Railway signalling

Railway signalling

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Railway signalling is a system used to control railway traffic safely, essentially to prevent trains from colliding
Collision
A collision is an isolated event which two or more moving bodies exert forces on each other for a relatively short time.Although the most common colloquial use of the word "collision" refers to accidents in which two or more objects collide, the scientific use of the word "collision" implies...

. Being guided by fixed rails
Rail tracks
The track on a railway or railroad, also known as the permanent way, is the structure consisting of the rails, fasteners, sleepers and ballast , plus the underlying subgrade...

, trains are uniquely susceptible to collision; furthermore, trains cannot stop quickly, and frequently operate at speeds that do not enable them to stop within sighting distance of the driver. In the UK, the Regulation of Railways Act 1889
Regulation of Railways Act 1889
The Regulation of Railways Act 1889 was an Act of the Parliament of the United Kingdom of Great Britain and Ireland...

 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
Armagh rail disaster
The Armagh rail disaster happened on 12 June 1889 near Armagh, Ireland when a crowded Sunday school excursion train had to negotiate a steep incline; the steam locomotive was unable to complete the climb and the train stalled. The train crew decided to divide the train and take forward the front...

 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
Signalman (rail)
A signalman or signaller is an employee of a railway transport network who operates the points and signals from a signal box in order to control the movement of trains.- History :...

 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 safeworking (Aus.). Not all these methods require the use of physical signals
Railway signal
A signal is a mechanical or electrical device erected beside a railway line to pass information relating to the state of the line ahead to train/engine drivers. The driver interprets the signal's indication and acts accordingly...

 and some systems are specific to single track
Single track (rail)
A single track railway is where trains in both directions share the same track. Single track is normally used on lesser used rail lines, often branch lines, where the traffic density is not high enough to justify the cost of building double tracks....

 railways.

The earliest rail cars were first 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 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


The simplest form of operation, at least in terms of equipment, is to run the system according to a timetable. A fixed schedule is drawn up with which every train crew must be familiar. Trains may only run on each section of track at their scheduled time, during which they have 'possession' and no other train is permitted to use the same section.

When trains are running in opposite directions on a single-track railroad, 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
Detonator (railway)
A railway detonator is a device used to make a loud sound as a warning signal to train drivers. The detonator is the size of a large coin with two lead straps, one on each side. The detonator is placed on the top of the rail and the straps are used to secure it...

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 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


With the advent of the telegraph in 1851, 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 order
Train order
Train order operation, or more accurately Timetable and Train order operation, is a largely obsolete system by which the railroads of North America conveyed operating instructions before the days of centralized traffic control, direct traffic control, and the use of track warrants conveyed by radio...

s
. 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
Wabash Railroad
The Wabash Railroad was a Class I railroad that operated in the mid-central United States. It served a large area, including trackage in the states of Ohio, Indiana, Illinois, Iowa, Michigan, Missouri and Ontario. Its primary connections included Chicago, Illinois, Kansas City, Missouri, Detroit,...

 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 favor 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.

Block signalling



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.

History of block signalling


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', and 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
Stopwatch
A stopwatch is a handheld timepiece designed to measure the amount of time elapsed from a particular time when activated to when the piece is deactivated. A large digital version of a stopwatch designed for viewing at a distance, as in a sports stadium, is called a stopclock.The timing functions...

 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
Electrical telegraph
An electrical telegraph is a telegraph that uses electrical signals, usually conveyed via telecommunication lines or radio. The electromagnetic telegraph is a device for human-to-human transmission of coded text messages....

, it became possible for staff at a station or signal box
Signal box
On a rail transport system, signalling control is the process by which control is exercised over train movements by way of railway signals and block systems to ensure that trains operate safely, over the correct route and to the proper timetable...

 to send a message (usually a specific number of rings on a bell
Bell (instrument)
A bell is a simple sound-making device. The bell is a percussion instrument and an idiophone. Its form is usually a hollow, cup-shaped object, which resonates upon being struck...

) 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
Signalman (rail)
A signalman or signaller is an employee of a railway transport network who operates the points and signals from a signal box in order to control the movement of trains.- History :...

 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.

The block system came into use gradually during the 1850s and 1860s and became mandatory in the United Kingdom after Parliament
Parliament of the United Kingdom
The Parliament of the United Kingdom of Great Britain and Northern Ireland is the supreme legislative body in the United Kingdom, British Crown dependencies and British overseas territories, located in London...

 passed legislation
Regulation of Railways Act 1889
The Regulation of Railways Act 1889 was an Act of the Parliament of the United Kingdom of Great Britain and Ireland...

 in 1889 following a number of accidents, most notably the Armagh rail disaster
Armagh rail disaster
The Armagh rail disaster happened on 12 June 1889 near Armagh, Ireland when a crowded Sunday school excursion train had to negotiate a steep incline; the steam locomotive was unable to complete the climb and the train stalled. The train crew decided to divide the train and take forward the front...

. This required block signalling for all passenger railways, together with interlocking
Interlocking
In railway signalling, an interlocking is an arrangement of signal apparatus that prevents conflicting movements through an arrangement of tracks such as junctions or crossings. The signalling appliances and tracks are sometimes collectively referred to as an interlocking plant...

, 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
Single track (rail)
A single track railway is where trains in both directions share the same track. Single track is normally used on lesser used rail lines, often branch lines, where the traffic density is not high enough to justify the cost of building double tracks....

 railways in the UK, particularly those with low usage, it is common to use token
Token (railway signalling)
In railway signalling, a token is a physical object which a locomotive driver is required to have or see before entering onto a particular section of single track. The token is clearly endorsed with the name of the section it belongs to...

 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



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, he must inform the signalman controlling entry to the block. Even if the signalman receives advice that the previous train has left a block, he is 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, he 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 white disc by day or a steady or flashing red lamp. If a train has entered the next block before the signalman sees that the disc or lamp is missing, he will ask the next signal box to stop the train and investigate.

Permissive and absolute blocks


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 driving by sight. This allows improved efficiency in some situations and is mostly used in the USA, and in most countries is restricted to freight trains only, and 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 20 mph or less) so that they are able to stop short of any obstruction. In most cases this will not be allowed during times of poor visibility (e.g. fog or falling snow).

Even when an absolute block system is implemented, multiple trains may enter a block with authorisation. This may be necessary e.g. in order to split or join trains together, or to rescue failed trains. In giving authorisation, the signalman also ensures the driver knows precisely what to expect ahead, and the driver must operate the train in a safe manner taking this information into account. Generally, the signal will remain at danger, and the driver will be given verbal authority, usually accompanied by a yellow flag, to pass a signal at danger, and the presence of the train in front will be explained. At locations where trains regularly enter occupied blocks, such as stations where coupling takes place, a subsidiary signal, sometimes known as a "calling on" signal, will be provided for these movements, otherwise they are accomplished through train orders.

Automatic block


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


Most blocks are "fixed", i.e. they include the section of track between two fixed points. On timetable, train order, and token
Token (railway signalling)
In railway signalling, a token is a physical object which a locomotive driver is required to have or see before entering onto a particular section of single track. The token is clearly endorsed with the name of the section it belongs to...

-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:
  • 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


One disadvantage of having fixed blocks is that the faster trains are allowed to run, the longer the stopping distance, and therefore the longer the blocks need to be, thus decreasing the line's capacity.

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: active and passive markers along the track and trainborne tachometers and speedometers (GPS systems cannot be used because they do not work in tunnels.) With a moving block, lineside signals are unnecessary, and instructions are passed directly to the trains. This has the advantage of increasing track capacity by allowing trains to run closer together while maintaining the required safety margins.

Moving block is in use on Vancouver's Skytrain
SkyTrain (Vancouver)
SkyTrain is a light rapid transit system in Metro Vancouver, British Columbia, Canada. SkyTrain has of track and uses fully automated trains on grade-separated tracks, running mostly on elevated guideways, which helps SkyTrain to hold consistently high on-time reliability...

, London's Docklands Light Railway
Docklands Light Railway
The Docklands Light Railway is an automated light metro or light rail system opened on 31 August 1987 to serve the redeveloped Docklands area of London...

, New York City's BMT Canarsie Line
BMT Canarsie Line
The Canarsie Line is a rapid transit line of the BMT Division of the New York City Subway system, named after its terminus in the Canarsie neighborhood of Brooklyn...

, and London's Jubilee Line
Jubilee Line
The Jubilee line is a line on the London Underground , in the United Kingdom. It was built in two major sections—initially to Charing Cross, in central London, and later extended, in 1999, to Stratford, in east London. The later stations are larger and have special safety features, both aspects...

. It was supposed to be the enabling technology on the modernisation of Britain's West Coast Main Line
West Coast Main Line
The West Coast Main Line is the busiest mixed-traffic railway route in Britain, being the country's most important rail backbone in terms of population served. Fast, long-distance inter-city passenger services are provided between London, the West Midlands, the North West, North Wales and the...

 which would allow trains to run at a higher maximum speed (140 mph), but the technology was deemed not mature enough, considering the large number of junctions on the line, and the plan was dropped. It forms part of the European Rail Traffic Management System
European Rail Traffic Management System
The European Rail Traffic Management System is an initiative backed by the European Union to enhance cross-border interoperability and signalling procurement by creating a single Europe-wide standard for train control and command systems....

's level-3 specification for future installation in the European Train Control System
European Train Control System
The European Train Control System is a signalling, control andtrain protection system designed to replace the many incompatible safety systems currently used by European railways, especially on high-speed lines.- History :...

, which will (at level 3) feature moving blocks that allow trains to follow each other at exact braking distances.

Track circuits


One of the most common ways to determine whether a section of line is occupied is by use of a track circuit
Track circuit
A track circuit is a simple electrical device used to detect the absence of a train on rail tracks, used to inform signallers and control relevant signals.- Principles and operation :...

. The rails at either end of each section are electrically isolated from the next section, and an electrical current is fed to both running rails at one end. A relay
Relay
A relay is an electrically operated switch. Many relays use an electromagnet to operate a switching mechanism mechanically, but other operating principles are also used. Relays are used where it is necessary to control a circuit by a low-power signal , or where several circuits must be controlled...

 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 check that the entire train has left the section. If part of the train is left in the section, that part will continue to be detected by the track circuit.

This type of circuit is used to detect the absence of trains, both for the purpose of setting the signal indication and for providing various interlocking functions — for example, not permitting points to be moved when a train is standing over them. Electrical circuits are also used to prove that points are in the appropriate position before a signal over them may be cleared. Modern UK trains, and staff working in track circuit block areas, carry Track Circuit Clips (TCC) so that, in the event of something fouling an adjacent running-line, the track circuit can be short-circuited. This places signals on that track to 'danger' and can be used to help prevent a collision before the signalman can be alerted.

Axle counters


An alternative method of determining the occupied status of a block is using devices located at its beginning and end that count the number of axles entering and leaving. If the same number leave the block as enter it, the block is assumed to be clear. Although axle counters can provide similar functionality to track circuits, they 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. When a block section has been left in an undetermined state, it may be worked under pilot working. The first train to pass through the section would typically do so at a speed no greater than 20 mph or walking pace in areas of high transition, reverse curvature and may have someone who has a good local knowledge of the area acting as the pilotman. A track circuited section will detect the presence of a train in section immediately.

Fixed signals


On most railways, physical signals
Railway signal
A signal is a mechanical or electrical device erected beside a railway line to pass information relating to the state of the line ahead to train/engine drivers. The driver interprets the signal's indication and acts accordingly...

 are 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


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' or 'caution', 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 day time viewing and another for night time 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



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


Signalling of British origin generally conforms to the principle of route signalling. Most railway systems around the world, however, use what is known as speed signalling.

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 his 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 a route onto which he has been diverted due to some emergency condition. Several accidents have been caused by this alone. For this reason, in the UK 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.

Under speed signalling, the driver is not informed which route the train will take, but the signal aspect informs him at what speed he may proceed. Speed signalling requires a far greater range of signal aspects than route signalling, but less dependence is placed on drivers' route knowledge.

Approach release


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 employed. This involves holding the junction signal at a restrictive aspect (typically 'stop') in order that the signals on the approach show the correct sequence of caution aspects. The driver will brake 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 will permit. 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 will display aspects appropriate to control the trains speed, so no 'approach release' is required.

Safety systems


The consequence of a train driver failing to respond to a signal's indication can be disastrous. As a result, various auxiliary safety systems have been devised. Any such system will necessitate the installation of trainborne equipment to some degree. Some systems only intervene in the event of a signal being passed at danger
Signal passed at danger
A Signal passed at danger , in British railway terminology, occurs when a train passes a stop signal without authority to do so. It is a term primarily used within the British Railway Industry, although it can be applied worldwide.-Categories of SPAD:...

 (SPAD). Others include audible and/or visual indications inside the driver's cab to supplement the lineside signals. Automatic brake application occurs if the driver should fail to acknowledge a warning. Some systems act intermittently (at each signal), but the most sophisticated systems provide continuous supervision.

In-cab safety systems are of great benefit during fog
Fog
Fog is a collection of water droplets or ice crystals suspended in the air at or near the Earth's surface. While fog is a type of stratus cloud, the term "fog" is typically distinguished from the more generic term "cloud" in that fog is low-lying, and the moisture in the fog is often generated...

, when poor visibility would otherwise require that restrictive measures be put in place.

Cab signalling




Cab signalling is a system that communicates track status information to the train cab (driving position), where the train driver can see the information. The simplest systems display the trackside signal aspect, while more sophisticated systems also display allowable speed and dynamic information about the track ahead. In modern systems, a train protection system is usually overlaid on top of the cab signalling system to warn the driver of dangerous conditions, and to automatically apply the brakes and bring the train to a stop if the driver ignores the dangerous condition. Cab signalling systems range from simple coded track circuits, to transponders that communicate with the cab, and communication-based train control systems.

Interlocking


In the early days of the railways, signalmen were responsible for ensuring any points
Railroad switch
A railroad switch, turnout or [set of] points is a mechanical installation enabling railway trains to be guided from one track to another at a railway junction....

 (US: switches) were set correctly before allowing a train to proceed. Mistakes were made which led to accidents, sometimes with fatalities. The concept of the interlocking
Interlocking
In railway signalling, an interlocking is an arrangement of signal apparatus that prevents conflicting movements through an arrangement of tracks such as junctions or crossings. The signalling appliances and tracks are sometimes collectively referred to as an interlocking plant...

 of points, signals and other appliances was introduced to improve safety. This prevents a signalman from operating appliances in an unsafe sequence, such as setting a signal to 'clear' while one or more sets of points in the route ahead of the signal are improperly set.

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 late 1980s, new interlocking systems have tended to be of the electronic variety.

Operating rules


Operating rules, policies and procedures are used by railroads to enhance safety. Specific operating rules may differ from country to country and even from railroad to railroad within the same country.

Australian operating rules



In Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

, operating rules are called Safeworking.

North American operating rules


In North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

 and especially the US
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, operating rules are called method of operation. There are five main sets of operating rules in North America:
  • Canadian Rail Operating Rules
    Canadian Rail Operating Rules
    The Canadian Rail Operating Rules is a set of operating rules for railways in Canada. The CROR is used by every Canadian railway.-Overview:The CROR rules are intended to enhance railway safety...

     (CROR), used by most Canadian railroads
  • General Code of Operating Rules
    General Code of Operating Rules
    The General Code of Operating Rules is a set of operating rules for railroads in the United States. The GCOR is used by nearly every Class I railroad west of the Mississippi River, most of the Class II railroads, and many Short-line railroads....

     (GCOR), used by many Class I railroad
    Class I railroad
    A Class I railroad in the United States and Mexico, or a Class I rail carrier in Canada, is a large freight railroad company, as classified based on operating revenue.Smaller railroads are classified as Class II and Class III...

    s, Class II railroad
    Class II railroad
    A Class II railroad in the United States is a mid-sized freight-hauling railroad, in terms of its operating revenue. , a railroad with revenues greater than $20.5 million but less than $277.7 million for at least three consecutive years is considered a Class II railroad...

    s, and many Short-line railroads
  • Northeast Operating Rules Advisory Committee
    Northeast Operating Rules Advisory Committee
    The Northeast Operating Rules Advisory Committee is a set of operating rules for railroads in North America. The NORAC rulebook is used by full and associate member railroads, located mostly in the Northeast United States.-Overview:...

     (NORAC), used by many railroads in the Northeast US
  • Class I Norfolk Southern uses a unique set of operating rules.
  • Class I CSX Transportation
    CSX Transportation
    CSX Transportation operates a Class I railroad in the United States known as the CSX Railroad. It is the main subsidiary of the CSX Corporation. The company is headquartered in Jacksonville, Florida, and owns approximately 21,000 route miles...

     uses a unique set of operating rules.

UK operating rules


In the UK
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

, operating rules are called method of working. It is commonly known 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/Freight Operating Company. Most heritage railway
Heritage railway
thumb|right|the Historical [[Khyber train safari|Khyber Railway]] goes through the [[Khyber Pass]], [[Pakistan]]A heritage railway , preserved railway , tourist railway , or tourist railroad is a railway that is run as a tourist attraction, in some cases by volunteers, and...

s operate to a simplified variant of a British Railways rule book.

Italian operating rules


In Italy
History of Railways in Italy
The railways in Italy are one of the most important infrastructure in the country, with c. of track.-Origins:Railways were introduced in Italy when it was still a divided country....

, railway signalling is described in a particular instruction called Regolamento Segnali (Signal Regulation).

Indian operating rules


In Indian Railways operating rules are called 'The General Rules'. The General Rules are common for all zonal railways of Indian Railway and can be amended only by the Railway Board. Subsidiary rules are added to the General Rules by zonal railways, which does not infringe the general rule.

See also

  • Institution of Railway Signal Engineers
  • Railroad chronometer
    Railroad chronometer
    Railroad chronometers, or Railroad Standard Watches, are specialized timepieces that once were crucial for safe and correct operation of trains in many countries...

  • Railroad switch
    Railroad switch
    A railroad switch, turnout or [set of] points is a mechanical installation enabling railway trains to be guided from one track to another at a railway junction....

  • Railway signal
    Railway signal
    A signal is a mechanical or electrical device erected beside a railway line to pass information relating to the state of the line ahead to train/engine drivers. The driver interprets the signal's indication and acts accordingly...

  • Railway slide fence
    Railway slide fence
    Part of a railway signaling system, a slide fence is a fence whose purpose is to prevent trains from being derailed by rock slides in mountainous areas where rock slides may occur without warning. The fence is designed to be displaced by a rock slide, causing the signaling system to display a stop...

  • Toronto subway and RT signals
  • Train speed optimization
    Train speed optimization
    Train speed optimization, also known as Zuglaufoptimierung, is a system that reduces the need for trains to brake and accelerate, resulting in smoother and more efficient operation....

  • Webb C. Ball
    Webb C. Ball
    Webster Clay Ball was a jeweler and watchmaker born in Fredericktown, Ohio. After a two-year apprenticeship to a jeweler, Ball settled in Cleveland, Ohio to join a jewelry store...


External links