Rail terminology

Rail terminology is a form of technical terminology. The difference between the American term railroad and the British term railway (also used by other English-speaking countries outside the US) is the most obvious trans-Atlantic difference in rail terminology (see usage of the terms railroad and railway for more information). There are also others, due to the parallel development of rail transport systems on both sides of the Atlantic. Various terms are presented here alphabetically; where a term has multiple names, this is indicated. The note "US" indicates a term peculiar to North America, or "CA" may represent Canada while "UK" refers to terms originating in the British Isles and normally also used in former British colonies outside North America (such as Australia "AU", New Zealand "NZ", etc.). Exceptions are noted; terms whose currency is limited to one particular country, region, or railway are also included.

• 10 wheeler or ten wheeler (US): A steam locomotive with a 4-6-0 wheel arrangement.

• Air brake: Railroad brakes which operate using compressed air.
• Alco: American Locomotive Company - the second largest builder of steam locomotives in the U.S.
• Alerter: Similar to the Dead man's switch other than it does not require the operator's constant interaction. Instead an alarm is sounded at a preset interval in which the operator must respond by pressing a button to reset the alarm and the timer. If the operator does not respond within a preset time the brakes are applied. May also be called a 'Watchdog'.
• American: A steam locomotive with a 4-4-0 wheel arrangement.
• Angel Seat or Angel's Perch: (US) A term often used when referring to the second level seats on a Cupola style caboose.
• Annett's key (UK), Annett key (Aus.): A large key which locks levers or other items of signalling apparatus, serving as a portable form of interlocking. With the key removed from the lock, the lever or apparatus is locked in its position. When the key is turned in the lock, it cannot be removed.
• Articulated locomotive: A steam locomotive with one or more engine units that can move relative to the main frame.
• Atlantic: A steam locomotive with a 4-4-2 wheel arrangement.
• A unit (US): A diesel locomotive with a driving cab, or crew compartment, for operating on the road. When equipped with MU, it can control other A units, or B units.
• Auto brake A type of fail-safe system that uses air pressure to hold the brakes off so that in the event the air pressure is lost in the brake pipe the brakes will automatically apply.
• Auto-brake gauge: A gauge recording the application and pressure of an automatic braking system; usually repeated in the guard's van in historic rolling stock.
• Autocoach (UK): A passenger coach fitted with a driving cab and controls for use in an Autotrain (UK).
• Automatic Equipment Identification (AEI) (US): Automatic tracking system using RFID technology.
• Automatic Train Control (ATC)
• Automatic train operation (ATO)
• Automatic train protection (ATP)
• Automatic Warning System (UK): Refers to the specific form of limited cab signalling introduced in 1948 in the United Kingdom to help train drivers observe and obey warning signals.
• Autorack (also called auto carrier) (US): A specialized freight car for transporting automobiles. Car transporter wagon / Car transporter van (UK).
• Autotrain (UK): A branch line train consisting of a steam locomotive and passenger carriages that can be driven from either end by means of rodding to the regulator and an additional vacuum brake valve. The fireman remains with the locomotive and, when the driver is at the other end, the fireman controls the cut off and vacuum ejectors in addition to his usual duties. Also: Push-pull train, Motor train (UK).
• Auto Train (US): A passenger train service first operated by Auto-Train Corporation and then by Amtrak between Lorton, Virginia and Sanford, Florida that carries the passengers' automobiles aboard the same train in autoracks.

• B unit (US): A cabless booster locomotive, controlled via MU from a cab-equipped A unit. Sometimes equipped with limited controls for hostling.
• Bacon slicer (UK): Slang term for a cutoff controlled by a wheel operating through a worm and nut, rather than the more usual quadrant lever. The device was slow to operate, but very precise, and therefore only fitted to long-distance locomotives where frequent changes of cut-off were not required.
• Bad order A tag or note applied to a defective piece of equipment. Generally, equipment tagged as bad order is not to be used until repairs are performed and the equipment is inspected and approved for use.
• Baldwin: American locomotive manufacturer.
• Ballast: aggregate stone, gravel or cinders forming the track bed on which sleepers (ties) and track are laid to ensure stability and proper drainage.
• Balloon: A large section of looped track usually at the end of a spur or branch which allows trains to turn around for the return trip.
• Bank: A particularly steep section of line that requires additional bank (or banking) engines (US: helper engines) to help trains climb.
• Base plate (UK), tie plate (US): An iron or steel plate used to spread the weight of rail over a larger area of sleeper (tie) and facilitate a secure, low maintenance, fastening with bolts or clips. It derives from the former Rail chairs.
• Bay platform: A type of platform/track arrangement where the train pulls into a siding, or dead-end, when serving the platform.
• Beep: A one-of-a-kind switcher locomotive (also referred to as the SWBLW) built by the Atchison, Topeka and Santa Fe Railway in 1970.
• Blower: On a steam locomotive, a steam pipe leading into the smokebox, causing necessary draft in the stack when the engine is not running. However, UK practice is to turn on the blower also when entering tunnels, etc, to avoid dangerous blow-back into the cab. The UK loading gauge is much smaller than that in the US and the tunnel roof would otherwise spoil the normal draft created from the exhaust. On a Diesel engine, the blower is a mechanical device that increases the supply of air to the combustion chamber. Also known as a "Supercharger". The most common type of supercharger used on a diesel locomotive engine is a Roots type supercharger.
• Bobber: (archaic, US): A slang word for a small caboose with just four wheels, all rigidly mounted to the frame. This design was common in the 1800s. Bobber refers to the bouncing motion of such a caboose in motion.
• Bo-Bo (Europe): A locomotive with a 4 wheel per truck configuration, each individually powered, as opposed to a 6-wheel "Co-Co" configuration.
• Bogie: The undercarriage assembly incorporating the wheels, suspension, brakes and, in powered units, the traction motors.
• Boiler: A cylindrical container adjacent to the firebox in which steam is produced to drive a steam locomotive.
• Bonds: Short wires used to bridge gaps in electrical circuits, usually at track circuit joints or between rails.
• Booking Clerk: A person at a station whose job is specifically selling tickets.
• Boom barrier: A barrier at a level (rail) crossings.
• Booster: (Steam locomotive) - An extra set of cylinders that can be engaged to drive a trailing truck or tender truck to give additional tractive effort at starting and low speeds.
• Boxcar (US): a type of rolling stock with a flat bottom enclosed on all sides and top, which is loaded and unloaded from sliding doors on each side. Same as van (UK).
• Brakeman: A train crew member who performs railcar and track management; often a single job description along with switchman ("brakeman/switchman"). A brakeman manually activated brakes on railroad cars before the advent of air brakes.
• Brake Pipe (US): The main air pipe of the trains pneumatic braking system.
• Brake van (UK): A heavy vehicle with powerful brakes which was attached to the rear of goods trains in the days when most wagons were not fitted with a continuous braking system. Its function was to supplement the locomotive's braking power in slowing and stopping the train and to keep the couplings uniformly tight by selective light braking to avoid snatching and breakages. It also conveyed the train guard, hence its alternative name of "guards van". Partly analogous to caboose and its synonyms.
• Branch line: A secondary railway line that branches off a main line.
• Broad gauge: Track where the rails are spaced more widely apart than (which is called standard gauge). Many early railroads were broad gauge, for example the Great Western Railway in the UK which adopted 7 ft 1/4 in (2141 mm) gauge until it was converted to standard gauge in the 1860s - 1890s. Russia still has over 80,000 km of broad gauge (1520 mm or 5 ft) railroads. Broad gauge is also normal in Spain, Portugal, and India (1680 mm or 5ft 6ins), as well as Ireland (1600 mm or 5ft 3ins). It is also still used in Australia (1600 mm).
• Bubble Car: A DMU consisting of a single coach (UK), e.g. British Rail Class 121
• Buckeye coupler: A form of coupler which will lock automatically when the two parts are pushed together.
• Buck (US): A term used for pushing railroad cars with a locomotive then allowing them to roll under their own momentum into a siding. (Assuming a brakeman hangs on for a free ride) Also; Kick.
• Buffer A device that cushions the impact of rail vehicles against each other.
• Buffer stop: The barrier installed at the end of a dead end track to prevent rail vehicles from proceeding further.
• Bull head rail (UK): A steel rail section commonly used in 60ft lengths on almost all railway lines throughout Britain until c1950, which due to its shape must be supported in cast iron chairs that are screwed to the sleepers. It is still found on secondary and preserved lines and in yards.
• Bustitution: The practice of replacing train service, whether light rail, tram/streetcar systems, or full-size railway systems, with a bus service, either on a temporary or permanent basis. Somewhat derogatory and mainly used in the UK. The word is a portmanteau of the words "bus" and "substitution".

• Cabin car (PRR): See caboose.
• Cabless: A locomotive without a cab. Commonly referred to as a B unit or a Slug. Although not all Slugs are cabless.
• Caboose: A railroad car attached usually to the end of a train, in which railroad workers could ride and monitor track and rolling stock conditions. Partly analogous to brake van (UK). Largely obsolete, having been replaced by the electronic End of Train (EOT) device, or Flashing Rear End Device called "FRED".
• Cant: Angle. Can be used in the context of the cant of the track (the relative level one rail to another); and the cant of a rail, being the angle of an individual rail relative to vertical.
• Carbody unit or cab unit (US): A locomotive which derives its structural strength from a bridge-truss design framework in the sides and roof, which cover the full width of the locomotive. It refers to both A units and B units.
• Catenary or catenary structure: The overhead wire system used to send electricity to an electric locomotive or multiple unit, tram or light rail vehicle.
• Carman (US): A mechanic responsible for maintaining and inspecting the rolling stock.
• Centralized traffic control (CTC) (US, AU): A system in which signals and switches for a given area of track are controlled from a centralized location. May or may not be computerized.
• Cess (UK): The area either side of the railway immediately off the ballast shoulder. This usually provides a safe area for workers to stand when trains approach.
• Chair (UK): A cast iron bracket screwed to the sleeper and used to support bull head rail that is held in place by a wooden key (wedge) or spring steel clip. Still found on preserved railways and in yards.
• Ches-C (US): Chessie System's kitten logo.
• Chimney (UK): Smokestack or stack (US), or funnel.
• Co-Co (EU): A heavier duty locomotive with 6 wheels per bogie configuration as opposed to a 4-wheel "Bo-Bo" configuration. The correct classification is Co'Co', but Co-Co is used more often.
• COFC: Abbreviation for "Container On Flat Car".
• Colour light signal: A signal in which the colour of the light(s) determine the meaning of the aspect shown.
• Colour position signal: A signaling system that uses both colour and light position to determine the meaning of the aspect shown.
• Combined Power Handle: A handle or lever which controls both the throttle and the dynamic braking on the locomotive: forward (away from operator) past center is throttle up, backward (toward operator), past center, operates the dynamic brake.
• Compound locomotive: A steam locomotive passing steam through two sets of cylinders. One set uses high pressure steam, then passes the low pressure exhausted steam to the second.
• Compromise joint: A special joint bar used to join rail ends of two different cross-sections while holding the top running surface and inside gauge surface even.
• Conductor (US), guard (UK): The person "in charge" of a train and its crew. On passenger trains, a conductor is also responsible for tasks such as assisting passengers and collecting tickets. In Australia, both terms are used, "conductor" for the person checking tickets, etc. on a tram or train, and "guard" for the person in charge of the train.
• Consist (US), formation (UK): A noun to describe the group of rail vehicles making up a train, or more commonly a group of locomotives connected together for Multiple-Unit (MU) operation.
• Continuous welded rail (CWR): In this form of track, the rails are welded together by utilising the thermite reaction or flash butt welding to form one continuous rail that may be several kilometres long.
• Control Point (CP) (US): An interlocking, or the location of a track signal or other marker with which dispatchers can specify when controlling trains.
• Coupler (US), coupling(UK): Railroad cars in a train are connected by couplers located at the ends of the cars.
• Coupling rods or connecting rods: Rods between crank pins on the wheels, transferring power from a driving axle to a driven axle of a locomotive.
• Cow and calf: A diesel locomotive with a crew cab permanently coupled to and acting as a controller for a similar slave diesel locomotive without a crew cab, primarily used for switching/shunting duties for large groups of rolling stock. Also known as master and slave, as in the British Rail Class 13 shunters at Tinsley Marshalling Yard.
• Cowl unit (US): A locomotive whose sides and roof are non-structural, and cover the full width of the locomotive. Structural strength comes from the underframe.
• Crank pin: A pin protruding from a wheel into a main or coupling rod.
• Crew driver (US): Person(s) operating ground transportation vehicles for transporting railroad crews to and from various locations.
• Crosshead: The pivot between the piston rod and the main rod on a steam locomotive.
• Cross-tie (U.S): sleeper (UK): See Railroad tie.
• Cut off: A variable device on steam locomotives which closes the steam valve to the steam cylinder before the end of the piston stroke, thus conserving steam while allowing the steam in the cylinder to expand under its own energy. Also: Reverser.
• Cutting: A channel dug through a hillside to enable railtrack to maintain a shallow gradient. See also embankment
• Cylinder: The central working part of a reciprocating engine, the space in which a piston travels.

• Dead man's handle or Dead man's switch: A safety mechanism on a train controller which automatically applies the brake if a lever is released. It is intended to stop a train if the driver is incapacitated. In some forms, this device may be pedal-actuated.
• Defect detector: A track side device used to detect various defects such as Hotboxes (Overheated axle bearings), dragging equipment, leaning cars, overloaded cars, overheight cars, seized wheels, etc.
• Demurrage A charge levied by a railroad to a shipper for excessive delay in unloading cargo.
• Derailer, a safety device that will derail vehicles passing it.
• Detonators: Small charges placed on the running rail which explode when run over; used to warn drivers in following trains of an incident ahead. Also called torpedoes (US).
• *Diamond: Trackage which allows a rail line to cross another at grade.
• Diesel multiple unit or DMU: A set of diesel-powered self-propelling passenger rail vehicles able to operate in multiple with other such sets. Such units, especially those consisting of a single vehicle, are sometimes termed railcars.
• Direct Traffic Control (DTC): A system in which train dispatchers communicate directly with train crews via radio to authorize track occupancy in predefined blocks.
• Ditch lights: A pair of lights, usually found on modern locomotives, located several feet below and outboard of the main headlight, that may alternately flash while the train is in motion.
• DOO: Driver-only operation
• Doodlebug: Gasoline-electric self-powered passenger car used for small capacity rural commuter service. Also a British Rail Class 153 DMU.
• Down: (UK) A direction (usually away from London, other capital city, or the headquarters of the railway concerned) or side (on left-running railways, the left side when facing in the down direction). The opposite of up. The down direction is usually associated with odd-numbered trains and signals. In Australia it is used relative to the state's capital city. US railways use the compass points northbound, southbound, eastbound and westbound.
• Dragging equipment detector: See Defect detector
• Drift Cutting off power and allowing a train to coast.
• Driver (UK), Engineer (US): The operator of a railroad locomotive.
• Driver (UK): Steam locomotive driving wheel, particularly in "single driver" (one driven axle) engines.
• Driving Van Trailer or DVT: An end carriage from which the train can be driven when the locomotive is at the rear of the train, push-pull operation. (See Also: DBSO - predecessor to the DVT)

• Ejector: Component of vacuum brake system. Steam passing through a cone sucks air from the train pipe to create the vacuum. Usually fitted in pairs: a small ejector running continuously to overcome leaks and to restore the vacuum after light braking and a large ejector operated when needed to release the brakes quickly after a heavy application or to create the initial vacuum ("making a brake" – UK) after coupling up.
• Electric multiple unit (EMU): A set of electrically powered self-propelling passenger rail vehicles able to operate in multiple with other such sets.
• Elephant style (US) - Railfan jargon to describe how multiple locomotives are coupled together in a train; the front of the second locomotive is coupled to the rear of the first locomotive, the front of the third locomotive is coupled to the rear of the second locomotive, and so on down the line. The term is reminiscent of a parade of circus elephants where the elephant behind the front elephant would hold the leading elephant's tail in its trunk.
• Elevated railway: One typically built on supports over city streets, commonly called "the el" or simply the "The L".
• Embankment: A raised pathway on which rail tracks are placed to maintain a shallow gradient when passing over depressions in the terrain. See also cutting.
• Empty Coaching Stock train, or ECS: A train used to bring carriages into (or out of) service. They usually run between sidings and main stations, with the carriages then forming a service train to another destination. They are often worked under freight train rules - eg without needing a guard in the UK.
• EMD: Electro-Motive Diesels, Inc, the world's second largest builder of railroad locomotives. EMD was previously Electro-Motive Division of GM before being sold off.
• Engineer (US), driver, engine driver, train driver (UK): The operator of a locomotive.
• EOT (US): End of train device. A form of an electronic caboose also called FRED.
• EP gauge (UK): Electro-pneumatic brake gauge; recording the application and pressure of the service brake, usually repeated in the guards van in historical rolling stock.
• Event recorder - A device that continuously captures analog and digital train systems information and stores that data for a minimum of 48 hours. This data is used to evaluate incidents and accidents. Typical stored data includes speed, brake pressure, dynamic brake, horn activation, track signal, etc. In the U.S., event recorders are mandated by the Federal Railroad Administration (FRA) for freight, passenger and commuter rail. Regulations for railroad outside the U.S. vary by country. Transit operations are not generally required to have event recorders, but have begun to add them voluntarily.
• Ex-con (US): An ex-Conrail locomotive (jargon) or former conrail employee. Not to be confused with the more common meaning of a convicted criminal who has been released after serving prison time.
• Express train: A train that passes selected stations without stopping.
• Extra train: A train that is not included in the normal schedule of a railroad. In train order territory, extras are required to clear the main line for scheduled trains to pass.

• Facing: A turnout is facing if it can select which way to diverge a train. Opposite of trailing.
• Fairlie: A type of articulated locomotive, typically (but not exclusively) with two boilers and connected fireboxes in a central cab.
• Fallen flag (US): A railroad which is defunct, having either merged or discontinued operations.
• Feedwater heater: A device to preheat the water for a steam locomotive; improves efficiency.
• Fettle, fettling: Making repairs to rail track, especially concerned with maintaining the drainage of the ballast, and the proper cant of the rail track and rails.
• Fiddle Yard: A concealed group of sidings used in model railways to provide more realistic operation in limited space.
• Firebox: In steam railroading, a firebox was a chamber in which a fire would produce sufficient heat to create steam once the hot gases from the firebox were carried into the adjacent boiler via tubes or flues.
• Fireman (also Stoker, Boilerman): A worker whose primary job is to shovel coal into the firebox and ensure that the boiler maintains sufficient steam pressure; a driver's assistant.
• Fishplate (UK), Joint bar (US): A metal plate that joins the ends of rails in jointed track.
• Flat: A wheel defect where the tread of a wheel has a flat spot and is no longer round; flats can be heard as regular clicking noises when the wheel passes by.
• Flatcar (US): A type of rolling stock, which can be a flat-bottomed car with no sides on which freight (including intramodal shipping containers) can be stacked. A bulkhead is a flatcar with walls on the front and rear. A center-beam bulkhead is a bulkhead flatcar with an additional wall dividing one side of the flatcar from the other, but still without any sides. Flat wagon (UK).
• Flying junction: A railway junction that has a track configuration in which merging or crossing railroad lines provide track connections with each other without requiring trains to cross over in front of opposing traffic.
• Foamer (US): A colloquial term for a railfan, specifically one whose enthusiasm is excessive, "foaming at the mouth".
• Four-foot: The part of the line between a pair of running rails. An abbreviation for four foot, eight-and-a-half-inches. Also see six-foot and ten-foot.
• Four-quadrant gate: A type of Boom barrier, see above.
• FRA: (US) The Federal Railroad Administration. This agency oversees rail operation regulations and safety requirements for U.S. freight, passenger and commuter rail operations.
• FRED (US): A Flashing rear-end device a small marking device with a flashing red light mounted on the end of the train. FRED also monitors various train functions such as brake pipe pressure, motion and GPS location. A form of an electronic caboose. Also called an EOT (end of train) device.
• Free-mo: A type of modular layout in model railroading.
• Freight (US) goods (UK): the product(s) in which are carried.
• Frog: (US) A casting with "X" shaped grooves used in switches and crossovers.
• Funnel: A Thomas the Tank Engine misnomer for a chimney (UK) or smokestack (US), although it is also used in Australia (Victoria at least). Some early steam engines had a smokestack consisting of a straight vertical flue and a funnel-shaped top, probably leading to the use of "funnel" to describe the entire stack.
• Fusee: A pyrotechnic device similar to an automotive flare that is used for signalling.
• Fusible plug: A threaded plug, with a soft metal core, that is screwed into the crown plate of a firebox. If the water level gets too low the core melts and the noise of the escaping steam warns the enginemen.

• Gage: An alternate (US) spelling of "Gauge" as in "track or rail gage".
• Gandy dancer (slang, US): A track maintenance worker.
• Garratt: A type of articulated locomotive.
• Gauge: The width between the inner faces of the rails.
• Geep: A slang term for any of the GP ("general-purpose") series of Electro-Motive four-axle diesel locomotives; originally applied only to EMD GP7, GP9, and GP18 models.
• Glad hand A quick-coupling/uncoupling connector at the end of a trainline air hose that resembles a pair of "shaking hands" when hoses are connected.
• Go-devil: A hand-powered railroad car (see Handcar and Draisine ), or a small gasoline powered railroad car .
• Gondola: A type of rolling stock with a flat bottom and relatively low sides, used to haul material such as ore or scrap, and loaded and unloaded from the top. May be covered or uncovered. Open wagon (UK).
• Goods (UK): Freight (US): Both terms are used in Australian English
• Goods wagon or Goods van (UK): Freight car or Box car (US): A flat car with sides and a top, usually with a large sliding door in the middle of each side.
• Grab bar: A handle on the side of a car to allow switching personnel to hold on (also known as a "grab iron").
• Green: A colour associated with go or proceed.
• Guard (UK): Conductor (US) See Conductor above.
• Guard rail (US) Check rail (UK): A double rail section of track, sometimes found in train yards and on bridges to prevent derailments or limit damage caused by derailments , by having rail on both sides of the wheel flange. Also found on curves with a tight radius and switches and crossings
• Gunzel (AU) Railway enthusiast, in Melbourne, Victoria often refers to tramway enthusiast.

• Hack (slang, US): A caboose, since it carried the crew around like a taxicab.
• Hammerhead style (slang, US): The practice of running a Diesel locomotive with its long hood forward. This has been done for a variety of reasons, such as crew safety in case of a collision. On short runs, operating the locomotive "backwards" is more economical than using a wye or turntable or operating a second locomotive. Some locomotives may have a second control stand to facilitate operation in the "reverse" direction.
• Handcar(US), A small, hand-powered railroad car used for track inspection. Pump trolley (UK).
• Head end power or HEP: A scheme whereby the locomotive engine or a separate generator provides 'hotel' power to carriages.
• Headshunt (UK), Shunting neck (US): A length of track feeding a number of sidings that permits the sidings to be shunted without blocking the main line, or where two lines merge into one before ending with a buffer, to allow a run-round procedure to take place.
• Heavy haul: Heavy freight operations.
• Heavy rail (US): A city-based transit rail system that runs on its own dedicated track and often underground. Subways are considered heavy rail.
• Heavyweight (US): During the period between about 1910 and the mid nineteen thirties, most passenger cars in the US were built with three axle trucks, concrete floors, and riveted, double walled sides and often weighed 90 - 100 tons or more. Heavyweight construction was used to improve ride quality.
• High rail: The upper rail in a curve or superelevation which typically experiences the higher lateral loads and greater wear.
• Hogger (slang, US): A locomotive engineer.
• Hoodlebug (slang, US): A small commuter passenger train or trolley.
• Hood unit (US): A locomotive whose sides and roof are nonstructural and do not extend the full width of the locomotive. Structural strength comes from the underframe.
• Horn blocks: Plates lining the axlebox cut-outs in a locomotive frame to allow smooth vertical movement under control of the springs.
• Hotbox: An axle bearing that has become excessively hot due to friction.
• Hotbox detector: A device attached to the track which monitors passing trains for hot axles, and then reports the results via a radio transmission (US) or a circuit to the signal box (UK). (see defect detector).
• Hotel power (US): Electric power used to provide for the comfort of passengers aboard a train en-route. See "HEP" above.
• Hot rail (US): 1. Any section of track over which a train movement is imminent. The closer and/or faster the approaching train, the "hotter" the rail. 2. On some electrified railroads and rapid transit lines, the third rail which supplies power to locomotives or cars.
• Hotshot (US): A fast, long-distance train given priority on the track over other trains.
• Hump: A raised section in a rail sorting yard that allows operators to use gravity to move freight railcars into the proper position within the yard when making up trains of cars (that is, humping the cars). This is faster and requires less effort than moving cars with a switching engine.
• Hunting: Swaying motion of a railway vehicle or bogie caused by the coning action on which the directional stability of an adhesion railway depends. The truck or bogie wanders from side to side between the rails, "hunting" for the optimum location based on the forces at play.

• Infill station (sometimes in-fill station): A train station built on an existing passenger line to address demand in a location between existing stations.
• Injector: A device to force water into a steam locomotive's boiler by steam pressure.
• Interlocking (US): Any location that includes a switch or crossing of two tracks, derived from the early practice of installation of a system of mechanical equipment called an interlocking plant to prevent collisions. See also signal box. Interlocking is also the term for the actual mechanical or electrical apparatus that prevents switch/points and signals from being operated in ways that would allow for conflicting train movements.
• Intermodal: Moving goods or people by more than one type of vehicle. Intermodal freight can be transported using shipping containers which can easily be transferred among railroad flatcars, ships, airplanes, and tractor-trailer trucks.
• IRJ, IBJ: Insulated rail joint/insulated block joint. Rail joints incorporating insulation to isolate individual track circuits.
• Island platform: A railway platform that has tracks along the full lengths of both sides.

• Jack: A dwarf signal (slang, Boston and Maine and New York New Haven and Hartford Railroads)
• Jerk a lung (North America): To break a train in two, usually by shearing the knuckle pin in a coupler, often caused by the application of excessive head end power. Example: "The engineer jerked a lung on the upgrade."
• Johnson bar (US): On a locomotive, a long, heavy lever that operates the cutoff, etymology unknown.
• Joint bar, fishplate (UK): Joins the ends of rails in jointed track. Also referred to in North America as a rail joiner or angle bar.
• Jointed track: Track in which the rails are laid in lengths of around 20 m and bolted to each other end-to-end by means of fishplates (UK) or joint bars (US).
• Journal bearing: a bearing without rolling-elements
• Junction: A point at which two lines or separate routes diverge from each other.

• KE: (Kinematic Envelope) The outline of the space beside and above the track that must be kept clear of obstructions for the train to pass. This can be larger than the static clearance around an unmoving engine or car.
• Key (UK): Timber or sprung steel block used to secure Bullhead rail into the chairs.

• Lantern (US): A portable (often handheld) light source that is used to signal train crews. Lamp (UK).
• Leaner (US): (slang) A car in which the load has shifted, or it has been improperly loaded, or a mechanical failure has occurred that causes the car to lean to one side. This could potentially cause a collision or derailment.
• Level crossing The term level crossing (also called a railroad crossing, railway crossing, train crossing or grade crossing) is a crossing on one level ("at-grade intersection") — without recourse to a bridge or tunnel — generally of a railway line by a road or path, but sometimes used for a crossing by (not a junction with) another railroad.
• Level junction (US), Flat junction (UK): A junction in which all track crossings take place at grade and routings must therefore be controlled by signals and an interlocking plant.
• Light engine: A locomotive travelling without cars attached except perhaps a caboose (brake van).
• Light rail: A city-based rail system that typically shares its operational space with other vehicles (e.g. automobiles) and often runs on, across or down the center of city streets. Light rail vehicles (LRV) generally have a top speed of around 60 mph (100 km/h) though mostly operating at much lower speeds, more akin to road vehicles. Light rail vehicles usually run on trackage that weighs less per foot (due to a smaller track profile) than the tracks used for main-line freight trains; thus they are "light rail" due to the smaller rails usually used.
• Local train: A train that stops at most, if not all, stations along its route. Often referred to in North America as a "milk train" or "milk run" (usage from the days when trains stopped at dairy farms to pick up fresh milk).
• Location case (UK): A trackside cabinet used to house signalling equipment such as relays or transformers.
• Loop (UK), siding (US): Used on single-track railway lines, a loop is a second parallel track (running for a short distance), allowing two trains to pass by one another.
• Lunar, as in lunar white, is a color of Railway signal light. It is an off-white color, achieved by the use of a clear lens of very light blue, to make it distinct from a light that has a broken lens. In UK practice, it is the color used for the type of junction indicator known as a feather, so-called for its resemblance to a popular inn sign.

• Mainline or Main line: The principal artery of a railway system.
• Main rod (US): The drive rod connecting the crosshead to a driving-wheel or axle in a steam locomotive. Connecting rod (UK).
• Maintenance of way (US): The maintenance of railroad rights of way, including track. Often abbreviated to MOW (as in MOW car).
• Mallet (pronounced "mallay"): type of articulated locomotive designed by Anatole Mallet. See "Compound Engine" above.
• Matchbox tank (UK slang): a type of pannier tank where the tanks are square and do not rest of the locomotive frame.
• Mating worms (US): Penn Central logo (jargon/slang).
• Mechanical semaphore signal: A signal in which the aspect is conveyed by moving an arm.
• Merry-go-round (MGR) train (UK): coal train running between a coal mine and a power station, loading and unloading without stopping or shunting.
• MLW: Montreal Locomotive Works, bought by Bombardier and closed.
• Mogul: A steam locomotive with a 2-6-0 wheel arrangement.
• Motor train (UK): See Auto train (UK) above.
• Multiple aspect signalling: A system of colour-light signalling in which signals may show 3 or 4 aspects.
• Multiple unit (UK) MU (US): a self-propelled rail vehicle that can be joined with compatible others and controlled from a single driving station. The sub-classes of this type of vehicle; Diesel Multiple Unit (DMU), Diesel-Electric Multiple Unit (DEMU) and Electric Multiple Unit (EMU) are more common terms. These may also be termed railcars.
• Multiple-unit train control (US), Multiple working (UK): generally seen as the abbreviation MU, this normally refers to the ability of diesel and electric locomotives or multiple units to be joined together and controlled from one driving station. Such a set of joined locomotives is called (US) a consist or (colloquially) "lash-up" and is said to be "MUed together".
• Multiple working (UK): see Multiple unit (above).

• narrow gauge: Railroad track where the rails are spaced less than apart. There are many common gauges narrower than standard, amongst them 3 ft 6 in (1067 mm) widely in Africa and Asia; 3 ft (914 mm), which was the most common narrow gauge in the U.S.; and 2 ft (600 mm), which saw widespread use in the UK. Meter gauge (1000 mm) is also been used. Narrow-gauge lines are often found in mountainous terrain where the cost savings of building a smaller railroad can be considerable.

• Open wagon (UK), Gondola (US). A form of freight hauling car for bulk goods.
• Overlap (UK): A distance (normally 180 metres or set according to the permitted speed of the line) beyond a stop signal which must be clear before the preceding stop signal can display a proceed aspect; allows a margin in case a train overshoots a signal before stopping.

• P-train: An SNCB commuter train.
• Pacific: A steam locomotive with a 4-6-2 wheel arrangement.
• Pannier tank: A tank locomotive with the water tanks mounted on the boiler like panniers.
• Pantograph: An arm to pick up current from overhead lines.
• Per diem: A fee paid by a rail company to the owner of a car (US) (wagon (UK)) for the time it spends on the company's property; also an authorized living expense payment for some workers forced away from their home terminal. Pronounced by some U.S. railroaders per die-um, not per dee-um.
• PICOP (UK): Person In Charge Of Possession – the railway or contractor's official responsible for safe working during engineer's possession.
• Piston: The moving component in the cylinder of a steam engine or internal combustion engine that translates into motion the force exerted by pressurised steam or exploding fuel.
• Point machine (UK): A motor or device which operates points.
• Points (UK): switch (US). Also "turnout".
• Pony truck: A two-wheel truck (US) or bogie (UK) at the front of a locomotive.
• Porter: A Porter had various roles: A Baggage Porter assisted with luggage; an Operating Porter assisted with Safeworking duties; a Station Porter assisted with general station duties and a Lad Porter was a junior Station Porter.
• Position light signal: A signal in which the position of the lights determine the meaning of the aspect shown.
• Pound (rail): Term describing the weight (and thus the cross section) of a length of rail. A heavier rail can carry heavier loads with less distortion and less damage to the rails themselves and the roadbed.
• Power: A slang term referring to a locomotive or group of connected (MU'd) locomotives serving as the motive power for a train (as in "the hostler brought the power to the service pit.")
• Prairie: A steam locomotive with a 2-6-2 wheel arrangement.
• Push-pull: A mode of operation whereby a locomotive-hauled train may be driven with the locomotive at the front, middle or back of the train. Also: Auto train (UK), above. See Top and tail for train with locomotives at both front and back.

• Railbus: A DMU the size of a bus, sometimes made using bus components.
• Railcar: A powered passenger car.
• Railfan: A hobbyist or enthusiast of trains (q.v. "Foamer").
• Rail grinder: a machine used to remove irregularities in the surface of the rails. May be self powered or part of a consist.
• Rail profile The cross section shape of rail. There are many rail profiles which are often specific to individual railroads. Rails need to be periodically scanned electronically, the data inspected and analysed, then re-profiled with rail grinding machines to maintain the safe and proper "rail profile". Rails that cannot be brought back to the proper rail profile are condemned and replaced.
• Railroad car: A railroad vehicle that is not a locomotive.
• Railroadiana: Artifacts of railways around the world.
• Rail sled (US): A form of wheel chock that slips onto the rail under the wheel of rolling stock which prevents the vehicle from rolling.
• Rail Tractor: A small petrol (gas) or diesel shunting (switcher) locomotive.
• Railway station : A train station.
• Rake: (UK) A group of passenger coaches coupled together.
• Red: A colour generally associated with stop, when shown by signals or flags.
• Reefer: A refrigerated railcar, used to transport perishable goods.
• Rent-a-Wreck (slang, U.S.): A (usually old) locomotive owned by a leasing company.
• Reporting mark: A two- to four-letter code, assigned by the Association of American Railroads, that is applied to equipment operating on North American railroads to identify the owner.
• Reverser or Reverser handle: See Cut off, above. The handle that controls the directional control on a locomotive.
• Ribbon Rail: Continuously welded rail.
• Right-side failure: A failure in a signalling system which leaves the system in a safe condition.
• Rolling stock: (UK) A railroad vehicle that is not a locomotive; 'railroad car'. (US) Any railroad car and/or locomotive.
• Rookie: See Trainee.
• Run-round (runaround (US)): the practice of detaching a locomotive from its train, driving it to the other end of the train and re-attaching it, to allow the train to proceed in the direction it has just come from (e.g. when it reaches its destination and forms a service in the other direction).
  (See headshunt for diagram of a 'run-round loop'.)

• Saddle tank: A tank locomotive with the water tank mounted on top of the boiler like a saddle.
• Safety Appliance Act (US): A law mandating air brakes, grab bars, and automatic couplers
• Safeworking: The system of rules and equipment designed to ensure the safe operation of trains.
• Schnabel car: A specialized type of freight car for extra heavy and over sized loads; the car is loaded in such a way that the load forms part of the car superstructure.
• Searchlight: A signal with a single light source usually capable of displaying three different colors. An internal mechanism governs the color displayed.
• Section: The division of the track for security (occupation).
• Semaphore: A type of signal that has a moving arm; any signalling using semaphores.
• Shay: A type of geared steam locomotive built to the patents of Ephraim Shay.
• Shoofly: A temporary stretch of track that takes trains around construction or an accident scene.
• Shunt (UK): To move trains or vehicles from one track to another.
• Shunt (US): To bond the rails/power feeds between sections on trolley/light rail systems, so as to temporarily bridge past dead areas.
• Shunter (UK): switcher (US) or shifter (PRR only): A small locomotive used for assembling trains and moving railroad cars around. Also, a person involved in such work.
• Shuttle service: A train, usually a passenger service, that runs back and forth over a relatively short distance, such as between a junction station and a branch-line terminus.
• Side tank: A tank locomotive with water tanks mounted each side of the boiler.
• Siding: A section of track off the main line. Sidings are often used for storing rolling stock or freight. A sidiing is also used as a form of rail access for warehouses and other businesses, where the siding will often meet up with loading docks at rail car height in the building. In the U.S. the term is also used to cover the British term: loop. Also, a passing track in the U.S.
• Signal: A device that indicates to the driver of a train information about the line ahead.
• Signal aspect: The information conveyed to a railroad vehicle operator by a block signal. Signals may use colored lights, position-significant lights or mechanical semaphores to generate various aspects.
• Signal box: A building or room which houses signal levers (usually in a frame), a control panel or a VDU-based control system.
• Signal Passed At Danger or SPAD (UK): where a train disobeys a stop signal.
• Signalman: A person in charge of the signalling at a station or junction, often in a Signal-box.
• Six-foot: The narrow corridor between a pair of closely-spaced tracks, nominally six feet wide. See also four-foot and ten-foot.
• Slack: A temporary speed restriction to protect, for example, sections of track in poor condition and awaiting repair. (UK) Also, looseness in a train caused by mating clearances in couplers. (UK / U.S.)
• Sleeper (UK), tie (US): Bars placed at 90° to the rail tracks to support the rails. Generally of wood, concrete or steel, with hardware to affix the rails, usually spikes, nails or bolts. Note in the UK baseplates and clips are used to affix the rail to the sleeper. Spikes are widely used in North America.
• Slippery rail: The condition of fallen leaves or other debris lying on and clinging to a railroad track that could cause train wheel slippage, resulting in premature wheel wear and train delays.
• Slow order: A local speed restriction below the track's normal speed limit. Slow orders can be imposed on a temporary basis to protect, for example, maintenance of way employees while sections track are under repair. Widely used in areas where track is substandard and in need of repair.
• Slug: A locomotive that contains traction motors yet lacks the diesel engine to create its own power, which is instead supplied by a connected 'mother' locomotive.
• Smokebox: An enclosed (normally cylindrical) space attached to the end of the boiler opposite the firebox on a steam locomotive (normally the front). Supports the stack/chimney; steam pipes to and from the cylinders pass through here; contains the blastpipe/exhaust nozzle where the exhaust steam is used to provide draft for the fire. In superheated locomotives, also contains the superheater header and (optionally) a front-end throttle. A smokebox door allows access for cleaning.
• Smokestack (abbr. stack) (US): chimney (UK).
• SPAD (UK): Signal Passed At Danger, where a train disobeys a stop signal. Sometimes referred to as a "blown red" in U.S. railroad slang.
• Speeder (US): A small vehicle used to let track inspectors and work crews move quickly to and from work sites. (Obsolete) Speeders have mostly been replaced by trucks and SUVs with retractable flanged wheels.
• Spike: A bolt, pin or nail used to hold rails, or plates connected to the rails (known as tie plates), to sleepers (ties).
• Spiral easement See Track transition curve. Also known as tangent lead-in.
• SPT (UK): Signal-post telephone - A direct no-dial telephone link to the relevant Signal-box, positioned on or near a signal.
• Spur (US): A stretch of rail that branches off the main line. Different from a siding or stub, spurs can be miles in length, and usually have only one destination at the end.
• SPURT (India): An acronym for Self Propelled Ultrasonic Rail Testing, a self-propelled rail defect detector car.
• Staff and ticket: A method of safeworking involving a token.
• Standard gauge: Railroad track where the rails are spaced apart. This is by far the most common gauge of railway worldwide.
• Station-master: The person in charge of a station.
• Station pilot (UK): Shunting engine based at a major passenger station and used for passenger train shunting duties.
• Steam generator: A device generally used in passenger trains to create steam for heating. The steam generator is usually in the locomotive but may also be located in other cars.
• Steam reverser: A Cut Off worked by a steam piston controlled from the cab.
• Steeplecab (US): An electric locomotive with a central cab and sloping "noses" on each end.
• Steward: A person in a dining car with a role similar to that of a Maitre d’Hotel.
• Stub (North America) A relatively short section of track that ends at a bumper or wheelstop, most often found in a terminal. Not to be confused with a spur, which may be miles (kilometers) in length.
• Subway (UK): A tunnel passing underneath the railway tracks to allow passengers to cross from one platform to another.
• Subway (US): A railroad that runs underground, generally in a large city. Subways are also considered "heavy rail" because they operate on their own dedicated track. Not to be confused with the interurban definition of subway, which is normally a light-rail passenger service running mostly underground.
• Supercharger A mechanical device that increases the supply of air to the combustion chamber on a Diesel engine. Also known as a "Blower" The most common type of supercharger used on a diesel locomotive engine is a Roots type supercharger.
• Superelevation (UK): Synonymous with cant: the banking of railroad track on curves. Specifically, the practice on high speed lines (where the cant needs to be higher) of gently introducing the elevation of the outer rail before the bend starts, in order to avoid sudden lurches.
• Superheater: A device in a steam locomotive that raises the temperature of saturated steam substantially beyond the boiling point of water, increasing power and efficiency.
• Switch (US): points (UK). Also "turnout".
• Switcher (US), shunter (UK): A small locomotive used for assembling trains and moving railroad cars around.
• Switchman: A railroad worker responsible for assembling trains and switching railroad cars in a yard; now often used together with brakeman as a single job description (\"brakeman/switchman\").

• Union station or union terminal (US), joint station (UK): A railway station (q.v.) at which tracks and facilities are shared by two or more railway companies.
• Up (UK, etc.): A direction (usually towards London, other capital city, or the headquarters of the railway concerned) or side (on left-running railways, the left side when facing in the up direction). The opposite of down. The up direction is usually associated with even-numbered trains and signals.
• UP (US): The common name and reporting mark for the Union Pacific Railroad.

• Vacuum brake A continuous train brake which is fail-safe in operation: the brake is powered by a vacuum from the locomotive but the application is actually by atmospheric pressure when the vacuum is released. Now largely superseded by the air brake.
• (goods) Van (UK), boxcar (US): An enclosed railroad car, or piece of rolling stock, used to transport freight.
• Van (CA): slang word for caboose.

• Water glass/gauge: A device showing the level of water in the boiler.
• Way car: A term used by the Chicago, Burlington and Quincy Railroad, Chicago and North Western Railway and Atchison, Topeka and Santa Fe Railway instead of caboose.
• Wayobjects or Wayside objects: Trackside objects are any structures at the wayside or beside the rail tracks usually within the right-of-way, such as:

*railway signals

*third rails

*overhead lines and their supports

*electrification systems

*platforms

*boom barriers

*Etcetera

• Wayside: Trackside. The term presumably has its origin from the term right-of-way.
• Well tank: A type of tank locomotive. The water tank is mounted between the frame plates, beneath the cab and boiler.
• Well wagon: A flat wagon that has a depressed centre and is used for carrying extra tall loads.