Token (railway signalling)
Encyclopedia
In railway signalling
Railway signalling
Railway signalling is a system used to control railway traffic safely, essentially to prevent trains from colliding. Being guided by fixed rails, trains are uniquely susceptible to collision; furthermore, trains cannot stop quickly, and frequently operate at speeds that do not enable them to stop...

, 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
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....

. The token is clearly endorsed with the name of the section it belongs to. A token system is used for single lines because of the very much greater risk of serious collision in the event of irregular working by signalmen or traincrews, than on double lines.

Principle

The operation of a bidirectional single track line has obvious problems, the most serious of which is the possibility of two trains traversing the line travelling towards each other, both drivers unaware that the other is using the line. The simplest method of controlling such a line is to only have a single engine operational, on the basis that a single train cannot collide with itself, and in the absence of another engine, there is nothing else for it to collide with. Such a system is known as 'one engine in steam'. Such schemes were used, and indeed still are used on some branches of rail networks, and on heritage railways. The main problem with such a scheme is that it is best suited to a completely isolated branch of single track line. Where the section has to be integrated into a larger railway system, it becomes exceptionally limiting in the level of operations that it allows, and the opportunity for a mistake to be made, and an ensuing accident to occur, is high.

Instead, rather than rely on a single engine, reliance is placed on having a single physical object available for the single track section and ruling that only if an engine driver is in physical possession of that object, is he permitted to traverse the single line section. That object is known as a token and is identified as to which single track section it belongs.

Forms of token

Tokens have existed in a variety of physical forms:
  • staff
  • tablet
  • ball
  • key

Token only

The token system was developed in Britain
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...

 in the 19th century, to facilitate safe working of single-line railways. If a branch line is a dead end with a simple shuttle train service, then a single token is sufficient. The driver of any train entering the branch line (or occupying any part of it) must be in possession of the token, and no collision with another train is possible. For convenience in passing it from hand to hand, the token was often in the form of a staff, typically 800 mm long and 40 mm diameter, and is referred to as a train staff. Such a staff is usually literally a wooden staff with a brass plate stating the two signal boxes between which it is valid.

In UK terminology, this method of working on simple branch lines was originally referred to as One Engine in Steam (OES), and later One Train Working (OTW). However the system was used on long through lines as well; R H Dutton, Chairman of the London and South Western Railway
London and South Western Railway
The London and South Western Railway was a railway company in England from 1838 to 1922. Its network extended from London to Plymouth via Salisbury and Exeter, with branches to Ilfracombe and Padstow and via Southampton to Bournemouth and Weymouth. It also had many routes connecting towns in...

 explained in 1876 the slow journey time between Exeter and Plymouth by saying, "the cause of the delay is the stopping at every station on the staff system. That really does cause a great delay because if the staff is not there, the train must stop while a man is sent on a horse to get it [from the other end of the section]"; quoted in Williams.

Staff and Ticket

Using only a single token does not provide convenient operation when consecutive trains are to be worked in the same direction. The simple token system was therefore extended: if one train was to be followed by another in the same direction, the driver of the first train was required to be shown the token, but not take possession of it (in theory he was supposed to physically touch the token, but this was not strictly followed). He was given a written authority to enter the single line section, referred to as the ticket. He could then proceed, and a second train could follow. In the earliest days the second train could proceed after a designated time interval, as on double lines at the time; for example in the circumstances 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...

 of 1889. Later, adoption of the electric telegraph system enabled a form of block working to be implemented.

Seeing the train staff provided assurance that there could be no head-on collision. To ensure that the ticket is not issued incorrectly, a book of numbered tickets is kept in a locked box, the key to which is permanently fastened to the token, or is the token. In addition, the lock prevents the token being removed until the ticket box is closed, and it cannot be closed unless the book of tickets is in the box. Once a ticket is issued, its number is recorded in a Train Register book, and the token is locked in a secure place. This system is known as staff and ticket. This system is still in use today as part of the Melbourne Metropolitan System between Eltham and Hurstbridge.

In a variation on this principle, called divisible train staff, a section of the token referred to as the ticket portion was designed to be removed and handed to the driver instead of a paper ticket.

Electric token

The staff and ticket system was still too inflexible for busy lines, as it did not allow for the situation where the train intended to carry the actual token was cancelled or running very late. To provide for this, the electric train token system was developed. Each single-line section is provided with a pair of token instruments, one at the 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...

 at each end. A supply of identical tokens is stored in the instruments, which are connected together. A token can be removed from one instrument only if both signalmen co-operate in agreeing to the release. Once a token has been removed, another cannot be removed until the token which is "out" is replaced in either instrument. (There are variations on this sequence of events.) By this means, it can be ensured that at any one time, only one token is available to be issued to a driver. Tokens belonging to adjacent sections have different configurations to prevent them being inserted into the wrong instrument.

Nevertheless, in the Abermule train collision
Abermule train collision
The Abermule train collision was a head-on collision which occurred at Abermule, Montgomeryshire, Wales on 26 January 1921, killing 17 people. The crash arose from misunderstandings between staff which effectively over-rode the safe operation of the Electric Train Tablet system protecting the...

 in 1921, lax working procedures allowed the safeguards provided by the electric token system to be circumvented.

Collection of the token

In a basic railway situation, the token can be collected personally by the driver at the start of his work on a branch line, and surrendered by him at the end of his work there.

Where the single line section is part of a through route, then it is likely that each passing train would require to surrender and collect a token at each token station. Where the trains stop at every station this is a convenient arrangement, but where some trains run through without requiring to make a call, it was necessary for the signalman to exchange tokens with the fireman (in the case of steam trains) as the train passed at slow speed. In the case of driver-only operated trains, the train must stop for the token exchange.

A large staff could be handed over without any special apparatus, but if the system in use employed miniature staffs, tablets or key tokens, these were usually placed in a leather pouch attached to a hoop, and the fireman could put his arm through the hoop held up by the signalman, and vice versa as the locomotive ran past. In UK practice the permitted speed for this was 15 mph in daylight, but there are stories of drivers anxious to make up lost time when running late, and passing the exchange point at much higher speeds; bruised upper arms were common among signalmen and firemen on such lines.

Fixed token exchange apparatus was used on some railways. Trackside equipment was fitted near each signal box to hold the pouch containing the token and to receive the token pouch that was being given up.

Automatic exchange

Certain railways developed mechanical systems that enabled faster handover, using catcher devices that could be extended from the locomotive cabside just before the train passed the exchange point and which automatically retracted clear after the actual exchange. These enabled handover speeds of 40 mph; such a system was the Whitaker system on the Somerset & Dorset Railway, and the Manson system on the Great North of Scotland Railway
Great North of Scotland Railway
The Great North of Scotland Railway was one of the smaller Scottish railways before the grouping, operating in the far north-east of the country. It was formed in 1845 and received its Parliamentary approval on June 26, 1846, following over two years of local meetings...

. When the Aberdeen to Inverness passenger service was converted to diesel multiple unit operation in the late 1950s, the train-borne equipment was fixed adjacent to the train guard's compartment, and he was responsible for managing the mechanical handover; a special buzzer code enabled him to confirm to the driver that the correct token had been successfully received.

Electronic token systems

Developments in electronic systems have led to the development of electronic token systems. Trains are able to run over consecutive single-track sections, with the whole operation being controlled from a single central control room. Every train carries a special electronic unit that receives and sends an encrypted block of data which represents the token. The system is designed such that the control centre can only issue one token for any particular section until it is returned. Trains cannot send tokens to each other. This system allows the whole line to operate without any further signalling personnel. The system has operated without major incident.

Intermediate block posts

In certain circumstances it was convenient to shorten the single line sections by providing an intermediate signal box equipped with token instruments without providing a passing loop there. This was done if there was, for example, an important siding connection at the intermediate location. It also enabled following through trains to run at closer headways, but did not facilitate opposing movements.

Because of the greater risk of collision in the event of irregular working, the practice was deprecated in the UK, although some examples did exist for example at Beddington Lane on the Wimbledon - West Croydon line before resignalling. Usually in such cases special interlocking was provided between the two instruments at the intermediate signal box to ensure that trains could not be accepted from opposing directions at the same time.

A disaster at such an intermediate location occurred on the Somerset & Dorset Joint Railway at Foxcote, near Radstock, in the Foxcote collision of 1876
Radstock rail accident
The Radstock rail accident took place on the Somerset and Dorset Joint Railway in south west England, on 7 August 1876. Two trains collided on a single track section, resulting in fifteen passengers being killed....

. This occurred before the S&DJR was equipped for token working and was relying on block instruments only - a catalogue of errors led to two passenger trains entering the same section from opposite ends.

Long section working

In double line working, at times when traffic is light it is convenient to "switch out" an intermediate signal box, allowing the signal boxes on either side to communicate directly for train control. On single lines this is more complicated because of the train tokens being identified with single line sections, but the difficulty can be overcome by some form of long section working.

A simple system used separable train staffs which fit together when intermediate block post
Block post
A block post in railway signalling is the signal box at one end of a block section. -German practice:In Germany block posts are known as Blockstellen and are defined as railway facilities on the open line that, as part of a block system, mark the end of a block section. The usually have a home...

s are closed, so that a driver receives the train staff for two or more consecutive sections from the first signalman. An alternative system employs special long-section token systems; when long section working is to be instituted, all the short section tokens must be in their respective instruments; by switching to the long-section method, tokens for the long section can then be obtained in the ordinary way. Obviously all the long-section tokens must be restored before the normal working can be resumed.

Working examples of this scheme may be found at:
  • North Yorkshire Moors Railway
    North Yorkshire Moors Railway
    The North Yorkshire Moors Railway is a heritage railway in North Yorkshire, England. First opened in 1836 as the Whitby and Pickering Railway, the railway was planned in 1831 by George Stephenson as a means of opening up trade routes inland from the then important seaport of Whitby. The line...

     in North Yorkshire, England
Between Goathland
Goathland railway station
Goathland railway station is a station on the North Yorkshire Moors Railway and serves the village of Goathland in North Yorkshire, England. It is famous for appearing in the television series Heartbeat and as Hogsmeade station the Hogwarts Express stop at in the Harry Potter films...

 and New Bridge Signal Box
Pickering railway station
Pickering railway station is the southern terminus of the North Yorkshire Moors Railway and serves the town of Pickering in North Yorkshire, England.-Whitby and Pickering Railway :...

 (via Levisham
Levisham railway station
Levisham railway station is a station on the North Yorkshire Moors Railway and serves the village of Levisham in North Yorkshire, England. Holiday accommodation is available in the form of a camping coach.-Origins :...

)
  • Severn Valley Railway
    Severn Valley Railway
    The Severn Valley Railway is a heritage railway in Shropshire and Worcestershire, England. The line runs along the Severn Valley from Bridgnorth to Kidderminster, following the course of the River Severn for much of its route...

     in Shropshire, England
Between and (via )
Between and Bewdley North
Bewdley railway station
Bewdley railway station serves the town of Bewdley in Worcestershire, England. It is the administrative headquarters of the Severn Valley Railway, and is the principal intermediate station on the line.-History:...

 (via )
  • West Somerset Railway
    West Somerset Railway
    The West Somerset Railway is a railway line that originally linked and in Somerset, England.It opened in 1862 and was extended from Watchet to by the Minehead Railway in 1874. Although just a single track, improvements were needed in the first half of the twentieth century to accommodate the...

     in Somerset, England
Between and stations (via )
  • Ffestiniog Railway
    Ffestiniog Railway
    The Ffestiniog Railway is a narrow gauge heritage railway, located in Gwynedd, Wales. It is a major tourist attraction located mainly within the Snowdonia National Park....

     in Gwynedd, Wales
Between and (via Rhiw Goch)
  • Ecclesbourne Valley Railway
    Ecclesbourne Valley Railway
    The Ecclesbourne Valley Railway is a long heritage railway in Derbyshire, the headquarters of the railway centre around Wirksworth station and services operate between Wirksworth and Duffield and Wirksworth and Ravenstor...

     in Wirksworth, Derbyshire, England
Between Wirksworth station yard and Duffield station
Between Wirksworth station and Ravenstor station on the Ravenstor 1 in 27 incline
  • Gloucestershire Warwickshire Railway
    Gloucestershire Warwickshire Railway
    The Gloucestershire Warwickshire Railway is a volunteer-run heritage railway on the Gloucestershire/Worcestershire/Warwickshire Borders that has reopened the closed railway line between Laverton Halt and Cheltenham Racecourse railway stations in Gloucestershire/Worcestershire., it currently...

     in Gloucestershire, England
Between and Cheltenham
Cheltenham Racecourse railway station
Cheltenham Racecourse railway station is a railway station serving Cheltenham Racecourse on the outskirts of Cheltenham in Gloucestershire, England....

 (via )

Unattended operation

Token instruments can be arranged for unattended operation, when they are operated by the train crew at intermediate crossing loops or at the terminus of the line. This system is widely found in Australia, where traffic density on many lines is low.

In the UK it is known as the "No-signalman key token system". Examples on the UK national network are the North Devon Line
Tarka Line
The Tarka Line is a railway line from Exeter to Barnstaple in Devon, England. The line follows the River Creedy, River Yeo and River Taw for some of its route...

, where the system was brought into use on December 1, 1987, the Heart of Wales Line
Heart of Wales Line
The Heart of Wales Line is a railway line running from Craven Arms in Shropshire to Llanelli in South Wales. It runs, as the name suggests, through some of the heartlands of Wales. It serves a number of rural centres en route, including several once fashionable spa towns, including Llandrindod Wells...

 (commissioned in 1986 ), the Matlock branch in Derbyshire and the Liskeard to Looe line
Looe Valley Line
The Looe Valley Line is an community railway from Liskeard to Looe in Cornwall, United Kingdom, that follows the valley of the East Looe River for much of its course...

 in Cornwall
Cornwall
Cornwall is a unitary authority and ceremonial county of England, within the United Kingdom. It is bordered to the north and west by the Celtic Sea, to the south by the English Channel, and to the east by the county of Devon, over the River Tamar. Cornwall has a population of , and covers an area of...

. Here the train guard not only operates the Tyer's No.9 electric token instrument controlling the upper section of the branch, but operates the points as well. The lower section is operated on the 'One Engine in Steam' principle with a simple wooden staff. Possession of the staff is required to unlock the ground frame controlling the points at Coombe Junction, where the two sections meet. There is no other signalling on the branch except to control entry and exit to and from the main line.

Token interlinking

After early experience with token systems, it became customary for the starting signal at token stations to be interlinked with the token instrument; on withdrawal of a token, the starting signal lever was released for one pull.

Sometimes an intermediate siding is provided on the single line section, and the token itself, or a key fixed to the end of it, unlocks the points for shunting there. The token is locked in the apparatus there, and the driver cannot retrieve the token until the points have been set to the through running position and locked again. In special situations where the sidings at the intermediate location are extensive, the equipment is arranged for the shunting train to be put wholly inside the sidings, clear of the main line; in this situation an intermediate token instrument can be provided, enabling the driver to surrender the token so that normal through working can take place on the single line while his train is at the sidings.

A corresponding arrangement sometimes applied where permanent way maintenance was carried out by motorised trolley. Usually this used special 'occupation key' instruments which were interlocked with the normal token instruments and provided at intermediate places where the trolley might be off-tracked (or stored overnight).

Working by pilotman

A variation of the token system is working by pilotman, where the place of the token is taken by a person who is designated the pilotman. This system is instituted if there is a failure of the token apparatus, or on double lines when one line is blocked and all the traffic in both directions is to be worked over the other line. The pilotman (identified by a red armband with 'PILOTMAN' in white letters) rides on the locomotive, or if another train is due to follow, the pilotman must personally instruct the driver to proceed through the section. The signalman must not pull the starting signal off until instructed by the pilotman to do so. The pilotman rides on the locomotive or in the driving cab of the last train to run in the same direction. Thus pilotman working is analogous to the 'staff and ticket' system, described above, where the pilotman himself becomes the token and his verbal instruction is the equivalent of the ticket.

It is sometimes necessary to provide the pilotman with a personal locomotive to cater for disruptions to the service. In such a case the pilotman's locomotive is usually coupled to the front of the actual train, but practice may vary depending on local track layout, types of trains etc.

The use of a pilotman for such purposes pre-dates the use of tokens.

Present day use

Until the late 20th century, the token system was standard on British single-track lines and it still remains on a number of lines there as well as elsewhere, such as the line between and Stranraer
Stranraer Harbour railway station
Stranraer railway station is a railway station that serves both the town of Stranraer, Dumfries and Galloway, Scotland and the port for ferries to Belfast, Northern Ireland. The station is 94.5 miles southwest of Glasgow and is the terminus of the Glasgow South Western Line...

 in south west Scotland
Scotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...

. Traditional token systems are also in use on 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 in Britain, for example on the Mid Hants Railway and the West Somerset Railway
West Somerset Railway
The West Somerset Railway is a railway line that originally linked and in Somerset, England.It opened in 1862 and was extended from Watchet to by the Minehead Railway in 1874. Although just a single track, improvements were needed in the first half of the twentieth century to accommodate the...

 which is fitted throughout with Tyer's electric token instruments.

The token system is currently used in Melbourne, Australia suburban system between Eltham and Hurstbridge on the Hurstbridge line.

The token method of working is sometimes still used for temporary situations such as through engineering works or where the signalling system has yet to be provided. In December 1981, a new underground line was opened in Melbourne
Melbourne
Melbourne is the capital and most populous city in the state of Victoria, and the second most populous city in Australia. The Melbourne City Centre is the hub of the greater metropolitan area and the Census statistical division—of which "Melbourne" is the common name. As of June 2009, the greater...

, Australia which provided a circular service around the city's central business district. Although normal services were not to begin for some time, for two months special services operated on Sundays to allow people to try the new line, and for this period the line operated with a train staff, although there was no provision for tickets to be used.

A very unusual token working was instituted on the line between Pakenham and Traralgon in Victoria
Victoria (Australia)
Victoria is the second most populous state in Australia. Geographically the smallest mainland state, Victoria is bordered by New South Wales, South Australia, and Tasmania on Boundary Islet to the north, west and south respectively....

, Australia for several months in 2006 whilst the line was being upgraded. During this period, the line was closed during the day, but opened each night to allow a few goods trains
Freight train
A freight train or goods train is a group of freight cars or goods wagons hauled by one or more locomotives on a railway, ultimately transporting cargo between two points as part of the logistics chain...

 through. The line is double track
Double track
A double track railway usually involves running one track in each direction, compared to a single track railway where trains in both directions share the same track.- Overview :...

 between Pakenham and Moe (except for a short 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....

 section). Three staffs were provided for the 100 km
Kilometre
The kilometre is a unit of length in the metric system, equal to one thousand metres and is therefore exactly equal to the distance travelled by light in free space in of a second...

 length, one each for the sections Pakenham—Warragul, Warragul—Moe, and Moe—Traralgon. The first two of these are partly or totally double-track sections, but the staffs in this case were applicable to both tracks, the effect being that only one of the tracks could be used at a time.

New South Wales

  • Ordinary Train Staff (OTS)
  • Ordinary Train Staff and Ticket (OTST)
  • Electric Train Staff (ETS)

See also

  • Annett's key
    Annett's key
    In railway signalling, an Annett’s key or Annett key is a large key that locks levers or other items of signalling apparatus, thereby functioning as a portable form of interlocking. When not in use, the key is normally held in an Annett's lock that is fixed to the lever or apparatus concerned...

  • Radio Electronic Token Block
    Radio Electronic Token Block
    Radio Electronic Token Block is a system of railway signalling used in the United Kingdom. It is a development of the physical token system for controlling traffic on single lines.- How it works :...

  • Signalling block systems
  • Single-line working
    Single-line working
    On a double track railway, single-line working refers to the practice of using one track out of two, usually when one of the tracks is out of use for maintenance or because of damage or some obstruction.- Circumstances :...

  • Tyers Electric Train Tablet
    Tyers Electric Train Tablet
    Tyer's Electric Train Tablet system is a form of railway signalling for single line railways used in several countries; it was first devised in Great Britain by engineer Edward Tyer after the Thorpe rail accident of 1874, which left 21 people dead...

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