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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.
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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.
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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.
944:, 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.
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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.
993:) 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.
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1133:(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.
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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).
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onto which they have been diverted due to some emergency condition. Several accidents have been caused by this alone. 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.
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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.
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1140:, 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.
857:'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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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)
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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. Cab signalling systems rely on tachometers, accelerometers, ultra-wideband
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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
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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
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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 de-energized. This method does not explicitly need to
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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
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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
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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.
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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
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the red signal. With progressive speed signalling, each cautionary aspect before a red signal imposes a successively lower speed limit on the driver. It should not be confused with speed signalling as used at junctions; progressive speed signalling can be used in conjunction with route signalling.
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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
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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
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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
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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
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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
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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.,
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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
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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
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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
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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. Early interlocking
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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
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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
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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
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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
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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.
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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
501:. 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).
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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
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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.
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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.
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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.
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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.
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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.
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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
791:(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.
849:. 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).
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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.
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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.
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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.
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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
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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
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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
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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.
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Hong Kong
Railway signalling originated from the British railway signalling principle, and continues to be based on the principles to develop rulebooks and procedures under the operating organisation MTR.
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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.
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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.
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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.
1213:. Microprocessors decide what point switch movements are permissible. Modern interlocking systems and subsystems allow and prohibit certain point switch positions to enhance train safety.
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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
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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.
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The operating rulebook for the United
Kingdom is called the "GE/RT8000 Rule Book", more commonly known simply as "The Rule Book" by railway employees. It is controlled by the
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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.
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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
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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
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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
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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.
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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.
1201:(US: switches) were set correctly before allowing a train to proceed. Mistakes, however, led to accidents, sometimes with fatalities. The concept of the mechanical
309:. 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
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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
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774:. 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
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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
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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
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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.
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Timetable and train order operation was commonly used on
American railroads until the 1960s, including some quite large operations such as the
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Beginning around the 1930s, electrical relay interlockings were used. Since the mid 1980s, new interlocking systems have tended to be of the
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An example of a signal from Melbourne Victoria: this signal is displaying a speed signalling aspect, in conjunction with a route indicator
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Although signals vary widely between countries, and even between railways within a given country, a typical system of aspects would be:
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The braking characteristics of trains (different types of train, e.g., freight, high-speed passenger, have different inertial figures)
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On some railways, colour light signals display the same set of aspects as shown by the lights on mechanical signals during darkness.
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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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The lengths of blocks are designed to allow trains to operate as frequently as necessary. A lightly used line might have blocks many
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check that the entire train has left the section. If part of the train remains in the section, the track circuit detects that part.
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subway system. A train (not visible) has just passed the most distant, leftmost signal, and the two most distant signals are red (
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676:-based systems, blocks usually start and end at selected stations. On signalling-based systems, blocks start and end at signals.
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identification along the track, ultra-wideband, radar, inertial measurement units, accelerometers and trainborne speedometers (
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The absolute block system came into use gradually during the 1850s and 1860s and became mandatory in the United Kingdom after
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Most blocks are "fixed", i.e. they include the section of track between two fixed points. On timetable, train order, and
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A second problem is the system's inflexibility. Trains cannot be added, delayed, or rescheduled without advance notice.
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1613:"Rulebook Master: Module M1 Section 3.1 "Dealing with a train accident or evacuation - Providing emergency protection""
1301:'s US operations, which uses a modified, proprietary version of the GCOR, known as USOR (United States Operating Rules)
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perfected a shade of yellow without any tinges of green or red that yellow became the accepted colour for 'caution'.
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tells them permissible speed across the diverging junction, and they will begin to slow the train upon seeing the
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systems used mechanical devices both to operate the signalling appliances and to ensure their safe operation.
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controls railroad interlockings and traffic flows in portions of the rail system designated as CTC territory.
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between trains for the crew of a failed or delayed train to walk far enough to set warning flags, flares, and
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On the 4-aspect system, if the route through the junction is clear the junction signal will display a single
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involve movement authority being passed from those responsible for each section of a rail network (e.g. a
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between Norwich and Brundall, Norfolk, in 1874. As a result, the system was phased out in favour of
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This article is about the principle of railway signalling. For the physical signals themselves, see
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restricted to freight trains only, and it may be restricted depending on the level of visibility.
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is often employed. This involves holding the junction signal at a restrictive aspect (typically
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British lower-quadrant semaphore stop signal (absolute) with subsidiary arm (permissive) below
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The Indian operating rules, called the "General Rules", are common for all zonal railways of
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3033:
2988:
2928:
2830:
2754:
2744:
1512:
1448:
1432:
1198:
873:
756:
Train detection refers to the presence or absence of trains on a defined section of line.
435:
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1828:
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France and Germany), by far the most common form of mechanical signal worldwide is the
821:
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485:
349:
310:
31:
1154:
770:
The most common way to determine whether a section of line is occupied is by use of a
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3639:
3634:
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2153:
1507:
1283:
1279:
788:
771:
765:
333:
1423:
893:
Green: Proceed at line speed. Expect to find next signal displaying green or yellow.
3949:
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1023:
aspect together with an illuminated junction indicator showing the selected route.
858:
800:
722:
574:
2423:
1090:. It is also used on high traffic lines to allow for higher capacity, such as the
278:(now Great Western Railway) passenger train (left) crosses its path at a junction.
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3799:
3709:
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3614:
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637:
indication if the signalman sets the signal accordingly and the block is clear.
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302:
83:
1197:
In the early days of the railways, signalmen were responsible for ensuring any
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2473:
2346:
2311:
2069:
1925:
680:
524:
442:. Train order traffic control was used in Canada until the late 1980s on the
423:. These allow the cancellation, rescheduling and addition of train services.
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3604:
3419:
2874:
2840:
2820:
2769:
2759:
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1392:
comprises color-light signals and fixed signs. It is used together with the
985:, the aspects necessary to control speed do not exist, so a system known as
837:
683:
long, but a busy commuter line might have blocks a few hundred metres long.
551:
511:
413:
306:
17:
1705:
584:
railways in the UK, particularly those with low usage, it is common to use
573:. This required block signalling for all passenger railways, together with
1920:
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2729:
2468:
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4129:
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3186:
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2418:
2266:
2236:
1954:
1879:
Director of S&T Engineering, West Midlands Project Group (1991).
1422:, railway signalling is described in a particular instruction called
1393:
387:(UK and US terminology, respectively) to alert any other train crew.
489:
A block signal and a 130 km/h speed limit at kilometer post 547 in
4144:
4081:
3389:
2196:
1153:
969:
872:
836:
Traditional mechanical signals on display at a railway station in
831:
775:
644:
545:
484:
476:
265:
1867:(Seventh ed.). GCOR Committee. April 1, 2015. Archived from
4086:
2186:
1842:
1649:
Red for Danger: The Classic History of British Railway Disasters
1290:. There are five main sets of operating rules in North America:
729:
700:
Gradient (to compensate for longer or shorter braking distances)
3190:
2680:
1958:
937:(see below) to inform a driver of an upcoming change of route.
3332:
1916:
1577:"Subset-023 Glossary of Terms and Abbreviations (issue 3.1.0)"
1297:(CROR), used by most Canadian railways, with the exception of
1137:
694:
Line speed (the maximum permitted speed over the line-section)
183:
77:
36:
1917:
The Signal Page (TSP) – railway signalling world wide (Dutch)
697:
Train speed (the maximum speed of different types of traffic)
1396:
900, an automatic train control system better known as JKV,
1358:(RSSB), which is independent from Network Rail or any other
1049:
As the train approaches the junction signal, the signal may
918:
are two different ways of notifying trains about junctions.
1944:
580:
Not all blocks are controlled using fixed signals. On some
527:
to send a message (usually a specific number of rings on a
360:
used elevated flags or balls that could be seen from afar.
569:
in 1889 following a number of accidents, most notably the
348:(Aus.). Not all these methods require the use of physical
1026:
The signal prior to the junction signal will now show a
27:
The principle of signals used to control railway traffic
1949:
633:
controlled by a signalman, so that they only provide a
1780:. Ministry of Railways (Railway Board). March 29, 2019
550:
Railway infrastructure on the hill-country main line,
274:
locomotive (right) is waiting at a red signal while a
1230:
The Argentinian operating rules are described in the
1030:
aspect and the signal prior to that one will display
4168:
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3991:
3948:
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3823:
3532:
3224:
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2803:
2715:
2563:
2512:
2406:
2370:
2172:
2141:
2108:
2060:
1992:
1325:(NORAC), used by many railroads in the Northeast US
896:
Yellow: Prepare to find next signal displaying red.
112:. Unsourced material may be challenged and removed.
1136:In-cab safety systems are of great benefit during
706:Sighting (how far ahead a driver can see a signal)
1848:Institute of Electrical and Electronics Engineers
1586:. ERTMS USERS GROUP. May 12, 2014. Archived from
1098:These systems are often used in conjunction with
628:The invention of train detection systems such as
1736:. Rochester, NY: General Railway Signal Company.
1065:) depending on how far ahead the line is clear.
592:Entering and leaving a manually controlled block
446:and some spurs of the Canadian Pacific Railway.
523:, it became possible for staff at a station or
297:), is a system used to control the movement of
3202:
2692:
1970:
463:prevent conflicting tokens being handed out.
8:
2282:Interoperable Communications Based Signaling
1323:Northeast Operating Rules Advisory Committee
4217:Global telecommunications regulation bodies
2217:Automatic Train Protection (United Kingdom)
1950:The Institution of Railway Signal Engineers
1930:Railways: History, Signalling, Engineering
71:Learn how and when to remove these messages
4253:
3209:
3195:
3187:
2699:
2685:
2677:
1977:
1963:
1955:
1926:RailServe.com Signals & Communications
1232:Reglamento interno técnico de operaciones
252:Learn how and when to remove this message
234:Learn how and when to remove this message
172:Learn how and when to remove this message
1827:. Kalmbach Publishing Co. Archived from
1072:
1046:so they must be prepared to stop there.
294:
197:This article includes a list of general
100:Relevant discussion may be found on the
2182:Advanced Civil Speed Enforcement System
1565:
1498:Institution of Railway Signal Engineers
950:
664:), and the nearest signal shows green (
286:
1642:
1640:
1251:The application of operating rules in
660:). The next closest signal is yellow (
305:, making them uniquely susceptible to
2342:Train Protection & Warning System
1370:operate to a simplified variant of a
1339:uses a unique set of operating rules.
1332:uses a unique set of operating rules.
1053:to a less restrictive aspect (single
907:Route signalling and speed signalling
7:
4263:
2075:Integrated Electronic Control Centre
1890:. British Rail Board. Archived from
1836:Colburn, Robert (October 14, 2013).
1819:"Railroad's Traffic Control Systems"
1571:
1569:
877:Vertical colour light signal on the
110:adding citations to reliable sources
2337:Train automatic stopping controller
2257:Continuous Automatic Warning System
1651:(2nd ed.). The History Press.
1179:that communicate with the cab, and
974:4-aspect flashing yellow signalling
352:, and some systems are specific to
2017:Communications-based train control
1388:The signalling system used on the
1171:units, inertia measurement units,
1016:is the driver's first indication.
933:Many route signalling systems use
203:it lacks sufficient corresponding
25:
1487:Communication Based Train Control
1181:communication-based train control
52:This article has multiple issues.
4262:
4252:
4243:
4242:
4231:
3852:Free-space optical communication
1274:North American railway signaling
953:
188:
82:
41:
2499:Westinghouse Brake & Signal
2262:ContrĂ´le de vitesse par balises
2128:North American railroad signals
1861:General Code of Operating Rules
1838:"A History of Railroad Signals"
1817:Brian, Frank W. (May 1, 2006).
1713:(2.00 ed.). pp. 23–25
1356:Rail Safety and Standards Board
1305:General Code of Operating Rules
1236:technical operating rule-book).
853:another for nighttime viewing.
315:Regulation of Railways Act 1889
93:needs additional citations for
60:or discuss these issues on the
2357:Transmission balise-locomotive
2322:Sistema Controllo Marcia Treno
2232:Automatische treinbeĂŻnvloeding
2118:Application of railway signals
1618:. Network Rail. Archived from
601:Permissive and absolute blocks
301:traffic. Trains move on fixed
1:
2307:Punktförmige Zugbeeinflussung
2027:European Train Control System
1734:Elements of Railway Signaling
1707:Railway Signalling Principles
1538:Toronto subway and RT signals
1295:Canadian Rail Operating Rules
1286:, operating rules are called
1247:Australian railway signalling
1131:signal being passed at danger
789:track circuit operating clips
709:Reaction time (of the driver)
4238:Telecommunication portal
4019:Telecommunications equipment
2247:Chinese Train Control System
2037:Radio Electronic Token Block
1704:Pachl, Jörn (October 2021).
1111:Progressive speed signalling
1106:Progressive speed signalling
1100:progressive speed signalling
3755:Alexander Stepanovich Popov
2012:Centralized traffic control
1732:Collins, Gerald E. (1979).
1553:Norwegian railway signaling
820:On most railways, physical
743:Centralized traffic control
737:Centralized traffic control
649:Short signal blocks on the
505:History of block signalling
4310:
3459:Telecommunications history
2907:Transfer table (traverser)
2212:Automatic train protection
1459:
1414:Italian railway signalling
1411:
1390:railway network in Finland
1384:Finnish railway signalling
1381:
1347:
1271:
1244:
1190:
1147:
1121:
1007:There is also a system of
813:
798:
763:
740:
720:
651:Toronto Transit Commission
621:
470:
405:
29:
4226:
4067:Public Switched Telephone
3879:telecommunication circuit
3840:Fiber-optic communication
3585:Francis Blake (telephone)
3380:Optical telecommunication
2895:ground-level power supply
2504:Westinghouse Rail Systems
2362:Transmission Voie-Machine
2207:Automatic train operation
2159:Track circuit interrupter
2007:Automatic block signaling
2002:Absolute block signalling
1945:Signalling Record Society
1881:"Mechanical Interlocking"
1431:December 7, 2014, at the
1364:freight operating company
1299:Canadian National Railway
1069:Speed-controlled approach
733:required safety margins.
624:Automatic block signaling
402:Timetable and train order
3978:Orbital angular-momentum
3415:Satellite communications
3254:Communications satellite
2302:Pulse code cab signaling
2227:Automatic Warning System
2133:Railway semaphore signal
2095:Solid State Interlocking
1647:Rolt, L. T. C. (2009) .
1543:Train speed optimization
1518:Railway semaphore signal
1462:Japanese railway signals
554:, including a gantry of
473:Signalling block systems
3857:Molecular communication
3680:Gardiner Greene Hubbard
3509:Undersea telegraph line
3244:Cable protection system
2880:Railway electrification
2202:Automatic train control
1528:Signalling block system
1360:train operating company
1168:train protection system
1124:Train protection system
412:With the advent of the
218:more precise citations.
3999:Communication protocol
3785:Charles Sumner Tainter
3600:Walter Houser Brattain
3545:Edwin Howard Armstrong
3353:Information revolution
2378:Level crossing signals
2297:Positive Train Control
2292:Linienzugbeeinflussung
2022:Direct traffic control
1678:. RSSB. Archived from
1467:outside of junctions.
1401:
1159:
1079:
1034:aspects. The driver's
1028:single flashing yellow
1014:single flashing yellow
975:
882:
841:
669:
558:
494:
482:
444:Algoma Central Railway
279:
3973:Polarization-division
3705:Narinder Singh Kapany
3670:Erna Schneider Hoover
3590:Jagadish Chandra Bose
3570:Alexander Graham Bell
3301:online video platform
3019:Platform screen doors
2100:Westlock Interlocking
2090:Rail operating centre
2052:Train order operation
2047:Track Warrant Control
1778:indianrailways.gov.in
1774:"General Rules, 1976"
1762:on December 14, 2008.
1350:UK railway signalling
1307:(GCOR), used by many
1282:, and especially the
1158:Example of cab signal
1157:
1076:
973:
876:
835:
648:
549:
533:absolute block system
488:
480:
408:Train order operation
269:
3815:Vladimir K. Zworykin
3775:Almon Brown Strowger
3745:Charles Grafton Page
3400:Prepaid mobile phone
3328:Electrical telegraph
2969:Anti-trespass panels
2222:Automatic train stop
1888:dickthesignals.co.uk
1854:on October 22, 2013.
1831:on October 17, 2007.
1503:Railroad chronometer
1319:in the United States
1317:Short-line railroads
1040:two flashing yellows
869:Colour light signals
662:proceed with caution
571:Armagh rail disaster
521:electrical telegraph
319:Armagh rail disaster
121:"Railway signalling"
106:improve this article
4294:Rail infrastructure
3765:Johann Philipp Reis
3524:Wireless revolution
3486:The Telephone Cases
3343:Hydraulic telegraph
2816:Classification yard
1685:on December 5, 2016
1523:Railway slide fence
1425:Regolamento Segnali
1288:method of operation
1092:City Circle Railway
1032:two flashing yellow
364:Timetable operation
342:method of operation
276:First Great Western
4289:Railway signalling
3963:Frequency-division
3940:Telephone exchange
3810:Charles Wheatstone
3740:Jun-ichi Nishizawa
3715:Innocenzo Manzetti
3650:Reginald Fessenden
3385:Optical telegraphy
3218:Telecommunications
3075:Motive power depot
3029:Signalling control
2062:Signalling control
1986:Railway signalling
1811:General references
1625:on August 10, 2018
1548:Wrong-side failure
1533:Signalling control
1337:CSX Transportation
1313:Class II railroads
1211:electronic variety
1160:
1080:
976:
883:
879:Enshū Railway Line
859:Corning Glassworks
842:
828:Mechanical signals
670:
559:
495:
483:
369:the same section.
291:railroad signaling
283:Railway signalling
280:
4276:
4275:
4014:Store and forward
4009:Data transmission
3923:Network switching
3874:Transmission line
3720:Guglielmo Marconi
3685:Internet pioneers
3550:Mohamed M. Atalla
3519:Whistled language
3184:
3183:
2902:Railway turntable
2723:
2674:
2673:
2484:Smith and Yardley
1897:on April 18, 2023
1874:on June 19, 2018.
1658:978-0-7524-5106-0
1593:on August 7, 2020
1437:Signal Regulation
1402:junakulunvalvonta
1368:heritage railways
1309:Class I railroads
1261:method of working
556:semaphore signals
440:Nickel Plate Road
338:method of working
262:
261:
254:
244:
243:
236:
182:
181:
174:
156:
75:
16:(Redirected from
4301:
4266:
4265:
4256:
4255:
4246:
4245:
4236:
4235:
4234:
4107:Notable networks
4097:Wireless network
4037:Cellular network
4029:Types of network
4004:Computer network
3891:Network topology
3805:Thomas A. Watson
3660:Oliver Heaviside
3645:Philo Farnsworth
3620:Daniel Davis Jr.
3595:Charles Bourseul
3555:John Logie Baird
3264:Data compression
3259:Computer network
3211:
3204:
3197:
3188:
3079:Railway workshop
2795:Transition curve
2765:Fastening system
2719:
2701:
2694:
2687:
2678:
2550:Transport Canada
2434:General Electric
2371:Crossing signals
2252:Cityflo 650 CBTC
2174:Train protection
1979:
1972:
1965:
1956:
1906:
1904:
1902:
1896:
1885:
1875:
1873:
1866:
1855:
1850:. Archived from
1832:
1804:
1803:
1796:
1790:
1789:
1787:
1785:
1770:
1764:
1763:
1758:. Archived from
1744:
1738:
1737:
1729:
1723:
1722:
1720:
1718:
1712:
1701:
1695:
1694:
1692:
1690:
1684:
1677:
1669:
1663:
1662:
1644:
1635:
1634:
1632:
1630:
1624:
1617:
1609:
1603:
1602:
1600:
1598:
1592:
1581:
1573:
1372:British Railways
1330:Norfolk Southern
1009:flashing yellows
1002:approach release
998:speed signalling
987:approach release
983:route signalling
966:Approach release
957:
942:speed signalling
935:approach control
923:route signalling
916:speed signalling
912:Route signalling
847:semaphore signal
467:Block signalling
296:
288:
257:
250:
239:
232:
228:
225:
219:
214:this article by
205:inline citations
192:
191:
184:
177:
170:
166:
163:
157:
155:
114:
86:
78:
67:
45:
44:
37:
21:
4309:
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4303:
4302:
4300:
4299:
4298:
4279:
4278:
4277:
4272:
4232:
4230:
4222:
4164:
4101:
4023:
3987:
3944:
3893:
3885:
3826:
3819:
3725:Robert Metcalfe
3580:Tim Berners-Lee
3528:
3348:Information Age
3220:
3215:
3185:
3180:
3140:
3058:
3034:Structure gauge
2989:Defect detector
2961:
2953:
2799:
2755:Clip and scotch
2745:Breather switch
2711:
2705:
2675:
2670:
2559:
2508:
2402:
2366:
2168:
2142:Train detection
2137:
2104:
2056:
1988:
1983:
1913:
1900:
1898:
1894:
1883:
1878:
1871:
1864:
1858:
1835:
1816:
1813:
1808:
1807:
1798:
1797:
1793:
1783:
1781:
1772:
1771:
1767:
1752:rgsonline.co.uk
1748:"The Rule Book"
1746:
1745:
1741:
1731:
1730:
1726:
1716:
1714:
1710:
1703:
1702:
1698:
1688:
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1615:
1611:
1610:
1606:
1596:
1594:
1590:
1579:
1575:
1574:
1567:
1562:
1557:
1513:Railroad switch
1482:
1473:
1464:
1458:
1449:Indian Railways
1445:
1433:Wayback Machine
1416:
1410:
1386:
1380:
1352:
1346:
1276:
1270:
1249:
1243:
1228:
1219:
1217:Operating rules
1195:
1189:
1152:
1146:
1126:
1120:
1108:
1071:
1036:route knowledge
968:
961:
958:
927:route indicator
909:
871:
830:
818:
812:
803:
797:
768:
762:
754:
752:Train detection
745:
739:
725:
719:
643:
626:
620:
618:Automatic block
603:
594:
507:
475:
469:
436:Wabash Railroad
410:
404:
366:
258:
247:
246:
245:
240:
229:
223:
220:
210:Please help to
209:
193:
189:
178:
167:
161:
158:
115:
113:
99:
87:
46:
42:
35:
28:
23:
22:
15:
12:
11:
5:
4307:
4305:
4297:
4296:
4291:
4281:
4280:
4274:
4273:
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4270:
4260:
4250:
4240:
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4224:
4223:
4221:
4220:
4213:
4208:
4203:
4198:
4193:
4192:
4191:
4186:
4178:
4172:
4170:
4166:
4165:
4163:
4162:
4157:
4152:
4147:
4142:
4137:
4132:
4127:
4122:
4117:
4111:
4109:
4103:
4102:
4100:
4099:
4094:
4089:
4084:
4079:
4074:
4069:
4064:
4059:
4054:
4049:
4044:
4039:
4033:
4031:
4025:
4024:
4022:
4021:
4016:
4011:
4006:
4001:
3995:
3993:
3989:
3988:
3986:
3985:
3980:
3975:
3970:
3965:
3960:
3958:Space-division
3954:
3952:
3946:
3945:
3943:
3942:
3937:
3936:
3935:
3930:
3920:
3919:
3918:
3908:
3903:
3897:
3895:
3887:
3886:
3884:
3883:
3882:
3881:
3871:
3870:
3869:
3859:
3854:
3849:
3848:
3847:
3837:
3831:
3829:
3821:
3820:
3818:
3817:
3812:
3807:
3802:
3797:
3795:Camille Tissot
3792:
3787:
3782:
3777:
3772:
3770:Claude Shannon
3767:
3762:
3760:Tivadar Puskás
3757:
3752:
3747:
3742:
3737:
3732:
3730:Antonio Meucci
3727:
3722:
3717:
3712:
3707:
3702:
3700:Charles K. Kao
3697:
3692:
3687:
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3677:
3675:Harold Hopkins
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3662:
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3647:
3642:
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3632:
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3577:
3575:Emile Berliner
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3557:
3552:
3547:
3542:
3536:
3534:
3530:
3529:
3527:
3526:
3521:
3516:
3514:Videotelephony
3511:
3506:
3505:
3504:
3499:
3489:
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3456:
3451:
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3410:Radiotelephone
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3308:
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3298:
3296:Internet video
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3051:
3046:
3041:
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3024:Railway signal
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3016:
3011:
3009:Level crossing
3006:
3001:
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2934:Track geometry
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2926:
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2924:
2914:
2909:
2904:
2899:
2898:
2897:
2892:
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2885:overhead lines
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2860:
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2836:Gauntlet track
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2823:
2818:
2813:
2807:
2805:
2801:
2800:
2798:
2797:
2792:
2787:
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2780:Minimum radius
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2713:
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2709:infrastructure
2706:
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2696:
2689:
2681:
2672:
2671:
2669:
2668:
2666:United Kingdom
2663:
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2319:
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2299:
2294:
2289:
2284:
2279:
2277:Integra-Signum
2274:
2269:
2264:
2259:
2254:
2249:
2244:
2239:
2234:
2229:
2224:
2219:
2214:
2209:
2204:
2199:
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2178:
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2166:
2161:
2156:
2151:
2145:
2143:
2139:
2138:
2136:
2135:
2130:
2125:
2123:Cab signalling
2120:
2114:
2112:
2106:
2105:
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2102:
2097:
2092:
2087:
2082:
2077:
2072:
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2058:
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2029:
2024:
2019:
2014:
2009:
2004:
1998:
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1984:
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1981:
1974:
1967:
1959:
1953:
1952:
1947:
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1928:
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1911:External links
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1173:track circuits
1150:Cab signalling
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1144:Cab signalling
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1122:Main article:
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1118:Safety systems
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324:Most forms of
321:in that year.
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162:September 2019
104:. Please help
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32:railway signal
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3984:
3983:Code-division
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3979:
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3971:
3969:
3968:Time-division
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3899:
3898:
3896:
3894:and switching
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3858:
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3846:
3845:optical fiber
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3835:Coaxial cable
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3750:Radia Perlman
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3648:
3646:
3643:
3641:
3640:Lee de Forest
3638:
3636:
3635:Thomas Edison
3633:
3631:
3628:
3626:
3625:Donald Davies
3623:
3621:
3618:
3616:
3613:
3611:
3610:Claude Chappe
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3460:
3457:
3455:
3454:Smoke signals
3452:
3448:
3445:
3443:
3440:
3438:
3435:
3434:
3433:
3432:Semiconductor
3430:
3426:
3423:
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3292:
3291:Digital media
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3272:
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3070:Coaling tower
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3039:Signal bridge
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3017:
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3014:Loading gauge
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2513:Organisations
2511:
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1994:Block systems
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1508:Rail sabotage
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1489:Signal System
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1289:
1285:
1284:United States
1281:
1280:North America
1275:
1268:North America
1267:
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1254:
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1143:
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1134:
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1125:
1117:
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1112:
1105:
1103:
1102:(see below).
1101:
1096:
1093:
1089:
1084:
1075:
1068:
1066:
1064:
1060:
1056:
1052:
1047:
1045:
1041:
1037:
1033:
1029:
1024:
1022:
1021:steady yellow
1017:
1015:
1010:
1005:
1004:is required.
1003:
999:
994:
992:
988:
984:
979:
972:
965:
956:
951:
949:
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943:
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931:
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919:
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906:
904:
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895:
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890:
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880:
875:
868:
866:
862:
860:
854:
850:
848:
839:
834:
827:
825:
823:
817:
810:Fixed signals
809:
807:
802:
795:Axle counters
794:
792:
790:
786:
780:
777:
773:
772:track circuit
767:
766:Track circuit
759:
757:
751:
749:
744:
736:
734:
731:
724:
716:
714:
708:
705:
702:
699:
696:
693:
692:
691:
688:
684:
682:
677:
675:
667:
663:
659:
657:
656:stop and stay
652:
647:
640:
638:
636:
631:
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617:
615:
611:
607:
600:
598:
591:
589:
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583:
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347:
343:
339:
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334:stationmaster
331:
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326:train control
322:
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147:
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137:
133:
130:
126:
123: –
122:
118:
117:Find sources:
111:
107:
103:
97:
96:
91:This article
89:
85:
80:
79:
74:
72:
65:
64:
59:
58:
53:
48:
39:
38:
33:
19:
3950:Multiplexing
3825:Transmission
3790:Nikola Tesla
3780:Henry Sutton
3735:Samuel Morse
3665:Robert Hooke
3630:Amos Dolbear
3565:John Bardeen
3484:
3464:Telautograph
3368:Mobile phone
3323:Edholm's law
3306:social media
3239:Broadcasting
3054:Wayside horn
3004:Interlocking
2984:Catch points
2958:
2944:Water trough
2846:Passing loop
2826:Pocket track
2811:Balloon loop
2775:Ladder track
2494:Union Switch
2398:Wayside horn
2242:Catch points
2149:Axle counter
2080:Interlocking
2032:Moving block
1985:
1901:November 26,
1899:. Retrieved
1892:the original
1887:
1869:the original
1860:
1852:the original
1841:
1829:the original
1822:
1794:
1784:December 13,
1782:. Retrieved
1777:
1768:
1760:the original
1751:
1742:
1733:
1727:
1715:. Retrieved
1706:
1699:
1687:. Retrieved
1680:the original
1667:
1648:
1629:February 12,
1627:. Retrieved
1620:the original
1607:
1597:February 17,
1595:. Retrieved
1588:the original
1583:
1474:
1465:
1446:
1436:
1424:
1417:
1387:
1353:
1287:
1277:
1260:
1256:
1250:
1235:
1231:
1229:
1220:
1208:
1203:interlocking
1196:
1193:Interlocking
1187:Interlocking
1177:transponders
1165:
1161:
1135:
1127:
1110:
1109:
1099:
1097:
1085:
1081:
1062:
1058:
1054:
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1031:
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1001:
997:
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986:
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922:
920:
915:
911:
910:
902:
888:
884:
863:
855:
851:
843:
819:
804:
801:Axle counter
784:
781:
769:
755:
746:
726:
723:Moving block
717:Moving block
712:
689:
685:
678:
671:
665:
661:
655:
634:
627:
612:
608:
604:
595:
582:single track
579:
575:interlocking
560:
537:
517:
508:
498:
496:
452:
448:
433:
425:
420:train orders
418:
411:
396:
392:
389:
384:
378:
375:
371:
367:
358:
354:single-track
346:safe-working
345:
341:
337:
323:
290:
282:
281:
263:
248:
230:
221:
202:
168:
159:
149:
142:
135:
128:
116:
95:verification
92:
68:
61:
55:
54:Please help
51:
18:Block signal
4150:NPL network
3862:Radio waves
3800:Alfred Vail
3710:Hedy Lamarr
3695:Dawon Kahng
3655:Elisha Gray
3615:Yogen Dalal
3540:Nasir Ahmed
3474:Teleprinter
3338:Heliographs
2979:Buffer stop
2939:Water crane
2851:Track gauge
2790:Tie/Sleeper
2656:Switzerland
2631:New Zealand
2626:Netherlands
2332:Slide fence
2085:Lever frame
1800:"Hong Kong"
1374:rule book.
1257:Safeworking
1078:underneath.
1059:two yellows
641:Fixed block
567:legislation
429:dispatchers
216:introducing
4283:Categories
4196:Antarctica
4155:Toasternet
4077:Television
3560:Paul Baran
3492:Television
3476:(teletype)
3469:Telegraphy
3447:transistor
3425:Phryctoria
3395:Photophone
3373:Smartphone
3363:Mass media
3152:Industrial
3136:Water stop
3097:for trains
3089:Roundhouse
3063:Structures
3049:Train stop
2999:Guard rail
2974:Block post
2962:and safety
2959:Signalling
2890:third rail
2863:Rail track
2856:dual gauge
2740:Baulk road
2564:By country
2347:Train stop
2312:RS4 Codici
2070:Block post
1689:August 18,
1255:is called
899:Red: Stop.
681:kilometres
563:Parliament
525:signal box
406:See also:
380:detonators
356:railways.
224:April 2009
199:references
132:newspapers
57:improve it
4180:Americas
4169:Locations
4140:Internet2
3901:Bandwidth
3605:Vint Cerf
3502:streaming
3480:Telephone
3420:Semaphore
3311:streaming
3102:for goods
3044:Tell-tale
2875:Rail yard
2841:Guide bar
2821:Headshunt
2804:Trackwork
2770:Fishplate
2760:Date nail
2721:(history)
2571:Australia
2424:AŽD Praha
2383:Crossbuck
2287:Crocodile
1921:(English)
1471:Hong Kong
1253:Australia
1241:Australia
1226:Argentina
1183:systems.
840:, Germany
838:Steinfurt
552:Sri Lanka
541:signalman
512:stopwatch
493:, Finland
456:collision
414:telegraph
385:torpedoes
330:signalman
307:collision
102:talk page
63:talk page
4248:Category
4135:Internet
4125:CYCLADES
4042:Ethernet
3992:Concepts
3916:terminal
3867:wireless
3690:Bob Kahn
3533:Pioneers
3358:Internet
3249:Cable TV
3157:Military
3114:building
3084:Platform
2994:Derailer
2912:Roll way
2831:Junction
2730:Axe ties
2661:Thailand
2469:Safetran
2459:Magnetic
2444:Griswold
2393:E-signal
1717:June 27,
1480:See also
1429:Archived
1335:Class I
1328:Class I
1088:Moorgate
438:and the
344:(US) or
272:Class 66
4268:Commons
4258:Outline
4211:Oceania
4130:FidoNet
4115:ARPANET
3928:circuit
3497:digital
3226:History
3167:station
3162:Private
3109:Station
2785:Profile
2735:Ballast
2606:Germany
2596:Finland
2581:Belgium
2576:Bavaria
2479:Siemens
2454:Hitachi
2429:Federal
2414:Adtranz
2317:SelTrac
2164:Treadle
2110:Signals
1398:Finnish
1378:Finland
1366:. Most
1051:step up
881:, Japan
822:signals
666:proceed
635:proceed
565:passed
519:of the
491:Iisalmi
350:signals
299:railway
212:improve
146:scholar
4206:Europe
4176:Africa
4160:Usenet
4120:BITNET
4057:Mobile
3933:packet
3442:MOSFET
3437:device
3234:Beacon
2929:Switch
2917:Siding
2717:Tracks
2651:Sweden
2646:Poland
2641:Norway
2611:Greece
2601:France
2586:Canada
2489:Thales
2419:Alstom
2388:Wigwag
2267:EBICAB
2237:Balise
1824:Trains
1655:
1493:Gantry
1394:EBICAB
1315:, and
1259:. The
1199:points
1055:yellow
996:Under
981:Under
940:Under
921:Under
658:aspect
499:blocks
340:(UK),
313:, the
289:), or
201:, but
148:
141:
134:
127:
119:
4189:South
4184:North
4145:JANET
4082:Telex
4072:Radio
3911:Nodes
3906:Links
3827:media
3405:Radio
3390:Pager
3318:Drums
3284:video
3279:image
3269:audio
3145:Types
3124:ghost
3119:clock
3093:Shed
2707:Rail
2621:Japan
2616:Italy
2591:China
2525:AREMA
2474:Saxby
2327:SACEM
2272:IIATS
2197:ATACS
2042:Token
1895:(PDF)
1884:(PDF)
1872:(PDF)
1865:(PDF)
1711:(PDF)
1683:(PDF)
1676:(PDF)
1623:(PDF)
1616:(PDF)
1591:(PDF)
1580:(PDF)
1560:Notes
1456:Japan
1443:India
1420:Italy
1408:Italy
1175:, to
1063:green
785:prove
776:relay
674:token
586:token
460:token
303:rails
153:JSTOR
139:books
4201:Asia
4087:UUCP
4047:ISDN
3172:list
3129:list
2750:Cant
2545:IRSE
2540:HMRI
2449:Hall
2192:ASFA
2187:ALSN
1939:and
1903:2023
1843:IEEE
1786:2020
1756:RSSB
1719:2023
1691:2019
1653:ISBN
1631:2017
1599:2024
991:stop
914:and
730:GNSS
529:bell
125:news
4092:WAN
4062:NGN
4052:LAN
3333:Fax
3274:DCT
2949:Wye
2555:UIC
2535:FRA
2530:ERA
2520:AAR
2439:GRS
1439:).
1418:In
1362:or
1278:In
1138:fog
1061:or
1044:red
535:".
383:or
332:or
108:by
4285::
1919:,
1886:.
1846:.
1840:.
1821:.
1776:.
1754:.
1750:.
1639:^
1582:.
1568:^
1404:.
1400::
1311:,
1057:,
668:).
311:UK
295:AE
287:BE
270:A
66:.
4219:)
4215:(
3210:e
3203:t
3196:v
3077:/
2700:e
2693:t
2686:v
1978:e
1971:t
1964:v
1905:.
1802:.
1788:.
1721:.
1693:.
1661:.
1633:.
1601:.
1435:(
1234:(
293:(
285:(
255:)
249:(
237:)
231:(
226:)
222:(
208:.
175:)
169:(
164:)
160:(
150:·
143:·
136:·
129:·
98:.
73:)
69:(
34:.
20:)
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