Glossary of Terms


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

Safe Braking Distance
A distance indicated to rail traffic crew that would allow rail traffic to stop with the application of normal service braking.

Preferred
Disciplines: Operations, Rolling Stock
Safe Distance
A distance between workers and equipment and exposed electrical wires and equipment that an Rail Infrastructure Manager deems as safe.

Preferred
Disciplines: ALL Disciplines
Safe Place
1. A place where workers and equipment cannot be struck by rail traffic.
2. A Safe Place is a place where no track worksite protection is provided and is either:
- a properly constructed refuge to an approved design;
- behind the safety line on a platform;
- a place where a structure or physical barrier has been erected to provide protection but includes subways and overhead bridges;
- a place that is not on or near the track.

Preferred
Disciplines: ALL Disciplines
Safe System Of Work
Formal method of work devised from taking account of all likely sources of danger to provide for the safety of those involved, affected by, or in the vicinity of the work.

Overseas
Disciplines: Operations
Safety Action
An action which is proposed or has been taken to address a particular safety deficiency which has come to light during an investigation.

Preferred
Disciplines: ALL Disciplines
Safety Assessment
An assessment process used to identify hazards for all work planned for the Rail Corridor and its potential to intrude on the Danger Zone.

Preferred
Disciplines: ALL Disciplines
Safety Case
A formal presentation of evidence, arguments and assumptions aimed at providing assurance that a system, product or other change to the railway has met its safety requirements and that the safety requirements are adequate.

Preferred
Disciplines: ALL Disciplines
Safety Critical
Directly influencing safety (when applied to equipment or systems).

Preferred
Disciplines: ALL Disciplines
Safety Critical Worker
A worker whose action or inaction may lead directly to a serious incident affecting the public or the rail network.

Preferred
Disciplines: ALL Disciplines
Safety Culture
The product of individual and group values, attitudes, perceptions, competencies and patterns of behaviour that determine commitment to, and the style and proficiency of, an organisation's health and safety management.

Preferred
Disciplines: ALL Disciplines
Safety Data Register
The list of key safety-related characteristics of a particular (class of) rolling stock as listed in the AS 7500 series of Australian Rolling Stock Standards.

Preferred
Disciplines: Rolling Stock
Safety Deficiency
Any situation related to the operation or management of the railway system that can reasonably be regarded as having the potentialto adversely affect the safety of railway operations.

Preferred
Disciplines: ALL Disciplines
Safety Integrity
The probability of a safety-related system performing its required safety function under the required conditions and within the required time interval.

Preferred
Disciplines: ALL Disciplines
Safety Interface Agreement
An agreement between parties to manage safety risks.

Preferred
Disciplines: ALL Disciplines
Refer Interface Coordination Plan.
Alternative
Disciplines: ALL Disciplines
Safety Management System
Any system whose primary objective is to achieve safe rail operations. Under co-regulation the Accreditation Authority has the role of defining the minimum requirement forwhat must be included in a specific safety management system. Rail Transport Operators, Rail Infrastructure Managers and Rail Transport Operators are free to nominate equivalent or superior standards for their safety management system.

Preferred
Disciplines: ALL Disciplines
Safety Related System
A system by which the safe operation of equipment or process is achieved, either as an integral part of the control function or as a system designed to respond to a hazardous condition independently of the control function.
(a) Driving and operation of trains.
(b) Control of the movement of trains.
(c) The design, construction, repair, maintenance, upgrading, inspection or testing of track, rollingstock, civil and electric traction infrastructure, and signalling and telecommunications equipment.
(d) Development, design, implementation and management of safety related processes.
(e) Any other duties prescribed by an organisation as safety-related work.

Preferred
Disciplines: ALL Disciplines
Safety Validation
A systematic and structured process to ensure that all risks associated with a change are identified and are reduced to as low as reasonably practicable (ALARP) before the change is implemented.

Preferred
Disciplines: ALL Disciplines
Safeworking Breach
A departure from safeworking procedures which could compromise safety.

Preferred
Disciplines: ALL Disciplines
Safeworking System
Refer System Of Safeworking

Alternative
Disciplines: ALL Disciplines, Train Control
Sameness
the measure of being one or identical, though having different names, aspects, etc.

Preferred
Disciplines: ALL Disciplines
SAS
Section Authority System


Disciplines:
SCADA
Supervisory Control and Data Acquisition system


Disciplines:
SCADA System
A supervisory control and data acquisition telemetry system.

Regional
Disciplines: Train Control
Scarf
The position on a crossing where a (Scarf) rail joins into a machined notch in the nose rail.

Preferred
Disciplines: Infrastructure
Scarf Rail
The rail forming a V which joins the nose rail at the machined notch. Also referred to as the male half of vee.

Preferred
Disciplines: Infrastructure
Scheduling
Scheduling is the process of co-ordinating arrival and departure times for train services at the beginnning, intermediate and destination locations of a journey. This scheduling meets the requirements of individual railway operators, their customers and the integration of other planned and unplanned requirements such as maintenance.

Preferred
Disciplines: ALL Disciplines, Operations
Scheme Plan
A longitudinal scaled or dimensioned track layout plan that is produced to depict new or altered signalling systems.

Overseas
Disciplines: Train Control
Refer to Signalling Plan.
Alternative
Disciplines: Train Control
Related Term: Signalling Plan
Scissor (crossover)
Two intersecting crossovers.

Regional
Disciplines: Infrastructure
SCOTI
Standing Committee of Transport and Infrastructure


Disciplines:
Abbreviated term for 'Standing Committee of Transport and Infrastructure'.
Alternative
Disciplines: ALL Disciplines
SCOTI Rail Group
Sub-committee of the 'Standing Committee of Transport and Infrastructure'.

Alternative
Disciplines: ALL Disciplines
Screwspike
A threaded fastener used to attach plates to sleepers.


Disciplines:
SCT
Specialised Container Transport


Disciplines:
Abbreviated term for 'Specialised Container Transport'
Preferred
Disciplines: ALL Disciplines
Sealed Release
An emergency release which requires a seal to be broken prior to operation.

Overseas
Disciplines: Train Control
Seamless
without knowledge of change occurring

Preferred
Disciplines: ALL Disciplines
Searchlight Signal
A colour light signal that can display red, yellow and green aspects from a single optical assembly. Modern forms employ LED or fibre optic technology; heritage types change aspect by placing separate coloured lenses in front of a single lamp.

Overseas
Disciplines: Train Control
Seat Utilisation
A measure of the total number of passengers per train divided by the total seating.

Regional
Disciplines: Operations
Section
The line between the departure end yard limit of one location and the arrival end yard limit of another location. A section consists of one or more blocks.

Preferred
Disciplines: Train Control, Operations
Section Authority System (SAS) Territory
The portions of line where the Section Authority System of Safeworking is used.

Non-preferred
Disciplines: Train Control, Operations
Section Insulator
Insulation introduced into the contact/catenary wires between two electrical subsections of overhead line equipment, arranged so that the pantographs may pass from one subsection to the other smoothly and without break of electrical contact whilst still providing isolation between the subsections.

Preferred
Disciplines: Electrical
Section Running Time
The train running time between one block station and the block station in advance.

Preferred
Disciplines: Train Control, Operations
Section Signal
A stop signal controlling the entrance to a block section or Intermediate block section ahead.
Also see Accept/home Signal, Starting Signal and Advanced Starting Signal.

Overseas
Disciplines: Train Control
Sectional Route Release Locking
Route locking, the action of which ceases on those points over which the train has run and on the corresponding protecting points.

Regional
Disciplines: Electrical
Secure
To place and keep something in a known or prepared place or position to safeguard it against accidental or unauthorised access or movement.

Preferred
Disciplines: ALL Disciplines
Secure Power Supply
A power supply system that can be relied upon to keep certain safety-critical signalling functions operating for a predetermined minimum time, in the event of a total incoming supply failure.

Overseas
Disciplines: Electrical
Security
Protection of persons, property and railway operation by means of arrangements to reduce the risk of harm from criminal acts of other parties such as theft, assault, sabotage and terrorism.

Preferred
Disciplines: ALL Disciplines
Selection
The logic by which signals are allowed to show a proceed indication only when all conditions have been satisfied.

Regional
Disciplines: Train Control
Self-normalising Points
Points which are automatically returned to the normal position after rail traffic movement.

Preferred
Disciplines: Infrastructure
Self-propelled Passenger Rolling Stock
Non-locomotive hauled passenger-carrying rolling stock, e.g. multiple unit trains and rail motors.

Preferred
Disciplines: ALL Disciplines, Rolling Stock
Semaphore Signal
A signal which informs a driver by means of the position of a mechanical arm during daylight and by coloured lights during darkness.

Legacy
Disciplines: Train Control, Infrastructure
Semi-automatic Signal (or 'controlled Automatic Signal')
A fixed signal which can be controlled by a signaller but which can also be switched to 'automatic'. When the signal is in 'automatic', it is operated by the location of train over track circuits on the departure side of the signal.

Regional
Disciplines: Train Control
Sense And Brake Unit
End of train device which forms part of the end of train monitoring system (ETMS). Sends a signal to the in-cab integrated function display (IFD).

Regional
Disciplines: Rolling Stock, Operations
Sequential Interlocking
Interlocking which compels a certain sequential order in the working of the levers.

Regional
Disciplines: Train Control
Sequential Locking
Locking applied to successive running signals to enforce the replacement of one lever (arm or aspect) before the lever controlling the signal in rear is free to be pulled. This locking is non-reciprocal and may be performed electrically or mechanically.

Overseas
Disciplines: Train Control
Series Bonding
The fail safe method of bonding track circuits with rail sections connected in series, such that a single failure results in the track circuit showing occupied.

Overseas
Disciplines: Train Control, Electrical
Series/parallel Bonding
The bonding of one rail of a turnout as series bonding and the other rail of the turnout as parallel bonding.

Regional
Disciplines: Train Control, Electrical
Service Braking Distance
The distance to stop a train under normal braking, when travelling at its maximum permissible speed for the line, and with regard to the performance capability of the train and its location.

Preferred
Disciplines: Rolling Stock, Operations
Service Period
The period of time in service use until scheduled withdrawal for the next overhaul.

Preferred
Disciplines: Rolling Stock
Service Provider
An organisation contracted to an operator to provide locomotives, wagons and crews or other service to enable the operation of the train on the network.

Preferred
Disciplines: ALL Disciplines
Serviceable Material
Previously used or part worn material which is suitable for re-use.

Preferred
Disciplines: Infrastructure
Set (points)
Refers to the interlocking function which controls the movement of the points to their correct position. Successful completion of the setting process results in correspondence.

Overseas
Disciplines: Train Control
Set Back
To move in the reverse direction to that provided in the current proceed authority.

Preferred
Disciplines: Train Control, Operations
Set In Rail
A permanent sharp bend or curve in a rail.

Preferred
Disciplines: Infrastructure
Set To Work Test
This is not a certification test but part of the process of setting the equipment to work correctly. It is the initial powering up of the signalling circuitry and local apparatus at a relay room or location case to test that it is able to carry out its function correctly.

Regional
Disciplines: Train Control
Setting
The interlocking function controlling the movement of points or other moveable components to the correct position.

Regional
Disciplines: Train Control
SFAIRP
So Far As Is Reasonably Practical

In this context, and under the RSNL (s47), reasonably practicable means that which is, or was at a particular time, reasonably able to be done to ensure safety, taking into account and weighing up all relevant matters including:
a) the likelihood of the hazard or the risk concerned occurring; and
b) the degree of harm that might result from the hazard or the risk; and
c) what the person concerned knows, or ought reasonably to know, about the hazard or risk, and ways of eliminating or minimising the risk; and
d) the availability and suitability of ways to eliminate or minimise the risk; ande) after assessing the extent of the risk and the available ways of eliminating or minimising the risk, the cost associated with available ways of eliminating or minimising the risk, including whether the cost is grossly disproportionate to the risk.

Preferred
Disciplines: ALL Disciplines
Abbreviation for 'so far as is reasonably practicable'.
Preferred
Disciplines: ALL Disciplines
Shall
Indicates that a statement is mandatory.

Preferred
Disciplines: ALL Disciplines
Shelf Mounted Plug In Relay
A conversion unit which directly replaces a shelf type relay. Once installed, any further relay replacement is by replacing the plug in relay portion of the assembly.

Regional
Disciplines: Electrical
Shelf Type Relay
A relay designed for installation on a shelf or other flat surface. The electrical connections are made to individual terminals on its top surface.

Regional
Disciplines: Electrical
Shielding Impedance Track Circuit
A series resistor, parallel inductance impedance unit inserted in a single rail 50 Hertz AC track relay circuit to limit, divert and prevent traction return DC current affecting the AC track relay.

Regional
Disciplines: Electrical
Short Welded Rail
Track where the rail is welded into lengths less than 110m, with the rail lengths joined by mechanical joints.

Preferred
Disciplines: Infrastructure
Should
Indicates a recommendation.

Preferred
Disciplines: ALL Disciplines
Shunt
To move rail traffic, rakes of vehicles or vehicles on lines for purposes other than through movements.

Preferred
Disciplines: ALL Disciplines, Infrastructure
Shunt Authority
An Authority for rail traffic to move and occupy a block for the purpose of shunting.

Regional
Disciplines: Train Control, Operations
Shunt Locomotive
1. A locomotive used solely for movement of vehicles in a yard or terminal;
2. A locomotive assigned to shunting duties.

Preferred
Disciplines: Operations, Rolling Stock
Shunter
A Competent Worker who directs train movements for amalgamation, division or altering train consists.

Preferred
Disciplines: Operations
Shunting Movements
Any movement authorised by a Proceed Restricted Authority (PRA), Work Authority (WA) or Shunt Authority (SHA).

Preferred
Disciplines: Train Control, Operations
Shunting Sensitivity
The shunting sensitivity of a track circuit is expressed in terms of its drop shunt value.

Regional
Disciplines: Electrical
Shunting Signal
A fixed signal provided to authorise and control shunting movements.

Regional
Disciplines: Train Control, Operations
Shunting Yard
A system of tracks, within defined limits, used for shunting.

Legacy
Disciplines: ALL Disciplines
Side Bearers
Brackets or assemblies on both sides of the longitudinal centre of a bogie that limit the roll of the underframe on the bogie bolster.

Preferred
Disciplines: Rolling Stock
Side Light
A small aperture at the side of a colour light signal repeating the main aspect and giving a close-up indication.

Regional
Disciplines: Train Control
Siding
A portion of track where vehicles can be placed clear of the running lines.

Preferred
Disciplines: Train Control, Operations
Refer to Intermediate Siding.
Alternative
Disciplines: Train Control, Operations
Related Term: Intermediate Siding
Sighting Distance
The distance that someone can clearly see along the track.

Preferred
Disciplines: ALL Disciplines
Sighting Distance, Signals
The distance along the track where a limit of authority or warning prior to a limit of authority can be first reasonably viewed by the train crew of an approaching train, and the physical location of that limit of authority warning.

Preferred
Disciplines: Operations
Also referred to as 'sighting point'.
Alternative
Disciplines: Operations
Signal
A visual display device which conveys instructions or provides prior warning of instructions regarding the driver's authority to proceed.

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

Preferred
Disciplines: ALL Disciplines
Signal Backlight
A light displayed at the back of a signal to show that the aspect is illuminated.

Preferred
Disciplines: Electrical
Signal Box
The place where points, signals, interlocking apparatus or signal control panels are operated.

Regional
Disciplines: Train Control
Signal Box Diagram
A diagrammatic representation of the area controlled by the signal box exhibited in the signal box for the guidance of the signaller.

Overseas
Disciplines: Train Control
Signal Box Indicator
A visual device which displays the position or condition of an item of signalling equipment.

Obsolete
Disciplines: Train Control
Signal Circuit Controller
Electric circuit controller, the position of which depends on that of the arm or of the target of a signal. It is used to check that signal.

Preferred
Disciplines: Electrical
Signal Head
The part of a colour light signal from which the aspects are displayed.

Regional
Disciplines: Train Control
Signal Identification Plate
The plate attached to the signal post for unique identification of the signal.

Regional
Disciplines: Train Control
Signal Indication
The visual indication of the position or aspect of a fixed signal.

Preferred
Disciplines: Train Control, Operations
Signal Key Switches
A specially fitted device which enables the aspect of a signal to be restricted to 'red' in the field.

Regional
Disciplines: Electrical
Signal Number
The number associated with a signal for identification.

Regional
Disciplines: Train Control, Operations
Signal Off
The signal displaying a proceed indication.

Regional
Disciplines: Train Control
Signal On
The signal at stop.

Regional
Disciplines: Train Control
Signal Passed At Danger (SPAD)
Unauthorized passing of a signal displaying a stop indication as follows:
1. completely missed;
2. driver misjudged;
3. Restored as train approached;
4. other.

Preferred
Disciplines: Operations, Train Control
Signal Position
A term used to describe indications of signals given by semaphore arms.

Regional
Disciplines: Train Control
Signal Post Replacement Switch
A switch on or near the post of a colour light signal which enables the signal to be turned and maintained at red by means of a key.

Overseas
Disciplines: Train Control
Signal Post Telephone
A telephone provided at a signal, enabling the driver to communicate with the signaller, to report a fault or incident or to remind the signaller of the presence of a train detained at the signal that is displaying a danger aspect.

Overseas
Disciplines: Train Control
Signal Proving
Checking the aspect or the control of a signal.

Preferred
Disciplines: Electrical, Train Control
Signal Repeater
An indicator, in a signal box, which indicates whether a signal is at stop or clear.

Regional
Disciplines: Train Control, Operations
Signal Route
A section of track from a signal which provides an authority to proceed into that section up to the next signal, buffer stop, stop board, or limit of shuntboard, that represents the limit of the authority to proceed.

Preferred
Disciplines: Train Control, Operations
Signal Section
A section of track between two consecutive running signals in the direction of travel.

Preferred
Disciplines: ALL Disciplines, Train Control
Signal Sighting
The activity of locating a site for the placement of a signal for the purposes of optimum approach view by the driver.

Preferred
Disciplines: Train Control, Operations
Signaller
A Competent Worker who issues proceed authorities, and works points, signals and other signalling equipment usually located in a signal box, to manage routes for safe and efficient transit of rail traffic.

Preferred
Disciplines: ALL Disciplines, Train Control
Signallers Route Lists
A list of all point ends and releases between the entrance-exit signals of a signalled route, showing the position to which each is required to be set. Used primarily in degraded mode operation.

Preferred
Disciplines: Train Control
Signalling And Telecommunications Infrastructure
Signalling equipment and telecommunications equipment used as part of the safeworking and operating systems of the network .

Preferred
Disciplines: ALL Disciplines
Signalling And Telecommunications System
A system which provides a means to safely regulate the movement of trains on a railway through the use of appropriate technology.

Preferred
Disciplines: ALL Disciplines
Signalling Controls
Signalling functions that control, release or are released by other signalling functions for a particular layout. signalling controls are expressed in a control table.

Overseas
Disciplines: Train Control
Signalling 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.

Overseas
Disciplines: Train Control
Signalling Diagram
A term for Signal Box Diagram.

Preferred
Disciplines: Train Control
Signalling Facilities Diagram
A plan, produced at an early stage in the development of a project, showing operating requirements and infrastructure features, including the track layout, stations, level crossings. It is used as a basis for producing the scheme plan.

Overseas
Disciplines: Train Control
Signalling Function
A signal, set of points or other part of the train control system.

Overseas
Disciplines: Train Control
Signalling Plan
A longitudinally scaled or dimensioned track layout plan showing the signalling functions with their identities. It generally relates to a specific signal box control area and is a derivative of the scheme plan.

Overseas
Disciplines: Train Control
Signalling Rail
The rail of a single rail track circuit that is independent from the traction return path and is used only for the track circuit current.

Preferred
Disciplines: Train Control
Signalling System
A series of electrical, electronic, electro-mechanical units brought together to form a system which controls the safe movement of trains.

Preferred
Disciplines: Train Control, Electrical
Signalling Workstation
The generic term used for the signallers display system.

Overseas
Disciplines: Train Control
Signals Engineer
A person with the appropriate delegated authority and signals engineering competence to make judgments about signalling safety.

Preferred
Disciplines: ALL Disciplines
Signals Maintenance Representative
A qualified and authorised signals maintenance worker.
Review.

Preferred
Disciplines: ALL Disciplines
SIL
Abbreviated term for 'safety integrity level'.

Alternative
Disciplines: Train Control
SIMBIDS
Simplified Bi-Directional Signalling


Disciplines:
Abbreviated term for 'simplified bi-directional signalling'.
Alternative
Disciplines: Train Control, Operations
Similar Flexure
A turnout on a curve where the direction of the turnout diverging move is the same as for the curve.

Preferred
Disciplines: Infrastructure
Similarity
having likeness or resemblance, especially in a general way

Preferred
Disciplines: ALL Disciplines
Simple Curve
A curve with single radius connecting two straight lengths.

Preferred
Disciplines: Infrastructure
Simplified Bi-directional Signalling (SIMBIDS)
Bi-directional signalling where the signalling in the opposite direction to normal traffic provides for a lower speed and/or capacity than that in the normal direction, and bi-directional operation is only required in connection with possessions or emergencies affecting the other line(s).

Regional
Disciplines: Train Control
Single Aspect
A colour light signal capable of displaying only one aspect. This may be red (fixed red) or yellow (Fixed Distant Signal).

Regional
Disciplines: Train Control
Single Light Signalling
A system of colour light signalling where the running signal indication is given by a single colour light (plus a band of three lights for a turnout indication).

Regional
Disciplines: Train Control
Single Line
A single running line on which trains can travel in either direction.

Preferred
Disciplines: ALL Disciplines
Single Line Automatic Block Signalling (SLABS) Territory
The portions of line where the Single Line Automatic Block Signalling system of Safeworking is used

Preferred
Disciplines: ALL Disciplines
Single Line Track Block
A track block system of safeworking used on single lines which allows only one train to be in the section between interlockings at any one time.

Regional
Disciplines: Train Control
Single Line Working
Rail traffic working in both directions over a single line where multiple line unidirectional operation normally applies.

Preferred
Disciplines: Train Control, Operations
Single Rail Track Circuit
A track circuit in which one rail is dedicated for signalling purposes and contains insulated joints, the other rail being used as the common traction retrun current and signalling current rail.

Regional
Disciplines: Electrical, Train Control
Single Track
A line that consists mostly of only one track where only one train is able to travel/pass at one time.

Preferred
Disciplines: ALL Disciplines
Single Yellow (aspect)
Displayed by a colour light signal, informs the driver to expect the next main signal to be at Stop.

Preferred
Disciplines: Train Control, Operations
Single-slip Points
A combination of a crossing and single connecting track, located within the limits of the crossing, and made up of a right-hand switch from the other track, which unite to form the connecting track without additional crossings.

Regional
Disciplines: Infrastructure
Single-unit (SU) Vehicle
A vehicle designed to operate as a stand-alone vehicle, with a drivers compartment and control unit at one or both ends.

Regional
Disciplines: Rolling Stock
Skeletal Wagon
A wagon whose only longitudinal load bearing structure between the bogies is the centre sill. The load support structure consists of lateral members attached to the centre sill.

Regional
Disciplines: Rolling Stock
SL Lock
A general safeworking padlock with keys held by authorised operations and engineering staff.

Regional
Disciplines: Train Control, Operations
Slab Track
Track fixed with fixation assemblies to a concrete slab under the rails.

Preferred
Disciplines: Infrastructure
SLABS
Single Line Automatic Block Signalling


Disciplines:
Single Line Automatic Block Signalling

Disciplines:
Sleeper
Sleepers are bearers used to hold the rail in place at the correct gauge and to transmit loads through the ballast to the formation. They have traditionally been made of wood but are gradually being replaced by concrete or steel sleepers.

Preferred
Disciplines: Infrastructure
Slip Detector
A device capable of detecting track instability, and operated when the distance over the ground increases between two fixed points being monitored. The detector is used to raise alarms and/or place protecting signals to stop.

Regional
Disciplines: Train Control
Slot
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: Operations, Rolling Stock
Refer 'slots' or 'teus'.
Alternative
Disciplines: Operations, Rolling Stock
Slot ID
A three digit identification code identifying a particular slot on a wagon.

Regional
Disciplines: Operations, Rolling Stock
Slotted Signal
This is a manually operated mechanical signal fitted with an electric device ('replacer' or 'reverser'), by means of which the signal is automatically put to the stop position by interruption of a track circuit or other controlling device.

Regional
Disciplines: Train Control
Slotting
The control of a signalling function that requires co-operation between two signal boxes or other controlling points.

Overseas
Disciplines: Train Control
Slow Pick-up Relay
A relay which, when energy is applied, will pick up slower than an ordinary relay.

Regional
Disciplines: Electrical, Train Control
Slow Release Relay
A relay which, when the controlling circuit is opened or completely shunted, will drop away slower than an ordinary relay.

Regional
Disciplines: Electrical, Train Control
Snubbing Device - Electrical
Diode or mechanically operated contacts within the points circuitry that are employed to steer the high inductive load currents (snubbing) away from the point motor. This is in addition to the clutch mechanism.

Overseas
Disciplines: Train Control, Electrical
Snubbing Device - Level Crossing Boom
A feature of a level crossing boom mechanism.

Overseas
Disciplines: Infrastructure, Train Control
Snubbing Device - Rolling Stock
A term applied to the friction wedge damping arrangement in the suspension of a 3-piece freight bogie.

Regional
Disciplines: Rolling Stock
Soffit
The underside of a sleeper.

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

Preferred
Disciplines: ALL Disciplines
Solebar
Main longitudinal structural member of vehicle underframe which forms the extreme edges of the frame. Also known as a 'side sill'.

Preferred
Disciplines: Rolling Stock
Solenoid
An electromagnetic device consisting of a plunger moving inside an electromagnetic coil, used to open and close contacts in an electrical circuit or to open and close a valve in an electro-pneumatic or hydraulic pressure line.

Preferred
Disciplines: Electrical
Solid State Interlocking (SSI)
A first generation processor based system for controlling the interlocking between points and signals, as well as communication with lineside signalling functions using a high integrity microprocessor based technology both for the central interlocking (multi-processor module - MPM) and for the trackside controls (trackside function modules - TFM's).
Also see 'computer based Interlocking'.

Preferred
Disciplines: Train Control
Spacing (sleeper)
The separating distance of sleepers, or rail supports on slab track, measured from the centreline of the sleepers or supports.

Preferred
Disciplines: Infrastructure
SPAD
Signal Passed At Danger


Disciplines:
Abbreviation for 'signal passed at danger'.
Alternative
Disciplines: ALL Disciplines
Spare Lever
In a lever frame, a lever which is not used for the operation of any signalling equipment.
Also see 'lever (worked to maintain locking)'.

Overseas
Disciplines: Train Control
Spark Gap
An electrical device installed at level crossings in single rail track circuit areas, which is connected between the rails on both sides of the level crossing to afford protection to the signalling equipment in the event of a fault between overhead line equipment and the signalling rail.

Regional
Disciplines: Electrical
Special Loads Officer
An officer whom inspects and assesses loading to determine compliance with the prescribed loading outline, configuration, dimensions or mass limitations.

Regional
Disciplines: Operations
Special Locking
Interlocking between two movable parts occasioned by the particular position of other parts.

Regional
Disciplines: Electrical, Train Control
Special Proceed Authority (SPA)
A method of special working in NSW which may be used when the normal system of safeworking using proceed authorities is not available.

Non-preferred
Disciplines: Train Control, Operations
Refer 'Alternate Proceed Authority'
Alternative
Disciplines: Train Control, Operations
Special Train Notice (STN)
A published notice providing details of train operations or events that might affect train operations.

Regional
Disciplines: Operations
Special Working
Working rail traffic using an Alternate Proceed Authority (APA) or manual block working.

Preferred
Disciplines: Train Control, Operations
Speed Signalling
System of signalling in which signal indications of the speed at which a train may travel, and of any speed change required.

Regional
Disciplines: Train Control
Spike
A fastener used to attach plates and/or rails to sleepers, e.g. dogspikes, springspikes, screwspikes.

Preferred
Disciplines: Infrastructure
Spike Killed (sleeper Or Timber)
The condition of a sleeper or timber in which dog spikes or screw spikes have been previously inserted whereby there is insufficient sound wood available in the region of the rail flange or sleeper plate for further installation of spikes.

Preferred
Disciplines: Infrastructure
Splay Rail
A rail outside the running rails placed at the start of an internal guard rail used to direct a derailed wheel to the correct side of a guard rail.

Preferred
Disciplines: Infrastructure
Split Detection
The proof and indication of the position of multiple ended sets of points, individually for each point end.

Overseas
Disciplines: Train Control
Spreader Bar
Bars used to hold the points in the correct position relative to each other.

Preferred
Disciplines: Infrastructure
Spring Points
Points equipped with a spring device which forces the point switches to their original position after being trailed through and holds them under spring compression.

Preferred
Disciplines: Infrastructure
Springspike
A fastener used to attach sleeper plates to sleepers on clip fastened track. The spike comprises two leaves from one piece of spring steel, folded to produce a square shank and an eye.

Preferred
Disciplines: Infrastructure
Spur (track Circuit)
A section of running rail required to be electrically common to a series bonded rail, but which is not itself series bonded.

Overseas
Disciplines: Train Control
SSAI
System Safety Accident Investigation


Disciplines:
SSAI Investigation
A standard method of investigation known as 'system safety accident investigation'.

Preferred
Disciplines: ALL Disciplines
SSI
Solid State Interlocking


Disciplines:
Stable
To leave rail traffic unattended and secured, usually in a siding.

Preferred
Disciplines: ALL Disciplines
Staff
The token (usually a rod) used in a train staff system, the possession of which gives the train permission to enter a block section.

Regional
Disciplines: Train Control, Operations
Staff And Ticket Territory
The portions of line where the Staff and Ticket system of Safeworking is used.

Preferred
Disciplines: Train Control, Operations
Staff Station
An interlocking which is provided in order to work the staff and ticket or electric train staff system.

Regional
Disciplines: Train Control
Staff Ticket
A written authority issued after a rail traffic crew has seen the staff for a section.

Preferred
Disciplines: Train Control, Operations
Stageworks
The phased installation and commissioning of signalling equipment, as part of a large resignalling scheme, often of a temporary nature as alterations proceed.

Overseas
Disciplines: Train Control
Stakeholders
Those people and organizations who may affect, be affected by,a decision or activity.

Preferred
Disciplines: ALL Disciplines
Standard
An authorised document, including specification, procedure, instruction, directive, rule or regulation, which may set mandatory requirements.

Preferred
Disciplines: ALL Disciplines
Standard Gauge
The name given to the gauge of track of 1435mm (4' 8

Preferred
Disciplines: ALL Disciplines
Standard Length Rail
The common length of rail supplied by the manufacturer.

Preferred
Disciplines: Infrastructure
Standardisation
to cause (something) to conform to a standard or to adopt (something) as one's standard

Preferred
Disciplines: ALL Disciplines
Standing Room
The distance along the track between points of minimum allowable clearance where rolling stock is permitted to stand.

Preferred
Disciplines: Train Control, Operations
Starting Signal
A controlled signal which, when cleared, gives the driver authority to enter the section provided that, where required, the driver is in possession of the authority for the section.

Regional
Disciplines: Train Control
Static Clearance (electrical)
The safe distance between the earthed materials of any structure and the live parts of the overhead line equipment, under all permissible conditions and tolerances.

Regional
Disciplines: ALL Disciplines
Static Outline
An outline drawing or specification of a notional vehicle cross-section which prescribes maximum permissible rolling stock dimensions under specified conditions of load and suspension displacements in vertical directions. The static outline will have an associated kinematic outline and swept outline.

Preferred
Disciplines: Rolling Stock
Static Switch Power Supply
An all electronic emergency changeover device for power supplies.

Preferred
Disciplines: Electrical
Station Protection System
A system that alerts the driver to stations and other trackside features via the use of track magnets.

Preferred
Disciplines: Rolling Stock, Operations
Station Yard
All tracks at a station protected by signals or yard limit boards.

Preferred
Disciplines: ALL Disciplines
Stick
A term often used to describe a function which stores or remembers specific conditions of the signalling equipment.

Legacy
Disciplines: Train Control
Stick - Non-stick Semi-automatic Signal
This is a signal which will operate automatically as long as all contacts (including manually controlled contacts) other than track relay contacts, affecting its control, are closed.

Legacy
Disciplines: Train Control
Stick - Semi-automatic Signal
This is a signal which will not automatically assume the warning or clear aspect after it has been put to stop by interruption of the track circuit, until its manually operated control has been restored to the normal position and reversed again.

Legacy
Disciplines: Train Control
Stick - Semi-stick Semi-automatic Signal
This is a signal which will not automatically assume the warning or clear aspect after it has been put to stop by interruption of the track circuit, until a manually operated control, other than its own direct control, has been restored to the normal position.

Legacy
Disciplines: Train Control
Stick Circuit
A term applied to a circuit used to maintain a relay or similar unit energised through its own contact.
Signalling relay control circuits may include approach sticks (re: approach locking), route sticks (re: route locking), direction sticks (re: direction proving), track sticks (re: signal control relay down proving), and/or lever sticks (re: reclearing of a controlled signal after train passage).

Regional
Disciplines: Electrical, Train Control
STN
Special Train Notice


Disciplines:
Stock Rail
The rail to which a point fits up against in the closed position. A switch set is made up of the point and stock rails and associated components. The term is also sometimes used loosely to describe other plain rail sections in a points and crossings structure.

Preferred
Disciplines: Infrastructure
Stop Block
A structure fixed at the termination of a running line or siding to arrest slow-moving vehicles.

Non-preferred
Disciplines: Infrastructure
Refer to Buffer Stop.
Alternative
Disciplines: Infrastructure
Related Term: Buffer Stop
Stop Light
Light indicating a brake application.

Preferred
Disciplines: Rolling Stock, Operations
Stop Sign
A safeworking notice board inscribed 'stop', at which all trains must stop and must not pass until authorised.

Regional
Disciplines: Train Control, Operations
Stop Signal
Any signal capable of showing a danger aspect.

Overseas
Disciplines: Train Control
Stopping Place
A designated location, next to the line and is a stopping place for the setting down or picking up of passengers or personnel.

Regional
Disciplines: Operations
Stored Control
Pre-setting control acting on several units, the movements of which are carried out successively.

Preferred
Disciplines: Electrical
Straddle Crane
See Gantry Crane.

Alternative
Disciplines: Operations
Straight-ahead Route
The non-diverging (and usually the fastest) route from a junction signal.

Overseas
Disciplines: Train Control
Stress Free Temperature
Actual temperature at which there are no temperature induced stresses in the rail.

Preferred
Disciplines: Infrastructure
Stretcher
A bar connecting the two switch rails in a point end, keeping them in the correct position relative to each other.

Overseas
Disciplines: Infrastructure
Structure Bond
A bond connecting the steelwork of an overhead line structure, bridge, or other metal structure to the traction earth. This bond is provided to prevent the rise of hazardous voltages on structures and steelwork.

Preferred
Disciplines: Electrical, Infrastructure
Structure Clearance Register
A register of all structures that have been built inside the structure outline standard for the line section and therefore require to be part of a formal inspection and assessment process. The register should detail the structure location and type, and the clearance standards required at the location.

Preferred
Disciplines: ALL Disciplines
Structure Defects
Defects in civil or electrical infrastructure items which have the potential to cause accidents unless urgent corrective action is taken.

Preferred
Disciplines: ALL Disciplines
Structure Gauge
Refer to Structure Outline.

Alternative
Disciplines:
Related Term: Structure Outline
Structure Outline
The desired minimum outline for structures along a route.

Preferred
Disciplines: ALL Disciplines
SU
Single Unit


Disciplines:
Sub-surface Railway Station
A railway station to which members of the public have access and of which more than 50% of any one platform is within a tunnel or under a building.

Overseas
Disciplines: Infrastructure, Operations
Subsidiary Signal
An additional small semaphore or light signal provided below a running signal for the purpose of controlling shunting movements and movements onto occupied tracks.

Regional
Disciplines: Train Control
Substation
A place (including substations, traction substations, transformer rooms, switchrooms, sectioning huts, pole-mounted or pad-mounted transformers) containing high-voltage electrical equipment.

Preferred
Disciplines: Electrical
Subsystem
means the whole or, as the context requires, part of a subdivision of the rail system

Preferred
Disciplines: ALL Disciplines
Sufficient Warning Time
The minimum time needed for workers to react to a Lookout's warning and move themselves and equipment to a safe place; should include time for the Lookout's reaction and a margin for safety

Preferred
Disciplines: ALL Disciplines
Sum L/V Axle
Sum of the absolute values of the individual wheel L/V of both wheels on the same axle at a given instant in time.

Preferred
Disciplines: Rolling Stock
Superelevation
The height difference, at a common location, between the running surface of both rails. Also known as Superelevation or Cross Level.

Alternative
Disciplines: Infrastructure
Alternate Term: Superelevation or Cross Level
Refer to Cant.
Alternative
Disciplines: Infrastructure
Related Term: Cant
Superior Train Order Station
An attended train order crossing station protected by fixed signals.

Regional
Disciplines: Train Control
Supplementary Detector
An additional device for detection of points in association with supplementary drives.

Overseas
Disciplines: Train Control
Supplementary Drive
An additional drive connected to the switch rails of a set of points at a position closer to the crossing than the switch tips.

Overseas
Disciplines: Train Control
Refer 'backdrive points'.
Alternative
Disciplines: Train Control
Supply Substation
A compound containing electrical switchgear, transformers and equipment to which main supplies from the supply authority are brought and from which the feeder station is fed.

Preferred
Disciplines: Electrical
Suppression (AWS Or TPWS)
Inhibition of the operation of automatic warning system (AWS) or train protection and warning system (TPWS) track equipment for movements to which it does not apply.

Preferred
Disciplines: Operations
Surface Concrete Troughing
A series of lidded troughs, usually laid in the cess, comprising a cable route.

Regional
Disciplines: Electrical, Infrastructure
Surge Protection
Equipment and systems for protecting electrical operating systems from transient electrical overload conditions due to external influences such as lightning, power supply switching, fault conditions.

Preferred
Disciplines: Electrical
Suspend
Practice used in some Networks when a work on track authority is suspended and then reinstated at a later time.

Preferred
Disciplines: Train Control, Operations
Swage Lock Fastening
A high tensile strength mechanical fastening system employing swaging of a collar onto annular locking grooves of a fastening utilsing a special hydraulic tool. The system is designed to provide consistent and predictable installed values of tension.

Preferred
Disciplines: Infrastructure
Sway
The displacement of any point on the vehicle body in a direction parallel to the plane of the rails that arises as a result of a combination of lateral displacement and roll
displacement of the vehicle suspension.

Preferred
Disciplines: Rolling Stock
Swept Outline
The swept outline is a two-dimensional cross-section for the vehicle that consists of the kinematic outline plus the inner and outer curve throw produced by the vehicle on a 100m radius curve.

Preferred
Disciplines: Rolling Stock
Swept Path
The swept path is the generic name for the 3-dimensional shape of the vehicle on any radius curve made up from the kinematic outline plus the inner and outer curve throws produced by the vehicle on that curve.

Preferred
Disciplines: Rolling Stock
Swing Crossing
Refer to Switchable Vee.

Alternative
Disciplines: Infrastructure
Related Term: Switchable Vee
Swing Nose Crossing
Refer to Switchable Vee.

Alternative
Disciplines: Infrastructure
Related Term: Switchable Vee
Swing Test
A physical test whereby the underframe or bogie is yawed to a particular position that replicates the rolling stock negotiating a nominated track geometry.

Preferred
Disciplines: Rolling Stock
Swinging Overlaps
The ability to maintain the overlap free of locking where there are facing points and a choice of overlap exists, thus enabling late selection of the overlap while the train is approaching. Usually associated with time of operation locking and conditional locking requirements.

Overseas
Disciplines: Train Control
Switch
Refer to 'point'.

Alternative
Disciplines: Infrastructure
Switch Blade
See Point Switch.

Alternative
Disciplines: Infrastructure
Switch Diamond
A type of diamond crossing with movable switches in place of fixed crossings (points).
Also known as 'moveable angles' or 'moveable elbows'.

Regional
Disciplines: Infrastructure
Switch Lever
A spring loaded lever connected by rods to the toe of a switch to enable manual changing of the switch position in yards or sidings.

Regional
Disciplines: Infrastructure
Switch Machine
See Point Machine.

Alternative
Disciplines: Infrastructure
Switch Rail
The moving portion of rail on each side of a set of points.

Overseas
Disciplines: Infrastructure
Switchable Vee
Vee designed to switch against the stock rail to eliminate the flangeway gap between the conventional fixed nose vee and the stock rail.
A 'V' crossing with movable points to facilitate a high turnout speed.
Also known as Swing Crossing or Swing Nose Crossing.

Preferred
Disciplines: Infrastructure
Alternate Term: Swing Crossing or Swing Nose Crossing
Switched K Crossing
A 'K' crossing with movable points.

Regional
Disciplines: Infrastructure
Switches And Crossings
The generic term used (sometimes points and crossings) to represent all the ironwork associated with a set of points. It covers switch yoes, switch rails, heels of switch rails, closure rails, stock rails, crossings and check rails.

Non-preferred
Disciplines: Infrastructure
System
a combination of interacting elements organised to achieve one or more stated purposes.

Preferred
Disciplines: ALL Disciplines
System Of Safeworking
An integrated system of operating procedures and engineered systems used in the Network, for safe operation of rail traffic, and protection of people and property.
Includes Double Line CTC, Single Line CTC or Train Order Working.

Preferred
Disciplines: Train Control, Operations
System Operational Notice
A notice of information and instructions, authorised and issued by the train operations manager and distributed electronically or by hard copy to relevant rail staff.

Regional
Disciplines: Operations
Systemic Safety Deficiency
A safety deficiency which is present throughout all or a substantial part of the railway organisation and is not simply a localised problem.

Preferred
Disciplines: ALL Disciplines