staff and ticket

the basic principles

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 heritage railways and branches of national networks. The main problem with such a scheme is that it is only suited to a completely isolated piece of single track line. Where the section has to be integrated into a larger railway system, it is completely impractical.

Instead, rather than rely on a single engine, reliance is placed on having a single physical object available for the single track section a
nd 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.

token only

The token system was developed in Britain 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.

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.

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.

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 at each end. A supply of identical tokens is stored in the instruments. These instruments are connected together electrically, and one token can be removed from either instrument provided that both signalmen co-operate in agreeing to the release. When a token is "out" a second token cannot be removed, but when the token is put into either instrument, a token can then be removed from either instrument. (There are variations on this sequence of events.)

By this means, it was ensured that at any one time, only one token was available to be issued to a driver. Tokens belonging to adjacent sections have different configurations to prevent them being inserted into the wrong instrument.

collection of the token

Passing a miniature staff between station and train, with the use of a hoop. 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.

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.

Radio Electronic Token Block (RETB)

The development of modern electronics and "vital" or secure radio transmission systems has allowed railways to develop more cost effective signalling.  In rural areas of the UK, where long sections of single line require token block operation, a system for centralised control, using modern computer technology, was adopted.  It is known as Radio Electronic Token Block (RETB).

 At a number of locations in the UK, this system (shown in the diagram, left) has been in operation for over 10 years and allows one signalman to control several single line sections between passing loops.  One installation in Scotland controls over 100 miles of railway.

Each train operating over the single line is equipped with a special speech and data radio transmitter/receiver with a unique identity.  At the start of the single line, the driver stops and calls the control centre for authority to enter the section.  If the line is clear, the signalman in the control centre transmits a coded "electronic token" data message which is received by the train and then shows the authority for that section on a cab display.  The driver will then call for confirmation that he can enter the section.  Once in the single line section, he will advise the control centre that he has cleared the loop track.  A clearance marker board is specially provided to help him. When he has reached the end of the single line section, the driver calls the control centre again and offers to give up the token.  After a "handshake" procedure by the control centre, he sends the token back by radio data transmission to release the section.

The signalman is provided with a computer controlled radio system which allocates the coded tokens to each section and prevents more than one token being issued for an occupied section.  It also receives the tokens sent back by each train as it reaches the end of the single line section.  At the exits of the single line sections, the points are permanently set in the direction of normal running and are "trailable" for trains entering the section, i.e. they allow a train to pass through at reduced speed using the wheel flanges to move the point (switch) blades aside reset to the normal position.

A "Distant Board" complete with AWS ramp, warns the driver that he must slow down for the movement over the points leaving the single line.  The Points Indicator shows the position of the points.  A "Stop Board" at the end of the passing loop warns the driver to stop and ask for permission to enter the next single line section.  The "Loop Clear" board shows when the rear of the train is clear of the points. 

Tyer's Key-Token instrument

This system is commonly found on modern narrow gauge railways such as the Festiniog.

Token apparatus was pioneered from 1870 onwards by Tyer and Company Ltd., the early tokens taking the form of discs or tablets. Key token apparatus was first introduced in 1912 and with the greatly increased flexibility together with economy the system was widely adopted on single line railways all over the world.

Development of the instrument since the earliest days has been continuous and the latest instruments have many novel features and yet retain the component reliability which has been a feature of this design since its inception. Full use is made of die cast light alloys, thermo-plastic mouldings and rust-resisting alloy steels. Complete interchangability of component parts is ensured by extensive tooling and quality control

Paints and plating finishes are of the highest quality with the object of ensuring long life with the minimum of maintenance in the severest of environments


The No.12 Key Token Instrument is a multi-purpose unit, the basic design being common to all applications. As the requirements for each application varies i.e. length and impedance of electrical line, type of operating function, accessories required etc., a separate design is produced to suit the individual application.


It has long been accepted that the Key Token system provides the simplest and safest means of operating trains over a single line from one block post to another. The acceptance and retention of the token for that block section provides the driver with authority to occupy the line and only simple forms of signalling are necessary to ensure compliance with Operating Regulations. The token may also be used for such supplementary functions as the release of points for the occupation of an intermediate siding.

The first requirement of a token system is that extraction of a token from either end of a block section shall require the co-operation of both signalmen for that section and that it shall be impossible for a second token to be obtained (except where permissive working is in operation) until the token, already extracted, has been replaced in one or other of the section instruments.


The instrument is extremely simple to operate, and easy to maintain. It is absolutely foolproof, and no tampering can take place.

The instrument is neat and compact. It has only one moving part, viz., an electrically controlled rotary commutator directly operated by the key tokens. A key token can be restored to the instrument from which it was with­drawn in the event of a train being cancelled, or after having been used for shunting purposes only a small amount of battery power is required. No permanent currents are necessary. A minimum of working parts and in consequence, a minimum amount of maintenance.

Optional Accessories

Further accessories which are available include:­

a) The Key Token Balancer - a detachable unit which permits for the safe and efficient transfer of key tokens between instruments when out of balance working occurs. This situation occurs particularly when auxiliary instruments are employed.

b) The Key Token Stand - a ventilated metal cupboard onto which the instru­ment is placed which also provides space for the storage of the batteries which can be supplied as necessary.

c) Hand Generators

d) Telephones