Glossary of Terms


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

P2 Force
Total vertical force (static plus 'low frequency' dynamic forces) per wheel when the rolling stock operates over a defined angular discontinuity (ramp) in the rail vertical profile, representing an idealised dipped rail joint.

Preferred
Disciplines: Rolling Stock
PA
Abbreviation for Proceed Authority

Proceed Authority

Preferred
Disciplines: Operations
Pacific National
Freight train operator throughout all Australian states.

Preferred
Disciplines: ALL Disciplines
Package Axle Bearings
A single packaged (or cartridge) unit, containing all the bearing assembly parts, pre-set, lubricated and sealed for assembly on the axle.

Preferred
Disciplines: Rolling Stock
Packing
The process for consolidating the ballast under the sleepers, timbers or bearers for the proper support of the track.

Preferred
Disciplines: Infrastructure
Pad
An item manufactured from elastic, electrically insulated or low friction material which is placed under the rail and intended to perform a specific function, e.g. vibration isolation, electrical insulation.

Preferred
Disciplines: Electrical
Pandrol
A trade name, Pandrol supplies plates and resilient fastenings.

Other
Disciplines: Infrastructure
Panel (track)
A section of plain track or crossingwork comprising rails, track fastenings and sleepers (tie bars if applicable) which has been assembled for transport or installation into track as a unit.

Preferred
Disciplines: Infrastructure
Panel Processor
A microprocessor interfacing between the operator interface and the signalling interlocking and building the information sets required from the input data elements.

Regional
Disciplines: Train Control
Pantograph
An apparatus fixed to the roof of electric traction vehicles to draw current from the overhead supply.

Preferred
Disciplines: Rolling Stock
Parallel Bonding
The bonding of both rails of a turnout such that they are connected in parallel with the other straight rails comprising the track circuit.

Overseas
Disciplines: Electrical, Infrastructure
Park Brake
A device to secure a rail vehicle against movement.

Preferred
Disciplines: Rolling Stock
Part Worn Rail
Any recycled rail that has previously carried traffic, including rail used for closures and inserts.

Preferred
Disciplines: Infrastructure
Parting
Rail traffic becoming uncoupled en route (Also known as dividing in some Networks).

Preferred
Disciplines: Operations, Rolling Stock
Pass
To overtake other rail traffic travelling in the same direction in single line territory.

Preferred
Disciplines: Train Control, Operations
Passenger Kilometre
Unit of measure representing the transport of one passenger over a distance of one kilometre.

Preferred
Disciplines: ALL Disciplines
Passenger Line
A line signalled to the standard required for trains conveying passengers.

Overseas
Disciplines: Train Control
Passenger Rolling Stock
Rolling stock that carries people and facilities for these people. Excludes locomotive and infrastructure maintenance rolling stock.

Preferred
Disciplines: ALL Disciplines, Rolling Stock
Passenger Vehicle (or Passenger Car)
Refer to Passenger Rolling Stock.

Alternative
Disciplines: ALL Disciplines, Rolling Stock
Related Term: Passenger Rolling Stock
Passing Contact
Contact which closes or opens for a short period only and usually when the controller is operated in a certain direction only, e.g. normal to reverse.

Preferred
Disciplines: Electrical
Passing Loop
A passing loop is a section of track that runs parallel and connected at both ends to the main line. This allows, for example, two trains in oposite directions to cross each other, or a faster train to pass and overtake a slower one that is waiting in the loop. Passing loops are generally used on lines with only one track, and allows for increased running capabilities and minimalised running times.

Preferred
Disciplines: Train Control, Operations
Passing Movement
Refer to Pass.

Alternative
Disciplines: Train Control, Operations
Related Term: Pass
Passive Control Level Crossing
Road and pedestrian level crossing incorporating line markings and or warning or advisory signs to alert vehicular or pedestrain traffic that they are approaching a crossing and to take care.
Road and pedestrian level crossings have static warning signs (stop or give way) that are visible on approach. This signage is unchanging with no mechanical aspects or light devices.

Preferred
Disciplines: ALL Disciplines
Passive Level Crossing Warning System
Control of the movement of vehicular or pedestrian traffic across a railway level crossing by signs or devices, none of which are activated during the approach or passage of a train, and which rely on the road user detecting the approach or presence of a train by direct observation.

Preferred
Disciplines: Operations, Infrastructure
Path
A train path is the right to use consecutive sections of rail track for defined periods of time.

Preferred
Disciplines: ALL Disciplines, Train Control
Patrol Inspections
Visual inspections for obvious unsafe conditions, changed conditions, or evidence of high rates of deterioration of the infrastructure that indicate unacceptable risk to operations. Patrols should be sufficient to enable the need for more detailed inspections to be determined.

Preferred
Disciplines: Infrastructure, Operations
Pedestrian Crossing
A crossing at substantially the same level as a railway track that is used by pedestrians to cross the railway track

Preferred
Disciplines: ALL Disciplines, Operations
Per Way Patroller
An approved person having responsibility for regular
permanent way inspections to ensure the safety of the line.

Regional
Disciplines: Infrastructure
Periodical Ticket
A ticket valid for more than one day.

Preferred
Disciplines: Operations
Permanent Rail Joint
Non-welded rail joints intended for use in track in the long term. They include fishplated joints, glued insulated joints and expansion joints.

Preferred
Disciplines: Infrastructure
Permanent Record
A record made in writing or in an electronic system, and kept for reference and audit.

Preferred
Disciplines: ALL Disciplines
Permanent Speed Board
A fixed board which indicates to the driver the maximum allowable speed for trains on the portion of line ahead up to the next speed board.

Preferred
Disciplines: Operations
Permanent Way
The system of earthworks, drainage, structures, and trackwork (but excluding signalling and communications systems) completed to the required clearance, grade and alignment in readiness for traffic.

Preferred
Disciplines: ALL Disciplines
Permissible Rollingstock Outline
The outline that defines the limiting cross-sectional geometry for rollingstock and its load including kinematic effects. It includes the static rollingstock outline and the affects of vehicle centre and end throw, track tolerances and dynamic rollingstock limits. Also referred to as maximum kinematic rollingstock outline.

Preferred
Disciplines: Rolling Stock
Refer 'rollingstock outline'.
Alternative
Disciplines: Rolling Stock
Permissible Speed
The maximum allowable safe speed over a section of line which applies to all trains when not operating at an EPS. Normally identified in the sectional appendix, and sometimes shown as a differential speed.

Overseas
Disciplines: Operations
Permissible Structure Outline
The outline relative to the track cross-section that defines the limiting cross-sectional geometry which no part of any structure or trackside fixture may infringe.

Preferred
Disciplines: Infrastructure
Permissive Block Working
A system whereby two or more trains travelling in the same direction and spaced a block apart, may consecutively enter a block section of single line on signal indication.

Regional
Disciplines: Train Control, Operations
Permissive Working
A system whereby rail traffic travelling in the same direction may enter a single line on a signal indication and are permitted to proceed at restricted speed to the preceding train or next stop indication.

Regional
Disciplines: Operations, Train Control
Permmisive Signal
A fixed signal that is normally controlled by the passage of rail traffic and its normal indication is a Proceed Authority.

Regional
Disciplines: ALL Disciplines, Operations
Phantom Aspect
An aspect displayed by a colour light signal, different from the aspect intended, caused by a light from an external source being reflected by the optical system of the signal.

Regional
Disciplines: Train Control
Pick-up
The energisation of an electromagnetic device to pick up and close its front contacts.

Regional
Disciplines: Electrical
Pick-up Value
The electrical value which, when applied to an electromagnetic instrument, will cause the moving member to move to the position which will just close the front contacts or visually indicate its energised position.

Regional
Disciplines: Electrical
Piggyback
Transporting complete road trailers on railway flat wagons.

Regional
Disciplines: Operations
Pilot
A Competent Worker, who accompanies, directs and advises rail traffic crews.

Preferred
Disciplines: ALL Disciplines
To direct or guide rail traffic crews and tell them about local conditions and operating restrictions on running lines and at worksites.
Preferred
Disciplines: Operations, Train Control
Pilot Staff
A metal staff that authorises travel through a pilot staff section.

Regional
Disciplines: Operations
Pilot Staff Lock
An annett lock at a single line starting signal which holds a half pilot staff for the single line section. Removal of the half pilot staff operates a pilot staff lock contact which disconnects the section control circuits and prevents the starting signals at each end of the section from clearing.

Regional
Disciplines: Train Control
Pilot Staff Notice (PSN)
A form used to give details of pilot staff working.

Regional
Disciplines: Train Control, Operations
Pilot Staff Ticket
A written authority issued after a driver or track vehicle operator has seen the pilot staff or half-staff for a section.

Regional
Disciplines: Train Control, Operations
Pilot Staff With Key
A staff in two halves with a key at each end. Each half is secured in a pilot staff lock box at each end of a single line track block or track control signalling section. For use in the case of starting signal failure or obstruction on the single line.

Regional
Disciplines: Train Control, Operations
Pilot Staff Working
A method of working rail traffic when the normal system of safeworking is not available.

Regional
Disciplines: Train Control, Operations
Pilotman
A person who has been appointed to manage the passage of trains over a single line during the failure of equipment, during repairs or due to an obstruction.

Overseas
Disciplines: Train Control, Operations
Pin
A round spike used to fasten some types of plates to timbers or a connecting pin used in point spreader bars and connecting rods.

Preferred
Disciplines: Infrastructure
Plain Axle Bearings
Bearings using sliding motion between the moving load-bearing surfaces.

Preferred
Disciplines: Rolling Stock
Plate
A steel plate fitted between the rail and sleeper or timber to spread the load on the sleeper. Plates may be double shoulder, clip fastening, taper, level or cant to suit requirements.

Preferred
Disciplines: Infrastructure
Plateau
The level elevated platform in a flangeway or a flange bearing third rail transfer or crossing unit which reduces excessive wear and batter on the nose.

Preferred
Disciplines: Infrastructure
Platform
A raised or level area, next to the line, that allows people to enter and leave trains.

Preferred
Disciplines: ALL Disciplines, Operations
Platform Sharing
Permitting two passenger trains to occupy a platform line simultaneously, other than for the purposes of attaching, detaching or removing vehicles, without the existence of a mid-platform signal.

Overseas
Disciplines: Operations
Platform Starting Signal
A stop signal located such that either the longest passenger (or empty coaching stock) train authorised to use the platform would, if stopped at the signal, still have a portion of the passenger accommodation alongside the platform, or the leading end of the train passes over the AWS equipment associated with the signal before it is despatched from the platform.

Overseas
Disciplines: Train Control
Plug Bond
A traction bond with the termination on each end of the bond consisting of a cylindrical plug which forms a close fit in a hole drilled in the rail web. It is secured in place by the expanding action of a bond plug being driven into a hole through its centre.

Regional
Disciplines: Electrical
Plug In Relay
A relay designed to plug into a plug board. The electrical connections are permanently made to the plug board allowing the relays to be changed without any disconnection of individual wires. The plug boards are usually pin coded to prevent an incorrect type of relay being fitted.

Regional
Disciplines: Electrical
Plunger
A button that is depressed to activate signalling equipment.

Regional
Disciplines: Train Control
Plunger (facing Point Lock)
The part of a facing point lock which secures the lock rod to the plunger stand when the points switch is locked.

Regional
Disciplines: Train Control
Plunger Proving Of Switch Blades
Check of the blades of a switch effected by the driving in of a spring piston under the action of a switch blade at the end of its movement towards the stock rail.

Regional
Disciplines: Train Control
PN
Pacific National


Disciplines:
Abbreviated term for Pacific National.
Alternative
Disciplines: ALL Disciplines
Point (s)
A track component that provides a path for a wheel to transfer from one track to another and usually consists of a section of bent and planed rail (known as the switch rail) and its connecting parts (for example switch rod brackets, reinforcing bars and high strength tips where appropriate). The term point is also used to describe the end of the switch rail that is machined into a sharp tip.

Preferred
Disciplines: Infrastructure
Point Blade
The machined pivoting or flexing running rail component of a half set of points.

Preferred
Disciplines: Infrastructure
Point Clamp
A lockable heavy duty clamp for manually securing a point switch to the stockrail for an extended period.

Preferred
Disciplines: Infrastructure
Point Clip
A lockable clip for manually securing a point switch to the stock rail.

Preferred
Disciplines: Infrastructure, Operations
Point Contact
The fixed contact piece for either a front or back contact of a relay.

Preferred
Disciplines: Electrical
Point Detector
A device for proving that points are correctly set before a signal can be cleared to authorise passage of a train over the points.

Overseas
Disciplines: Train Control
Point Extension Iron
A bracket bolted to the toe of a point switch which provides an extended connection point for point detector rods.

Regional
Disciplines: Train Control, Infrastructure
Point Handle
A collective term for Crank Handle and Pump Handle.

Overseas
Disciplines: Train Control
Point Machine
The encased equipment for the powered operation of a set of points.

Preferred
Disciplines: Train Control, Infrastructure
Point Machine With Hand Crank Or Long Lever
Point machine, the action of which, in the event of removal or failure of the motive power, may be effected by hand, under certain conditions, by means of a movable crank or a lever connected to the motor.

Overseas
Disciplines: Train Control, Infrastructure
Point Operating Mechanism
A mechanism for changing the direction a set of points is lying.

Regional
Disciplines: Train Control, Infrastructure
Point Pawl Lock
A point operating mechanism which provides direct switch to stockrail facing point locking through a vertically operating pawl arm which requires external point switch and lock detection and is powered by a purpose built electric point machine or electro-pneumatic (EP) motor.

Regional
Disciplines: Train Control
Point Slide Chair
A rail base plate under the stock rail and switch. It provides vertical support to the stock rail and a horizontal surface for the switch to slide on. Chairs are attached to the stock rail and to the timber under the points.

Preferred
Disciplines: Infrastructure
Point Switch
A movable tapered track rail, the point of which is designed to fit against the stock rail. The pointed end of the switch rail (Switch Blade) is referred to as the Toe and the other end, the pivot end, as the Heel.

Preferred
Disciplines: Infrastructure
Refer Toe, Heel
Alternative
Disciplines: Infrastructure
Point Switch Rollers
A roller under a point switch and fixed to the stockrail, which lifts the point switch off the slide plate as the switch moves from the closed to the open position and vice versa. Several rollers can be fitted along each point switch to facilitate movement, especially for heavy switches on super elevated track.

Preferred
Disciplines: Infrastructure
Points And Crossings
Track structures which provide for one track to join or cross another.

Preferred
Disciplines: ALL Disciplines, Infrastructure
Points Correspond-ence Test
This is a test to ensure that the position of a set of points is in agreement with that required by the interlocking.

Regional
Disciplines: Train Control
Points Fixed
Third rail crossingwork designed to permit the standard gauge or broad gauge track to turn out. The diverge move is effected by the use of ramped manganese blocks on which the wheel flange runs and guard rails.

Preferred
Disciplines: Infrastructure
Points Fixed Heel
Points which utilise permanently fastened heel blocks. Localised flexing of the switch occurs ahead of the fixed heel and the switch rail continues beyond the heel.

Preferred
Disciplines: Infrastructure
Points Securing Device
A device approved by Rail Infrastructure Managers used to prevent movement of points from the required position.

Preferred
Disciplines: ALL Disciplines
Polarised Circuit
A circuit path in which the flow of electric current is reversed from time to time.

Regional
Disciplines: Electrical
Polarity Reversal (phasing)
The reversal of the polarity between similar adjoining track circuits across the insulating block joints to prevent the possibility of one track circuit feed falsely energising the relay of the adjoining track circuit in the event of breakdown of the insulating block joints.

Regional
Disciplines: Electrical
Polarpak
The polarpak is a 40 kilowatt diesel engine driven portable generator unit fitted to some 5-pack well wagons to provide in-transit power for refrigerated containers.

Regional
Disciplines: Rolling Stock, Operations
Polyphase Relay
An alternating current relay having two or more windings, operating on an induction motor principle, all windings of which must be properly energised.

Regional
Disciplines: Electrical
Position Light Signal
A light signal, other than a main signal, that gives its indication by the position and colour of its lights.

Overseas
Disciplines: Train Control
Positive Train Identification (PTI)
A system that identifies a train directly from equipment on board the train for the purposes of train description, rather than from a train describer.

Overseas
Disciplines: Train Control
Positive Train Separation (PTS)
An American automatic train protection system specification evolving from their advanced train control system specification. The positive train separation system is intended to overlay existing signalling systems to provide enforcement and is transmission based using radio links to the train.

Overseas
Disciplines: Train Control
Possession Limit Marker
A red light, red flag or sign used to indicate a Local Possession Authority limit.

Preferred
Disciplines: ALL Disciplines
Possession Protection Officer
The Competent Worker responsible for coordinating protection of worksites under a Local Possession Authority (LPA).

Preferred
Disciplines: ALL Disciplines
Power Car (or Power Vehicle)
A vehicle that contains the equipment and facilities
necessary to produce, convert or distribute the power required for propulsion, control and auxiliary purposes.

Preferred
Disciplines: Rolling Stock
Power Frame
A lever frame controlling power operated equipment.

Regional
Disciplines: Train Control
Refer Miniature Lever Frame.
Alternative
Disciplines: Train Control
Power Interlocking
An interlocking area where the points and signals are operated electrically, hydraulically or pneumatically. They are controlled by a signaller using an interlocking machine or relay interlocking control unit.

Regional
Disciplines: Train Control
Power Interlocking Machine
An interlocking machine with small mechanical type levers or pistol grip slide levers with mechanical interlocking provided between the levers which operate circuit controllers for a power interlocking.

Regional
Disciplines: Train Control
Power Signal Box
A signal box from which the signalman controls the working of the apparatus by means of any power supply (pneumatic, electric, hydraulic).

Preferred
Disciplines: Electrical
Power Signal Box With Free Levers Or Thumb Switches
Power signal box with route or individual levers, in which the control levers or switches are always free and where interlocking is effected by the operation of electrical interlocking acting only on the control circuits.

Preferred
Disciplines: Electrical
Power Signal Box With Individual Levers
Power signal box from which the operation of each lever controls the working of only one apparatus or of a group of associated apparatus.

Preferred
Disciplines: Electrical
Power Signal Box With Route Levers
Power signal box where all the signalling apparatus, the movement of which is necessary to ensure complete setting up of the specified route, are simultaneously operated by route levers. This operation may be effected by one lever per route (or part of a rpoute) or two levers corresponding to the extremities of the route (or part of a route).

Preferred
Disciplines: Electrical
Power Supply Conditioner
A device which filters and corrects the waveform and voltage of a mains power supply for sensitive electronic equipment.

Regional
Disciplines: Electrical
Power Worked Signal
Fixed signals worked by electricity or compressed air.

Regional
Disciplines: Train Control
Pre-setting Control
A control which is carried out automatically when the safety conditions required are satisfied.

Preferred
Disciplines: Electrical
Pre-site Test
These are tests of manufactured equipment and circuits using temporary power supplies prior to site installation. These are not certification tests, but rather quality control tests.

Preferred
Disciplines: ALL Disciplines
Prescribed Train
A train laden in excess of a specified percentage of the maximum load that can be hauled by the motive power unit, for that portion of line.

Regional
Disciplines: Operations
Preselection
Refer Queuing

Non-preferred
Disciplines: Train Control
Prestressed Concrete Sleeper
A sleeper utilising compressed concrete and prestressing tendons to resist flexure.

Preferred
Disciplines: Infrastructure
Prestressing Tendon
A strand or wire within a sleeper, which under tension, compresses the concrete.

Preferred
Disciplines: Infrastructure
Prevent Shunt
The prevent shunt of a track circuit is the maximum value of the resistance which, placed between the two rails of a track circuit, will prevent the energisation of the track relay.

Overseas
Disciplines: Electrical, Train Control
Prime Length (rail)
Refer to Standard Length Rail.

Non-preferred
Disciplines: Infrastructure
Related Term: Standard Length Rail
Principles
Principles describe fundamentals applicable to all railways. Principles defined in ACOP may include a list of factors that should be considered.

Preferred
Disciplines: ALL Disciplines
Private Siding
A siding owned and maintained by a person who does not own, control or manage the running line with which the siding connects.

Preferred
Disciplines: ALL Disciplines
Proceed Authority
An Authority that allows rail traffic to enter and occupy a portion of line and proceed in the forward direction.

Preferred
Disciplines: ALL Disciplines
Proceed Indication
Any signal indication other than stop.

Regional
Disciplines: Train Control
Processing Capacity
The maximum number of control and indication input/output processing cycles per unit of time that can be handled without incurring any cycle processing delay. For any given system this will result in a maximum number of field objects the system is able to control, which is also a function of the complexity of the controlling / interlocking logic between the field objects.

Regional
Disciplines: Train Control
Processing Speed
The speed with which the system processes a control or indication input, and outputs the required response to the field or signaller respectively.

Regional
Disciplines: Train Control
Prohibition Notice
If an authorised officer is of the opinion that at any railway premises there is occurring or is about to occur any activity that involves or will involve an immediate risk to the health or safety of any person, the authorised officer may give to the person who has or may be reasonably presumed to have control over the activity a notice prohibiting the carrying on of the activity until the matters that give or will give rise to the risk are remedied.


Disciplines:
Propel
To push rail traffic away from the controlling locomotive or motive power unit.

Preferred
Disciplines: Operations, Rolling Stock
Protected Level Crossing
A level crossing with automatic flashing lights warning signals with or without bells and half boom gates.

Preferred
Disciplines: Train Control, Infrastructure
Protected Wrong Side Failure
A wrong side failure where another part of the signalling system provides an acceptable level of protection.

Overseas
Disciplines: Train Control
Refer Wrong Side Failure
Alternative
Disciplines: Train Control
Protecting Signal
A signal that protects a train from conflicting movements and/or obstructions.

Preferred
Disciplines: Train Control
Protection
The means used to prevent rail traffic from entering a worksite or other portion of track, or to prevent road or pedestrian traffic entering a level crossing.

Preferred
Disciplines: ALL Disciplines
Protection Officer
The Competent Worker responsible for managing the rail safety component of worksite protection.
Also see Worksite Supervisor and Work Site Safety Supervisor.

Preferred
Disciplines: ALL Disciplines
Protocol
A set of rules that govern the operation of functional units to achieve communication. In data transmission, mainly based on message structures and timing.

Preferred
Disciplines: ALL Disciplines
Proved
Evidence provided by electrical or other means that a function is in a specified state.

Preferred
Disciplines: Train Control, Electrical
Provisioning Centre
An area in which locomotives are fuelled and serviced.

Preferred
Disciplines: Rolling Stock, Operations
Proximity Detector
An induction loop device in the track which is operated electromagnetically by the proximity of a rail vehicle above the detector.

Regional
Disciplines: Electrical, Rolling Stock
PSN
Pilot Staff Notice


Disciplines:
PTA Of WA Network
Abbreviation for Abbreviation for Public Transport Authority of Western Australia.
'Perth metropolitan narrow gauge network'.

Alternative
Disciplines: ALL Disciplines
PTAWA
Public Transport Authority of Western Australia


Disciplines:
PTI
Positive Train Identification


Disciplines:
Abbreviated term for 'positive train identification'.
Overseas
Disciplines: Train Control
PTS
Positive Train Separation


Disciplines:
PTV
Public Transport Victoria


Disciplines:
Abbreviation for 'Public Transport Victoria'.
Alternative
Disciplines: ALL Disciplines
Public Timetable
Contains the list of scheduled passenger services (but not a complete list of all train movements as per working timetable).

Regional
Disciplines: Operations
Pull Apart
A rail failure where the ends separate producing a gap in the rail.

Preferred
Disciplines: Infrastructure
Pull Rod
The rod connecting the spreader bar and (point lever) crank to facilitate operation of the points.

Preferred
Disciplines: Infrastructure
Pulling List
The listed sequence in which point and signal controls must be operated to set routes.

Regional
Disciplines: Train Control
Pulsating (light)
A regular variation in light intensity, used to distinguish the indication from a steady light of the same colour.

Regional
Disciplines: Electrical
Pulsating Current Fed Track Circuit
Track circuit in which the current is successively switched off and established, possibly reversed, and operating on the total effect of the action which each interruption or impulse of current causes in the receiving apparatus without consideration of the frequency or duration of the impulses.

Preferred
Disciplines: Electrical
Pump Handle
A portable handle for the manual operation of a clamp lock or a set of train operated points.

Regional
Disciplines: Operations