Rail terminology is a form of technical terminology. The difference between the American term railroad and the international term railway (used by the International Union of Railways and English-speaking countries outside the US) is the most significant difference in rail terminology. There are also others, due to the parallel development of rail transport systems in different parts of the world.
Various terms are presented here; where a term has multiple names, this is indicated. The abbreviation "UIC" refers to standard terms adopted by the International Union of Railways in its official publications and thesaurus.
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 timer if no other controls are operated. If the operator does not respond within a preset time, the prime mover is automatically throttled back to idle and the brakes are automatically applied.
Tubes connected to the water-space of the boiler provided in and across the firebox in order to add extra high-temperature heating surface. They also serve to support the brick arch or equivalent.
A feature of a locomotive which has the some form and purpose as the domestic variety (i.e. to collect the ashes which fall through the bars of the grate). The only significant difference is the size, measured in feet rather than inches.
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.
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.
To release the locomotive brakes while the train brakes are being applied in order to permit smoother handling and prevent excessive slack, wheel slide and flat wheels
The reciprocation and revolving masses of any steam, diesel or electric locomotive need balancing, if it is to work smoothly. Revolving masses can easily be balanced by counterweights, but the balancing of reciprocating parts is a matter of compromise and judgement.
A looped length of track, usually at the end of a spur or branch, which allows trains to turn around for the return trip without reversing or shunting. Can be used as part of a freight installation to allow the loading or unloading of bulk materials without the need to stop the train (see merry-go-round train (MGR)).
A brick or concrete baffle provided at the front of a locomotive firebox below the tubes, in order to extend the flame path. Early Locomotives burnt coke; provision of a brick arch was necessary before coal could be used without producing excessive smoke.
Track where the rails are spaced more widely apart than 1,435 mm (4 ft 81⁄2 in) (which is called standard gauge). Many early railroads were broad gauge, for example the Great Western Railway in the UK which adopted 7 ft (2,134 mm) gauge until it was converted to standard gauge in the 1860s - 1890s. Russia still has over 80,000 km (50,000 mi) of broad gauge (1,520 mm (4 ft 1127⁄32 in)) railroads. Broad gauge is also normal in Spain and Portugal (1,668 mm (5 ft 521⁄32 in) Iberian gauge), in India (1,676 mm (5 ft 6 in) Indian gauge), as well as Ireland and used in some parts of Australia (1,600 mm (5 ft 3 in) Irish gauge).
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, Canada, USA, and Australia. The word is a portmanteau of the words "bus" and "substitution".
A steam locomotive with its cab at the leading end of the boiler, rather than the usual trailing end adjacent to the tender. The best known example is the Southern Pacific Railroad's AC type, built to handle drag freights through the SP's many tunnels and snow sheds without the danger of the exhaust asphyxiating the engine crew.
A railroad car attached usually to the end of a train, in which railroad workers could ride and monitor track and rolling stock conditions. Largely obsolete, having been replaced by the electronic end-of-train device (ETD), or flashing rear-end device (FRED).
A heavier duty locomotive with six wheels per bogie (all axles being separately driven) configuration as opposed to a four-wheel "Bo-Bo" configuration. The correct classification is Co'Co', but Co-Co is used more often.
A steam-operated device in the tender intended to push coal forward to a point where it can be shovelled directly into the fire
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: on a desktop-type control stand, forward (away from operator) past center operates the dynamic brake, backward (toward operator), past center, is throttle up
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.
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. See also: Reverser handle.
A channel dug through a hillside to enable rail track to maintain a shallow gradient. See also embankment.
Making repeated service brake reductions in short succession to maintain a constant speed on short but steep grades. Each reduction must be at least 5 PSI lower than the previous one in order to keep the brakes applying regularly, but excessive cycle braking can deplete the air supply and require an emergency application.
A cavity in a reciprocating engine in which a piston travels
On steam locomotives, this appurtenance allows condensed water to be drained from the steam cylinders when the throttle is opened, thus preventing damage to the pistons, running gear, and cylinder heads
A block signal that is displaying no discernible aspect, often due to burned out lamps or local power failure. Most railroads require that a dark signal be treated as displaying its most restrictive aspect (e.g. stop and stay for an absolute signal).
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.
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.
A practice employed to move large trains through the mountains. Consists of the locomotives on the head end, a "swing" (mid-train) helper or two, and pusher locomotive(s) on the rear; today, all units are remotely controlled by the engineer in the lead unit. The power distribution alleviates stress on the couplers and relieves the lead units of the full weight of the train, making it easier to move on grades.
A configuration in which two steam locomotives are coupled head-to-tail in order to haul a heavy train up a long or steep hill. In the present day, double heading (and occasionally triple heading) are done primarily on large passenger trains or as a show for railfans.
The part of a coupler that attaches to the frame of the car or locomotive; may be equipped with a pneumatic cushion depending on a freight car's design cargo (e.g. an autorack). Alternately, the pinned double bars coupling a steam locomotive to its tender.
A signal light that is considerably smaller and closer to the ground than a high-mast signal; often absolute, and placed within interlocking limits, its aspects tend to differ from those conveyed by a taller signal for certain indications. Also called 'pot' or 'jack'.
A component of vacuum brake system usually fitted in pairs. Steam passing through a cone sucks air from the train pipe to create the vacuum.
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 after coupling
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 (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 (e.g. without needing a guard in the UK).
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.
A train that passes selected stations without stopping
A train not included in the normal schedule of a railroad They often run during busy holiday travel periods in order to handle larger crowds and reduce the number of passengers that are forced to stand or are stranded at a station. In train order territory, extras are required to clear the main line for scheduled trains to pass.
A heavy, hinged steel plate attached in a horizontal position to the rear of the locomotive footplate or front of a locomotive tender. When the tender is attached to its locomotive the plate is allowed to fall to cover the gap in the "floor" between the two units. The sliding edge is not fixed and has a smooth chamfer so as to avoid a trip hazard.
A worker whose primary job is to shovel coal into the firebox and ensure that the boiler maintains sufficient steam pressure
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 or banging noises when the wheel passes by. This is caused either by a locked bearing, or a brake that was not fully released before the car was moved, dragging the wheel without turning.
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
The point of a switch turnout where a car or locomotive on one track will obstruct movement on the adjacent track
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.
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".
A device attached to the track which monitors passing trains for hot axles, and then reports the results via a radio transmission (typical in the US) or a circuit to the signal box (typical in the UK). See defect detector.
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.
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.
Moving goods 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.
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
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.
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
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
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 (LRV) generally have a top speed of around 55 mph (89 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.
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 by the Railroad Safety Appliance Act of 1893.
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 every station and stop along their route to pick up fresh milk brought to the stations daily from local dairy farms).
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. 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.
Railroad track where the rails are spaced less than 1,435 mm (4 ft 81⁄2 in) apart. There are many common gauges narrower than standard, amongst them 3 ft 6 in (1,067 mm) widely in Africa and Asia; 3 ft (914 mm), which was the most common narrow gauge in the U.S.; 2 ft 6 in (762 mm), used in various locations across Europe, Asia and elsewhwere, South America and Australia, and 2 ft (610 mm), which saw widespread use in the UK. Meter gauge 1,000 mm (3 ft 33⁄8 in) is also widely used in Asia and Africa. Narrow-gauge lines are often found in mountainous terrain where the cost savings of building a smaller railroad can be considerable. (Historically, the term "narrow gauge" was once used in Britain for what is now called standard gauge, as the only other gauge then in common use was the Great Western Railway's 7 ft (2,134 mm) broad gauge.)
Per diem (pronounced by some U.S. railroaders per die-um, not per dee-um)
A fee paid by a rail company to the owner of a car (or wagon) for the time it spends on the company's property
An authorized living expense payment for some workers forced away from their home terminal
A block signal whose most restrictive indication is stop and proceed. A permissive signal is identified by the presence of a number plate affixed to the mast or supporting structure. Proceeding beyond a permissive signal at stop is allowed at restricted speed if operating conditions enable a train operator to stop before reaching any train or obstruction.
A deflective shield affixed to the front of a locomotive to protect its wheels from on-track debris; archaically called a "cowcatcher" See also: Pilot (locomotive)
An employee qualified on the operating rules and physical characteristics of a certain section of the railroad, assisting a crew who is not so qualified See also: Railroad engineer
Where it is necessary to temporarily work a section of line as single track (for instance if the other track of a double track line is out of use), a person (the pilot man) acts as the single track token.
A system of functional requirements for monitoring and controlling train movements to provide increased safety
A period of time when one or more tracks are closed for maintenance. For the duration of work a person in charge of possession (PICOP) has control of the line. When work is complete the possession is relinquished and control of the line handed back to the signaller.
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.
A locomotive or group of connected (MU'd) locomotives serving as the motive power for a train
Pulling against the train brakes at the higher end of the locomotive's power output (e.g. notches five through eight on a conventional throttle). This is considered wasteful of fuel and brake shoes, and is therefore discouraged by most operating departments.
The internal combustion engine of a diesel locomotive
A rail broken from cold-related contraction
A push pole
A pole about 12 feet (366 cm) long and having a diameter of 5 inches (127 mm). They were placed in receptacles called push pole pockets. The pole was placed between the locomotive and the freight car, and used to push the car on or off a siding or to another track. Used between 1870 and the mid-1960s.
A mode of operation whereby a locomotive-hauled train may be driven with the locomotive at the front, middle or back of the train. See also: Auto train. See Top and tail for train with locomotives at both front and back.
A passenger rail vehicle (typically non-articulated or rigid frame) that was derived from bus propulsion and construction technology, but which may evolve into larger dimensions, performance, and characteristics similar in appearance to a light DMU railcar
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.
A colour generally associated with stop, when shown by signals or flags
The area between, under, or within a few feet of cars and locomotives. To enter the zone, a ground employee must obtain protection from the locomotive engineer (if a locomotive is coupled) or a blue signal (if no locomotive is coupled).
A box or panel adjacent to a rail line at an interlocking, with several buttons for train operators to select a desired route, which is then either communicated to a signal tower where an operator fulfills the request, or switched automatically
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).
Locomotives that remain attached to a manifest or unit train from their home rails over the tracks of a receiving railroad until the train reaches its final destination
A container on locomotives and self-propelled multiple units, or trams, that run on tramways and adhesion railways. The container holds sand which can be dropped onto the rail to improve rail adhesion under wet, steep, or slippery rail conditions. The sandbox and operating mechanism are collectively known as sanding gear.
A section of track off the main line. Sidings are often used for storing rolling stock or freight. A siding 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.
A two-head color position signal on a CSXT mainline where the left head displays "Stop" and the right, "Clear"
A local speed restriction below the track's normal speed limit often designated by yellow and green flags. Slow orders can be imposed on a temporary basis to protect, for example, maintenance of way employees while sections of track are under repair. Widely used in areas where track is substandard and in need of repair.
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.
A reversing gear worked by a steam cylinder controlled from the cab
A person in a dining car with a role similar to that of a Maitre d’Hotel
Pulling against train brakes at the lower end of a locomotive's power output (e.g. notches one through four) of a conventional throttle, thus keeping coupler slack stretched and permitting smoother train handling. This is considered most effective on undulating track profiles or when dynamic braking is not available.
The trackage area within a division covered by a single timetable
A mechanical device that boosts the pressure of engine intake air to above atmospheric level, causing an increase in power. Not to be confused with the blower used to scavenge the cylinders of a naturally aspirated two-stroke Diesel engine.
To determine the position of constructed objects, including rail infrastructure, in relation to the earth's surface. This is accomplished by measuring angles and distances based on the principles of triangulation.
A specialized rail car attached to a steam locomotive to carry its fuel and water supplies, along with tools and flagging equipment
An area, usually at least ten feet wide, between a pair of widely spaced tracks, wide enough to form a place of safety in which railway workers can stand while a train goes past. See also four-foot and six-foot.
A passenger coach that is disconnected from one train and attached to another before continuing on with its journey, thus avoiding the need for passengers themselves to switch trains
The standard platform and track arrangement at a station. The train pulls alongside the platform, arriving from one end of the station, and may pass out the other end of the station by continuing along the same track
Combining two or more different railways onto a common length of track. This is often done to eliminate redundant trackage or improve service.
A plate which is bolted to sleepers, holding the rails in place
The general compass direction of a railroad or subdivision, as specified by its official timetable rulebook. Only the four cardinal compass points may be used to state a train's direction of travel.
The gradual application of superelevation and tighter curve radius, calculated with reference to the anticipated line speed and the final curve radius, on the approach to a bend. Also known as the transition spiral and spiral easement.
Trams that are designed to run both on the tracks of a city-based rail system and on the existing railway networks. Tram-trains' dual-voltage capability makes it possible to operate at lower speeds on city streets and at over 60 miles per hour (97 km/h) on main line tracks allowing travel in an extended geographical area without changing the method of transport.
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.
The rolling component typically pressed onto an axle and mounted on a rail car or locomotive truck or bogie. Wheels are cast or forged (wrought) and are heat treated to have a specific hardness. New wheels are trued to a specific profile before being pressed onto an axle. All wheel profiles need to be periodically monitored to insure proper wheel to rail interface. Improperly trued wheels increase rolling resistance, reduce energy efficiency and may create unsafe operation. A railroad wheel typically consists of two main parts: the wheel itself, and the tire around the outside. A railway tire is itself steel, and is typically heated and pressed onto the wheel, where it remains firmly as it shrinks and cools.
The process of a wheel climbing up and often off the inside or gauge side of the rail. It is a major source of derailments. Wheel climb is more likely to occur in curves with wheels whose flanges are worn or have improper angles. See Rail adhesion.
The inner section of a wheel that rides between the two rails. The angle between the wheel tread and flange is often specific to the rail to prevent wheel climb and possible derailments. See Rail adhesion. The wheel flange is part of the wheel tire.
The loss of traction due to a slippery rail or wheel. Wheel slip was common with steam engines as they started to move due to the excessive torque often generated at low speed. Steam engines carried sand dispensing gear to increase traction at the start of motion.
An historical railway occupation; people employed to tap train wheels with hammers and listen to the sound made to determine the integrity of the wheel; cracked wheels, like cracked bells, do not sound the same as their intact counterparts. The job was associated with the steam age, but they still operate in some eastern European countries. Modern planned maintenance procedures have mostly obviated the need for the wheel-tapper.
Train whistles are used as a safety warning and also by the engineer to communicate to other railroad workers. See train whistle for a description of the whistle code used to communicate. Also a nickname for an air horn on a diesel locomotive. Steam engine whistles were historically known as chimes in the US during the 19th century.
A system of describing steam locomotive wheel arrangements (e.g. 4-6-4, 2-10-2). The first number indicates the number of "pilot" wheels that help lead the engine into turns. The second is the number of coupled wheels ("drivers"). Third are the trailing idler wheels, usually to provide support to larger fireboxes. Articulated locomotives are similarly described. For example, a Union Pacific "Big Boy" would be described as a 4-8-8-4, wherein the pilot has four wheels, followed by two sets of drivers, eight wheels per set, and a four-wheel trailing bogie under the firebox. The numbers include the wheels on both sides of the engine, so a 2-8-2 engine would have one idler, four drivers, and a final idler on each side of the engine.
A largely superseded Level or Grade Crossing Warning Signal consisting of a swinging disc facing road traffic with a red light in the centre. The disc normally hangs straight down, but an approaching train will set it swinging from side to side, the red light will illuminate or flash, and a bell will ring.
Working water, foaming, or priming
The condition of a steam locomotive drawing water through its throttle valve, cylinders, and smokestack, often causing damage to the cylinders or running gear
^Hyman, Anthony (1982). Charles Babbage, Pioneer of the Computer. Oxford University Press. pp. 142–143. ISBN0-19-858170-X. Babbage suggested to Hodgson of the railway company what was later to be called a 'cow-catcher' for sweeping obstacles off the line.
^McCulloch, David S.; Bonilla, Manuel G. (1970). The Alaska Earthquake, March 27, 1964: Effects on Transportation and Utilities. Geological Survey Professional Paper. Washington, DC: United States Government Printing Office. p. D135.
Canadian National Railways: Linguistic Services. Freight Car Inspection & Maintenance: English-French Vocabulary = Surveillance et entretien des wagons: vocabulaire anglais-français. Montréal: Canadian National Railways, 1973. Without ISBN or SBN