Glossary of Terms


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HABD
Hot Axle Box Detector


Disciplines:
Abbreviated term for 'hot axle box detector'.
Alternative
Disciplines: Infrastructure, Operations
Half-staff
A metal staff located at the ends of a section, and interlocked with signals' circuits. Also known as half-pilot-staff. Two half staffs can be joined to provide a pilot staff for the section.

Preferred
Disciplines: Train Control, Operations
Hand (points)
Term used to denote the turnout direction of points.

Preferred
Disciplines: Train Control, Operations
Hand Brake
A mechanical device used to secure a rail vehicle against movement. Can also include spring parking brakes.

Alternative
Disciplines: Rolling Stock, Operations
Refer park brake
Alternative
Disciplines: Rolling Stock, Operations
Hand Points
Points not interlocked and worked manually by an independent lever adjacent to the points.

Legacy
Disciplines: Infrastructure, Operations
Hand Signal
A signal given by hand movements, with or without a flag or light. To give a signal by hand.

Preferred
Disciplines: ALL Disciplines
Handhold
A locally placed support at a change of level or direction, or where people are required to stand or wait, to stabilize themselves against the motion of the train.

Preferred
Disciplines: Rolling Stock
Handrail
A rail which runs parallel to the access path and assists movement by allowing the hand to slide over the top, while providing support to the person, and allowing for a sudden gripping action if needed.

Preferred
Disciplines: Rolling Stock
Handsignaller
A Competent Worker who gives handsignals to rail traffic crew

Preferred
Disciplines: ALL Disciplines, Operations
Hardened Rail
Rolled rail that has been head-hardened or full section hardened by in-line or off-line processes.

Preferred
Disciplines: Infrastructure
Hardening Process
The procedure of increasing the hardness of rail or other material to improve wear characteristics. Commonly employed processes for rails are heat treatment and work hardening.

Preferred
Disciplines: Infrastructure
Harmonisation
the act of bringing into agreement so as to work effectively together

Preferred
Disciplines: ALL Disciplines, Operations
Haul
To move rail traffic using a motive power source at the leading end.

Preferred
Disciplines: Operations
Hazard
A source or a situation with a potential to harm someone (injury or illness) or damage property or the environment.

Preferred
Disciplines: ALL Disciplines
Hazard And Operability Study (HAZOP)
A structured study to identify all deviations from design intent with undesirable effects on safety or operability.

Preferred
Disciplines: ALL Disciplines
Hazard Identification
The process of recognising that a hazard exists and defining its characteristics.

Preferred
Disciplines: ALL Disciplines
Hazard Light
Amber or orange flashing light fitted to a vehicle to provide warning.

Preferred
Disciplines: ALL Disciplines
hazard trees
Fault based diagrams showing infrastructure and rolling stock related hazards.

Preferred
Disciplines: ALL Disciplines
HAZID
Hazard Identification


Disciplines:
Abbreviated term for Hazard Identification.
Alternative
Disciplines: ALL Disciplines
HAZOP
Hazard and Operability Study


Disciplines:
Abbreviated term for 'hazard and operability study'.
Alternative
Disciplines: ALL Disciplines
Head
That part of the rail which provides a running and guiding surface for the wheel.

Preferred
Disciplines: Infrastructure
Refer to 'ball'.
Alternative
Disciplines: Infrastructure
Head-hardened Rail
Rolled rail in which the head has a hardened zone extending inwards from its top and side surfaces.

Preferred
Disciplines: Infrastructure
Headlamp
Lamp that forms part of a headlight.

Preferred
Disciplines: Rolling Stock
Headlight
Main bright light(s) on the front of rolling stock.

Preferred
Disciplines: Rolling Stock
Headlights
White or blue lights fitted at the front of rail traffic to provide visibility for the rail traffic crew and to improve the visibility of rail traffic.

Preferred
Disciplines: ALL Disciplines, Rolling Stock
Heads Level (points)
The position on a half set of points at which both the switch and stock rail top running surfaces are at the same level. It corresponds to the commencement of switch head top machining.

Preferred
Disciplines: Infrastructure
Headway
The distance or time between two or more trains needing to use the same section of the track, either in the same or opposite directions.

Preferred
Disciplines: Train Control, Operations
Heat Number
Markings on the centreline of the web of the rail in depressed numerals and letters. It indicates the cast, ingot and portion of ingot from which the rail was made. The heat number is repeated several times on a standard rail length and is on the opposite side of the web from the Rolling Brand. Quality assurance records include the rail Heat Number and permit the chemistry of the rail to be traced.

Preferred
Disciplines: Infrastructure
Heat Treatment
A heating and quenching process used to increase the hardness of rails or steel components. The most common processes are furnace heating and oil/water quenching and flame heating and air quenching.

Preferred
Disciplines: Infrastructure
Heavy Haul
The term for transportation by rail of bulk commodities.

Legacy
Disciplines: Operations
Heavy Track Equipment
Track maintenance machines or items of equipment which under normal conditions cannot be removed from the track manually by two workers. A road-rail vehicle that can only be removed from track at locations such as level crossings or machinery used where thermit welding is undertaken is regarded as heavy track equipment.

Preferred
Disciplines: Rolling Stock
Heel
The end of points about which the switch pivots.

Preferred
Disciplines: Infrastructure
Heel Block
The block at the heel end of points about which the switch pivots.

Preferred
Disciplines: Infrastructure
Heel Less Points
Refer to Fixed Heel Points.

Alternative
Disciplines: Infrastructure
Related Term: Fixed Heel Points
Heel Mechanism
The mechanism which provides support pivoting at the heel of a tramway switch.

Regional
Disciplines: Infrastructure
Helper Engines
A locomotive not assigned to a train for the whole journey. These units are normally marshalled in with the power consist under the control of the train crew but may, at times, be utilised as manned helpers at the rear, or anywhere within the train consist, to assist in moving a train over a ruling grade.

Legacy
Disciplines: Operations
Refer bank locomotive
Alternative
Disciplines: Operations
Heritage Rolling Stock
Rolling stock preserved or restored for its historical value.

Preferred
Disciplines: Rolling Stock
High Risk Failure
A wrong side failure where no other part of the signalling system provides protection.
Also known as an 'unprotected wrong side failure'.

Overseas
Disciplines:
High Voltage Impulse Track Circuit
A track circuit fed by high voltage pulses of particular shape and size which are recognised by a receiver and special track relay.

Regional
Disciplines: Electrical
High-rail Vehicle
A vehicle that is capable of running on both road and rail. Often these are standard road vehicles that have a pair of flanged rail wheels on the front and rear. Generally the vehicle accesses the rail via a level crossing, lowers the rail wheels onto the rails which will guide the vehicle without the need to steer, and is propelled by the road wheels that are in contact with the rails. High-rail equipment is fitted to inspection, personnel carrying vehicles and some track construction and maintenance machines.

Preferred
Disciplines: Rolling Stock
High-wide Load Detector
A device capable of detecting excessive heights or widths on a passing train with respect to accepted track structure clearances.

Regional
Disciplines: Train Control, Operations
Hold Clear
A term used to designate a device for holding a signal in any position other than its most restrictive.

Regional
Disciplines: Train Control
Holding Test
An air brake examination to check that the brakes on the last three vehicles of a train will remain applied for a predetermined time in the event of a break-away.

Regional
Disciplines: Operations, Rolling Stock
Holding Track
A track where vehicles are held, within a terminal, awaiting allocation orders.

Regional
Disciplines: Operations
Home Signal Or Starting Signal
A controlled signal which directly protects points, level crossings, or other permanent risks. When cleared, this signal also 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, Operations
Hood
A cover placed above individual aspects of a colour light signal or route indicator to reduce phantom aspects due to sunlight. Where necessary, long hoods may be used.

Regional
Disciplines: Train Control
Hopper Wagon (or Hopper Car)
A wagon with the floor and/or walls sloping from the sides and ends to one or more discharge points or hoppers. Hopper wagons may have open or covered tops and incorporate one or more of:
(a) bottom doors (sliding or swing) for gravity discharge;
(b) equipment for pneumatic pressure discharge;
(c) equipment for vacuum discharge.

Preferred
Disciplines: Rolling Stock
Horizontal Alignment
Refer to Alignment.

Alternative
Disciplines: Infrastructure
Related Term: Alignment
Horsepower
A unit of measurement to gauge the output of a locomotive that is then used to calculate the tonnage of loading that the locomotive can pull over a particular section of track. Now referred to in kilowatts.

Preferred
Disciplines: ALL Disciplines, Rolling Stock
Hot Axle Box Detector (HABD)
Wayside or train mounted system used to detect suspected defective axle bearings that are abnormally hot.

Preferred
Disciplines: Infrastructure, Rolling Stock
Hot Box
An overheated axle bearing on either a locomotive or wagon.

Legacy
Disciplines: Rolling Stock
Hot Standby
Form of redundancy in which the 'spare' or secondary equipment is continuously operating and generating output simultaneously with the primary equipment. Results in no discernible interruption to system function on failure of the primary unit.

Regional
Disciplines: Train Control
Hot Strip (in Signal Lens)
Popular name for 'close viewing sector'.

Regional
Disciplines: Train Control
Hot Wheel Detector
A device capable of detecting abnormal heating in wheels on passing trains.

Regional
Disciplines: Train Control, Rolling Stock
Housed Switch
A point switch which has a guide placed alongside it (and over it when in the open position), the purpose of which is to hold wheel flanges away from the tip of the opposite switch and/or away from a joggle in the stockrail.

Regional
Disciplines: Infrastructure
Refer to Stockrail, Joggled
Alternative
Disciplines: Infrastructure
HREOC
Human Rights and Equal Opportunity Commission


Disciplines:
Abbreviated term for 'Human Rights and Equal Opportunity Commission'.
Alternative
Disciplines: ALL Disciplines
Huck Bolts
Trade name for 'swagelok

Alternative
Disciplines: Electrical, Infrastructure
Human Factors
The scientific discipline that is concerned with the application of information about human characteristics, capacities, and limitations to the design of human tasks, machines, machine systems, and environments.

Preferred
Disciplines: ALL Disciplines
Hunting
Uncontrolled and undesirable cyclic lateral and yaw displacements of the wheelsets of a vehicle, generally worsening with increasing speed.

Preferred
Disciplines: Rolling Stock
Hydro-pneumatic Points
Alternative term for 'train operated points'.

Regional
Disciplines: Train Control