Railroading Glossary
The following glossary is arranged alphabetically with each term catalogued by first letter. Select a letter below to begin.
A | B | C | D | E | F | G | H | I | J | K | L | M
N | O | P | Q | R | S | T | U | V | W | X | Y | Z
Tangent
Straight track.
Tank car
Used to carry gases and bulk-quantity liquids such as corn syrup, petroleum products, and other chemicals. May be interconnected with hoses.
Tariff
A document detailing a railroad's rates and regulations for hauling passengers and freight.
TCS
Traffic Control System. See Centralized Traffic Control.
Team track
A rail siding for general usage by freight shippers, named for the teams of horses that once pulled the wagons to fetch the freight.
TEBU
Another designation for slug: Tractive Effort Booster Unit.
Tell-tale
Device placed along the track on either side of low structures such as bridges or tunnels to warn crew members on top of the cars that they could not remain in a standing position while passing under the structures. Most were removed when regulations no longer required or permitted crew to be atop cars in trains.
Terminal
Facility used for handling freight and to receive, break up, assemble, or dispatch trains.
Terminal railroad
A railroad whose business is not point-to-point transportation but rather pickup and delivery service for a connecting line-haul railroad. Switching and terminal companies usually receive a flat per-car amount for their services.
Theater car
A passenger car equipped with a large window at its rear, with rows of seats facing the window that step upward gradually on tiers, as in a theater. Used in executive or business trains.
Thermic syphon
In a steam locomotive firebox, a funnel-shaped steel fabrication that connects the bottom of the throat sheet and the crown sheet. Water flows upward through the syphon, connecting the coolest and hottest parts of the locomotive boiler. Syphons improved water circulation in the boiler and insured more uniform temperatures in the boiler, increasing fuel efficiency.
Third rail
A rail running parallel to one of the two running rails of a track; carries a supply of electricity used to power electric cars or locomotives.
Third-generation diesel
Third-generation units are those with on-board microprocessors to control various aspects of the locomotive's operation: EMD's 50 and 60 series and GE's Dash 8s.
Three-cylinder steam locomotive
A steam locomotive containing a third cylinder located under the smokebox between the two outside cylinders. It transmitted power to the driving wheels by means of a main rod which was connected to the center of a specifically designed crank axle.
Through freight
Train that is not scheduled to pick up or set out cars along its route.
Throwbar
A bar underneath the ties of a turnout to which the points are attached and which moves the points.
Tie
The crosswise member of the track structure to which the rails are fastened, usually made of wood or concrete.
Time-out
Safety feature that gives approaching trains time to stop before a conflicting route is established in their path.
Tires
The rims of locomotive driving wheels.
TOFC
The transportation of highway truck trailers on flatcars, also called "piggyback".
Ton-mile
The movement of one ton of freight a distance of one mile, a standard transportation industry measure.
Tonnage rating
The maximum permissible trailing load for a given locomotive over a given segment of railroad track. It depends on tractive effort and ruling grade.
Torpedo
A small explosive charge that can be clamped to the top of the rail. It detonates when a train rolls over it, alerting the crew that a potentially dangerous situation exists farther down the track.
Torpedo boat
Diesel locomotive with air reservoir tanks mounted atop the long hood instead of on the frame.
Track gauge
The distance between the pair of rails that comprise a set of railroad tracks. Measured from the inside vertical surface of the top, or head, of each rail. The gauge used throughout North America and most of Europe is 4 feet 8-1/2 inches, called "standard gauge".
Track mile
A mile of railroad track. Track mileage in segments of double-track territory would be double the amount of route miles, to account for both main tracks. See Route mile.
Track Warrant Control (TWC)
A method of traffic control wherein trains are authorized for movement only between specified locations. The form giving a train crew the authority to operate between two locations is called a track warrant.
Trackage rights
An arrangement in which one railroad (the "tenant") negotiates the right to operate its trains over specific segments of track owned by another railroad (the "owner"), usually without rights to serve customers located along that portion of the line. The tenant pays a fixed annual sum plus a variable fee based on the amount of the tenant's traffic relative to the total traffic over the line. ("Haulage rights" are similar but the tenant's traffic is hauled in the owner's trains.)
Trackmobile
A trademarked name by the Whiting Corp. for its car mover, a tractor equipped with rubber tires as well as flanged steel wheels, capable of hauling a few freight cars on a track or moving by itself off-rail. Essentially a cross between a tractor and a locomotive.
Traction
Railroads using electric locomotives (and/or trolley or interurban passenger cars) rather than steam locomotives.
Traction motor
Electric motor which turns a locomotive's wheels, providing traction with the rail and making the vehicle move. There is usually one traction motor geared to each axle.
Tractive effort
The force in pounds exerted by a locomotive to turn its driving wheels. Tractive effort equals the weight on the driving wheels multiplied by the adhesion factor. Also called tractive force.
Traffic department
The sales staff of a railroad.
Trailing truck
Wheels under the locomotive cab that would help stabilize the ride.
Train
One or more engines coupled, with or without cars, displaying a marker.
Train line
The continuous line of air-brake pipes in a train, formed of pipes on the locomotives and cars and the hoses connecting them.
Trainmen
Umbrella term for conductors, brakemen, yard foremen, and switchmen.
Transfer caboose
A caboose for short-haul, as opposed to over-the-road runs; generally has a short carbody and long end platforms.
Transfer locomotive
Early diesel locomotives built specifically for transfer runs, which demanded a lot of pulling power but not much speed. Transfer locomotives generally had high horsepower power plants, many driving axles, and low-speed gearing, but often lacked multiple-unit controls and dynamic braking.
Transfer run
A train that moves cars from one freight yard to another within a large terminal area.
Transit
Short-distance, high-density passenger service usually characterized by electric propulsion, fare payment by token, magnetic card, or cash, and operation under, above, and on streets.
Trestle
A structure of braced timber, piles, or steelwork with short spans.
Trim lead
Tracks in a yard used to move cars from the bowl to the departure yard.
Trolley
A streetcar, an electric-powered rail vehicle drawing current from an overhead wire. The term "trolley" is used in Britain to denote a small cart-a tea trolley or a luggage trolley-and it is being used more and more in the U. S. to mean a bus cosmetically altered to look like an old streetcar or even a San Francisco cable car.
TRRA
Terminal Railroad Association of St. Louis.
Truck
The wheel-axle-frame assembly under each end of a car or locomotive.
Tunnel Motor
An EMD SD40T-2 or SD45T-2. These engine models have low air intakes with fans mounted beneath the radiators at the rear of the long hood. This enables locomotives to gather cooler air from near track level while passing through tunnels and snowsheds.
Turn
A format of train operation in which a crew operates a train to a certain point, then returns to its point of origin during a single work shift.
Turnout
A track switch-the term "turnout" is used to avoid confusion with electrical switches.
Turntable
A rotating structure used for diverting locomotives or cars onto a specific track.
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