understands and adheres to a fixed
schedule. Trains may only run on each track section at a scheduled time, during
which they have 'possession' and no other train may use the same section.
When trains run in opposite directions on a single-track railway, meeting points
("meets") are scheduled, at which each train must wait for the other at a passing
place. Neither train is permitted to move before the other has arrived. In the US, the
display of two green flags (green lights at night) is an indication that another train is
following the first and the waiting train must wait for the next train to pass. In
addition, the train carrying the flags gives eight blasts on the whistle as it
approaches. The waiting train must return eight blasts before the flag carrying train
may proceed.
The timetable system has several disadvantages. First, there is no positive
confirmation that the track ahead is clear, only that it is scheduled to be clear. The
system does not allow for engine failures and other such problems, but the timetable
is set up so that there should be sufficient time between trains for the crew of a failed
or delayed train to walk far enough to set warning flags, flares,
and detonators or torpedoes (UK and US terminology, respectively) to alert any other
train crew.
A second problem is the system's inflexibility. Trains cannot be added, delayed, or
rescheduled without advance notice.
A third problem is a corollary of the second: the system is inefficient. To provide
flexibility, the timetable must give trains a broad allocation of time to allow for delays,
so the line is not in the possession of each train for longer than is otherwise
necessary.
Nonetheless, this system permits operation on a vast scale, with no requirements for
any kind of communication that travels faster than a train. Timetable operation was
the normal mode of operation in North America in the early days of the railroad.
Timetable and train order[edit]
See also: Train order operation
With the advent of the telegraph in 1841, a more sophisticated system became
possible because this provided a means whereby messages could be transmitted
ahead of the trains. The telegraph allows the dissemination of any timetable
changes, known as train orders. These allow the cancellation, rescheduling and
addition of train services.
North American practice meant that train crews generally received their orders at the
next station at which they stopped, or were sometimes handed up to a locomotive
'on the run' via a long staff. Train orders allowed dispatchers to set up meets at
sidings, force a train to wait in a siding for a priority train to pass, and to maintain at
least one block spacing between trains going the same direction.
Timetable and train order operation was commonly used on American railroads until
the 1960s, including some quite large operations such as the Wabash Railroad and
the Nickel Plate Road. Train order traffic control was used in Canada until the late
1980s on the Algoma Central Railway and some spurs of the Canadian Pacific
Railway.
Timetable and train order was not used widely outside North America, and has been
phased out in favour of radio dispatch on many light-traffic lines and electronic
signals on high-traffic lines. More details of North American operating methods is
given below.
A similar method, known as 'Telegraph and Crossing Order' was used on some busy
single lines in the UK during the 19th century. However, a series of head-on
collisions resulted from authority to proceed being wrongly given or misunderstood
by the train crew - the worst of which was the collision between Norwich and
Brundall, Norfolk, in 1874. As a result, the system was phased out in favour
of token systems. This eliminated the danger of ambiguous or conflicting instructions
being given because token systems rely on objects to give authority, rather than
verbal or written instructions; whereas it is very difficult to completely prevent
conflicting orders being given, it is relatively simple to prevent conflicting tokens
being handed out.
Block signalling[edit]
Main article: Signalling block systems
British lower-quadrant semaphore stop signal (absolute) with
subsidiary arm (permissive) below
a 130 km/h speed limit at kilometer post 547 in Iisalmi, Finland
A block signal and
Trains cannot collide with each other if they are not permitted to occupy the same
section of track at the same time, so railway lines are divided into sections known
as blocks. In normal circumstances, only one train is permitted in each block at a
time. This principle forms the basis of most railway safety systems. Blocks can either
be fixed (block limits are fixed along the line) or moving blocks (ends of blocks
defined relative to moving trains).[1]
History of block signalling[edit]
On double tracked railway lines, which enabled trains to travel in one direction on
each track, it was necessary to space trains far enough apart to ensure that they
could not collide. In the very early days of railways, men (originally called
'policemen', which is the origin of UK signalmen being referred to as "bob", "bobby"
or "officer", when train-crew are speaking to them via a signal telephone) were
employed to stand at intervals ("blocks") along the line with a stopwatch and use
hand signals to inform train drivers that a train had passed more or less than a
certain number of minutes previously. This was called "time interval working". If a
train had passed very recently, the following train was expected to slow down to
allow more space to develop.
The watchmen had no way of knowing whether a train had cleared the line ahead, so
if a preceding train stopped for any reason, the crew of a following train would have
no way of knowing unless it was clearly visible. As a result, accidents were common
in the early days of railways. With the invention of the electrical telegraph, it became
possible for staff at a station or signal box to send a message (usually a specific
number of rings on a bell) to confirm that a train had passed and that a specific block
was clear. This was called the "absolute block system".
Fixed mechanical signals began to replace hand signals from the 1830s. These were
originally worked locally, but it later became normal practice to operate all the signals
on a particular block with levers grouped together in a signal box. When a train
passed into a block, a signalman would protect that block by setting its signal to
'danger'. When an 'all clear' message was received, the signalman would move the
signal into the 'clear' position.
Railway infrastructure on the hill-country main line, Sri
Lanka, including a gantry of semaphore signals
The absolute block system came into use gradually during the 1850s and 1860s and
became mandatory in the United Kingdom after Parliament passed legislation in
1889 following a number of accidents, most notably the Armagh rail disaster. This
required block signalling for all passenger railways, together with interlocking, both of
which form the basis of modern signalling practice today. Similar legislation was
passed by the United States around the same time.
Not all blocks are controlled using fixed signals. On some single track railways in the
UK, particularly those with low usage, it is common to use token systems that rely on
the train driver's physical possession of a unique token as authority to occupy the
line, normally in addition to fixed signals.
Entering and leaving a manually controlled block[edit]
Before allowing a train to enter a block, a signalman must be certain that it is not
already occupied. When a train leaves a block, they must inform the signalman
controlling entry to the block. Even if the signalman receives advice that the previous
train has left a block, they are usually required to seek permission from the next
signal box to admit the next train. When a train arrives at the end of a block section,
before the signalman sends the message that the train has arrived, they must be
able to see the end-of-train marker on the back of the last vehicle. This ensures that
no part of the train has become detached and remains within the section. The end of
train marker might be a coloured disc (usually red) by day or a coloured oil or electric
lamp (again, usually red). If a train enters the next block before the signalman sees
that the disc or lamp is missing, they ask the next signal box to stop the train and
investigate.
Permissive and absolute blocks[edit]
Under a permissive block system, trains are permitted to pass signals indicating the
line ahead is occupied, but only at such a speed that they can stop safely should an
obstacle come into view. This allows improved efficiency in some situations and is
mostly used in the USA. In most countries it is restricted to freight trains only, and it
may be restricted depending on the level of visibility.
Permissive block working may also be used in an emergency, either when a driver is
unable to contact a signalman after being held at a danger signal for a specific time,
although this is only permitted when the signal does not protect any conflicting
moves, and also when the signalman is unable to contact the next signal box to
make sure the previous train has passed, for example if the telegraph wires are
down. In these cases, trains must proceed at very low speed (typically 32 km/h
(20 mph) or less) so that they are able to stop short of any obstruction. In most
cases, this is not allowed during times of poor visibility (e.g., fog or falling snow).
Even with an absolute block system, multiple trains may enter a block with
authorization. This may be necessary in order to split or join trains together, or to
rescue failed trains. In giving authorization, the signalman also ensures that the
driver knows precisely what to expect ahead. The driver must operate the train in a
safe manner taking this information into account. Generally, the signal remains at
danger, and the driver is given verbal authority, usually by a yellow flag, to pass a
signal at danger, and the presence of the train in front is explained. Where trains
regularly enter occupied blocks, such as stations where coupling takes place, a
subsidiary signal, sometimes known as a "calling on" signal, is provided for these
movements, otherwise they are accomplished through train orders.
Automatic block[edit]
Main article: Automatic block signaling
The invention of train detection systems such as track circuits allowed the
replacement of manual block systems such as absolute block with automatic block
signalling. Under automatic block signalling, signals indicate whether or not a train
may enter a block based on automatic train detection indicating whether a block is
clear. The signals may also be controlled by a signalman, so that they only provide
a proceed indication if the signalman sets the signal accordingly and the block is
clear.
Fixed block[edit]
Short signal blocks on the Toronto Transit
Commission subway system. A train (not visible) has just passed the most distant,
leftmost signal, and the two most distant signals are red (stop and stay aspect). The
next closest signal is yellow (proceed with caution), and the nearest signal shows
green (proceed).
Most blocks are "fixed", i.e. they include the section of track between two fixed
points. On timetable, train order, and token-based systems, blocks usually start and
end at selected stations. On signalling-based systems, blocks start and end at
signals.
The lengths of blocks are designed to allow trains to operate as frequently as
necessary. A lightly used line might have blocks many kilometres long, but a busy
commuter line might have blocks a few hundred metres long.
A train is not permitted to enter a block until a signal indicates that the train may
proceed, a dispatcher or signalman instructs the driver accordingly, or the driver
takes possession of the appropriate token. In most cases, a train cannot enter the
block until not only the block itself is clear of trains, but there is also an empty section
beyond the end of the block for at least the distance required to stop the train. In
signalling-based systems with closely spaced signals, this overlap could be as far as
the signal following the one at the end of the section, effectively enforcing a space
between trains of two blocks.
When calculating the size of the blocks, and therefore the spacing between the
signals, the following have to be taken into account:
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•
•
•
•
•
Line speed (the maximum permitted speed over the line-section)
Train speed (the maximum speed of different types of traffic)
Gradient (to compensate for longer or shorter braking distances)
The braking characteristics of trains (different types of train, e.g., freight,
high-speed passenger, have different inertial figures)
Sighting (how far ahead a driver can see a signal)
Reaction time (of the driver)
Historically, some lines operated so that certain large or high speed trains were
signalled under different rules and only given the right of way if two blocks in front of
the train were clear.
Moving block[edit]
Main article: Moving block
Under a moving block system, computers calculate a safe zone around each moving
train that no other train is allowed to enter. The system depends on knowledge of the
precise location and speed and direction of each train, which is determined by a
combination of several sensors such as radio frequency identification along the
track, ultra-wideband, radar, inertial measurement units, accelerometers and
trainborne speedometers (GNSS systems cannot be relied upon because they do
not work in tunnels). Moving block setups require instructions to be directly passed to
the train instead of using lineside signals. This has the advantage of increasing track
capacity by allowing trains to run closer together while maintaining the required
safety margins.
Centralized traffic control[edit]
Main article: Centralized traffic control
Centralized traffic control (CTC) is a form of railway signalling that originated in North
America. CTC consolidates train routing decisions that were previously carried out
by local signal operators or the train crews themselves. The system consists of a
centralized train dispatcher's office that controls railroad interlockings and traffic
flows in portions of the rail system designated as CTC territory.
Train detection[edit]
Train detection refers to the presence or absence of trains on a defined section of
line.[1]
Track circuits[edit]
Main article: Track circuit
The most common way to determine whether a section of line is occupied is by use
of a track circuit. The rails at either end of each section are electrically isolated from
the next section, and an electric current is fed to both running rails at one end.
A relay at the other end is connected to both rails. When the section is unoccupied,
the relay coil completes an electrical circuit, and is energized. However, when a train
enters the section, it short-circuits the current in the rails, and the relay is deenergized. This method does not explicitly need to check that the entire train has left
the section. If part of the train remains in the section, the track circuit detects that
part.
This type of circuit detects the absence of trains, both for setting the signal indication
and for providing various interlocking functions—for example, preventing points from
being moved while a train is approaching them. Electrical circuits also prove that
points are locked in the appropriate position before the signal protecting that route
can be cleared. UK trains and staff working in track circuit block areas carry track
circuit operating clips (TCOC) so that, in the event of something fouling an adjacent
running-line, the track circuit can be short-circuited. This places the signal protecting
that line to 'danger' to stop an approaching train before the signaller can be alerted. [2]
Axle counters[edit]
Main article: Axle counter
An alternate method of determining the occupied status of a block uses devices
located at its beginning and end that count the number of axles that enter and leave
the block section. If the number of axles leaving the block section equals those that
entered it, the block is assumed to be clear. Axle counters provide similar functions
to track circuits, but also exhibit a few other characteristics. In a damp environment
an axle counted section can be far longer than a track circuited one. The low ballast
resistance of very long track circuits reduces their sensitivity. Track circuits can
automatically detect some types of track defect such as a broken rail. In the event of
power restoration after a power failure, an axle counted section is left in an
undetermined state until a train has passed through the affected section. A track
circuited section immediately detects the presence of a train in section.
Fixed signals[edit]
Main article: Railway signal
On most railways, physical signals are erected at the lineside to indicate to drivers
whether the line ahead is occupied and to ensure that sufficient space exists
between trains to allow them to stop.
Mechanical signals[edit]
Traditional mechanical signals on display at a railway station
in Steinfurt, Germany
Older forms of signal displayed their different aspects by their physical position. The
earliest types comprised a board that was either turned face-on and fully visible to
the driver, or rotated so as to be practically invisible. While this type of signal is still in
use in some countries (e.g., France and Germany), by far the most common form of
mechanical signal worldwide is the semaphore signal. This comprises a pivoted arm
or blade that can be inclined at different angles. A horizontal arm is the most
restrictive indication (for 'danger', 'caution', 'stop and proceed' or 'stop and stay'
depending on the type of signal).
To enable trains to run at night, one or more lights are usually provided at each
signal. Typically this comprises a permanently lit oil lamp with movable coloured
spectacles in front that alter the colour of the light. The driver therefore had to learn
one set of indications for daytime viewing and another for nighttime viewing.
Whilst it is normal to associate the presentation of a green light with a safe condition,
this was not historically the case. In the very early days of railway signalling, the first
coloured lights (associated with the turned signals above) presented a white light for
'clear' and a red light for 'danger'. Green was originally used to indicate 'caution' but
fell out of use when the time interval system was discontinued. A green light
subsequently replaced white for 'clear', to address concerns that a broken red lens
could be taken by a driver as a false 'clear' indication. It was not until scientists
at Corning Glassworks perfected a shade of yellow without any tinges of green or
red that yellow became the accepted colour for 'caution'.
Mechanical signals are usually remotely operated by wire from a lever in a signal
box, but electrical or hydraulic operation is normally used for signals that are located
too distant for manual operation.
Colour light signals[edit]
Vertical colour light signal on the Enshū Railway Line, Japan
On most modern railways, colour light signals have largely replaced mechanical
ones. Colour light signals have the advantage of displaying the same aspects by
night as by day, and require less maintenance than mechanical signals.
Although signals vary widely between countries, and even between railways within a
given country, a typical system of aspects would be:
•
•
•
Green: Proceed at line speed. Expect to find next signal displaying green
or yellow.
Yellow: Prepare to find next signal displaying red.
Red: Stop.
On some railways, colour light signals display the same set of aspects as shown by
the lights on mechanical signals during darkness.
Route signalling and speed signalling[edit]
Route signalling and speed signalling are two different ways of notifying trains about
junctions.
Under route signalling, a driver is informed which route the train will take beyond
each signal (unless only one route is possible). This is achieved by a route
indicator attached to the signal. The driver uses their route knowledge, reinforced by
speed restriction signs fixed at the lineside, to drive the train at the correct speed for
the route to be taken. This method has the disadvantage that the driver may be
unfamiliar with the required speed over a junction onto which they have been
diverted due to some emergency condition. Several accidents have been caused by
this alone.[3] For this reason, in the UK, where all lines are route signalled, drivers are
only allowed to drive on routes that they have been trained on and must regularly
travel over the lesser used diversionary routes to keep their route knowledge up to
date.
Many route signalling systems use approach control (see below) to inform a driver of
an upcoming change of route.
Under speed signalling, the signal aspect informs the driver at what speed they
may proceed over a junction, but not necessarily the route the train will take. Speed
signalling requires a far greater range of signal aspects than route signalling, but less
dependence is placed on drivers' route knowledge, although the need for drivers to
learn the route is not eliminated as speed signalling does not usually inform drivers
of speed limit changes outside junctions. Usually speed limit signs are used in
addition to speed signals, with the driver following whichever shows the lower speed.
Many systems have come to use elements of both systems to give drivers as much
information as possible. This can mean that speed signalling systems may use route
indications in conjunction with speed aspects to better inform drivers of their route;
for example, route indications may be used at major stations to indicate to arriving
trains to which platform they are routed. Likewise, some route signalling systems
indicate approach speed using theatre displays so that drivers know what speed they
must travel.
•
An example of a signal from Melbourne Victoria: this signal is displaying a speed signalling
aspect, in conjunction with a route indicator
Approach release[edit]
4-aspect flashing yellow signalling
When the train is routed towards a diverging route that must be taken at a speed
significantly less than the mainline speed, the driver must be given adequate prior
warning.
Under route signalling, the aspects necessary to control speed do not exist, so a
system known as approach release is often employed. This involves holding the
junction signal at a restrictive aspect (typically stop) so that the signals on the
approach show the correct sequence of caution aspects. The driver brakes in
accordance with the caution aspect, without necessarily being aware that the
diverging route has in fact been set. As the train approaches the junction signal, its
aspect may clear to whatever aspect the current track occupancy ahead permits.
Where the turnout speed is the same, or nearly the same, as the mainline speed,
approach release is unnecessary.
Under speed signalling, the signals approaching the divergence display aspects
appropriate to control the trains speed, so no approach release is required.
There is also a system of flashing yellows used in the UK that allows trains to
approach a diverging route at higher speed. This informs the driver that the route
ahead is set onto a diverging line. With the advent of faster modern day trains and
junctions a better system for advising drivers was required and so the following
system was developed way back in the early 1980s. The system has been refined
over the years, now being used internationally and it is also used on lower speed 3-
aspect signalling systems where the single flashing yellow is the driver's first
indication.
On the 4-aspect system, if the route through the junction is clear the junction signal
will display a single steady yellow aspect together with an illuminated junction
indicator showing the selected route.[4]
The signal prior to the junction signal will now show a single flashing yellow aspect
and the signal prior to that one will display two flashing yellow aspects. The
driver's route knowledge tells them permissible speed across the diverging junction,
and they will begin to slow the train upon seeing the two flashing yellows. The
flashing signals tell the driver that the route through the junction is set and is clear,
but that beyond that the first signal on the diverging route is red so they must be
prepared to stop there.
As the train approaches the junction signal, the signal may step up to a less
restrictive aspect (single yellow, two yellows or green) depending on how far ahead
the line is clear.
Speed-controlled approach[edit]
Original 1932 operation of Sydney's speed controlled trips. Note: The signal that
allows the trains to proceed into the platform is a "call on" signal, consisting of a
double red signal with a smaller green light underneath.
Some systems in the world use mechanical speed control systems in conjunction
with signalling to ensure the speed of a train is limited to a specific value, in order to
ensure the train is travelling at a speed in which it is able to stop before an
obstruction. These systems most often use mechanical train stop devices (a small
arm coming up from the rails that will apply the brakes of a train when run over) to
"trip" the brakes of a train that is travelling too fast. Normally, once a train reaches a
certain point on the tracks, it sets off a timer, when the timer runs out the train stop
arm will lower, allowing a train to go past uninterrupted. The timing is designed so
that if the train is travelling at the intended speed (or slower) then the train will be
able to continue without issue, but if the train is travelling too fast, then the Train
Stop will trip the train and bring it to a halt. This system can be used to ensure a train
is travelling at a certain speed, which allows designers to be confident that shorter
signal overlaps will be sufficient, and thus employment of this system can help to
greatly improve capacity of a railway line.
The system is most often used on approach to dead end junctions to stop trains from
crashing into the buffers at the end, as has happened in places such as Moorgate. It
is also used on high traffic lines to allow for higher capacity, such as the City Circle
Railway in Sydney, where it was used on the western half from 1932 to allow 42
trains per hour to traverse the line in each direction, each station would have multiple
train stops along the length of the platforms that would progressively lower to ensure
an arriving train would not crash into the departing train, less than 100 meters ahead.
This system was modified in the early 1990s, so that an arriving train would not be
able to enter the platform until the previous train had departed, however the trips
continue to be used to overcome the signal overlap normally required.
These systems are often used in conjunction with progressive speed signalling (see
below).
Progressive speed signalling[edit]
Progressive speed signalling refers to systems that impose speed restrictions on
cautionary aspects. On systems that do not have progressive speed signalling,
aspects warning of an upcoming red signal do not force the driver to take any action;
it is up to their own judgment when to start slowing down in preparation to stop at the
red signal. With progressive speed signalling, each cautionary aspect before a red
signal imposes a successively lower speed limit on the driver.[5] It should not be
confused with speed signalling as used at junctions; progressive speed signalling
can be used in conjunction with route signalling.
Safety systems[edit]
Main article: Train protection system
A train driver failing to respond to a signal's indication can be catastrophic. As a
result, various auxiliary safety systems have been devised. Any such system
requires installation of some degree of train borne and wayside equipment. Some
systems only intervene in the event of a signal being passed at danger (SPAD).
Others include audible and/or visual indications inside the driver's cab to supplement
the line side signals. Automatic brake application occurs if the driver should fail to
acknowledge a warning. The most advanced train control systems have no driver at
all relying on computers to drive the system entirely such as Skytrain in Vancouver,
Canada and the metro system in Doha, Qatar.
In-cab safety systems are of great benefit during fog, when poor visibility would
otherwise require that restrictive measures be put in place. Safety systems are also
important in urban rail where it is impossible to see around corners in subway and
metro tunnels. On-board and wayside computers can track trains around tight
corners at higher speeds ensuring safety.
Cab signalling[edit]
Main article: Cab signalling
Example of cab signal
Cab signalling is a subsystem that communicates signalling information into the train
cab such as driving position, speed and failure alarms. Cab signaling units are
important human factors engineering subsystems in modern train signalling systems.
If there is an active cab, the orientation of the train is decided, i.e. the side of the
active cab is considered as the front of the train. In modern systems, a train
protection system is overlaid on top of the cab signalling system and will
automatically apply the brakes and bring the train to a stop if the driver fails to control
the speed of the train in accordance with the system's safety requirements. [6] Cab
signalling systems rely on tachometers, accelerometers, ultra-wideband units, inertia
measurement units, track circuits, to transponders that communicate with the cab,
and communication-based train control systems.
Interlocking[edit]
Main article: Interlocking
In the early days of the railways, signalmen were responsible for ensuring
any points (US: switches) were set correctly before allowing a train to proceed.
Mistakes, however, led to accidents, sometimes with fatalities. The concept of the
mechanical interlocking of point switches, signals and other appliances was
introduced to improve safety. This prevents a signalman from operating appliances
in an unsafe sequence using mechanical means, such as clearing a signal while one
or more sets of points are not set correctly for the route.[3] Early interlocking systems
used mechanical devices both to operate the signalling appliances and to ensure
their safe operation.
Beginning around the 1930s, electrical relay interlockings were used. Since the mid
1980s, new interlocking systems have tended to be of the electronic variety.
Microprocessors decide what point switch movements are permissible. Modern
interlocking systems and subsystems allow and prohibit certain point switch positions
to enhance train safety.
Operating rules[edit]
Operating rules, policies and procedures are used by railroads to enhance safety.
Specific operating rules often differ from country to country, and there may even be
differences between separate railroads within the same country.
Argentina[edit]
The Argentinian operating rules are described in the Reglamento interno técnico de
operaciones [R.I.T.O.] (technical operating rule-book).
Australia[edit]
Main article: Australian railway signalling
The application of operating rules in Australia is called Safeworking. The method of
working for any particular region or location is referred-to as the "Safeworking
system" for that region. Operating rules differ between states, although attempts are
being made to formulate a national standard.
North America[edit]
Main article: North American railway signaling
In North America, and especially the United States, operating rules are
called method of operation. There are five main sets of operating rules in North
America:
•
•
•
•
•
Canadian Rail Operating Rules (CROR), used by most Canadian railways,
with the exception of Canadian National Railway's US operations, which
uses a modified, proprietary version of the GCOR, known as USOR
(United States Operating Rules)
General Code of Operating Rules (GCOR), used by many Class I
railroads, Class II railroads, and Short-line railroads in the United States
Northeast Operating Rules Advisory Committee (NORAC), used by many
railroads in the Northeast US
Class I Norfolk Southern uses a unique set of operating rules.
Class I CSX Transportation uses a unique set of operating rules.
United Kingdom[edit]
Main article: UK railway signalling
The operating rulebook for the United Kingdom is called the "GE/RT8000 Rule
Book",[7] more commonly known simply as "The Rule Book" by railway employees. It
is controlled by the Rail Safety and Standards Board (RSSB), which is independent
from Network Rail or any other train operating company or freight operating
company. Most heritage railways operate to a simplified variant of a British
Railways rule book.
Finland[edit]
Main article: Finnish railway signalling
The signalling system used on the railway network in Finland comprises color-light
signals and fixed signs. It is used together with the EBICAB 900, an automatic train
control system better known as JKV, Finnish: junakulunvalvonta.
Italy[edit]
Main article: Italian railway signalling
In Italy, railway signalling is described in a particular instruction called Regolamento
Segnali Archived December 7, 2014, at the Wayback Machine (Signal Regulation).
India[edit]
The Indian operating rules, called the "General Rules", are common for all zonal
railways of Indian Railways and can be amended only by the Railway Board.
Subsidiary rules are added to the General Rules by zonal railways, which do not
infringe upon them. Corrections are brought about from time to time through
correction slips.[8]
Japan[edit]
Main article: Japanese railway signals
Japanese signalling was initially based on British railway signalling practice, and
Japanese railway signalling continues to be based on the UK route signalling system
for junctions. However, as signalling has advanced to meet the requirements of the
system, progressive speed signalling is used outside of junctions.
Hong Kong[edit]
Main article: Hong Kong railway signals
Hong Kong Railway signalling originated from the British railway signalling
principle,[9] and continues to be based on the principles to develop rulebooks and
procedures under the operating organisation MTR.
See also[edit]
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Communication Based Train Control Signal System
Gantry
Institution of Railway Signal Engineers
Railroad chronometer
Rail sabotage
Railroad switch
Railway semaphore signal
Railway slide fence
Signalling block system
Signalling control
Toronto subway and RT signals
Train speed optimization
Wrong-side failure
Norwegian railway signaling
Notes[edit]
1. ^ Jump up to:a b "Subset-023 Glossary of Terms and Abbreviations (issue
3.1.0)" (PDF). era.europa.eu. ERTMS USERS GROUP. May 12, 2014. Archived from the
original (PDF) on August 7, 2020. Retrieved February 17, 2024.
2. ^ "Rulebook Master: Module M1 Section 3.1 "Dealing with a train accident or evacuation Providing emergency protection"" (PDF). Network Rail. Archived from the
original (PDF) on August 10, 2018. Retrieved February 12, 2017.
3. ^ Jump up to:a b Rolt, L. T. C. (2009) [1966]. Red for Danger: The Classic History of British
Railway Disasters (2nd ed.). The History Press. ISBN 978-0-7524-5106-0.
4. ^ "Online Rulebook: Signals, Handsignals, Indicators and SignsHandbook RS521 Section
2.5 "Flashing yellow aspects"" (PDF). RSSB. Archived from the original (PDF) on
December 5, 2016. Retrieved August 18, 2019.
5. ^ Pachl, Jörn (October 2021). Railway Signalling Principles (PDF) (2.00 ed.). pp. 23–25.
Retrieved June 27, 2023.
6. ^ Collins, Gerald E. (1979). Elements of Railway Signaling. Rochester, NY: General
Railway Signal Company.
7. ^ "The Rule Book". rgsonline.co.uk. RSSB. Archived from the original on December 14,
2008.
8. ^ "General Rules, 1976". indianrailways.gov.in. Ministry of Railways (Railway Board).
March 29, 2019. Retrieved December 13, 2020.
9. ^ "Hong Kong".
General references[edit]
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Brian, Frank W. (May 1, 2006). "Railroad's Traffic Control
Systems". Trains. Kalmbach Publishing Co. Archived from the original on
October 17, 2007.
Colburn, Robert (October 14, 2013). "A History of Railroad
Signals". theinstitute.ieee.org. Institute of Electrical and Electronics
Engineers. Archived from the original on October 22, 2013.
General Code of Operating Rules (PDF) (Seventh ed.). GCOR Committee.
April 1, 2015. Archived from the original (PDF) on June 19, 2018.
Director of S&T Engineering, West Midlands Project Group
(1991). "Mechanical Interlocking" (PDF). dickthesignals.co.uk. British Rail
Board. Archived from the original (PDF) on April 18, 2023.
Retrieved November 26, 2023.
External links[edit]
Wikimedia Commons has media related to Railway signalling.
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The Signal Page (TSP) – railway signalling world wide (Dutch), (English)
RailServe.com Signals & Communications
Railways: History, Signalling, Engineering [1] [2] [3] [4] and [5]
Signalling Record Society
The Institution of Railway Signal Engineers
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