Glossary of Terms


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

Table Of Signal Routes
A comprehensive list of signal routes. They can either be shown on, or accompany signalling / scheme plans.

Overseas
Disciplines: Train Control
Tail Flashing Level Crossing
The term used to describe the effect on single lines of a level crossing warning system continuing to operate as the tail of the train departs, as if it were an opposite direction approaching train. It may occur in some systems with a light engine or other short, fast, self-propelled vehicle.

Regional
Disciplines: Train Control
Tail Light
Red lights used to designate the end of rail traffic. (see also 'end-of-train marker').

Preferred
Disciplines: Rolling Stock, Operations
Take-off Rail
A structure used to give track vehicles entry to and exit from the line.

Preferred
Disciplines: Infrastructure
Takeoff
Staging (usually a number of sleepers) beside the track for the purpose of removing and stabling track mounted maintenance vehicles or equipment clear of train movements.

Regional
Disciplines: Infrastructure
Tamping
The process by which ballast is packed around the sleepers of a track to ensure the correct alignment for the location, speed and curvature of the line.

Preferred
Disciplines: Infrastructure
Tang (crossing)
The cast extension at the V end of a rail bound manganese crossing to which the heel rails are fastened.

Preferred
Disciplines: Infrastructure
Tangent Point (TP)
The intersecting point of track centreline tangents between curves, transitions and straight track.

Preferred
Disciplines: Infrastructure
Tangent Track
Straight track with no applied cant.

Preferred
Disciplines: Infrastructure
Tangential Point Switch
A design of points where the stockrail forms a tangent to the curve through the point switch.

Preferred
Disciplines: Infrastructure
Tangential Turnout
Turnout where one route is straight track.

Preferred
Disciplines: Operations
Tank Wagon
A wagon comprising a horizontal, basically cylindrical container for the transport in bulk of liquids, compressed gases, granular or pelletised solids, etc.

Regional
Disciplines: Rolling Stock, Operations
Taper Base (sleeper Plate)
A sloped base rail seat. The taper of open (Railway) track sleeper plates is 1 in 20 to provide a rail inclination into the gauge of the track.

Preferred
Disciplines: Infrastructure
Tappet
A device, usually a notched metal bar, which actuates the mechanical locking of a mechanical interlocking machine by the movement of the lever.

Regional
Disciplines: Train Control, Infrastructure
Tare Mass
The mass of the rolling stock in the lightest condition under which it will be operated. This includes provisioning with sand and water but fuelled to no more than one-third of capacity.

Preferred
Disciplines: Rolling Stock
Tautliner
Brand name often used to refer to a curtain sided wagon. A box wagon in which the side walls consist entirely or predominantly of weather-proof flexible panels.

Regional
Disciplines: Rolling Stock
TCS
Train Control System


Disciplines:
Technically Competent Authority
A company or person having proven competence in the particular technology or process in which they are providing technical expertise.

Preferred
Disciplines: ALL Disciplines
Telemetry System
Equipment for multiplexing control and/or indication inputs for transmission over a telecommunications bearer or radio link. The messages for transmission are encoded and decoded by the telemetry equipment at the ends of the transmission line. Multiplexing may be Time Division Multiplexing (TDM) or Frequency Division Multiplexing (FDM). Used for remote control from a central office location to one or more field stations.

Regional
Disciplines: Train Control
Temporary Accreditation
The Administrating Authority may grant interim accreditation to an applicant to permit activities such as;
(a) site preparation;
(b) restoration or repair work;
(c) testing of railway track or other infrastructure;
Or for other purposes considered appropriate by the administrating authority.

Preferred
Disciplines: ALL Disciplines
Temporary Rail Joint
Non-welded rail joints intended for temporary joining of rails only, and generally requiring special measures to be implemented with their use. These measures permit the short-term passage of trains and may include special inspections or speed restrictions.

Preferred
Disciplines: ALL Disciplines
Temporary Speed Restriction (TSR)
An imposed reduction of the normal speed for a portion of track.

Preferred
Disciplines: Operations, Train Control
Temporary Speed Restriction Ahead Sign
A temporary speed ahead sign with a speed plate and distance metreage attached to warn rail traffic crew of the speed at which trains are to travel over the next portion of the line which may be unsafe at normal speed.

Preferred
Disciplines: Operations, Train Control
Temporary Traction Bond
An insulated cable fitted with rail clamps at eachend used to temporarily bridge gaps in the traction rail.

Preferred
Disciplines: Electrical
Tense (rail)
See Destress.

Alternative
Disciplines: Infrastructure
Terminal Line
A dead end line.

Preferred
Disciplines: ALL Disciplines


Disciplines:
TEU
Twenty Foot Equivalent Unit


Disciplines:
TGSI
Tactile Ground Surface indicator


Disciplines:
Abbreviated term for 'tactile ground surface indicator' as defined in the DSFAPT Part 18.
Alternative
Disciplines: ALL Disciplines
Thermit (weld)
A trade name for an aluminothermic weld.

Other
Disciplines: ALL Disciplines
Third Rail Crossingwork
Crossingwork arranged to permit broad and standard gauge traffic to turn out or transfer on one common rail. The units include fixed points and transfers and require no points operation equipment.

Preferred
Disciplines: Infrastructure
Third Rail Track
Trackwork comprising three rail arranged to permit both broad and standard gauge traffic. One rail is common to both gauges.
Review

Preferred
Disciplines: Infrastructure
Third Rail Transfer
Third rail crossingwork, without moving parts, which transfers the common rail from one side of the track to the other side.

Preferred
Disciplines: Infrastructure
Third Rail Turnout
A crossingwork assembly arranged to permit both broad and standard gauge traffic on the straight or through but only one gauge to turnout.

Preferred
Disciplines: Infrastructure
Three Aspect Block
Refer to 3 Aspect Block.

Preferred
Disciplines: Train Control
Related Term: 3 Aspect Block
Three Piece Bogie
Conventional three-piece freight bogie based on the technical requirements of the AAR Manual Of Standards And Recommended Practices.

Preferred
Disciplines: Rolling Stock
Three Position Signalling
Refer to 3 Position Signalling.

Preferred
Disciplines: Train Control
Related Term: 3 Position Signalling
Three Throw (points)
Two turnouts arranged within a length of less than the sum of the separate turnout lead lengths.
Also known as 'nested turnouts'.

Preferred
Disciplines: Infrastructure
Throat (crossing)
The position ahead of the nose(s) of a crossing between the inside edges of the wing rails at the knee or knuckle.

Preferred
Disciplines: Infrastructure
Through Function Test
This is a circuit function test of a circuit or series of related circuits running between locations, e.g. signal boxes, relay rooms, etc, to ensure the fuses, links and control devices effectively control the final function. It includes through function testing from a signaller's control on the operator interface to the operation of the trackside signalling equipment, and to its change-of-state indication back to the signaller's indicator diagram.

Regional
Disciplines: Electrical, Train Control
Through Movement
Transit or travel in the Network

Preferred
Disciplines: ALL Disciplines
Through Route Locking
Route locking, the action of which extends to all the points in a route and to the points leading to that route from the moment a train enters this route until it has completey left it.

Preferred
Disciplines: Electrical, Train Control
Tie
Alternative term for Sleeper.

Alternative
Disciplines: Infrastructure
Tie Bar
A rod used between rails of tracks to maintain gauge where other means are not appropriate.

Preferred
Disciplines: Infrastructure
Tie Plate
A long rail base plate, which ties the track gauge between each half set of points. It provides for attachment of the stock rail and a slide surface for the point switch. It is manufactured from pressed steel and is fastened to the timber.

Preferred
Disciplines: Infrastructure
Timber
A bearer which is used to support crossingwork assemblies.

Preferred
Disciplines: Infrastructure
Time Distance Curves
Time distance curves are employed in the planning of signal positions. The time is plotted vertically against a horizontal distance scale, and the curves indicate the position of a train at any particular time for the section of the line under consideration.

Regional
Disciplines: Train Control
Time Limit Relay
A relay which will not close its front contacts or open its back contacts, or both, until the expiration of a definite time interval after the relay has been energised.

Preferred
Disciplines: Electrical
Time Release
A device used to prevent the operation of an operative unit until after the expiration of a predetermined time interval after the device has been actuated.

Regional
Disciplines: Train Control
TOA
Train Occupancy Authority


Disciplines:
Toe
The machine end of a switch at which the turning out movement commences.

Preferred
Disciplines: Infrastructure
Toe Throw
The horizontal distance or travel at the toe of a switch from the home or closed position to the fully open position.

Preferred
Disciplines: Infrastructure
Token
A metal staff or a staff ticket used as the authority for rail traffic to occupy a section.

Preferred
Disciplines: Train Control, Operations
Tonnage Signal
Signals at which trains over a prescribed load must be brought to a stand unless the signal is showing thefull clear indication. The purpose is to prevent trains being brought to a stand on a heavy rising grade.

Regional
Disciplines: Train Control
A signal before a grade, with a sign that directs rail traffic crews, the sign may be before or fitted to the signal.
Preferred
Disciplines: Train Control, Operations
Top
Vertical alignment of the rails. Top is generally measured using the offset at a defined point along a chord of defined length. For lateral alignment see Line.

Preferred
Disciplines: Infrastructure
Top Event
The event classified as having the greatest adverse outcome - expressed (and detailed in OC-G1) in terms of casualties, damage or accident potential

Preferred
Disciplines: ALL Disciplines
Tourist And Heritage Railway
A railway preserved for its historical value that is not connected to another railway network, or operates independently from any other network that it is connected to.

Preferred
Disciplines: ALL Disciplines
TP
Tangent Point


Disciplines:
TPCS
Train Protection and Control System


Disciplines:
TPWS
Train Protection and Warning System


Disciplines:
Abbreviation for 'train protection and warning system'. It combines the elements of AWS with some train protection elements. This system will stop a train that passes a signal at danger within the overlap area beyond the signal.
Alternative
Disciplines: Train Control, Operations
Track
The combination of rails, rail connectors, sleepers, ballast, points, and crossings, and substitute devices where used.

Preferred
Disciplines: Infrastructure
Track Block System
A system of safeworking used on single or double lines in track-circuited areas.

Regional
Disciplines: Train Control
Track Buckle
A substantial misalignment contributed to by longitudinal thermal stresses overcoming the lateral or vertical resistance of the track.

Preferred
Disciplines: Infrastructure, Operations
Track Centres
The distance between the centrelines of parallel tracks.

Preferred
Disciplines: Infrastructure
Track Circuit
An electric circuit where current is carried through the rails and used to detect the presence of trains. Track-circuits are used in the operation and control of points and signalling equipment

Preferred
Disciplines: Train Control, Electrical
Track Circuit Drop Shunt
The maximum resistance in ohms which will cause the track relay contacts to drop away when this resistance is placed between the rails of the track circuit at the most adverse shunting location.

Regional
Disciplines: Train Control
Track Circuit Shorting Device
A device that can be applied to a line’s rails to activate track-circuits.

Preferred
Disciplines: Operations, Electrical
Track Circuited Territory
Portions of line where the system of safeworking relies on track circuits to detect the presence of rail traffic.

Preferred
Disciplines: ALL Disciplines, Train Control
Track Closure
A procedure to protect against the movement of trains which are part of the normal operating service, through a section of track/s, but allow for the passage, for example, of trains and on-track vehicles under special conditions such as published in train notice.

Preferred
Disciplines: ALL Disciplines
Track Control System
A system of safeworking used on single or double lines in track-circuited areas (or on single lines provided with axle counting equipment).

Regional
Disciplines: Train Control
Track Controlled Signal
Signals, partially or wholly controlled by track circuits, which return to their most restrictive position after a train passes.

Regional
Disciplines: Train Control
Track Defects
Defects in the track which have the potential to cause derailment unless a speed restriction is imposed, as follows:
(a) track defects involving horizontal alignment;
(b) track defects involving vertical alignment;
(c) broken rail;
(d) other track defects.

Preferred
Disciplines: ALL Disciplines, Infrastructure
Track Gauge
The distance between the gauge points of the rails.

Preferred
Disciplines: Infrastructure
Track Geometry
The horizontal and vertical alignment, cross-level and cant of the track.

Preferred
Disciplines: Infrastructure
Track Indicator
An indicator, in a signal box, which shows the signaller whether or not the portion of track-circuited line represented by that indicator is occupied by a train. At some interlockings, where only certain portions of lines are track-circuited, individual track indicators are provided. At fully track-circuited interlockings the indicators are grouped together to form a track indicator diagram.

Regional
Disciplines: Train Control
Track Indicator Diagram
A diagram that shows if tracks are occupied, and other relevant information.

Preferred
Disciplines: Train Control
Track Junction
A crossingwork assembly which provides for diverging and crossing of tracks.

Preferred
Disciplines: Infrastructure
Track Locking
Locking of signals or points applied and maintained by the presence of trains on particular sections of track, as detected by track circuits.

Regional
Disciplines: Train Control
Track Machine
A flange wheeled vehicle used for infrastructure maintenance, construction and inspections. Separate to freight rolling stock (e.g. wagons used for carrying rail, sleepers, spoil, ballast etc) and road-rail vehicles.

Preferred
Disciplines: Rolling Stock, Infrastructure
Track Magnet
Permanent or electro-magnet which under certain conditions operates by indiction induction an on apparatus on a vehicle passing by.

Preferred
Disciplines: Electrical
Track Occupancy Authority (TOA)
An authority for Competent Workers and their equipment to occupy a defined portion of track for a specified period.

Preferred
Disciplines: ALL Disciplines
Track Profile
The outline of the track in cross section in its completed condition on the formation.

Preferred
Disciplines: Infrastructure
Track Relay
A relay receiving all or part of its operating energy from a circuit of which the rails are the essential part, and responding to the presence of vehicles on the track.

Preferred
Disciplines: Electrical
Track Safety Awareness
Training in the risks present and safety measures necessary when a person is on or near track.

Preferred
Disciplines: ALL Disciplines
Track Section
The section of railway track between two locations specified for operating purposes. In different track networks this track element may be referred to as either a section or a block.

Preferred
Disciplines: ALL Disciplines
Track Speed
The allowed maximum speed for a portion of track.

Preferred
Disciplines: ALL Disciplines, Operations
Track Stick
A circuit provided to prove that a signal has returned to stop, and its signal control relays have de-energised, after the passage of a train.

Regional
Disciplines: Train Control, Electrical
Track Supervisor
A Competent Worker responsible for inspections, operations or instructions associated with the maintenance or construction of permanent way or works for a prescribed portion of the railway.

Preferred
Disciplines: ALL Disciplines, Infrastructure
Track Vehicle
A vehicle, usually self-propelled, used for inspecting and / or maintaining infrastructure.

Preferred
Disciplines: ALL Disciplines, Infrastructure
Track Vehicle Identification
The unique number displayed on a track vehicle.

Preferred
Disciplines: ALL Disciplines, Infrastructure
Track Vehicle Operator
A Competent Worker controlling the movement of a track vehicle.

Preferred
Disciplines: ALL Disciplines, Infrastructure
Track Work
Construction, maintenance or repair work on infrastructure in the Rail Corridor

Preferred
Disciplines: ALL Disciplines, Infrastructure
Track Work Authority (TWA)
Authority for non-exclusive occupancy of track by track workers and equipment within specified limits.

Preferred
Disciplines: ALL Disciplines, Train Control
Track Workers
Competent rail safety workers whose primary duties are associated with work on or around infrastructure in the Rail Corridor

Preferred
Disciplines: ALL Disciplines, Infrastructure
Track, Ballasted
Track in which the sleepers are supported and contained by ballast.

Preferred
Disciplines: Infrastructure
Track, Concreted
Track in which the rails are supported and contained by concrete.

Preferred
Disciplines: Infrastructure
Trackside
Parts of the Infrastructure directly involved with train operations and operational safeworking.

Preferred
Disciplines: Operations
Trackside Monitoring Equipment
Devices that monitor and respond to track, trackside and rail vehicle conditions.

Preferred
Disciplines: Train Control, Operations
Trackwork
Track, including crossingwork assemblies, with sleepers, timbers and fasteners, laid, lined or surfaced and connected with the track.

Preferred
Disciplines: Infrastructure
Trackwork Assembly
Refer to Crossingwork Assembly.

Alternative
Disciplines: Infrastructure
Related Term: Crossingwork Assembly
Traction Bond
A bond connecting together the various items of equipment in the traction current retrun circuit path. It shall be assumed that this bond will be carrying traction current at all times.

Preferred
Disciplines: Electrical
Traction Current Return
The electric current returning from the overhead power supply through the rails to substations.

Preferred
Disciplines: Electrical
Traction Earth
The earth for the traction distribution system which primarily consists of the traction return rails, earth wires and overhead structures.

Preferred
Disciplines: Electrical, Infrastructure
Traction Earth Wire
An aerial conductor used to connect a number of overhead line structures together in order to ensure that the traction earthing system continuity is appropriately maintained throughout the electrified area.

Preferred
Disciplines: Electrical
Traction Return Current
The electric current returning from the overhead power supply, via electric rail traffic, through the rails to sub-stations.

Preferred
Disciplines: Electrical
Traction Return Rail
The rail which carries the traction return current and is generally marked at intervals with blue paint on the rail web and has traction bonds connected to it. It is generally, but not always, the rail nearest to the mast.

Preferred
Disciplines: Electrical, Infrastructure
Tractive Effort
The power that a Motive Power Unit is able to deliver to the rail through its wheels notwithstanding the ability of the wheels to grip the rail.

Preferred
Disciplines: Rolling Stock, Operations
Trailable Points
Points designed to permit a trailing movement through points closed against the intended move. The wheelset opens the points which spring back to the normal position after the wheelset is through.

Preferred
Disciplines: Infrastructure
Trailer Car (or Trailer Vehicle)
A non-powered passenger vehicle, with or without a
drivers compartment and control facilities.drivers compartment and control facilities.

Preferred
Disciplines: Rolling Stock
Trailing Movement
A wheelset movement through a set of points from the heel end to the toe end.

Preferred
Disciplines: Operations
Trailing Points
Those switches over which rail traffic from two lines converge onto one line and the points of the switch blades are facing away from approaching rail traffic.

Preferred
Disciplines: Infrastructure
Train
A locomotive or self-propelled vehicle, alone or coupled to one or more vehicles

Preferred
Disciplines: ALL Disciplines
Train (identification) Number
A train or run number used to provide unique identification of a train.

Preferred
Disciplines: Train Control, Operations
Train Acceptance
The overall process of gaining permission from a Rail Infrastructure Manager to operate trains comprising particular rolling stock over specific parts of the network.

Preferred
Disciplines: ALL Disciplines, Rolling Stock
Train Announcement
Operation by which a section box advises the forward box that a train has just entered or is going to enter the section between the two boxes.

Regional
Disciplines: Train Control
Train Authority
An instruction in the prescribed format issued by the Network Control Officer in connection with the movement of a train.

Preferred
Disciplines: Train Control, Operations
Train Control Diagram (graph)
A diagram showing operational information for a train control area. Also known as a Train Control graph.

Preferred
Disciplines: Train Control
Train Control System (TCS)
One or more microprocessor based operator interface stations with the processing capacity to handle route setting, automatic route setting, train tracking, train describing, train reporting, event logging and all similar functionality.

Regional
Disciplines: Train Control
Train Controller
A Competent Worker who authorises, and may issue, Occupancy Authorities, and who manages rail traffic paths to ensure safe and efficient transit of rail traffic in the Network.

Alternative
Disciplines: ALL Disciplines, Train Control
Refer to 'Network Control Officer'.
Alternative
Disciplines: ALL Disciplines, Train Control
Train Describer
Signalling equipment provided to identify trains individually on a signaller's track indicator diagram, console unit, video display unit or video projection screen.

Regional
Disciplines: Train Control
Train Describer Fringe Box
A signal box controlling a location that is an entry point for a train describer system. The fringe box contains train describer equipment and train identification details can be entered manually for the next train(s) to depart the particular controlled location.

Regional
Disciplines: Train Control
Train Detection System
A system that detects the presence of a train or any other on track vehicle intended to be detected on a section of track. Systems include track circuits, axle counters, treadles and global positioning systems.

Preferred
Disciplines: Train Control
Train Graph
A plot of actual and projected train movements on a graph with axis of location versus time. Used by train controllers to predict crossing locations for opposing trains on single line sections and to manage the train movements accordingly. It serves also as a record of actual crossing locations and times.

Regional
Disciplines: Train Control
Train Notice
Operational information issued by or on behalf of the Rail iInfrastructure Manager.

Preferred
Disciplines: ALL Disciplines
Train Number
Unique character codes identifying rail traffic.

Preferred
Disciplines: Train Control, Operations
Train Operated Route Release
Refer to Automatic Route Normalisation.

Regional
Disciplines: Train Control
Related Term: Automatic Route Normalisation
Train Order
An instruction, on the prescribed form, issued by the train controller, in train order territory to direct the movement of rail traffic.

Regional
Disciplines: Train Control, Operations
Train Order Crossing Station
A train order station within or at the start of or end of train order territory at which trains may cross pass or run round.

Regional
Disciplines: Train Control, Operations
Train Order Non Crossing Station
A train order station in train order territory at which trains may not cross, pass or run round.

Regional
Disciplines: Train Control, Operations
Train Order Section
That portion of main line between two adjoining train order crossing or non-crossing stations.

Regional
Disciplines: Train Control, Operations
Train Order Station
A station where train orders may be received and which may or may not be in train order territory.

Regional
Disciplines: Train Control, Operations
Train Order Territory
That portion of main or branch line specified as being the territory in which the train order system of safeworking is used.

Regional
Disciplines: Train Control, Operations
Train Order Working
A system of Safeworking on single lines where train movements are governed by train orders issued by a train controller, who ensures that no conflicting train orders are on issue.

Regional
Disciplines: Train Control, Operations
Train Path
The track over which a train may be authorised to travel, consisting of a distinct entry, exit and journey time. It consists of routes linked consecutively.

Preferred
Disciplines: ALL Disciplines, Train Control
Train Protection And Control (TPC) System
A system used for authorising and safeguarding the safe operation of rail traffic and on-track work.

Preferred
Disciplines: ALL Disciplines, Train Control
Train Protection System
A system which is able to enforce the authority of the signalling system onto the vehicle.

Preferred
Disciplines: Train Control, Rolling Stock
Train Radio
A radio system use to aid train operations and to provide communications between train crews, train controllers, and track maintenance staff.

Preferred
Disciplines: Operations
Train Register Book
A book used in signal boxes, staff huts or at block posts to record information about the condition of the line or the movement of rail traffic.

Regional
Disciplines: Train Control
Train Roster
Assigns the rollingstock to cover the timetable. Each entry in this working is referred to as a Run.

Regional
Disciplines: Rolling Stock, Operations
Train Running Information (TRI)
Information about rail traffic movement and frequency for a particular location.

Preferred
Disciplines: Train Control, Operations
Train Safety Recording
A recording consisting of (or mainly of) sounds or images or data, or any combination of sounds, images or data, produced by a device installed in a train, a signal box, a train control complex or other railway premises for the purpose of recording operational activities carried out by rail safety workers in relation to the operation of a train.

Regional
Disciplines: Operations
Train Shunt
Value of the electrical resistance of the shunt connection created between the two rails of a track circuit by the axles of a train.

Preferred
Disciplines: Electrical
Train Stop System
A system (also known as trip gear) involving a trip cock on the vehicle and a trip arm located track side which, when engaged, directly initiates an emergency brake application. The train stop is employed at signals in conjunction with a red aspect and also in areas where train speed is required to be externally controlled.

Preferred
Disciplines: Operations, Rolling Stock
Tram
A vehicle which runs on rails on a highway, road or easement specifically designated for use by a tram or light rail vehicle. Alternative name for a light rail vehicle.

Alternative
Disciplines: ALL Disciplines
Trammelling
Measurement of the bogie frame, e.g. centre line to centre line, check for squareness.

Preferred
Disciplines: Rolling Stock
Transformer
Static apparatus for supplying an alternating current at one voltage when fed with alternating current at a different voltage.

Preferred
Disciplines: Electrical
Transit
Through-movement along a portion of line.

Preferred
Disciplines: ALL Disciplines
Transition
the physical movement from one jurisdiction to another through a designated boundary

Preferred
Disciplines: ALL Disciplines
Transition (track)
Track of variable radius, usually applied between tangent track and curved track or track comprising curves of different radii.

Preferred
Disciplines: Infrastructure
Transition Curve
A curve of uniformly varying radii used to connect straight and curved tracks or curves of different radii.

Preferred
Disciplines: Infrastructure
Transmission Based Signalling
A closed loop system which uses digital radio to provide vital data transmission between on-board train systems and signalling control systems.

Regional
Disciplines: Train Control
Transom
Transverse members of track-supporting structures generally made from timber, to which the running and guard rails are fastened. These members are designed specifically as structural members of the track-supporting structure and should not be treated as sleepers.

Preferred
Disciplines: Infrastructure
Transponder
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.

Regional
Disciplines: Train Control
Refer to Beacon and Balise.
Alternative
Disciplines: Train Control
Related Term: Beacon and Balise
Trap Points
Catch-points or other facing points on a line which provide protection for another line by diverting train and vehicle movements on the line away from the protected line.

Regional
Disciplines: Train Control, Infrastructure
Travel
Purposeful movement from one location to another .

Preferred
Disciplines: ALL Disciplines
Travel Mode
When infrastructure maintenance rolling stock have their infrastructure maintenance equipment stowed and are able to travel between work sites.

Preferred
Disciplines: Infrastructure, Rolling Stock
Tread Line
The circumference of the wheel around the wheel tread measured 70 mm from the back face of the wheel (i.e. circumference at the nominal wheel/rail contact point), also known as the taping line.

Preferred
Disciplines: Rolling Stock
Treadle
A device mounted next to a rail by which the deflection of the rail (due to the passage of an engine or vehicle) or the impact of the train wheels, or other means, operates a contact to open or close an electric circuit to detect the passage of train wheels.

Regional
Disciplines: Train Control
Treadplate
The slip resistant platform adjacent to the door sill on rolling stock used by workers for boarding and alighting.

Preferred
Disciplines: Rolling Stock
trespass
The unauthorised access to the rail corridor by a person, livestock or vehicle. Trespass is either:-
(a) Intentional: where an individual deliberately sets out to surmount or ignore a physical boundary measure or otherwise intentionally gain unauthorised entry to the rail corridor.
or
(b) Unintentional: where no physical barrier is provided or has otherwise been removed or an access gate has been left open or unlocked and an individual strays into the rail corridor.

Preferred
Disciplines: Infrastructure, Operations
TRI
Train Running Information


Disciplines:
Abbreviation for 'train running information'.
Information about rail traffic movement and frequency provided for a particular location.
Alternative
Disciplines: Train Control, Operations
Triangle
A track formation in the shape of a triangle which allows a locomotive do a three point turn so that it faces in the opposite direction. An alternative to a turntable.

Preferred
Disciplines: Infrastructure
Trip
A service in a working timetable.

Regional
Disciplines: Train Control, Operations
Trip Cock
The trip valve and lever mechanism fitted on train stop systems.

Regional
Disciplines: Rolling Stock, Operations
Trip Valve
A pneumatic value mounted near the left-hand leading axle of multiple unit electric trains. If a train passes a trainstop when the trainstop arm is in the raised position, the trip valve arm will be moved backwards by the raised trainstop arm. The train's brakes will then be automatically applied.

Preferred
Disciplines: Rolling Stock, Operations
Troughing
Steel or concrete casing located alongside the track to carry electrical cables for signalling and communications.

Preferred
Disciplines: Electrical
TSR
Temporary Speed Restriction


Disciplines:
Turnout
A combination of a set of points, V crossing and guard rails which permits traffic to turnout from one track to another.

Preferred
Disciplines: Infrastructure
Turnout, Ladder
An arrangement of turnouts leading from one turnout and providing two or more parallel tracks on the one side of the parent track.

Regional
Disciplines: Infrastructure
Turnout, Nested
Refer to 'three throw (points)'.

Regional
Disciplines: Infrastructure
Turnout, Repeater
A indicator displaying a white band of light on a black background, on the first warning signal in rear of a signal at a junction with a turnout speed significantly less than line speed. When that signal is cleared for the diverging route, the turnout repeater displays a white band of light inclined towards the direction the route ahead is set. Generally used to provide drivers of trains with advance information that a route through a low-speed turnout is ahead.

Regional
Disciplines: Train Control, Operations
Turntable
A deck, usually over a circular pit, onto which a locomotive is driven and which pivots about its centre to turn a locomotive or allow it to run off onto other radiating tracks for storage.

Regional
Disciplines: Infrastructure, Operations
TWA
Track Work Authority


Disciplines:
Twenty Foot Equivalent Unit (TEU)
The unit of measure used to refer to the freight carrying space on a wagon required to carry a standard 6.1 metre (20 foot) container. Wagon sizes and train capacities are typically referred to in 'slots' or 'teus' (twenty-foot equivalent units).

Regional
Disciplines: Rolling Stock, Operations
Refer 'slots' or 'teus'
Alternative
Disciplines: Rolling Stock, Operations
Twist
The variation in the cross-level between two track locations separated by a nominated distance interval.

Preferred
Disciplines: Infrastructure
Two Position / Two Aspect Signalling
Signalling using stop signals that only show two indications, 'stop' and ;clear', preceded by distant signals showing only 'caution' or Clear.

Regional
Disciplines: Train Control
See also 2 Aspect Block and 2 Position Signalling.
Alternative
Disciplines: Train Control
Related Term: 2 Aspect Block and 2 Position Signalling
Type Test
A test conducted on one vehicle that will be assumed to be typical of all vehicles constructed to the same specifications.

Preferred
Disciplines: Rolling Stock