Rail transport terms are a form of technical terminology applied to railways. Although many terms are uniform across different nations and companies, they are by no means universal, with differences often originating from parallel development of rail transport systems in different parts of the world, and in the national origins of the engineers and managers who built the inaugural rail infrastructure. An example is the term railroad, used (but not exclusively) in North America, and railway, generally used in English-speaking countries outside North America and by the International Union of Railways. In English-speaking countries outside the United Kingdom, a mixture of US and UK terms may exist.
Various terms, both global and specific to individual countries, are listed here. The abbreviation "UIC" refers to terminology adopted by the International Union of Railways in its official publications and thesaurus.
For more elaborate country-specific guides, see Glossary of United Kingdom railway terms and Glossary of North American railroading.
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Harmonic rock or harmonic rock and roll The condition of locomotives and cars swaying in opposite directions when traversing depressions on the roadbed. A potentially dangerous condition that can cause coupler damage, lading damage, or derailments at slower speeds. Head-End Power A scheme whereby the locomotive engine or a separate generator provides hotel power to carriages Headboard A sign attached to a locomotive to identify a named train or charter, or for other special occasions Headstock A transverse structural member located at the extreme end of a rail vehicle's underframe. The headstock supports the coupling at that end of the vehicle, and may also support buffers, in which case it may also be known as a "buffer beam". Heavy haul Heavy freight operations High rail The upper rail in a curve or superelevation, which typically experiences higher lateral loads and greater wear Hole A passing siding. Inferior trains "lay over in the hole" to let superior ones pass. Home signal See absolute signal. Horn blocks Plates lining the axlebox cut-outs in a locomotive frame to allow smooth vertical movement under control of the springs Hostling The action of shuttling a locomotive from the yard to the engine house or vice versa Hotbox An axle bearing that has become excessively hot due to friction Hotbox detector A device attached to the track that monitors passing trains for hot axles, and reports results via radio transmission (typical in the US) or a circuit to the signal box (typical in the UK). See defect detector. Hudson type A steam locomotive with a 4-6-4 wheel arrangement 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. 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.
I Independent brake or locomotive brake The braking system that applies or releases the brakes of a locomotive independently from its train Infill station or 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 Insulated rail joint (IRJ) or insulated block joint (IBJ) Rail joints incorporating insulation to isolate individual track circuits Interchange Any track or yard where rail cars are transferred from one carrier to another Interlocking An arrangement of switches and signals interconnected in a way that each movement follows the other in a proper and safe sequence Intermodal freight transport Moving goods by more than one type of vehicle, often achieved using shipping containers that are transferred among railroad flatcars, ships, airplanes, and tractor-trailer trucks Intermodal passenger transport Moving people by more than one type of vehicle Interoperability Ability of a transport network to operate trains and infrastructures to provide, accept and use services so exchanged without any substantial change in functionality or performance Island platform A railway platform that has tracks along the full lengths of both sides Island railway station A railway station with a station building on an island platform
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Jacobs Bogie A Bogie, or truck (American), shared between two pieces of rolling stock. Cars joined with Jacobs bogies are semi-permanently joined in an articulated configuration. A weight-saving feature used on lightweight passenger trains. Joint bar or rail joiner A metal plate that joins the ends of rails in jointed track 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 or joint bars Journal bearing A bearing without rolling elements; a plain bearing Journal box The housing of a journal bearing. See also Axlebox above. Jubilee type A steam locomotive with a 4-4-4 wheel arrangement Junction A point at which two lines or separate routes diverge from each other
K Keeper A padlock or hook securing the lever of a hand-operated switch, thereby preventing the switch points from moving as rolling stock passes over them Kick To shove a car a short distance and uncouple it in motion, allowing it to roll free under gravity and/or its own inertia onto a track. Commonly practiced in bowl or hump yards to make up or break down trains or classify large numbers of cars in an expedient fashion. Differs from a flying switch in that the locomotive is pushing the car rather than pulling it when the cut is made. Kicker A freight car with a defect in its brake valve that causes the entire train's brake system to go into emergency when any application is made Kinematic envelope (KE) 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. See also: loading gauge and structure gauge Knuckle The articulating part of a coupler that locks automatically in its closed position to join rail cars; so named because its movement resembles that of the human finger
L Lead track A non-main track from which several others branch within a short distance, such as within a rail yard or engine terminal Level crossing (LC), railroad crossing, railway crossing, train crossing, or grade crossing 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. Not to be confused with non-dead-end railways (see Rail crossing)
A locomotive travelling on its own, or perhaps with just a caboose (brake van) attached Light rail A city-based rail system based on tram design standards that operates mostly in private rights-of-way separated from other traffic but sometimes, if necessary, mixed with other traffic in city streets. Light rail vehicles (LRVs) generally have a top speed of around though mostly operating at much lower speeds, more akin to road vehicles. Link and pin An obsolete method of coupling rail cars, consisting of manually dropping the coupling pin into the drawbar as the cars joined. Extremely hazardous to the brakemen of its day, it was outlawed in the United States by the Railroad Safety Appliance Act of 1893. Local train A train that stops at most, if not all, stations along its route Lunar An off-white color of railway signal light, like the Moon, achieved by the use of a clear lens of very light blue, to make it distinct from a light that has a broken lens.
M Maglev A system of high speed train transportation that uses two sets of magnets: one set to repel and push the train up off the track, and another set to move the elevated train ahead, taking advantage of the lack of friction. Main generator The electric generator in a diesel–electric locomotive that is coupled directly to the prime mover and feeds electrical energy to the traction motors Main reservoir The compressed-air tank of a locomotive containing source air for the brakes and other pneumatic appliances Mallet locomotive A type of compound articulated locomotive designed by the Swiss mechanical engineer Anatole Mallet (pronounced "mallay"). See Compound engine. Manifest An express freight train carrying a variety of general merchandise Mars Light A nose-mounted mechanically oscillated light used to warn traffic of an approaching locomotive. Functionally replaced by ditch lights on modern locomotives. Mechanical semaphore signal A signal in which the aspect is conveyed by moving an arm Meet In rail transport operations, a meet occurs when two trains arrive at a location and pass each other on parallel tracks, such as on a siding, usually in opposing directions. This is also sometimes referred to as a crossing of two trains. Mikado type A steam locomotive with a 2-8-2 wheel arrangement
In the U.S., milk trains ran from the countryside to cities making numerous stops at minor depots to pick up cans of fresh milk, making them a colloquial expression for a very slow train. In the U. K., an aggregator for transporting milk from farms to dairies, such as British Railways Milk Trains; as these trains invariably ran very early in the morning, "milk train" became a colloquialism for a particularly early train. Modalohr An inter-modal car Mogul type A steam locomotive with a 2-6-0 wheel arrangementWhite (1968), p 62-65.
A track that is still serviceable but no trains are running on them. Mountain type A steam locomotive with a 4-8-2 wheel arrangement Mud ring The bottom of the water space surrounding a steam locomotive's firebox that collects solids precipitating from the water supply during the boiling process Multiple aspect signalling A system of colour-light signalling in which signals may show three or four aspects Multiple unit (MU) A self-propelled rail vehicle that can be joined with compatible others and controlled from a single driving station. The names of 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 The control of multiple locomotives or MUs from a single set of controls.
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Narrow gauge Railroad track where the rails are spaced less than apart, Northern type A steam locomotive with a 4-8-4 wheel arrangement, also known in North America as "Pocono", "Niagara", "Confederation", "Greenbrier", and "Potomac" or run 8 The eighth notch of a locomotive throttle control, indicating full power on the standard American diesel locomotive control scheme
O Open wagon (UIC) A form of freight hauling car for bulk goods Out to foul When equipment is placed ahead of the fouling point of a switch turnout
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Pacific type A steam locomotive with a 4-6-2 wheel arrangement Pannier tank A tank locomotive where the water tanks are mounted on the boiler in pannier-like fashion Pantograph An apparatus mounted on the roof of a rail vehicle to allow the collection of electric current from overhead lines Paperwork As a reason for delays, written instructions conveyed to a train's engineer in which the train must proceed slower than its normal speed. These instructions are either handed to the crew or recited and read back over radio. Pennsy Abbreviation for the former Pennsylvania Railroad Per diem (pronounced by some U.S. railroaders per die-um, not per dee-um)