Glossary of Railroad-Related Terms

Railroad definitions included here with permission of Dmitry Zinoviev, the keeper of SEJS and P. Veltman. If you have any additional definitions, be sure to contact Dmitry. The list is continuously growing.


AB Valve
The operating device used on freight cars for charging, applying, and releasing the brakes. Also called a triple valve
ABD Valve
An improvement of the AB Valve that features a quick release.
ABDW Valve
An improvement of the ABD Valve. Modifies the Emergency Portion and provides for accelerated buildup of brake cylinder pressure during quick service applications.
Absolute Block
A length of track in which no train or engine is permitted to enter while it is occupied by another train or engine.
Absolute Permissive Block (APB)
A designated section of track or tracks within which the movement of trains will be governed by block signals, whose indications supersede the superiority of trains. The block signals may be controlled manually or automatically.
Absolute Signal
A block or interlocking signal designated by an "A" market or the absence of a number plate.
Add, to
Couple car(s) to a train
Air Brake System
All of the devices and parts included in making an air brake for controlling the speed and stopping a locomotive or train. It is made up of the operating devices, the pipes, fittings and foundation brake gear.
A clear track in a switching yard.
Angle Cock
An appliance used for the purpose of opening or closing brake pipe on ends of cars, rear ends of tenders, and front ends of switch engines so equipped. Provision is made for supporting hose at proper angle.
Consists of all of the operations from the time the brake pipe reduction is started until the brake is released.
Approach Signal
A signal that governs the approach to another signal.
American Railway Union, Crushed durring the Pullman strike in 1894
Automatic Block Signal System (ABS)
A series of consecutive blocks governed by block signals, cab signals or both, actuated by a train, engine or by certain conditions affecting the use of a block.
Automatic Cab Signal System (ACS)
A system which provides for the automatic operation of the cab signals and cab warning whistle.
Automatic Train Stop System (ATS)
A system actuated by wayside inductors, so arranged that its operation will automatically result in the application of the brakes until the train has been brought to a stop.


Baby Lifter
A brakeman.
Bad Order
A piece of rolling stock that needs repair.
By moving the independent brake handle sideways, the engineer can release locomotive brake cylinder pressure that is due to an automatic brake application (a brake pipe pressure reduction). The bail has no effect on brake cylinder pressure that is due to an independent brake application.
Fireman (because his head was near the door of firebox when shoveling coal)
Beans, Go To
Going to eat a meal
Big Boy
Union Pacific 4-8-8-4 600 ton steam freight locomotive
Big C
The conductor (from the Order of Railway Conductors)
Big E
A railroad engineer (for Brotherhood of Locomotive Engineers)
Emergency application of airbrakes, usually when initiated by engineer, i.e. put her in the big hole
Brakes In Emergency; application of the emergency braking system.
Initials of Brotherhood of Locomotive Engineers union
Initials of Brotherhood of Locomotive Firemen and Enginemen union
A length of track between consecutive block signals or from a block signal to the end of block system limits, governed by block signals, cab signals or both.
Block Occupancy Indicator
An indicator used to convey information regarding block occupancy.
Block Signal
A fixed signal at the entrance of a block to govern trains and engines entering and using that block.
Block System
A block or series of consecutive blocks within APB, ABS, ACS, CTC or interlocking limits.
Blue Flag
A blue flag or signal that is placed on a car or locomotive when workers are around or under it. When a car or locomotive is blue-flagged, then it must not be coupled to or moved in any manner. The only person allowed to remove a blue flag is the person who put it there in the first place.
Brooklyn Manhattan Transit - subdivision B-1 of the New York City Transit Authority (NYCTA) subway
The Brains
The conductor
Brake Beam
A cross-piece in the foundation brake gear for a pair of wheels to which the leverage delivers its force to be transmitted through the attached brake head and brake shoes to the tread of the wheels.
Brake Cylinder
A cast metal cylinder with a piston that is forced outward by compressed air in applying the brakes and returned by a release spring in releasing the brakes.
Brake Pipe
Commonly called a train line, it is the pipe, hose, connections, angle cocks, cut-out cocks, fittings, etc., connecting the locomotive and all cars from one end of the train to the other for the passage of air to charge and control the brakes.
Brake Rigging
A term commonly used instead of foundation brake gear.
Brakes, Automatic
Automatic brakes are the brake controls in the locomotive that regulate the pressure of the brake pipe and apply or release the brakes for the entire train including the locomotives
Brakes, Independent
Independent brakes are the brake controls in the locomotive that apply the brakes on the locomotives only. The air hose marked ACT or BR CYL enables the lead unit to control the trailing units brakes
A portion of a division designated by a timetable. Rules and instructions pertaining to subdivisions apply on branches.
Branch Line
A secondary line of a railroad, not the main line.
Brass Hat
AA railroad executive, usually a division manager or higher, a.k.a. suits
Bridge Line Haul Road
See overhead line haul road.
Brotherhood Notch
On steam locomotive - reverse gear hooked up nearer dead center, light throttle, thus using less steam, pulling light train - making it easier on fireman
Initials of Brotherhood of Railrway Trainmen union


Cab Signal
A signal located in engineer's compartment or cab, indicating a condition affecting the movement of a train or engine and used in conjunction with interlocking signals and in conjunction with or in lieu of block signals.
End of train non revenue car
Caboose Valve
A rotary valve type of device providing means for making a controlled rate of brake pipe reduction for making a service or emergency application from the caboose.
Car Toad, Car Tonk
Car inspector who checked the condition f freight and passenger cars and conducted the air brake tests
Centralized Traffic Control (CTC)
A remotely controlled block signal system under which train movements are authorized by block signals whose indicators supersede the superiority of trains.
Clear Block
A block not occupied. Sometimes used to denote a clear signal indication.
Container on flat car. Referred to in intermodal traffic.
Color Light Signal
A fixed signal in which the indications are given by the color of a light only.
Color-Position Light Signal
A fixed signal in which the indications are given by color and position of two or more lights.
Brakeman, with or without brains, displaying pencils.
Controlled Point
A location designated by number where signals and /or switches of a CTC system are controlled by a control operator.
Controlled Siding
A siding within CTC or interlocking limits, the authorization for use of which is governed by signal indication or control operator.
Controlled Signal
An absolute signal, the aspect of which, is controlled by a control operator.
Clean, Oil, Test & Stencil. Applies to air brake rework.
Covered Wagon
A nickname that is generally attached to EMD E and F units.
A length of track that carries one track across another.
A track connection between two adjacent tracks.
A wooden, two truck or bobber trucked, caboose. Also called a way car, hack or, in the days of living in them, a bean shack
Current of Traffic
The movement of trains on a main track, in one direction, specified by the rules.
Cut, to
Separate car(s) from a train


Date Nail
A small nail used by railroads from late 1800's to present used to mark the year a tie was placed in roadbed. Nails are distinctive in that each has the last two digits of placement year stamped in head. Usually found within six inches of tie end, but some are located mid tie to allow easier inspection. Rarer nails value in 100's of dollar range to collectors
Dead Head
A railroad employee traveling on a pass.
A yardmaster.
Distant Signal
A fixed signal outside of a block system, used to govern the approach to a block signal, interlocking signal or switch point indicator. It will not convey information as to conditions affecting the use of the track between the distant signal and block signal, interlocking signal or switch point indicator to which approach is governed. It will be identified by a "D" marker.
A portion of the railroad designated by timetable.
A brakeman or switchtender - someone who throws switches.
Double Slip Switch
Used only where space is limited, combines the functions of a crossing and turnouts to allow any one of four routings.
Double Track (DT)
Two main tracks, on one of which the current of traffic is in a specified direction, and on the other in the opposite direction.
Drawbar Horsepower
The total horsepower of a locomotive less the amount of horsepower that it takes to move the locomotive itself, the balance being available to pull the load.
Drill Track
A track connecting with the ladder track, over which locomotives and cars move back and forth in switching.
Dual Control Switch
A power-operated switch, also equipped for hand operation.
Dump the air
Emergency application of the air brakes causing a train to stop abruptly, usually causing damage to the merchandise being carried or to the train equipment, itself
Dwarf Signal
Two or three lens signal used to control a move over a switch in a yard.
Dynamic Braking
A method of train braking where the kinetic energy from the train movement generates current at the locomotive traction motors, and is dissipated in a resistor grid on the locomotive.
Initiation of an emergency application.
A term commonly given to an brake operating valve that goes into quick-action emergency when it should not. Also called a Kicker.


Electric Switch Lock
An electrically controlled lock device affixed to a hand operated switch or derail to control it's use.
Emergency Application
An application resulting from an emergency rate of brake pipe reduction which causes the brakes to apply quickly and with maximum braking force for the shortest practical stopping distance.
A unit propelled by any form of energy, or a combination of such units operated from a single control, used in train or yard service.
Engine Whistle Signals
* means a short blast of the whistle or horn
- means one long blast
*apply brakes, stop
* *answer to any signal not otherwise provided for
* * *when standing, back
* * * *call for signals
-test train brakes
- -release train brakes
- - -when running, stop at next passenger station
- - -when standing, train parted
- - - -recall flagman from south or west
- - - - -recall flagman from north or east
- * *calling attention to another train that signals are displayed for a following section
- * * *flagman protect the rear of train
* * * -flagman protect the front of train
- - *approaching meeting or waiting points
- - * -approaching crossing at grade
- * * -answer to yellow temporary reduced speed flag placed 1 1/2 miles in advance of restricted tracks
End Of Train unit (see also Caboose). An EOT transmits brake pipe pressure to the lead unit (head end locomotive), while a two way EOT is also capable of receiving a transmission from the lead unit to open the brake pipe and put the train into emergency stop (clarified by Bob Murphy).
Extra Train
A train not authorized by timetable schedule. It may be designated:
Extra -
For any extra train except work extra, the movement of which is authorized in a specified direction.
Work Extra -
For any extra train authorized by Form H train order, the movement of which may be in either direction within specified limits.


Facing Point Lock
A locking device which automatically locks the switch points of a spring switch in normal position.
Fixed Signal
A signal of fixed location indicating a condition affecting the movement of a train.
Flashing Rear End Device -- end of train telmetry device
The intersection of two rails of a switch.
Full Service Application
Corresponds to a handle position for the automatic brake handle. In this position the brake pipe should be at 62 PSI (down from a 90 PSI release charge pressure). When an application is made on the automatic brakes, the equalizing reservoir pressure drops in proportion to the handle movement. The self lapping valve (Automatic Brake Valve) then vents brake pipe pressure at a service rate until the equalizing reservoir and brake pipe pressures are equal. This pressure is measured on the locomotive only. It may be less further back on the train due to leakage. A minimum reduction is a 6 PSI drop to 84 PSI. After a minimum reduction is made, the automatic brake valve handle is linear down to zero. If the locomotive has a direction on the reverser handle, or the independent brakes are released, below 45 PSI BPP an emergency will occur and a valve will blow the brake pipe to zero in a hurry (corrected by Bob Murphy).


Gandy Dancer
A railroad track worker. Name came from the Gandy Mfg Co. in the 19th century that made a lot of track tools.
See Interchange Point
Broad gauge (Spain): 1674 mm 5' 5 9/10th"
Broad gauge (Portugal): 1665 mm 5' 5 11/20th"
Broad gauge (Ireland): 1600 mm 5' 3"
Broad gauge (Finland): 1524 mm 5' exactly
Broad gauge (former USSR): 1520 mm 5'
Standard gauge: 1435 mm 4' 8 1/2"
Narrow gauge (Cape gauge): 1067 mm 3' 6"
Narrow gauge (meter gauge): 1000 mm 3' 3 37/100"
Narrow gauge (US narrow): 914 mm 3' 0"

The metal attachments to which train line air hoses connect
A yard engine.
Grade Resistance
Resistance that results from the energy you must put into a train to lift it vertically. The energy is returned without loss when the train comes back down again.
Green Eye
A slang term for a clear signal.


A signal given to proceed at maximum permissible speed.
A locomotive
Hoghead, Hogger
A railroad engineer
Horsepower per Trailing Ton.
The total horsepower of all working locomotives divided by the total trailing weight of the train in tons.
A person who operates engines in engine house territory and works under the direction of the engine house foreman
Hostler's Controls
A simple throttle to allow independent movement of locomotives not equipped with engineers controls.
Hot Box
On friction bearings, an overheated journal bearing.
House Track
A track entering, or along side a freight house. Cars are spotted here for loading or unloading.


INDependent City Subway - subdivision B-2 of the New York City Transit Authority (NYCTA) subway
Initial Station
The first station on each subdivision from which a train is authorized to occupy the main track.
Interchange Point
The point at which two or more railroads join. Traffic is passed from one road to another at interchange points.
An arrangement of signal appliances so interconnected that their movements must succeed each other in proper sequence. It may be operated manually or automatically.
Interlocking Limits
The tracks between the outer opposing absolute signals of an interlocking.
Interlocking Signals
The fixed signals of an interlocking, governing trains using interlocking limits.
Freight traffic that refers to containerization of freight for easy transloading to different modes of transportation. See TOFC,COFC, Piggyback.
Interboro Rapid Transit - subdivision A of the New York City Transit Authority (NYCTA) subway


Joint Facilities
Any facilities owned by two or more railroads.
Jones, Casey
A locomotive engineer famous for having died at his post. Here's the full story.


A common expression for an emergency brake application which occurs when a service brake application is intended or when no application is intended.


Ladder Track
A series of turnouts providing access to any of several parallel yard tracks.
Line Haul Road
A railroad that handles freight over a medium to long distance.
Locomotives are units propelled by any form of energy, or a combination of such units operated from a single control station, used in train or yard service
Low Arm
A nickname for a restricting signal in the days of the semaphor with the arm down 45 degrees.


Main Track
A track extending through yards and between stations which must not be occupied without authority or protection.
Reference to the Mallet Articulated Cab Forward steam locomotives used by Southern Pacific railroad in the 30's, 40's and 50's.
Manual Block System
A series of consecutive blocks, governed by block signals operated manually, upon information by telegraph, telephone or other means of communication.
A train signal that is used to indicate the end of the train.
Multiple Main Tracks
Two or more main tracks, the use of which is designated in the timetable.
Multiple Unit. A lead locomotive followed by one or more locomotives. Cables between the MU connectors bring the electrical signals in party line fashion to the trailing units (clarified by Bob Murphy).


Number Dummies
Clerks who worked as yard checkers


Old Reliable Conductors -- The union that represented conductors during the mid to late 19th century
Originating Line Haul Road
The railroad where any freight shipment starts.
Originating Station
The first station on each subdivision from which a train is authorized to occupy the main track.
Overhead Line Haul Road
Any railroad or railroads between the originating line haul road and the terminating line haul road. Also known as a bridge line haul road.
Overlap Sign
A sign marking the limit of control of a block signal.


Paired Track
When two railroads own single track lines, they may reach an agreement whereby one railroads track services both roads in one direction, while the other railroads track services both roads in the other direction.
Partial Service Application
Reducing the brake pipe pressure at a service rate but not enough to cause the reservoir and cylinder pressure to equalize.
TOFC or trailer on a flat car. Originally used when truck trailers were loaded onto flat cars for shipment by rail.
A locomotive engineer trainee.
An employee assigned to a train when the engineer or conductor is not acquainted with the rules or portion of a railroad over which the train is to be moved.
Portion of track within a terminal on which a train may stand for a period of time
Position Light Signal
A fixed signal in which the indications are given by the position of two or more lights.
Prime Mover
A V-type diesel with 8 to 20 cylinders rated at about 125 hp per cylinder if normally aspirated or 250 hp per cylinder if Turbo charged.
Private Car/Business Car
Coaches owned by private individuals/railroad (for use of coporate officials or supervisors). Cars were positioned at end of trains and train crew were to remain off these cars except in performance of duties. Crew was also to see that occupants of these cars were not disturbed at all costs


Rail Weight
The number of pounds per yard that rail weighs. Currently rail is being rolled at 112 to 145 pounds per yard.
Wagons/carriages semi permanently joined in an articulation rather than via a coupler
Register Station
A station at which a train register is located.
Regular Train
A train authorized by a timetable schedule.
Repeater Signal
Signal placed on the oppsite side of the track from the controling signal. It repeats the aspect of the controlling signal for a greater range of vision.
Restricted Speed
A speed that will permit stopping within one half the range of vision; short of train, engine, railroad car, stop signal, derail or switch not properly lined, looking out for broken rail, not exceeding 20 MPH.
Revenue Collection Train
A train which picks up the revenue collected by the railroad clerk.
Rip Track
A small car repair facility, often a single track in a small yard. Name derived from "Repair, Inspect and Paint."
Rolling Resistance
Resistance that is made up of wheel friction, journal friction, and wind resistance. It is non recoverable.
Ruling Grade
The particular point on the run at which the combination of grade and curve resistance makes the train pull hardest and , therefore, "rules" how heavy a load can be given to the locomotive.


Sense and Brake Unit (see also Caboose)
Non union member doing work usualy contracted by railroads for railway union labor contracts.
That part of a timetable which prescribes class, direction, number and movement for a regular train.
One of two or more trains running on the same schedule, displaying signals or for which signals are displayed.
Semaphore Signal
A signal in which the day indications are given by the position of a semaphore arm.
The effect of a sudden change in speed of a car, locomotive or train, or part of a train.
Shoe Fly Track
A temporary track built around a train wreck or washout
Side Track
A track auxiliary to the main track.
A track auxiliary to the main track for meeting or passing trains. The timetable will indicate stations at which sidings are located.
Signal Aspect
The appearance of a fixed signal conveying an indication as viewed from the direction of an approaching train; or the appearance of a cab signal conveying an indication as viewed by an observer in the cab.
Signal Dolly
Train that delivers supplies to towers.
Signal Indication
The information conveyed by the signal aspect.
The man who controls the signals and authorises the movements of trains on running lines
Single-Car Test Device
Is used to test the air brake equipment on car that is sent to a repair track
Single Track
A main track upon which trains are operated in both directions.
The conductor
The motion, forward or back, that one or more cars, locomotives, or parts of a train has without moving other coupled cars, locomotives, or parts of the train. Loose slack is the free movement or lost motion between parts of a train. Spring slack is the movement beyond the free or lost motion brought about through compressing the draft gear springs. Slack is necessary so as to start one car at a time and so that the train may be operated around curves and over high and low places.
Slack Action
Movement of part of a coupled train at a different speed than another part of the same train.
A small, ballasted, four or six axle unit, semipermanently coupled to a locomotive that does not have a prime mover, but does have traction motors. Generally used in yard duty where the switcher has enough horsepower, but not enough tractive force to push long strings of cars up a hump.
Spring Switch
A switch equipped with a spring mechanism to restore the switch points to original position after having been trailed through.
A place designated in the timetable station column by name.
Stub Track
A form of side track connected to a running track at one only and protected at the other end by a bumping post or other obstruction.
A portion of a division designated by timetable.
Initials of Switchmens Union of North America
Superior Train
A train having precedence over another train.
Swing Man
The rear brakeman
Switch Point Indicator
A light type indicator used in connection with facing point movement over certain switches to indicate switch points fit properly.


Tallow Pot
Tangent Track
Straight track.
Tare Weight
The weight of an empty car.
Team Track
A track on which rail cars are placed for the use of the public in loading or unloading freight.
Terminating line haul road
The last railroad over which any shipment travels.
Terminating Station
The last station on each subdivision to which a train is authorized to occupy the main track.
The authority for the movement of regular trains subject to the rules. It may contain classified schedules and includes special instructions.
Trailer on a flat car. Refers to intermodal shipments.
Tons per Operative Brake
Gross trailing tonnage of the train divided by the total number of cars having operative brakes. (not including locomotives)
Track Bulletin
A notice containing information as to track conditions or other conditions, necessary for the safe operation of trains or engines.
Track Circuit
An electrical circuit of which the rails of the track form a part. The track circuit is the basis of signaling systems.
Track Gauge
The distance between the inner faces of the track heads. Nominally, 4' 8.5".
Track Head
The top of the track on which the wheels roll.
Track Permit
A form used to authorize occupancy of main track where designated by special instructions.
Track Side Warning Detector
Wayside detectors which are provided at various locations as shown in the timetable which detect such conditions as overheated journals, dragging equipment, excess dimensions, shifted loads, high water and slides.
Track Warrant Control (TWC)
A method of authorizing movements of trains or engines or protecting men or machines on a main track within specified limits in territory designated by special instructions or general order.
Track Web
The thin section of track between the base and the head.
Trackage Rights
An agreement between two railroads according to which, one railroad buys the right to run its trains on the tracks of the other, and usually pays a toll for the privilege. That toll is called a "wheelage" charge.
Tractive Force
The amount of force at the driving wheel rims to start and move tonnage up various grades.
An engine or more than one engine coupled, with or without cars, displaying a marker and authorized to operate on a main track.
Train Brake
The combined brakes on locomotive and cars that provides the means of controlling the speed and stopping of the entire train.
Train Line
See Brake Pipe
Train of Superior Right
A train given precedence by train order.
Train of Superior Class
A train given precedence by time table.
Train of Superior Direction
A train given precedence in the direction specified in the time table as between opposing trains of the same class.
Train Order
A message changing the meeting point between two trains.
Train Order Signal
Fixed signal near the entrance to a river tube, bridge or at stations with moving platforms. Two lunar white mean Proceed without orders according to rules, two red mean Stop, stay and call for orders.
Train Register
A book or form used at designated stations for registering time of arrival and departure of trains, and such other information as may be prescribed.
Triple Valve
An operating valve for charging the reservoir, applying the brake, and releasing the brake.
Truck Hunting
Rapid oscillation of an empty car truck at high speeds where the flanges tend to ride up on the head of the rail.
Turnout Number
The ratio of the length of the tangent track to an equal unit of space between the tangent track and a point on the branch track.


A term used in Canada for a caboose.
Variable Switch
A switch, designated by letter "V" or bowl painted yellow, when trailed through the switch points remain lined in the position to which forced.
Term used to refer to passenger trains, dating back to the late 19th century and the varnished passenger coaches of the luxury trains such as those employed on the LV's Black Diamond and the C&O's Sportsman


Wheel Pull
Caused by the friction between the brake shoe and the wheel and transmitted to the rail.
Wheel Rolling
The wheel rotating on its axle theoretically without motion existing between the wheel and the rail at the area of contact.
Wheel Slipping
The wheel rotating on its axle with motion existing between the wheel and rail at the area of contact.
Wheel Sliding
The wheel not rotating on its axle and motion existing between the wheel and rail at the area of contact.
Whyte System
F. M. Whyte's system of classification is used to describe the wheel arrangement of conventional steam locomotives. In this system, the first number is the number of leading wheels, and the last is the number of trailing wheels. The middle number (or numbers) give the number and arrangement of drivers. A "T" at the end indicates a tank engine.
A track shaped like the letter "Y", but with a connector between the two arms of the "Y".


A system of tracks, other than main tracks and sidings, used for making up trains, storing of cars and for other purposes.
Yard Limits
A portion of main track designated by yard limit signs and by timetable, train order Form T or track bulletin, which trains and engines may use as prescribed by Rule 93.
Yard Engine
An engine assigned to yard service.
Yellow Eye
A slang term for a yellow signal.

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This page last updated 2/1/2002