Glossary of Terms


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

Back Contact
That contact of a relay which is closed (made) only when the relay is de-energised (dropped).

Preferred
Disciplines: Electrical
Back Drive Points
A second drive position on the point switches used where the length of the switch is such that a single drive will leave the back part of the switch hanging off the stockrail. Location of the back drive is determined by switch length and it may be operated by rodding from the drive or by a separate point operating mechanism.

Regional
Disciplines: Train Control
Back Interlocking
Interlocking produced on the interlocking part by the position taken up by the interlocked part.

Regional
Disciplines: Train Control
Back Light
A light showing through a small glass covered opening in the back of a signal lamp. A back light is used to provide signallers at night with a means of checking the position of a semaphore signal arm and the operation of the signal light.

Regional
Disciplines: Train Control
Back Rod
The bar or rod connecting the switches usually placed one sleeper bay back from the front rod to provide extra support for the switches.

Regional
Disciplines: Train Control
Backdrive
An alternative term for Supplementary Drive.

Regional
Disciplines: Train Control
Background Plate
A plate set behind the light units of a signal to improve the visibility.

Regional
Disciplines: Train Control
Backlocking
Prevention of completion of a lever stroke to the fully normal position until the conditions required by the interlocking are satisfied.

Regional
Disciplines: Train Control
Refer Check Locking.
Alternative
Disciplines: Train Control
Backup Coupling Device
A secondary coupling device, which is in addition to the normal coupling system, for preventing the separation of two coupled vehicles whilst in traffic.

Preferred
Disciplines: Rolling Stock
Balance Speed
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
Balise
A track mounted spot transmission unit that uses transponder technology. Its function is to transmit/receive messages to/from the train passing overhead.

Preferred
Disciplines: Train Control
Refer Transponder.
Alternative
Disciplines: Train Control
Ballast
Stone or aggregate material spread on the ground for the purpose of holding the track in line laterally and longitudinally and also to provide drainage.

Preferred
Disciplines: ALL Disciplines
Ballast Depth
Distance from the formation to the base of the sleeper measured below the lowest rail seat. For steel sleepers the base of the sleeper is considered to be the sleeper toe.

Preferred
Disciplines: Infrastructure
Ballast Resistance
The resistance offered by the ballast, sleepers, etc., to the flow of leakage current from one rail of a track circuit to the other.

Preferred
Disciplines: Infrastructure
Ballast Shoulder
The ballast each side of the railway track.

Preferred
Disciplines: Infrastructure
Ballast Shoulder Height
Height of the shoulder ballast above the sleeper base as measured at the end of the sleeper.

Preferred
Disciplines: Infrastructure
Ballast Shoulder Width
Width of the shoulder ballast as measured from the sleeper end.

Preferred
Disciplines: Infrastructure
Balloon Loop
A circular portion of line that allows rail traffic to change direction of travel without change to the leading end.

Preferred
Disciplines: ALL Disciplines, Operations
Bank Locomotive
A locomotive provided to assist rail traffic on a steep grade (bank).

Legacy
Disciplines: Operations
Banner Repeating Signal
A signal that provides the driver with preliminary information about whether a signal is on or off, usually provided where sighting of that signal is inadequate.

Regional
Disciplines: Train Control
Banner Signal
A type of semaphore signal with a small semaphore arm enclosed behind glass, which gives its indication by horizontal or inclined positions of the arm which is illuminated a night.

Regional
Disciplines: Train Control
Barrack Working
A train crew undertaking a journey from their home depot to another location, booking off duty and staying at a barrack for a minimum period as required, and return to their home depot. In any leg of these journeys the crew could either be working a train or travelling passenger.

Legacy
Disciplines: Operations
barrier
A physical, man-made, continuous barrier which is clearly identifiable and of sturdy construction, erected to deter unauthorised access to the rail corridor. Barriers include:-
(a) Walls – Constructed from, but not limited to, brick, stone and concrete panels
(b) Fences – Constructed from, but not limited to, post and wire, timber panelling, timber rails, steel railings and wire mesh
and are at the appropriate minimum height specified according to a risk assessment and which can be fitted with topping to create an additional deterrent.
(c) Boundary Measure - A man-made barrier or ‘natural’ feature (possibly modified), including but not limited to a ditch, hedge, watercourse or any other form of delineation which deters unauthorised access on to the rail corridor.

Preferred
Disciplines: Infrastructure, Operations
Base Ride Acceleration
Measurement of the vertical and lateral acceleration of the body of a rail vehicle under specific test conditions to assess its ride performance. Used to quantitatively assess the ride offered by the vehicle for comparison against dynamic performance requirements.

Preferred
Disciplines: Rolling Stock
Baulk
A device placed across the rails and anchored to the track to stop vehicles should they begin to roll away.

Regional
Disciplines: Infrastructure
Beacon
A unit usually mounted in the track and used to transmit information between track and train at short range radio frequencies. An antenna on the train passes over the transponder and one interrogates the other. The transponder may be passive and powered by carrier energy transmitted from the train, or be active, transmitting continuously or only when interrogated by a train. The transponder may hold fixed information and/or receive updated information through connection to the signalling system.

Alternative
Disciplines: ALL Disciplines
Refer Transponder
Alternative
Disciplines: ALL Disciplines
Bearer
A type of sleeper used under points and crossing track structures. Bearers are generally larger in dimension than standard sleepers to provide support for both tracks as well as the increased loading experienced under such track structures.

Preferred
Disciplines: Infrastructure
Bed Of Sleepers
All the sleepers that are stressed and cast together in one concreting operation, and then cured in the same batch.

Preferred
Disciplines: Infrastructure
Bell Continuity Test
This is the process whereby the wiring is checked to see that it is in conformity with the wiring diagrams and that all wires are continuous from termination point to termination point.
This test is generally carried out simultaneously with a wire count and insulation test.

Regional
Disciplines: Train Control
Bellows
The weather proof and self-supporting gangway and covering provided between adjoining passenger vehicles to allow passengers to walk from one vehicle in a train to another.

Preferred
Disciplines: Rolling Stock
Berth
A small sitting and/or sleeping compartment.

Preferred
Disciplines: Rolling Stock
Berth Track (or Berth Track Circuit)
The track circuit immediately on the approach side of a signal.

Regional
Disciplines: Train Control, Electrical
Bi-directional
Allowing for normal travel in either direction according to the infrastructure and system of Safeworking in use.

Preferred
Disciplines: Train Control, Operations
Bi-directional Line
A line on which the signalling permits trains to be signalled normally in either

Preferred
Disciplines: Train Control, Operations
Bi-directional Signalling
Signalling which permits trains to be signalled normally in either direction on a running line.

Preferred
Disciplines: Train Control, Operations
Bi-directional Track
Track which is signalled for trains to run in either direction.

Preferred
Disciplines: Train Control, Operations
Bi-directional Working
Operation of a line where the flow of traffic can be authorised to move in either direction.

Preferred
Disciplines: Train Control, Operations
Biased Relay
A relay which will operate to its energised position by current of one polarity only, and will return to its de-energised position when current is removed.

Regional
Disciplines: Train Control, Electrical
Bifurcated Contact
Contact which splits into two near the contact end, to provide two co-acting but independent contact actions for increased contact reliability.

Regional
Disciplines: Train Control, Electrical
Blade
Alternative term for Point Blade.

Alternative
Disciplines: Infrastructure
Blinder
A plate that covers a backlight to enable the signaller to see that a semaphore signal has correctly cleared to the off position.

Regional
Disciplines: Train Control
Block Bell
A single stroke bell for communicating between control points by means of a code of audible signals.

Legacy
Disciplines: Train Control
Block Indicator
The part of the block instrument that provides the signaller with a continuous visual indication of the state of a line within a block section.

Legacy
Disciplines: Train Control
Block Instrument
The equipment in a signal box for the operation and indication of block signalling. The instruments are fitted with visual indicators which act as a reminder to the signaller as to the state of that block telegraph section. The block indicator in these block instruments shows 'line closed', 'line clear', 'train on line' and 'train arrived'.

Legacy
Disciplines: Train Control
Block Joint
Refer 'insulated rail joint'.

Non-preferred
Disciplines: Infrastructure
Block Line
A portion of track with defined limits between which only one rail traffic movement is permitted at any one time.

Preferred
Disciplines: Operations, Train Control
Block Location
A defined location that separates block sections.
A location in Train Order territory that may be used as the limit of a Proceed Authority or as a reporting location, also known as 'block points'.

Regional
Disciplines: Operations
Block Point
A place where trains are not able to cross or pass that may be used as the limit of a Proceed Authority or as a reporting location.

Regional
Disciplines: Train Control, Operations
Block Post
A temporary block location.
A location in Train Order territory that may be used as the limit of a Proceed Authority or as a reporting location, also known as 'block points'.
A signal box at one end of a block section in block signalling.

Regional
Disciplines: Train Control, Operations
Block Proving
Block interlocking which prevents the sending of a 'section clear' indication for a train to the rear box, until the signals covering the block section entered by the train have been replaced to danger and locked in this position

Regional
Disciplines: Train Control, Operations
Block Section
Refer 'block' (Line).

Non-preferred
Disciplines: Train Control
Block Shelf
A shelf provided above the lever frame to hold equipment associated with control of the line, for example block Instruments, Indicators and other ancillary signalling equipment.

Regional
Disciplines: Train Control
Block Signal
A stop signal that controls the entrance to, or signifies the termination of, a block or signal section.

Regional
Disciplines: Train Control
Block Skip
Refer Joint Hopping.

Alternative
Disciplines: Train Control
Block Station
The station at either end of a block section at which equipment is provided to control the movements of trains, and maybe attended or unattended.

Preferred
Disciplines: Train Control, Operations
Block Switch
A switch located in a signal box by means of which the signalling block circuits to the signal boxes on either side may be connected together, enabling the signal box in which the switch has been so operated to close.

Regional
Disciplines: Train Control
Block Telegraph System
A system of safeworking used on double lines, usually in non track-circuited areas. Each interlocking is equipped with a block instrument(s). The instruments are electrically interconnected between interlockings to allow signallers to transmit train working signals to each other and to indicate the condition of the section. Under normal conditions, the authority for a train to occupy a section between interlockings is the clearing of the starting or home/starting signal.

Regional
Disciplines: Train Control, Operations
Block Telegraph Territory
The portions of line where the block telegraph system of safeworking is used.

Regional
Disciplines: Train Control, Operations
Block Track
A cast or fabricated spacer separating two rails or a rail and a check rail.

Preferred
Disciplines: Infrastructure
Block Wagons
A group of continuous wagons going to the same destination; or

Preferred
Disciplines: Rolling Stock, Operations
Block Working
Refer Manual Block Working

Non-preferred
Disciplines: Train Control, Operations
Blockage - Of Tracks
Refer Blocking Facility.

Non-preferred
Disciplines: ALL Disciplines
Blockage Of Tracks
A procedure to prevent the movement of electric trains, or all trains, into a section of track.

Regional
Disciplines: Train Control, Operations
Blocking
A means to prevent clearance of a signal when it is desired to inhibit entry of a train movement into the block section governed by the signal.

Regional
Disciplines: Train Control
Blocking Back
Term used in absolute block and electric token block, when a train or shunting movement is to be allowed to occupy the line within the clearing point or on the approach to the home signal.

Regional
Disciplines: Train Control
Blocking Facility
A facility or device used by a competent worker to prevent either the unintended issue of an occupancy authority, or the operation of points or signalling equipment.

Preferred
Disciplines: Train Control, Operations
Boarding Device
This includes ramps, on-board lifts mounted on rolling stock and on the platform.

Preferred
Disciplines: Rolling Stock, Operations
Bogie
A structure incorporating suspension elements and fitted with wheels and axles, used to support rail vehicles at or near the ends and capable of rotation in the horizontal plane. It may have one, two or more axle sets, and may be the common support of adjacent units of an articulated vehicle. (The bogie is commonly referred to as a 'truck' in AAR terminology.)

Preferred
Disciplines: Rolling Stock
Bogie Identification Code
A four letter group indicating ownership, bogie type and axle load.

Preferred
Disciplines: Rolling Stock
Bogie Identification Number
Each bogie is allocated a number comprising 5 digits in the range of 1 to 99999.

Preferred
Disciplines: Rolling Stock
Bogie Side L/V
Total sum of the lateral forces between the wheels and the rails on one side of a bogie divided by the total sum of the vertical forces on the same wheels of the bogie.

Preferred
Disciplines: Rolling Stock
Bogie Structures
This includes the bogie frame, axleboxes, and other structural bogie components. Structural bogie components includes but is not limited to the following items and their associated bracketry: bolsters, spring planks, swing links, control rods, frame adaptors, equaliser beams, brake beams, air springs, anti-roll bars and links, vertical dampers, lateral dampers, yaw dampers, traction rods, torque motor reaction links.

Preferred
Disciplines: Rolling Stock
Bolt Lock
A metal bar or plunger, combined with a cross-slide and arranged in such a manner as to prevent movement of the cross-slide when the plunger is inserted.

Regional
Disciplines: Train Control
Bolted Rail Track
Track in which rail lengths are joined with bolted mechanical joints, as opposed to welded track.

Alternative
Disciplines: Infrastructure
Refer Mechanical Rail Joint.
Preferred
Disciplines: Infrastructure
Bond
An electrical conductor complete with terminations which connects together items of equipment.

Preferred
Disciplines: Electrical
Bond Plug
The bullet-shaped piece of steel which is used to secure a plug bond.

Regional
Disciplines: Train Control
Bond Reference
A number allocated by customs which allows a particular consignment to travel on a service prior to customs inspection.

Regional
Disciplines:
Bond Wire
Solid or stranded wire which is welded or pinned with channel pins around rail joints to provide reliable electrical conductivity.

Regional
Disciplines: Train Control
Bonded Joints
Metallic connections at rail joints to provide a continuous metallic path for the passage of electric currents from one rail to the other.

Preferred
Disciplines: Electrical, Infrastructure
Bootleg
A protection for track circuit wires where the wires leave the conduit or ground near the rail. Generally a termination point between wires that connect to the rails and the corresponding cable leads that go to the trackside equipment location. Also known as 'bootleg riser' or 'pot head'.

Regional
Disciplines: Train Control, Electrical
Bottom Lift
A container which must be lifted from pockets in its base using special container grabs.

Preferred
Disciplines: Rolling Stock
Bounce
The vertical displacement of the vehicle body relative to the rails that may be expected to occur in response to track irregularities.

Preferred
Disciplines: Rolling Stock
Box
Alternative name for Container.

Non-preferred
Disciplines: Rolling Stock, Operations
Box Car (or Box Wagon)
A fully enclosed vehicle with floor, side walls, end walls and roof, having one or more doors in each side.

Non-preferred
Disciplines: Rolling Stock, Operations
Boxing Up
The process of filling the track with ballast to the specified ballast profile including the shoulder.

Legacy
Disciplines: Infrastructure
Brace
Refer Rail Brace.

Alternative
Disciplines: Infrastructure
Brake
A system fitted to rollingstock to decelerate, stop and inhibit further movement. Usually achieved by means of compressed air, by rheostatic braking on wheelsets with electric traction motors or manually through mechanical means for handbrakes.

Preferred
Disciplines: Rolling Stock, Operations
Brake Block Or Brake Shoe
The friction block (usually cast iron) that is placed onto the wheel rim via a series of rods and levers to slow the rolling stock down by the use of friction when the brakes are applied.

Preferred
Disciplines: Rolling Stock, Operations
Brake Cylinder
A steel cylinder attached to the body frame or bogie frame of rolling stock containing a piston which is forced outwards by compressed air to apply the brakes. When the air pressure is released, the piston is returned to the normal position by a release spring coiled about the piston inside the cylinder.

Preferred
Disciplines: Rolling Stock, Operations
Brake Delay Time
The time which elapses after a brake application is initiated until the train brakes start to apply.

Preferred
Disciplines: Rolling Stock, Operations
Brake Head
A casting attached to a brake beam which carries the detachable brake shoe.

Preferred
Disciplines: Rolling Stock, Operations
Brake Pipe
The pipe connecting the brake pipe to the air brake equipment on rollingstock.

Preferred
Disciplines: Rolling Stock, Operations
Brake Rigging
The term applied to the entire system of levers, rods, fulcrums, brake beams and associated connections that serve to multiply the force created by the air pressure in the brake cylinder and transmit it to the brake shoes.

Preferred
Disciplines: Rolling Stock, Operations
Braking Curves
Plots of speed against distance for the braking performance of particular trains from various speeds over various gradients.

Preferred
Disciplines: Rolling Stock, Operations
Braking Distance
For a nominated portion of railway the maximum distance which any train operating on such portion of railway at its maximum authorised speed, will travel during a full service application of the brakes, between the point where such application is initiated and the point where the train comes to a stop.

Preferred
Disciplines: Rolling Stock, Operations
Branch Line
A railway line that runs off a main line and generally carries less trains.

Preferred
Disciplines: ALL Disciplines
Branch Pipe
The pipe connecting the brake pipe to the air brake equipment on rolling stock.

Preferred
Disciplines: Rolling Stock, Operations
Broad Gauge (track)
Track gauge of 1600 mm (5' 3').

Preferred
Disciplines: Infrastructure
Broken Rail
A square or angular sudden rupture, transverse separation of the head, web and foot of the rail.

Preferred
Disciplines: Infrastructure
Broken Rail Detection
The detection of broken rails, usually through failure of track circuits which use the rails as conductors.

Preferred
Disciplines: Train Control
Brookfield Rail Network
Western Australia regional narrow and standard gauge network.

Preferred
Disciplines: ALL Disciplines
Buckle (track)
A substantial displacement of track from its original design alignment caused by longitudinal thermal stresses overcoming the lateral resistance of the track.

Preferred
Disciplines: Infrastructure, Operations
Buffer
A cushioning device mounted on the extreme ends of rolling stock to absorb shocks arising during coupling and motion.

Preferred
Disciplines: Rolling Stock
Buffer Lock
Entanglement of the buffers of adjacent rolling stock whilst traversing curves.

Preferred
Disciplines: Rolling Stock
Buffer Section
A buffer section consists of isolated and earthed subsection/s which provide electrical separation between energised and isolated overhead line equipment on which maintenance or repair work is to be carried out. The use of buffer sections is one of the methods used to prevent raised pantographs from energising isolated sections where workers are working on the overhead line equipment.

Preferred
Disciplines: Electrical
Buffer Stop
A structure erected across and at the end of a track at main line terminals or dead end sidings which is intended to stop rolling stock.

Preferred
Disciplines: Infrastructure, Operations
Buffer Stop Lights
Red or white lights (usually two, one above the other) mounted on the buffer stop or at the start of the sand drag.

Regional
Disciplines: Train Control
Built-up Crossing
A crossing utilising a hardened, machined block in the wheel transfer area. Extension wing and running rails are welded to the machined block utilising specialised techniques. Also known as welded crossing

Preferred
Disciplines: Infrastructure
Bulk Freight
Comprises commodities such as coal, iron ore, other minerals or grain.

Preferred
Disciplines: ALL Disciplines
Bund
A wall and floor of concrete or other approved impervious material, which may form part or the entire perimeter of a compound and is designed to prevent the escape of any material stored within it.

Preferred
Disciplines: Infrastructure