Glossary

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ABCL Abbreviation: Automatic Barrier Crossing, Locally Monitored.
Advanced Passenger Train A tilting train developed by BR in the 1970s.
AHB Abbreviation: Automatic Half Barriers.
AOCL Abbreviation: Automatic Open Crossing, Locally Monitored.
AOCR Abbreviation: Automatic Open Crossing, Remotely Monitored.
APT Abbreviation: Advanced Passenger Train.
Aspect A visual indication displayed by a lineside signal.
ATP Abbreviation: Automatic Train Protection.
Automatic Signal A stop signal normally controlled by train detection status alone.
Automatic Train Protection A supervisory system that enforces drivers' compliance with movement authorities and speed restrictions.
Automatic Warning System A system giving audible and visual indications inside the driver's cab to assist in the observance of certain lineside signals and signs.
AWB Abbreviation: Advance Warning Board.
AWI Abbreviation: Advance Warning Indicator.
AWS Abbreviation: Automatic Warning System.
Axle Counter Electronic equipment used for train detection purposes, as an alternative to a track circuit.
Banner Repeater A form of repeater signal comprising a movable 'banner' (or using modern technology to display similar indications).
Bi-directional Signalling Signalling that allows traffic to run in either direction along a running line.
BR Abbreviation: British Rail(ways).
Cab Secure Radio A secure radio system used with driver only operation for communication between driver and signalman.
Cab Signalling A system of signalling where movement authorities are presented to the driver on a display inside the cab rather than by lineside signals.
Calling-on Signal A type of subsidiary signal used to admit a train into an occupied line.
Catch Points Points installed on a running line to derail vehicles running away on a steep gradient (obsolescent).
Coasting A practice whereby the driver of an electric train shuts off power whilst the train is in motion, as a way of conserving energy.
Colour Light Signal A lineside signal in which the colour of the lights determine the meaning of its aspect.
CSR Abbreviation: Cab Secure Radio.
CTRL Abbreviation: Channel Tunnel Rail Link.
Differential Speed Restriction A speed restriction comprising different speed values applicable to different types of train.
Distant Signal A main signal that is not a stop signal.
DOO Abbreviation: Driver Only Operation.
DRA Abbreviation: Driver's Reminder Appliance.
Driver Only Operation The working of a train without a guard.
Driver's Reminder Appliance A device inside a driving cab which the driver operates when standing at a stop signal and which prevents power being applied to the train.
DVT Abbreviation: Driving Van Trailer.
Emergency Speed Restriction An unplanned temporary speed restriction imposed without prior notice.
Enhanced Permissible Speed A permanent speed restriction that applies exclusively to a tilting train running in tilt mode.
EPS Abbreviation: Enhanced Permissible Speed.
ESR Abbreviation: Emergency Speed Restriction.
Fail-safe Designed to fail in such a manner that safety will not be compromised.
Fouling Point Where two lines converge, the point beyond which no part of a vehicle may stand, to avoid collision with a movement on the other line.
'Four-foot' A name given to the space between the two running rails forming a railway track.
Full Capacity Bi-directional Signalling A form of bi-directional signalling that allows wrong direction movements to run at a similar frequency to the normal direction.
Ground Frame A small assembly of interlocked levers at the lineside, for the local control of points or signals, etc.
GSM-R Abbreviation: Global System for Mobile communications-Railway.
HABD Abbreviation: Hot Axle Box Detector.
Handpoints Manually operated points that are operated locally and are not interlocked.
Headshunt A dead-end line used during shunting moves between a group of sidings, to avoid occupying an adjacent running line.
Hot Axle Box Detector Lineside apparatus for detecting overheated axle bearings on passing trains.
HST Abbreviation: High Speed Train.
Interim Voice Radio System A GSM-R based system that facilitates emergency communications in designated areas where axle counters are used for train detection.
IVRS Abbreviation: Interim Voice Radio System.
Junction Signal A stop signal that has main routes to more than one destination.
LOS Abbreviation: Limit of Shunt.
Main Signal A signal that controls movements along a running line.
Method of Working The rules and regulations that apply on a specified section of line, as determined by the type of signalling equipment provided.
MGR Abbreviation: Merry-Go-Round.
Movement Authority Permission for a train to proceed, e.g. given by a signal aspect or by cab signalling.
MPV Abbreviation: Multi Purpose Vehicle.
MSL Abbreviation: Miniature Stop Lights.
Multi Purpose Vehicle A multiple unit designed to carry freight or equipment used during engineering activities, as opposed to carrying passengers.
MWL Abbreviation: Miniature Warning Lights.
National Radio Network A radio telephone system used on trains.
Neutral Section An arrangement of insulators in overhead electrified line catenary, for separating different electrical sections.
NRN Abbreviation: National Radio Network.
'Off' Refers to a signal displaying an aspect other than its most restrictive.
'On' Refers to a signal displaying its most restrictive aspect.
Overbridge A bridge over the railway.
Permanent Speed Restriction The normal speed restriction that applies to trains.
Permissive Working An operating practice that allows more than one train to simultaneously occupy a single signal section.
Points Indicator An indicator that confirms the lie of the associated points.
PoSA Abbreviation: Proceed on Sight Authority.
Position Light Signal A lineside signal in which the position of the lights determine the meaning of its aspect.
PRI Abbreviation: Preliminary Routeing Indicator.
Propelling A shunting movement where the driver is not driving from the front of the train.
PSR Abbreviation: Permanent Speed Restriction.
Radio Electronic Token Block A method of working in which a movement authority takes the form of an electronic token transmitted between the control centre and train via a radio network.
Reduced Capacity Bi-directional Signalling A form of bi-directional signalling that allows wrong direction movements to run at significantly lower frequency than in the normal direction.
Repeater Signal A lineside signal giving information about the aspect of the signal ahead.
RETB Abbreviation: Radio Electronic Token Block.
Route Indicator An indicator associated with a lineside signal that indicates which route is set, in conjunction with a 'proceed' aspect.
Running Line A line on which movements (apart from shunting) are signalled by main signals or equivalent.
Sandite A substance that may be applied to the rail head to improve adhesion.
SDO Abbreviation: Selective Door Operation.
Selective Door Operation A system for limiting the amount of power operated passenger doors that can be opened on a train when stopped at a station with a short platform.
Semaphore Signal A lineside signal that uses a pivoted arm to convey its meaning.
Shunting Signal A lineside signal that governs shunting movements.
Signal Passed at Danger A signal passed without authority while displaying a 'stop' aspect.
Signal Post Telephone A telephone provided at or near a signal for the driver to communicate with the signalman.
SIMBIDS Abbreviation: Simplified Bi-Directional Signalling.
Simplified Bi-directional Signalling An obsolescent form of reduced capacity bi-directional signalling lacking normal AWS functionality for wrong direction movements.
Single Line Working The temporary working of all trains over one line of a double track railway during engineering works or failure, etc.
SLU Abbreviation: Standard Length Unit.
Somersault Signal An obsolete form of semaphore signal with a centrally-pivoted arm.
SPAD Abbreviation: Signal Passed at Danger.
Splitting Distant Signal A main signal that gives advance information about which route is set at a junction signal ahead (may also function as a stop signal).
SPT Abbreviation: Signal Post Telephone.
Stop Signal A main signal equipped to show a 'danger' aspect.
Subsidiary Signal A signal provided in association with a main signal for use in circumstances where it is not appropriate to clear the latter.
TCB Abbreviation: Track Circuit Block.
Temporary Speed Restriction A speed restriction that applies for a limited duration, overriding the permanent speed restriction on the affected section of line.
Tilting Train A train equipped with a tilt mechanism that allows it to comfortably negotiate curves at higher speeds.
Time Interval System A primitive method of working in which trains are separated by time rather than by distance.
Token An object that the driver must have in his or her possession (where appropriate to the method of working) as authority to occupy a specific single line section.
TPWS Abbreviation: Train Protection and Warning System.
Track Circuit An electrical circuit that uses the running rails for train detection purposes.
Track Circuit Block A method of working featuring continuous train detection.
Train Detection Equipment for proving that a defined section of track is unoccupied.
Train Protection and Warning System A system designed to prevent or mitigate the result of a SPAD and, at certain locations, overspeeding.
Trainstop A mechanical device fitted near a stop signal that will, in the event of a SPAD, engage with a tripcock on the train and automatically apply the brakes.
Trap Points Points installed at the exits from sidings or goods lines to derail vehicles and thus prevent them running away onto a running line.
TSR Abbreviation: Temporary Speed Restriction.
Underbridge A bridge under the railway.
Wrong Direction Against the normal direction of traffic.

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