GCOR - Glossary
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Use only the following abbreviations:
ABS Automatic Block Signal System
ACS Automatic Cab Signal System
ATC Automatic Train Control
ATS Automatic Train Stop
BRT Block Register Territory
C&E Conductor and Engineer
COFC Container on Flat Car
CP Control Point
CTC Centralized Traffic Control
DT Double Track
DTC Direct Traffic Control
ESS East Siding Switch
HER Head End Restriction
MMT Multiple Main Track
MP Mile Post
MPH Miles Per Hour
MT Main Track
mw Maintenance of Way
NSS North Siding Switch
RC Radio Channel
sss South Siding Switch
TOFC Trailer on Flat Car
TWC Track Warrant Control
wss West Siding Switch
YL Yard Limits
Use the normal abbreviations for names of months.
See Automatic Block Signal System.
A length of track that no train is permitted to enter
while the track is occupied by another train.
A block or interlocking signal without a number
plate, or designated by an "A" marker.
See Automatic Cab Signal System.
See Automatic Train Stop System.
Automatic Block Signal System (ABS)
A series of consecutive blocks governed by block
signals, cab signals, or both. The signals are activated
by a train or by certain conditions that affect the block
Automatic Cab Signal System (ACS)
A system that allows cab signals and the cab warning
whistle to operate automatically.
Automatic Train Stop System (ATS)
A system activated by wayside inductors positioned
to apply the brakes automatically until the train stops.
A length of track between consecutive block signals
or between a block signal and the end of block system
Block Register Territory (BRT)
A method of operation in non-signaled territory
where trains, men, and equipment are authorized to
occupy the main track in limits designated by the
A fixed signal at the entrance of a block that governs
trains entering and using that block.
A block or series of consecutive blocks within ABS,
ACS, CTC, or interlocking limits.
See Block Register Territory.
A signal in the engineer's compartment or cab that
indicates a condition affecting train movement. Cab
signals are used with interlocking or block signals or
without block signals.
Centralized Traffic Control (CTC)
A block system that uses block signal indications to
authorize train movements.
Employee in charge of train or yard movement.
Employee assigned to operate a CTC or interlocking
control machine or authorized to grant track permits.
The location of absolute signals controlled by a
A siding within CTC or interlocking limits where a
signal indication authorizes the siding's use.
An absolute signal controlled by a control operator.
Crossings at Grade
Crossings that intersect at the same level.
A track connection between two adjacent tracks.
See Centralized Traffic Control.
Current of Traffic
The movement of trains in one direction on a main
track, as specified by the rules.
Direct Traff ic Control (DTC)
A DTC block or a series of DTC blocks where the train
dispatcher authorizes track occupancy.
A fixed signal outside a block system that govems the
approach to a block signal, interlocking signal, or
switch point indicator. A distant signal does not
indicate conditions that affect track use between the
distant signal and block or interlocking signals or
between the distant signal and switch point indicator.
A distant signal is identified by a "D."
Two main tracks where the current of traffic on one
track is in a specified direction and in the opposite
direction on the other.
Dual Control Switch
A power-operated switch, moveable point frog, or
derail that can also be operated by hand.
See Direct Traffic Control.
A length of main track specified by name. DTC block
name and limits are identified by wayside signs
reading, "Begin (name) Block" and "End (name)
Block" and by mile post location in the timetable.
Electric Switch Lock
An electrically controlled lock that restricts the use of
a hand-operated switch or derail.
A unit propelled by any form of energy or more than
one of these units operated from a single control.
Engines are used in train or yard service. Rules that
apply to engines also apply to cab control cars.
Also includes student engineers, firemen, and
A signal that is fixed to a location permanently and
that indicates a condition affecting train movement.
Any employee providing flag protection.
Employee in charge of work.
Signal appliances that are interconnected so that each
of their movements follows the other in a proper
sequence. Interlockings may be operated manually or
The tracks between outer opposing absolute signals of
The fixed signals of an interlocking that govern trains
using interlocking limits.
A track extending through yards and between
stations that must not be occupied without authority
Multiple Main Tracks
Two or more main tracks that are used according to
An employee assigned to a train to assist an engineer
or conductor who is unfamiliar with the rules or the
portion of railroad the train will operate on,
Any block signal indication that allows a train to
proceed without stopping.
A movement opposite the authorized direcfion.
A track connected to the main track and used for
meeting or passing trains. Location of sidings are
shown in the timetable.
The appearance of a fixed or cab signal.
The action required by the signal aspect.
A main track where trains are operated in both
Instructions contained in the timetable or other
A switch with a spring mechanism that retums the
switch points to the original position after they are
A place designated by name in the timetable station
Switch Point Indicator
A light type indicator used during movement over
certain switches to show that switch points fit
A publication with instructions On train, engine, or
equipment movement. It also contains other essential
A notice of conditions affecting train movement. It
may also authorize movement against the current of
traffic where Rule 9.14 (Movement with the Current
of Traffic) is in effect.
Track Occupancy Indicator
An indicator that tells whether a length of track is
occupied or not.
Trackside Warning Detector
A device that indicates conditions such as overheated
journals, dragging equipment, excess dimensions,
shifted loads, high water, or slides.
Track Warrant Control (TWC)
A method to authorize train movements or protect
men or machines on a main track within specified
limits in a territory designated by the timetable.
One or more engines coupled, with or without cars,
displaying a marker, and authorized to operate on a
main track. A term that when used in connection
with speed restrictions, flag protection, and the
observance of all signals and signal rules also applies
Conductors, assistant conductors, brakemen, yard
engine foremen, switchmen, and yard helpers.
See Track Warrant Control.
A switch identified by a "V" or a bowl painted
yellow. When trailed through, the switch points
remain lined in the posifion they were forced.
A system of tracks, other than main tracks and
sidings, used for making up trains, storing cars, and
A portion of main track designated by yard limit
signs and timetable special instructions or a track
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