Glossary of Terms


Navigate the Glossary either via the interactive search or filter by alphabet or number.

AAR
Abbreviation for 'Association of American Railroads'.

Overseas
Disciplines: ALL Disciplines
Absolute Block
A system of train operation that prevents more than one train being in the block section at any one time.

Preferred
Disciplines: Train Control, Operations
Absolute Permissive Block
US concept - (was/is used in South Australia).
Absolute in direction, permits following moves through section (where intermediate signals are provided).

Regional
Disciplines: Train Control
Absolute Signal
A signal that must not be passed at stop without the authority of the Network Control Officer.

Preferred
Disciplines: Train Control, Operations
Absolute Signal Blocking (ASB)
A method used by Competent Workers to carry out work on track using controlled absolute signals set and kept at STOP, without a formally issued Work on Track Authority.

Preferred
Disciplines: Operations
AC Immune
A signalling EMC term used to describe products or systems that provide a degree of immunity to Electromagnetic Interference from AC electric traction infrastructure or other electrical distribution systems.

Preferred
Disciplines: Train Control, Electrical
AC Relay
A type of relay which is operated by an alternating current. One type of AC relay is an AC vane relay.

Preferred
Disciplines: Train Control
AC Track Circuit
A track circuit with a 50 Hertz alternating current track feed.

Preferred
Disciplines: Train Control
AC/DC Track Circuit
A DC track circuit with a rectified alternating current track feed.

Preferred
Disciplines: Train Control
Accept Lever
The lever or control device that is operated in order to accept a train towards the signaller's interlocking from the adjacent interlocking or section.

Regional
Disciplines: Train Control, Operations
Accept Signal
A controlled signal fitted with a designation plate inscribed 'ACCEPT', or fitted with an interlocking name plate inscribed with the name of the controlling signal box.
An accept signal is provided at the entrance to an interlocking which is at the exit end of a double line automatic section. The signal is used by the signaller to control the approach of trains from an area outside of the signaller's control to the controlled signal next ahead.

Preferred
Disciplines: Train Control, Operations
Accept/home Signal
The signal directly protects points, level crossings or other risks and allows the signaller to control the approach of trains from an area outside of the signaller's control to the controlled signal next ahead.
A controlled signal provided in place of an accept signal at some interlockings which are located at the exit end of a double line automatic section.

Preferred
Disciplines: Train Control, Operations
Acceptance
A block signalling term where a train is permitted to proceed towards the 'accepting' signal box. Block regulations provide for circumstances under which a signaller may accept a train.

Preferred
Disciplines: Train Control, Operations
Access
1. A designated safe way into, along, across or out of a rail corridor; or
2. A right to the provision of railway services by an industry participant.

Preferred
Disciplines: Operations
Access Agreement
A formal agreement between a train operator and Rail Infrastructure Manager allowing the train operator to operate on the Rail Infrastructure Managers network under agreed commercial, technical and operational conditions.

Preferred
Disciplines: Operations
Access Device
This includes ramps, steps, stairs, ladders and guardrails.

Other
Disciplines: ALL Disciplines
Access Lighting
Lighting of access equipment e.g. ladders and steps.

Preferred
Disciplines: Infrastructure, Operations
Access Manager
An organisation that provides and manages a rail network and safe method of entry to that network for Rail Transport Operators (RTO's)

Legacy
Disciplines: ALL Disciplines
Refer Rail Infrastructure Manager (RIM)
Preferred
Disciplines: ALL Disciplines
Access Path
Walkway, corridor, aisleway, etc.

Preferred
Disciplines: ALL Disciplines
access road
A maintained road or unformed road that provides access to, and within, the rail corridor.

Preferred
Disciplines: Infrastructure, Operations
Access User
An organisation that has an agreement with a Rail Infrastructure Manager (RIM) to enter and use a rail Network.

Legacy
Disciplines: Operations
Refer also Rail Transport Operator (RTO)
Preferred
Disciplines: Operations
Accessibility
Requirements to provide equivalent access to people with disabilities which are defined in the DSFAPT for passenger rolling stock.

Preferred
Disciplines: ALL Disciplines
Accessible Information
Accessible information: Information that is provided in alternative formats (such as Braille, audible information, raised text signs, hearing augmentation) for people with hearing or vision impairment, intellectual or cognitive impairment.

Preferred
Disciplines: ALL Disciplines
Accident
An uncontrolled, unplanned, undesired event that results in loss to people, property and process or has an adverse impact on the environment. The principle outcome of an accident is that it will always result in loss.

Preferred
Disciplines: ALL Disciplines
Accommodating Crank
A two-arm crank with vertical axis, one arm of which is curved to facilitate connection.

Preferred
Disciplines: Train Control
Accreditation
The formal means of establishing the rail safety standards and practices for each railway covered by the Rail Safety Acts. Rail Infrastructure Managers and train operators need to be accredited before owning and/or operating a railway.

Preferred
Disciplines: ALL Disciplines
Accreditation Authority
An authority of the State or Territory authorised to grant rail safety accreditation to Rail Transport Operators consistent with Rail Safety National Law 2012.

Preferred
Disciplines: ALL Disciplines
Accredited Rail Organisation
A rail organisation accredited consistent with Rail Safety National Law or other State based rail safety legislation by the Regulator to be a Rail Transport Operator or provider of Rolling Stock.

Refer Rail Transport Operator

Legacy
Disciplines: Operations
ACOP
Australian Code of Practice


Disciplines:
Acoustic Detector
Line side system used to detect suspected defective axle bearings by sound wave signature.

Preferred
Disciplines: Rolling Stock
Active Control Level Crossing
Track crossing incorporating physical barriers, warning signs, line marking, lights and audible devices to alert vehicular or pedestrain traffic that a train is approaching or crossing. Examples include gates, booms, flashing lights, bells and sirens.

Preferred
Disciplines: ALL Disciplines
Active Suspension System
A positive feedback system for rail guidance wheels which ensures that they maintain constant contact with the rail to give continuous guidance.

Preferred
Disciplines: Rolling Stock
Actuation Device
A device in a deadman system which requires continuous control input from the driver, typically via pressing or grasping by feet or hands. Also known as 'operator enable device or Drivers Safety Contol'.

Preferred
Disciplines: Rolling Stock
Adaptor Coupling
A coupling that enables two railway vehicles with dissimilar coupling systems to be coupled together.

Alternative
Disciplines: Rolling Stock
ADG
Abbreviation for 'Australian dangerous goods code'.

Preferred
Disciplines: Operations
Adjacent
Near to, close to.

Preferred
Disciplines: Operations
Adjoining
In contact with, connected to.

Preferred
Disciplines: Operations
Adjustable Crank
A right-angle crank, one arm of which is provided with means for varying its effective length.

Preferred
Disciplines: Train Control
ADR
Abbreviation for 'Australian design rules' applied to motor vehicles.

Alternative
Disciplines: ALL Disciplines
Advance
A position along the line ahead of a given position, when facing the direction a train travels on the line. The area through which a train travels after passing a given position.

Alternative
Disciplines: Operations
Refer In Advance.
Preferred
Disciplines: Operations
Advanced Starting Signal
In block signalling, a stop signal beyond the starting signal, and worked from the same signal box.

Also an alternative term for Section Signal

A signal beyond the points controlling the entry into the section

Preferred
Disciplines: Train Control, Operations
Also an alternative term for Section Signal.
Alternative
Disciplines: Train Control
Advanced Train Control System (ATCS)
An incomplete American development for advanced signalling and train control systems founded on a standard specification for a digital data communications network including a train-based communications platform. ATCS specifications would incorporate transmission based positive train separation as well as non-signalling features such as locomotive health monitoring.

Overseas
Disciplines: Train Control
Advanced Train Management System (ATMS)
A specific type of communication based train management system

Preferred
Disciplines: Train Control
Advertise
To give written or electronic notice, usually in advance, of planned activities

Preferred
Disciplines: Operations
Advisory Speed Board
A distinctive speed board indicating to drivers to reduce the speed of the train so that the train is not travelling in excess of the speed shown on the board before passing the next signal ahead. However, as soon as the driver observes that the next signal ahead is displaying a full clear indication, normal track speed for that indication may be resumed. The driver does not allow the train to exceed any other lower temporary or permanent track or train speed restrictions, irrespective of the speed indicated by the advisory speed board.

Regional
Disciplines: Operations
Aerial Cable
A multi-conductor cable, designed for erection on an overhead line wire route.

Regional
Disciplines: Electrical
AF Track Circuit
Audio Frequency track circuits consist of a transmitter which transmits a modulated audio frequency signal along the track to a receiver, which operates at the same frequency at the other end of the track circuit.  The receiver will only respond to a signal with the correct frequency, modulation and/or code.

Preferred
Disciplines: Electrical, Infrastructure
Affected Signal
A signal not available for normal use.

Preferred
Disciplines: Train Control, Operations
Air Brake
A braking system activated by change in air pressure.

Preferred
Disciplines: Rolling Stock, Operations
Air Horn
A device used to give warning

Preferred
Disciplines: Operations
Refer Audible Warning Device
Preferred
Disciplines: Operations
ALARP
Abbreviation for 'as low as reasonably practicable'.

Alternative
Disciplines: ALL Disciplines
Refer SFAIRP
Preferred
Disciplines: ALL Disciplines
Alignment
Alignment of track, referred to as horizontal or vertical alignment. Horizontal alignment is the design horizontal alignment of track (i.e. straights, curves, etc.), vertical alignment is the design vertical alignment of track (gradients and vertical curves).

Preferred
Disciplines: Infrastructure
Alignment Control Coupler
Coupler where the rotation from the centre position is limited in order to reduce the sideways derailing force during buff conditions in train operation.

Preferred
Disciplines: Rolling Stock
All Signals On
A signaller's control device that places or maintains all signals in a designated area to Danger.

Regional
Disciplines: Train Control
Allocated Space
A three dimensional space defined in the RISSB Accessible Rail Services: Code of Practice as a designated and reserved area for people with mobility aids.

Preferred
Disciplines: ALL Disciplines
Alphanumeric Route Indicator
A route indicator that conveys its information by illuminated alphanumeric characters. The indicators are designated Standard and 'miniature' as a reference to the readability categorisation of the indications.

Regional
Disciplines: Train Control
ALRP
As low as reasonably practical

Refer SFAIRP

Preferred
Disciplines: ALL Disciplines
Alternate Proceed Authority (APA)
An APA may be used to authorise rail traffic movements when the Proceed Authority normally provided by the system of Safeworking is not available.

Preferred
Disciplines: Operations
Alternating Current Track Circuit
Track circuit fed with alternating current.

Preferred
Disciplines: Electrical
Refer AC Track Circuit.
Alternative
Disciplines: Electrical
Aluminothermic Weld
A welding process used to join rails together. An aluminothermic reaction takes place within a crucible and the resultant metal flows into a mould enclosing the rail ends that are to be joined.

Preferred
Disciplines: Infrastructure
Refer Cadweld.
Alternative
Disciplines: Infrastructure
Anchor Block
The group of sleepers, with rail anchors or resilient fastenings, at each end of a module of track to be destressed. The anchor block is used for restraining the longitudinal movement of the rail when it is tensed.

Preferred
Disciplines: Infrastructure
Anchor Point
A means of providing restraint to contraction, expansion and creep of rail.

Preferred
Disciplines: Infrastructure
Angle (crossing)
Crossings may be designated by a number which refers to the cotangent of the splay angle or rate of slope (commonly referred as 'angle').

Preferred
Disciplines: Infrastructure
Annett Key/lock
A locking mechanism for releasing a ground frame. The key to unlock the ground frame is held captive in an annett's instrument or lock which can be released remotely from the signal box and interlocked with the signalling.

Regional
Disciplines: Train Control
Annunciator
An audible indicator, for example a bell or buzzer in a signal box or gate box.

Regional
Disciplines: Train Control
ANRP
Australian Network Rules and Procedures

Preferred
Disciplines: ALL Disciplines
Abbreviated term for 'Australian network rules and procedures'.
Preferred
Disciplines: ALL Disciplines, Operations
Anti Climb Device
A device fitted at vehicle ends that engages with the same device on an adjacent vehicle in a collision to resist one vehicle over-riding the adjacent vehicle.

Preferred
Disciplines: Rolling Stock
APA
Alternate Proceed Authority

Refer to Alternate Proceed Authority (APA)

Preferred
Disciplines: Operations
Related Term: Alternate Proceed Authority (APA)
API
American Petroleum Institute


Disciplines:
Abbreviated term for 'American Petroleum Institute'.
Overseas
Disciplines:
Apparatus
Apparatus refers to the signalling equipment system as a whole or as separate items of signalling control and operating equipment, signalling materials, and structures housing signalling equipment

Regional
Disciplines: Train Control
Apparatus Case (or Cupboard)
A housing which is intended for unprotected outdoor use. It is usually of metal construction (or wooden if a cupboard), smaller than a building or REB and usually capable of being transported as a made-up unit.

Regional
Disciplines: Train Control
Apparatus Function Test
Generally refers to function tests of an item of installed equipment, particularly trackside apparatus when set to work from the local controls.

Regional
Disciplines: Train Control
Application Logic
Any technology based method that configures a product so as to provide site-specific command and control instructions. This includes mechanical logic, electro-mechanical logic, electronic switching or code.

Regional
Disciplines: Train Control
Applied Cant
On curves in main line track it is usual to incline the track such that the outer rail in the curve is higher than the inside rail. The amount of inclination applied to the track is defined by the difference in height between the inner and outer rail, and this height difference is the Cant of the curve, often referred to the Applied Cant. The purpose of the applied cant is to allow train to negotiate the curve at higher speeds whilst reducing the risk of rollover and reducing discomfort to passengers. In a similar fashion to a motorcyclist leaning into a curve, the inward applied cant of the track counteracts the outward centrifugal force on the train.
The amount of applied cant to the track is a compromise. A train travelling at the permitted line speed would benefit from a higher amount of applied cant to counteract its higher centrifugal force as a result of its higher speed. However, a train that is slow moving, or even stopped, on the curve requires little applied cant. Therefore, the amount of applied cant on a curve is usually between these two requirements.

Preferred
Disciplines: Infrastructure
Approach Clearing
A term used in connection with the clearing of a signal upon the approach of a train.

Preferred
Disciplines: Train Control
Approach Control
The restriction of the aspect of a signal, to ensure that the driver can comply with the turnout speed, or to control the speed of a train for a warning call-on, shunt or POSA class route.

Regional
Disciplines: Train Control
Approach Lighting
A method of illuminating signal lights upon the approach of a train.

Regional
Disciplines: Train Control
Approach Locking
Approach locking is track locking applied to prevent the alteration of points interlocked by a route, or the setting of an opposing route, once the signal for the route has been cleared and an approaching train has received an indication that the signal has been cleared.

Regional
Disciplines: Train Control
Approach Release
An alternative term for Approach Control.

Regional
Disciplines: Train Control
Approach To
In relation to equipment on or alongside the track, positioned such that a train passes the point before reaching another defined item of equipment.
Also known as Rear.

Regional
Disciplines: Train Control
Alternate Term: Rear
Appropriate Authority
A generic term used to describe authorities e.g. Work Authority, Alternative Proceed Authority, etc.

Preferred
Disciplines: Operations
Approved Document
A train control diagram, train register book or any other document for recording train or track machine movements over a section of railway.

Preferred
Disciplines: ALL Disciplines
Approved Employee
A qualified employee who has delegated authority approved and published by the commission.

Preferred
Disciplines: ALL Disciplines
APTA
Abbreviated term for 'American Public Transportation Association'.

Overseas
Disciplines: ALL Disciplines
ARA
Abbreviated term for 'Australasian Railway Association'.

Preferred
Disciplines: ALL Disciplines
Area Of Conflict
A section of line beyond the signal at danger on which a head-on, crossing or same direction converging collision with another legitimately positioned train could occur in the event of a SPAD.

Regional
Disciplines: Train Control
Area Of Control
The extent of track subject to the control of a single signaller. Includes any automatic signalling supervised by the signaller.

Regional
Disciplines: Train Control
AREMA
Abbreviated term for 'American Railway Engineering and Maintenance of Way Association'.

Overseas
Disciplines: Infrastructure
ARL
Abbreviated term for 'Above Rail Level', as used in dimensions for height measured from top of rails, perpendicular to the plane of the rails.

Alternative
Disciplines: Rolling Stock
Armature Contact
The moving contact piece of a relay that connects to, and moves in unison with, the relay armature.

Regional
Disciplines: Electrical
ARO
Abbreviation for Accredited Rail Organisation.

Legacy
Disciplines: ALL Disciplines
Refer: Rail Transport Operator
Preferred
Disciplines: ALL Disciplines
Arrival Train Examination
Either roll by or after placement examination is to be conducted by examining staff on arrival at the train destination.

Alternative
Disciplines: Operations
ARS
Abbreviated term for 'automatic route setting'.

Preferred
Disciplines: Train Control
ARSC
Abbreviated term for the 'Acts, regulations, standards and codes of practice' applicable to those systems involved in an incident.

Preferred
Disciplines: ALL Disciplines
ARTC
Abbreviated term for 'Australian Rail Track Corporation'.

Preferred
Disciplines: ALL Disciplines
Articulated Connector
Connects two adjacent rolling stock bodies allowing them to angle with respect to each other and the whole assembly is supported by a single bogie.

Preferred
Disciplines: Rolling Stock
Articulated Platform
The individual end and intermediate units of an articulated flat or well wagon.

Preferred
Disciplines: Rolling Stock
Articulated Wagon
A wagon comprising two or more units, the adjacent ends of individual units being supported on a common bogie and permanently connected by a device that permits free rotation in all planes.

Preferred
Disciplines: Rolling Stock
As Rolled Rail
Rail that is cooled off the mill without accelerated cooling, and is not subsequently heat treated.

Preferred
Disciplines: Infrastructure
ASB
Abbreviated term for 'Absolute Signal Blocking', a method used by track workers to carry out work on track using controlled absolute signals set and kept at stop, without a formally issued work on track authority.

Preferred
Disciplines: Operations
Aspect
The displayed pattern or position of lights or arms used to give a signal indication.

Preferred
Disciplines: ALL Disciplines
Aspect Level
The level of interlocking required to be satisfied before a signal can display a proceed aspect.

Regional
Disciplines: Train Control
Aspect Sequence
The order of the displayed aspects to give the driver information about the aspect of the signal or signals ahead.

Regional
Disciplines: Train Control
Aspect Sequence Chart
A diagram, used during testing, showing the sequence of the aspects displayed at successive signals.

Regional
Disciplines: Train Control
Assisting Locomotive
A crewed locomotive other than the main locomotive on a train.

Legacy
Disciplines: Operations
Asymmetric Point Switch
A design of switch in which the switch rail cross section is asymmetric about its vertical axis and the height of the switch rail is approximately 2/3 the height of the stockrail. Points with asymmetric switches are also tangential.

Preferred
Disciplines: Infrastructure
At Grade Crossing
A crossing of a track by a roadway or pedestrian crossing at the same elevation. Also known as 'grade crossing'.

Preferred
Disciplines: Infrastructure
ATCS
Advanced Train Control System


Disciplines:
ATMS
Advanced Train Management System

Refer to Advanced Train Management System (ATMS)

Preferred
Disciplines: Train Control
Related Term: Advanced Train Management System (ATMS)
ATO
Abbreviated term for 'automatic train operation'.

Automatic Train Operation (ATO)

Preferred
Disciplines: Operations, Train Control
ATP
Abbreviated term for 'Automatic Train Protection', a system that supervises train speed and target speed, alerts driver of the braking equipment, and enforces braking when necessary.

Automatic Train Protection (ATP)

Preferred
Disciplines: Operations, Rolling Stock
ATR
Automatic Train Reporting

Automatic Train Reporting (ATR)

Regional
Disciplines: Train Control, Operations
ATSB
Abbreviated term for 'Australian Transport Safety Bureau'.

Australian Transport Safety Bureau

Preferred
Disciplines: ALL Disciplines
Attainable Speed
The maximum speed a train is able to achieve at the location.

Preferred
Disciplines: Train Control
Attended Block Location
A block location at which an authorised worker is on duty for the working of trains. Also know as Attended Location.

Preferred
Disciplines: Operations
Attended Location
A signalling location or block location that is switched in and controlled by a Competent Worker either on-site or at a remote location.

Preferred
Disciplines: Operations
Audible Track Warning Signals
Refer to Railway Track Signal 

Non-preferred
Disciplines: Operations
Related Term: Railway Track Signal
Audible Warning Device
A device, such as a whistle, siren, horn or hooter, used to give warning

Preferred
Disciplines: Operations
Australian Code Of Practice (ACOP)
The Standards, Codes, Guidelines and Rules developed for the Austarlian rail industry.

Preferred
Disciplines: ALL Disciplines
Australian Network Rules And Procedures (ANRP)
The master set of rules and procedures that define how Rail Infrastructure Rail Infrastructure Managers and Rail Transport train Operators operate safely on the Australian Rail Network.

Preferred
Disciplines: ALL Disciplines
Australian Rail Safety Standards (AS4292)
The principles and standards prepared, approved and published by the Standards Association of Australia relating to railway safety management.

An Australian Standard no longer supported and superseded by Rail Safety National Law.

Legacy
Disciplines: ALL Disciplines
Australian Transport Safety Bureau
The Australian Transport Safety Bureau (ATSB) is Australia's national transport safety investigator.

The ATSB's function is to improve safety and public confidence in the aviation, marine and rail modes of transport.

The ATSB is Australia's prime agency for the independent investigation of civil aviation, rail and maritime accidents, incidents and safety deficiencies.

Preferred
Disciplines: ALL Disciplines
Authorise
To give formal written, spoken or signalled authority for an action.

Preferred
Disciplines: Operations
Authorised Speed
The maximum speed as determined by the Rail Infrastructure Manager, subject to any lesser speed shown in a special train notice, authorised electronic management system or imposed by warning and caution boards or a permanent speed board.

Preferred
Disciplines: Operations
Automatic Block
System of sectional division in which the section signals are operated automatically by means of apparatus worked directly by the occupation or clearing of the section by a train.

Regional
Disciplines: Train Control
Automatic Control
Control which itself carries out the operations according to pre-determined conditions.

Regional
Disciplines: Train Control
Automatic Coupler
A fitting on the end of rolling stock that engages with a compatible fitting on adjacent rolling stock by the action of propelling the vehicles together.

Preferred
Disciplines: Rolling Stock
Automatic Function
A function that, under ordinary operation, is operated automatically by the passage of trains and is not interlocked with any other signalling function.

Regional
Disciplines: Train Control
Automatic Level Crossing
A level crossing equipped with flashing lights, audible warning devices and, sometimes, half boom barriers, which are normally controlled entirely by the approach of a train and not normally interlocked with the signals.

Regional
Disciplines: Train Control
Automatic Normalisation Of Points
Points which are automatically operated to the normal position when the route is normalised after the passage of a train.

Preferred
Disciplines: Infrastructure
Automatic Reclearing
Automatic reclearing, when initiated by the signaller, enables a controlled running signal route which has already been set, to operate in the same manner as automatic signals and thus avoid the need for the signaller to 'restroke' the signal to clear it again after the passage of a train. This feature is not generally provided if there is risk of wrong road movements occurring.

Regional
Disciplines: Train Control
Automatic Route Normalisation
The automatic normalising of signal routes after a train passes the signal.

Regional
Disciplines: Train Control
Automatic Route Setting (ARS)
A system which is used in conjunction with an interlocking system to automatically operate signals and points for the passage of trains. Signal routes over facing points are set automatically for trains based on information derived from timetables, train describers and/or a priority based algorithm.

Regional
Disciplines: Train Control
Automatic Signal
A signal that is normally controlled exclusively by the operation of track-circuits, or more precisely it is a signal which is controlled by the passage of trains and automatically gives an indication of the condition - occupied or clear - of the section or sections in its control.

Regional
Disciplines: Train Control
Automatic Switch Box
Equipment associated with a staff instrument at an unattended station in an electric train staff section. The automatic switch box enables an electric train staff for the section to be withdrawn from the staff instrument at the opposite end of the section, provided the staff instruments are in phase, as they would be if there is no other staff already withdrawn.

Regional
Disciplines: Train Control
Automatic Tensioning (auto Tensioning)
The main conductors, catenary and contact wire/s of the overhead line equipment are pulled to a required tension. Where tension is kept constant by means of weights, springs, or hydraulic units, the equipment is said to be 'automatically tensioned'.

Preferred
Disciplines: Electrical
Automatic Track Warning System (ATWS)
A system that gives trackside staff audible and/or visible warning of the approach of trains independently of the signalling system.

Preferred
Disciplines: Operations
Automatic Train Control (ATC)
Used to describe on-board automation that contributes to or replaces the driver's judgement as to how to control the train. (ATC=ATO+ATP).

Regional
Disciplines: Train Control
Automatic Train Operation (ATO)
A high reliability system that automatically operates the train's driving controls in accordance with information usually received from the trackside signalling equipment or traffic control system.

Regional
Disciplines: Train Control
Automatic Train Protection (ATP)
A system that supervises train speed and target speed, alerts driver of the braking equipment, and enforces braking when necessary. The system may be intermittent, semi-continuous or continuous according to its track-to-train transmission updating characteristics.

Preferred
Disciplines: Operations, Rolling Stock
Automatic Train Reporting (ATR)
The automatic reporting of the running of individual trains which is compared against the timetable. The information is usually derived from computer based train describer systems and the train's identity is recorded at the time it passes nominated signals, or over nominated track circuits, or over track transponders, or is entered manually at nominated locations. The details are usually compared with the actual timetable stored in a computer and reported by exception to nominated terminals on the computer's network.

Regional
Disciplines: Train Control
Automatic Train Stop
A trackside device, normally linked to a signal, which can raise an arm to apply the automatic airbrake of trains fitted with trip valves.

Regional
Disciplines: Train Control, Operations
Automatic Vehicle Identification (AVI)
A system which positively identifies a vehicle as it passes a location by reading an identification label on the vehicle, and relays this information to a control centre.

Regional
Disciplines: Train Control, Rolling Stock
Automatic Warning System (AWS)
A system that provides audible and visual warnings to the driver on the approach to signals, certain level crossings and emergency, temporary and certain permanent speed restrictions. It supervises the driver's reaction to signal caution aspects and indicates to the driver the passing of a clear aspect. Mostly advisory, however it will cause a brake application to be made automatically if the driver fails to react when approaching a restrictive aspect.

Regional
Disciplines: Train Control, Operations
Automatic Working (of A Controlled Signal)
A control function that enables a controlled signal to work automatically.

Regional
Disciplines: Train Control
Automatic Worksite Warning System
An approved device designed to provide advanced warning of approaching trains.

Alternative
Disciplines: Operations
Refer: 'automatic track warning system'
Alternative
Disciplines: Operations
Auxiliary Optical System
Duplicate lamp or filament on hot or cold standby.

Regional
Disciplines: Train Control
Auxiliary Supply Transformers
A transformer connected to the 25,000 volt overhead line equipment for the purpose of supplying standby power to trackside equipment.

Preferred
Disciplines: Electrical
Auxiliary Token Instrument
A supplementary token instrument usually located at the end of a token section but away from the signal box to facilitate prompt issue/return of tokens.

Legacy
Disciplines: Operations
Availability
The percentage of time that an item or system is able to perform its designed function.

Preferred
Disciplines: ALL Disciplines
AVI
Automatic Vehicle Identification

Automatic Vehicle Identification (AVI)

Preferred
Disciplines: Train Control, Rolling Stock
AWARE
Abbreviated term for 'Australia Wide Augmented Radio Environments' train communications system.

Alternative
Disciplines: ALL Disciplines
AWS
Abbreviation for 'automatic warning system'. AWS is a system which warns the driver of the aspect of the next signal. It is an advisory system only.

Automatic Warning System (AWS)

Preferred
Disciplines: Train Control, Rolling Stock
Axle Bearings
Bearings mounted on the axle to transmit the main weight of the vehicle directly to the wheelset. Excludes bearings mounted on the axle to support traction motors, final drives etc.

Preferred
Disciplines: Rolling Stock
Axle Counters
Equipment used to detect the presence of rail vehicles by counting the number of axles entering or leaving a location. They may be used to operate signalling or other infrastructure equipment.

Preferred
Disciplines: ALL Disciplines
Axle Load
The weight force exerted on the rails by the two wheels on any axle of a vehicle when stationary on level track.

Preferred
Disciplines: Rolling Stock
Axlebox Bearings
Individual roller bearings that are set, lubricated and sealed after assembly on the axle.

Preferred
Disciplines: Rolling Stock