Glossary of Terms


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Earth Isolation
Signalling circuits are insulated/isolated from earth and the presence of any earth fault on wiring is a definite danger to signalling circuitry and calls for protective measures to be taken.

Regional
Disciplines: Electrical
Easer (tread) Rail
A rail placed with its head along the outside and close to the head of the running rail and sloped at the ends to provide a bearing for the overhanging portion of hollowed out treads of worn wheels.

Preferred
Disciplines: Infrastructure
EATO
Electronically Assisted Train Order


Disciplines:
ECO
Electric Control Operator


Disciplines:
Effective Communication
The ability to successfully send, receive and understand information. The communication does not need to be continuous.

Preferred
Disciplines: ALL Disciplines
Electric Control Centre
A building containing apparatus for ther control of the feeder stations, track sectioning cabins and equipment associated with the overhead line equipment.

Preferred
Disciplines: Electrical
Electric Control Operator (ECO)
The worker in charge of the electrical control room, who controls the power supply to the overhead traction wiring equipment, and is responsible for all switching operations and isolations of electrical equipment.

Preferred
Disciplines: Electrical, Operations
Electric Lock
An electromagnetic device which prevents or restricts the movement of a mechanical lever in an interlocking frame, or other appliance, from being partially or completely operated.

Regional
Disciplines: Electrical, Infrastructure
Electric Locomotive
As distinguished from a diesel locomotive, the traction motors obtain power from a wire suspended above the track. Contact is made to this wire by a pantograph mounted on the roof of the locomotive.

Preferred
Disciplines: Rolling Stock
Electric Staff
A metal rod of prescribed design used as a token to authorise train movements into or through a block in electric staff territory.

Legacy
Disciplines: Train Control, Operations
Electric Staff Instrument
An electrically operated instrument, installed at each end of an electric staff section, which contains and controls the issue of staffs for the section. The staff instruments are electrically interlocked so that only one electric staff for the section can be obtained from either of the two instruments at any one time.

Regional
Disciplines: Train Control, Operations
Also referred to as 'electric train staff instrument'.
Alternative
Disciplines: Train Control, Operations
Electric Staff System
A system of safeworking, usually used on single lines in non track-circuited areas, to allow trains to travel safely in either direction. Under normal conditions the authority for a train to occupy the section is a metal token known as an electric staff obtained from an electric train staff instrument.

Regional
Disciplines: Train Control, Operations
Also referred to as 'electric train staff system'.
Alternative
Disciplines: Train Control, Operations
Electric Staff Territory
The portions of line where the electric staff system of safeworking is used.

Regional
Disciplines: Train Control
Electric Token Block
A signalling system used on single lines controlled by the use of physical tokens, only one of which can be released from the instruments for a section at any one time. The released token is the prime authority to enter the token section.

Overseas
Disciplines:
Electric Token Instrument
The equipment in a signal box for the operation of electric token block. Contains one or more electric tokens.

Overseas
Disciplines:
Electric Traction Infrastructure
Equipment and systems associated with the supply and reticulation of electricity for traction purposes, but excluding elements of civil infrastructure supporting or otherwise associated with the equipment or systems.

Preferred
Disciplines: Electrical
Electric Train
A train comprising one or more electric multiple units or a train hauled by an electric locomotive.

Preferred
Disciplines: Rolling Stock
Electric Vehicle Maintenance Centre (EVMC)
A designated location where maintenance work is carried out on electric traction vehicles.

Preferred
Disciplines: Rolling Stock
Electrical Control
Control, the operation of which is effected by a device using electric current.

Preferred
Disciplines: Electrical
Electrical Depression Bar
Apparatus with a bar and contacts which are operated when the wheels of a vehicle depress the bar.

Preferred
Disciplines: Electrical
Electrical Infrastructure
Equipment and systems for supplying and distributing electricity for traction purposes,
Wires, cables, and electrical equipment associated with low-voltage electrical switch rooms, signalling and substations.

Preferred
Disciplines: Electrical
Electrical Interlocking
Interlocking utilising the action of an electric current and which may act on a piece of apparatus by:
a) immobilising its control lever (by electric lock)
b) making inoperative the actuating of its control

Preferred
Disciplines: Electrical
Electrical Point Indicator
A colour light signal for indicating the position of points or derail.

Regional
Disciplines: Train Control, Operations
Electrical Representative
A person with the appropriate delegated authority and electrical engineering competence to make judgments about electrical safety.

Preferred
Disciplines: Electrical, ALL Disciplines
Electrical Safety Instructions
Instructions provided by the Rail Infrastructure Manager's Electrical Maintenance Representatives for work on or near electrical infrastructure.

Preferred
Disciplines: Electrical, ALL Disciplines
Electrical Section Or Subsection
A length or part of overhead traction wiring equipment which may be isolated from all other lengths of overhead line equipment by the operation of overhead line isolators.

Preferred
Disciplines: Electrical
Electrical Shunt
A by-path introduced into an electric circuit.

Preferred
Disciplines: Electrical
Electrical System Operator
The person responsible for managing the Network electrical system and authorising the removal and restoration of overhead supply.

Alternative
Disciplines: Electrical
Refer to 'electric control operator'.
Alternative
Disciplines: Electrical
Electrified Area
Any section of track equipped with overhead line equipment, or any substation or supply substation used to provide power for electric trains.

Preferred
Disciplines: ALL Disciplines
Electro-magnetic Interference (EMI)
The signalling electrical system requires to be protected against and have immunity to electrical interference in its operating environment and is required to not generate electrical interference that adversely affects other important systems in its environment. This is called electromagnetic compatibility. Electromagnetic interference includes radiated interference due to magnetic induction, capacitive coupling and radio transmissions.

Regional
Disciplines: Electrical
Electro-mechanical Interlocking
An interlocking area with an interlocking machine controlling both power and mechanically operated signalling field equipment.

Regional
Disciplines: Electrical
Electro-mechanical Repeater
Repeater, the indications of which are given by one or more arms (or needles) operated by electric current.

Preferred
Disciplines: Electrical
Electro-pneumatic Signal Box
A signal box from which the operation of apparatus is effected by means of electric circuits controlling pneumatic motors.

Preferred
Disciplines: Electrical
Electrolysis Bond
A device for electrically connecting a buried utility service (pipeline or cable) to adjacent DC traction return rails, to prevent electrolysis damage to the service by stray traction currents. The electrolysis bond incorporates equipment for the control of magnitude and direction of current flowing between the buried service and traction rails.

Regional
Disciplines: Electrical
Electronic Authority System
A generic term for systems of Safeworking that use electronic assistance in preparation and in some cases delivery of Authorities.

Preferred
Disciplines: Train Control, Operations
Electronic Token
An electronic message transmitted by radio between a signal box and train. It performs the function of a token but no physical token is required.

Regional
Disciplines: Train Control, Operations
Refer to RETB.
Alternative
Disciplines: Train Control
Related Term: RETB
Electronic Train Order Working (ETOW) Territory
The portions of line where the Electronic Train Order system of Safeworking is used.

Preferred
Disciplines: Train Control, Operations
Electronically Assisted Train Order (EATO)
Train orders transmitted electronically to train crews.

Preferred
Disciplines: Train Control, Operations
EMC
Electro Magnetic Capability


Disciplines:
Emergency
Incident requiring urgent action. The incident might involve death or serious injury, health or safety effects, significant damage to property or infrastructure.

Preferred
Disciplines: ALL Disciplines
Emergency Alarm
A direct communication channel to alert a signaller in an adjacent signalling centre to an emergency. provided in track circuit block territory as a replacement for emergency bell communication.

Regional
Disciplines: Train Control
Emergency Brake Application
Maximum brake application made when a train must be stopped in the minimum distance possible, initiated by the driver or other crew member, or by a fault in the brake system such as rupture to the brake pipe, air hoses becoming disconnected, etc.

Preferred
Disciplines: Operations, Rolling Stock
Emergency Braking Distance
The distance in which a train is capable of stopping in an emergency. Dependent upon train speed, train type, braking characteristics, train weight and/or gradient.

Preferred
Disciplines: Rolling Stock, Operations
Emergency Changeover Contactor
A contactor which changes over the load on a power supply to the emergency standby supply when the normal power supplies fails and changes it back when the normal power supply is restored.

Regional
Disciplines: Electrical, Train Control
Emergency Cover
A type of blocking facility used to cover a staff box or Electric Staff instrument.

Regional
Disciplines: Train Control
Emergency Crossover
A crossover in a double line automatic section where the points at both ends of the crossover are directly protected by automatic signals and the points are XL locked.

Regional
Disciplines: Train Control
Emergency Exit
A supplementary means of escape from a compartment, other than by the normal access doors.

Preferred
Disciplines: Rolling Stock
Emergency Indicator
A lineside sign that informs the driver of an emergency speed restriction ahead.

Regional
Disciplines: Train Control, Operations
Emergency Isolation
A de-energising of part or the whole of the overhead traction line equipment in an emergency.

Preferred
Disciplines: Electrical
Emergency Lighting
Lighting powered from a separate source (eg. battery) to the vehicle's main power source, providing illumination for evacuation purposes.

Preferred
Disciplines: Rolling Stock, Operations
Emergency Manual Release
A bypassing of the safeguards built into an interlocking. Some failures of equipment within the interlocking will prevent the signalling of trains. Under certain controlled conditions and prescribed procedures it is sometimes acceptable for the safeguard to be momentarily bypassed to allow the signalling to be operated.

Regional
Disciplines: Train Control
Emergency Release
A device, usually sealed, to permit the operation of a signalling function in case of emergency or failure.

Regional
Disciplines: Train Control
Emergency Release Key
Keys that when removed from their emergency release lock hold protecting signals at stop and permit the emergency operation of points.

Regional
Disciplines: Train Control
Emergency Release Lock
Equipment which is interlocked with protecting signals and holds an emergency release key used to release points in an emergency.

Regional
Disciplines: Train Control
Emergency Replacement Switch
A switch or button located in the signal box that enables the signaller to replace an automatic signal to danger in an emergency. The signal is not proved to be replaced.

Regional
Disciplines: Train Control
Refer Replacement Switch and 'emergency signals on control'.
Alternative
Disciplines: Train Control
Emergency Roof Entrance
A roof hatch or an area identified on the roof exterior for emergency services to cut through to gain access the rollingstock interior.

Preferred
Disciplines: Rolling Stock
Emergency Services Organisation
Refer to the Rail Safety National Law for definition.

Other
Disciplines:
Emergency Signals On Control (ESOC)
Provided (generally in areas controlled by CBI) to replace all signals to danger in an area controlled by an interlocking, either:
1. in response to a traffic emergency, or
2. where the interlocking fails to respond to commands.

Regional
Disciplines: Train Control
Emergency Speed Restriction
A temporary speed restriction not shown in the weekly operating notice, or which is more restrictive than shown, or which applies at a time not shown.

Regional
Disciplines: Train Control, Operations
Emergency Switch Machine Lock (ESML)
Equipment which is interlocked with protecting signals and the controlling mechanisms of power operated points so that the points can be manually operated when required in an emergency.

Regional
Disciplines: Train Control
Emergency Switch Machine Lock Key
Key held in the signal box to unlock emergency equipment cupboard housing ESML handle.

Regional
Disciplines: Train Control
EMI
Electro Magnetic Interface


Disciplines:
Abbreviation for 'electromagnetic interference'.
Alternative
Disciplines: Rolling Stock, Electrical
EMU
Electrical Multiple Unit


Disciplines:
Abbreviation for 'electric multiple unit', a multiple-unit passenger train in which the propulsion power is provided by electric power supplied from an external source such as overhead wires.
Alternative
Disciplines: Rolling Stock
EN
Euro norm or European Standard


Disciplines:
Abbreviated term for 'Euronorm', or 'European Standard'.
Alternative
Disciplines: Rolling Stock
End Batter (rail)
A permanent plastic deformation of a rail end at a joint resulting from wheel impacts.

Preferred
Disciplines: Infrastructure
End Of Train Detector
A receiver mounted in the track which detects the passing of a transmitter (end-of-train-marker) mounted on the end of a train. On non track circuited lines, can be used at turnout clearance points to provide an indication to the signalling system that a train is in clear.

Regional
Disciplines: Train Control, Operations
End Post
Refer to Insulation End Post.

Alternative
Disciplines: Electrical, Infrastructure
Related Term: Insulation End Post
End Throw
The curve throw towards the outside of a horizontal curve at the vehicle end which is the position of maximum outwards curve throw for a uniform vehicle.

Preferred
Disciplines: Rolling Stock
End-of-train Marker
A device, including tail lights, fitted to the trailing end of the last vehicle of a rail traffic consist to indicate the end of the consist.

Preferred
Disciplines: Train Control, Operations
End-of-train Monitor
A device secured to the coupler of the last vehicle which communicates via radio link to the locomotive and provides real time end-of-train air pressure and other related information.

Preferred
Disciplines: Rolling Stock, Operations
Energise
To provide an electrically operated device with its operating current or voltage.

Preferred
Disciplines: Electrical
Engineering Token
A type of electronic token that gives engineering staff possession of the line.

Overseas
Disciplines: Train Control, Operations
Refer Electronic Token
Alternative
Disciplines: Train Control, Operations
Enhanced Permissible Speed (EPS)
The permitted speed (higher than permissible speed) that applies to a specific type of train over a section of line.

Regional
Disciplines: Train Control, Operations
Entrance - Exit (NX)
A type of route control system of interlocking whereby the signaller operates one pushbutton at the commencement (entrance) of the required route and a second at the finish (exit) of the route. This action initiates the setting of all points required by the route.

Regional
Disciplines: Train Control, Infrastructure
Entrance-exit Free Lever Signal Box
Free lever signal box in which the control of a route is effected by joint operation of two levers corresponding to the extremities of the route.

Regional
Disciplines: Train Control
EP
Electro Pneumatic


Disciplines:
Abbreviated term for 'electro-pneumatic'.
Alternative
Disciplines: Train Control, Rolling Stock
EP Points Indication Box
Contacts within a box mounted on track between the point switches and activated by the facing point lock plunger lock slide on facing points with an electro-pneumatic (EP) point operating mechanism. The contacts verify the position of the plunger.

Regional
Disciplines: Train Control, Infrastructure
EP Points Plunger Lock
An electrically operated lock which locks the facing point lock plunger lock slide on a set of electro-pneumatic (EP) operated facing points to prevent unlocking of the points except as required and provided critical track locking is not against the movement of the points.

Regional
Disciplines: Train Control, Infrastructure
EPS
Enhanced Permissible Speed


Disciplines:
Abbreviated term for 'enhanced permissible speed'.
Alternative
Disciplines: Train Control, Operations
Equilibrium Cant
A train travelling at an intermediate speed such that the outward centrifugal force is exactly balanced by the effect of the inward applied cant is said to be at Balance Speed or Equilibrium Cant. In this situation there is no net lateral force on the train as the forces inwards and outwards on the curve are balanced.

Preferred
Disciplines: Infrastructure, Rolling Stock
ERTMS
European Rail Traffic Management System


Disciplines:
Abbreviated term for 'European Rail Traffic Management System'.
Alternative
Disciplines: Train Control
ESML
Emergency Switch Machine Lock


Disciplines:
ESOC
Emergency Signals on Control


Disciplines:
ETCS
European Train Control System


Disciplines:
Abbreviated term for 'European Train Control System'.
Alternative
Disciplines: Train Control
ETOW
Electronic Train Order Working


Disciplines:
European Rail Traffic Management System (ERTMS)
A system for managing rail traffic, enabling it to operate on compatible signalling systems across European borders.

Overseas
Disciplines: ALL Disciplines
European Train Control System (ETCS)
A three level, unified, modular automatic train protection specification to enhance interoperability across Europe.

Preferred
Disciplines: Train Control
Evaluator Equipment
Computing equipment provided to compare the outputs from the counting heads located at the extremities of an axle counter section.

Regional
Disciplines: Electrical, Infrastructure
Event Recorder
A device installed on rolling stock capable of recording multiple input parameters, in digital or analogue format, related to the operation of the rolling stock.
Also known as a 'data logger' or 'data recorder'.

Preferred
Disciplines: Rolling Stock
EVMC
Electronic Vehicle Maintenance Centre


Disciplines:
Exclusion Zone
An exclusion zone is a safety envelope around an overhead electric line. No part of a worker, operating plant or vehicle should enter an exclusion zone while the overhead electric line is energised (live).
Exclusion zones keep people, operating plant and vehicles a safe distance from energised overhead lines.
An exclusion zone, for a person, operating plant or vehicle for an overhead electric line, means the distance from the line stated for the person, plant or vehicle.
Exclusion zones extend in all directions, not just sideways. The exclusion zone will vary depending on the:
- voltage of the line
- whether the line is insulated or bare
- the level of competence, training and authorisation of the person carrying out the work.

Preferred
Disciplines: ALL Disciplines
Exclusive Occupancy
Sole occupancy of track within defined limits.

Preferred
Disciplines: ALL Disciplines
Exit Signal
The signal or buffer stop/board to which a train traversing a route is directed.

Regional
Disciplines: Train Control, Operations
Expansion
The lengthening or rails under the influence of rising temperatures.

Preferred
Disciplines: Infrastructure
Expansion Switches
A crossingwork assembly which allows relative longitudinal movement between consecutive rails on the same leg while also providing continuous vertical support for wheels.

Preferred
Disciplines: Infrastructure
Extendable
A container which can be extended to accommodate long freight such as structural steel.

Preferred
Disciplines: Rolling Stock, Operations