Glossary of Model Railway Terms | Railwayscenics

Glossary of model railway terms

We have compiled a list of common names and materials used in model railways complete with a short definition of each item. This list is almost certainly not complete, and is to be used as a work in progress.

We have to thank the many sources, books and websites where the information in this list was found. Many thanks to all.

We have tried to define most names used in model railways. If you have noticed an error, or there are any ommissions please help us by letting us know. We, and other modellers will appreciate your help with this list.


A foundation designed to hold back the pressure of solid ground, such as an end pier of a bridge.
Alternating current. Electric current which changes polarity in a regular cycle. It is the normal mains supply.
Accessory decoder or module:
A decoder that remains at a fixed location and controls accessories such as signals, point motors, lighting in buildings or level crossing barriers. Also known as a Stationary Decoder.
Acrylic Paint:
Water based paint which is fast drying.
A number identifying each individual locomotive or accessory decoder on a layout. When a controller is set to a particular address, only the decoder set to the corresponding address can read the instructions from the controller.
The frictional grip of the wheel to rail; Maintenance of contact between the wheel s and the rail.
Advanced Uncoupling:
A system of automatic uncoupling where the rolling stock are pushed over an actuating mechanism which uncouples the locomotive/wagons.
A miniature paint sprayer that that is used by artists and model builders to give a controlled application of paint.
American Wire Gauge (AWG):
An American standard system to indicate wire diameter. The smaller the AWG number, the larger the wire diameter.
Ampere or Amp:
Unit used to measure electrical current strength.
Analogue control:
Conventional track voltage control system, typically varying between 0 and 12 volts DC for speed control and polarity reversal for direction control.
Auto Train:
An early form of multiple unit where a steam locomotive could be controlled by the driver sitting in a carriage. Removed the need for the engine to run around the train at a terminus.


Back to back:
The distance measured between the inside edges of the two wheels on an axle. This measurement is very important to see if your rolling stock will run through a piece of track that has check rails.
Back scene:
Printed or photographic scene on the wall behind the layout. Creates an illusion of distance.
The prototype track is laid on a bed of loose rock chippings, to provide drainage and support for the sleepers. In the model version this may be simulated by a foam rubber inlay or to be much more realistic, loose chippings held together with a dilute PVA mix.
The platform on which a model railway is built.
Base plate:
The plate upon which flat bottom rail is laid so that it can be fastened down. Referred to as chairs in model railway parlance.
Bay Platform:
Terminating platform alongside the main through platform. Used mainly by local trains or for unloading parcel vans. Sometimes used for stabling locomotives.
A diesel wheel arrangement indicated two four-wheeled driving bogies.
Movable wheel unit on rolling stock connected to the under frame by means of a pivot. Enables far greater weight to be carried on even short wheel based rolling stock.
The long large cylinder making up the bulk of a steam engine, contains the pipes etc through which water passes for heating.
Bracket signal:
A semaphore signal array with two or more arms indicating different routes ahead. Often termed a junction signal.
Brake Van:
A vehicle at the end of a goods train, in which the guard rides.
A portion of railway that diverges from the main line to serve a town or industry.
Brick paper:
Paper that has been printed to make it look like brickwork, roofing tiles etc. Very useful for scratch building or creating scenic details such as arches etc.
Broad Gauge:
A descriptive term for any railway who's track is wider than the standard gauge of 4 foot 8-1/2inches.
Modern automatic coupling hook.
Building Papers:
Paper that has been printed to make it look like brickwork, roofing tiles etc. Very useful for scratch building or creating scenic details such as arches etc.
Bullhead Rail:
This is rail having the same profile for upper and lower portions of the rail.
A space at the rear of a tank engine used for coal storage.


Cab Control:
A means of wiring a layout to enable track sections to be switched between two or more speed controllers.
Capacitor Discharge Unit (CDU):
An electrical devise for solenoid point motors. Giving a very short but intense burst of power to the motor when switched.
Card is used in model making. It is often free and can be obtained in various thicknesses.
Catch Point:
A single trailing point blade set into an ascending track to derail wagons which have come uncoupled and are running back down the hill. This prevents runaway collisions.
Centre Third:
A system of current collection using a central third rail. Now virtually obsolete.
Check Rail:
This is the length of rail which holds the inside of the wheel to stop the other wheel from going down the wrong side of the frog on your turnouts.
Circuit Breaker:
A switch or fuse that automatically opens the circuit in the event of a current overload.
Clerestory Roof:
Typical of certain passenger cars featuring raised centre sections and "clerestory windows" along the sides.
Closure Rail:
The piece of fixed rail between the points and the "frog" of a turnout (point).
Common Return:
A conductor which is common to more than one part of an electrical circuit and which forms the return path for the current from these parts of the circuit. Normally one rail of all sections or circuits of a layout is chosen as the common rail and current from all these sections or circuits returns to the power supply through this rail. The other rail can then be divided into sections or circuits as required.
Products that have passed the NMRAs testing procedures are eligible for a Conformance Warrant if the manufacturer also agrees to fix any discrepancies that might become apparent in the future. The Conformance seal is awarded by NMRA for products passing the Conformance and Inspection program for particular NMRA Standards.
A pair of turnouts arranged in such a manner as to allow a train to cross from one line to another.
A passage way under tracks for drainage of water.
A protective device built into an electrical circuit for the purpose of switching off the current when the load reaches a predetermined number of amps.
A large trench with sloping walls and railway tracks at the bottom.


D.C. current flows constantly in the same direction along its conductors which are termed positive and negative. The polarity of the conductors can be reversed and the current flows in the opposite direction.
Digital Command Control. The latest digital operating system for model railways and becoming increasingly popular.
Dead Frog:
Where the crossing V of a model turnout (point) is moulded of plastic so as to keep the two track circuits through the turnout entirely separate.
Circuit board used for operating Digital models. Any locomotive or accessory to be used on a digital system requires a decoder, which receives and interprets the Digital information sent by the Controller. Many decoders offer added functions such as lighting, sound and so on. These are referred to as multi-function decoders.
A train command system, fast gaining ground on older Analogue systems in terms of popularity. Whereas analogue systems work by providing a regulated supply of power to the track that increases or decreases according to user input, Digital systems supply a constant power supply to the entire layout. Trains are operated through a command signal, sent through the track to the locomotive. With each locomotive operating on its own frequency, locomotives can be commanded individually.
A solid state device which allows electric current to flow in one direction only.
A small scene with great detail. Can be used to set off your models or to photograph a particular model. Can be scenes which are added to your model railway as they are completed.
Distant Signal:
A signal showing advanced warning of the next signal but has no stop indication itself.
Diesel Multiple Unit. A piece of rolling stock that is self powered and carries passengers or parcels. Each outward coach has a cab at the outer end which enables the driver to drive the unit in both directions without having to turn the unit. Very useful on smaller layouts and end to end.
Double heading:
Often known as consisting or multi-traction, a means whereby two or more locomotives can be run together under the same address.
Double Slip:
In effect, this is four points and a crossover compressed into a very small space. Very useful if modelling a yard in limited space and where a head shunt is required.
DPDT Switch:
A double-pole changeover switch. Used on reversing loops and triangular junctions.
Driving Wheels:
The powered wheels of a steam engine, attached to the pistons.
Dropper Wire:
Feed wires soldered to the side or base of the rail and which then pass beneath the baseboard.
Dry Brushing:
A technique where an almost dry brush is used to highlight details on a model with paint. Can be used for weathering models or for scenic work, rocks and stone walling, for example.


In electrofrog turnouts the frog is full metal and is always live. It needs insulated rail joiners to be fitted at certain track positions.
Electrical Multiple Unit. A train consisting entirely of coaches, the outer of which have a cab enabling the train to be independently driven in both directions. An EMU is powered from an outside power source such as the overhead catenary or a third running rail.
Enamel Paint:
Typically an oil based paint, taking longer than Acrylic paint (above) to dry. Usually has a gloss finish but is available in matt and satin finishes also.
The type of layout where your train starting at one end will eventually have to stop before it can be returned to its starting point. This is where the "fiddle yard" comes in.
Epoxy Glues:
A very strong two-part adhesive used to glue different materials such as plastic, wood etc. Most commonly known under the trade name Araldite.


Facing Crossover:
A crossover arranged so that trains can pass from one track to the other while travelling forwards.
The place where a connection is made to supply power to the track. In model railway terms we refer to the feed as the positive.
Feedback controllers create a closed loop between the controller and the locomotive which senses the load in the circuit and constantly adjusts the output. This will maintain the locomotive at an even speed up and down gradients and around curves without altering the regulator of the controller. Feedback controllers are not suitable for Portescap or other coreless motors or for poor quality mechanisms particularly in N and other small gauges.
Fiddle Yard:
This is an out of sight, non scenery part of the layout where your trains go to when they have vanished from sight beneath a road over bridge, through a tunnel or behind a building somewhere, the choice is yours. The trains can be turned here, either by hand or by mechanical means, for their return journey.
Figure Eight:
The kind of layout where the continuous run crosses over itself in the shape of a figure eight.
Also known as rail joiners. Metal clips used to join track together to provide an unbroken electrical circuit.
The projection/lip on railway wheels, which keeps them on the track.
Flat bottom Rail:
The standard rail section in use on all modern systems. The rail has a wide base and, originally, was spiked directly to the sleeper. With increasing train loadings, base plates were introduced to spread the load and on all but lightly laid track now has the rail secured either by bolts and clips or patent clips.
As the name suggests this is flexible and can be cut and curved to suit your track plan, where a standard radius of track will not fit.
Foam board:
Foam board is a lightweight board made by sandwiching a layer of foam between two layer of thick paper to produce a strong but lightweight material.
The crossing nose on a turnout.


Gantry Signal:
A lightweight bridge structure crossing several tracks carrying many signal posts or colour light heads.
The distance between the two running rails on a single piece of track. In 4mm 00 that is 16.5mm.
Grey board:
Grey board is a cheap card product used in model making. Can be purchased in various sheet sizes and thicknesses.


A length of track which feeds any number of sidings and that allows those sidings to be shunted without blocking the main line.
Home signal:
The semaphore signal controlling entry into a block section.
Hot Knife:
Used for cutting polystyrene tiles. Just a piece of wire held in a special tool handle. It plugs into the electric mains, gets hot and melts the polystyrene tile as you move it through the material.
A diesel hydraulic locomotive produced for the Western region of British Rail that were designated Class 35.


As the name suggests these turnouts have an insulated tip to the frog, in other words, electrically dead. This keeps the two electrical circuits through the turnout completely separated and only requires insulated rail joiners to be fitted under certain circumstances.
Insulated Rail Joiner:
To be used when rails need to be connected to each other mechanically but isolated from each other electrically.
A system of mechanical and/or electrical controls allowing only one train to move through a junction of two or more tracks.



Kit Built:
A model built entirely from the parts supplied. An obvious one really but relevant to what follows.
Kit Bashed:
This is when you take a kit of some model and so alter or add to it that the model takes on your own personal stamp or may even become a totally different model.


Short for light-emitting diode. An electronic semiconductor device that emits light when an electric current passes through it. They are considerably more efficient than incandescent bulbs, and rarely burn out.
Loading Gauge:
The space either side and above the track so that locomotives and rolling stock can pass by without coming into contact with anything.
Low Relief:
A term usually applied to buildings close to the back edge of a model railway that have been modelled to a less than full depth. This helps to give the appearance that the layout extends much further than it really does.


Modern Image:
A term introduced in the 1960s to describe the then new diesel hauled and electrified trains on British Rail. The object was to distinguish between current practice and the steam hauled system. Over the past few years it has become necessary to distinguish between current practice and Historic Modern Image.
Mineral Wagon:
A wagon for transporting minerals such as coal or stone.




Passing Contact Switch:
A changeover switch which only connects momentarily as the switch is thrown. Used for solenoid type turnout motors.
Pannier Tank:
A type of tank engine with long rectangular tanks on either side of the boiler.
Folding current collection device mounted on the roof of trains operating with overhead power supply.
The UK name for white and black plastic or styrene sheets.
Polystyrene Cement:
A glue used for much plastic modelling and is specifically designed to weld plastic together.
The two directions of current flow, positive (+) and negative (-), or potential in an electrical circuit.
Primary winding:
This is the winding of a transformer which is connected to the source of supply, normally the mains.
The action of setting the internal parameters of decoders and other control equipment. During programming, values are set for CVs to determine the characteristics of locomotives, decoders and other programmable Digital devices.
The original on which a model is based.
Push Pull:
One of my favourite types of train where the train's carriages are kept permanently coupled to the locomotive which pulls them in one direction then pushes them in the other. On most layouts the locomotive would be of the tank variety.
(Poly Vinyl acetate) A glue most commonly used as wood glue, usually white in colour. Also used for other materials on model railways, including ballast when watered down.



An electronic device which converts AC current to DC.
The place where a connection is made to the track to allow current to flow back to the controller. In model railway terms this is called the negative.
Reverse Loop:
A reverse loop is created where a track leaves a circuit and then rejoins it with the train going in the opposite direction. This will result in a short circuit unless the section is isolated from the rest of the circuit. A DPDT switch is then used to reverse the polarity of the circuit concerned.


Saddle tank:
A type of tank engine in which the water tanks are draped over the boiler.
Scatter materials:
These are purchased or ready made ground up materials which are scattered on a sticky surface to represent grass, earth or foliage. Made from sawdust or different kinds of foam usually. Available in many colours and grades from various manufacturers.
Material used on the model layout to represent the land, trees, crops, grass, weeds, water, etc of real life. Structures are also considered scenery.
Scenic break:
A way of dividing up a model railway to make it look as if two or more sections are further apart than is the fact.. This effect can be achieved by making your train disappear through a cutting, or under a bridge. A tunnel, as in my own case, can be used and the exit is hidden by scenery so that it can be as far away as you want it to be, many miles or hours away if needs be.
The model is built from parts that you have made, or mostly made, yourself.
This is a method of marking out planking, brick or stonework etc on the material of your choice by using a pointed instrument or blade to indent or cut into the material so as to give the effect of relief. When colour is applied to the whole the cuts or indentations stand out.
Secondary winding:
This is the output winding of a transformer and is usually isolated from primary winding. Many transformers have two secondary windings.
This is sometimes called "inertia" or "momentum". It allows controllers so fitted to automatically accelerate a train, allow it to coast or be braked to a standstill. This is achieved by two controls, a regulator and a brake and gives more realistic acceleration and braking.
A coil of wire wound around a hollow core which creates a magnetic field within the core when electricity is passed through it.
SPDT Switch:
Single pole double throw. A single-pole changeover switch. Used to switch feed wires from one circuit to the next, as in Cab Control. May have a centre off position.
SPST Switch:
Single pole single throw. A single pole on-off switch that either makes or breaks a circuit.
Static Grass:
Used to simulate grass. This is short threads of a material that stand up when static is applied, giving the look of grass. Gives a more realistic grass look than scatter material. Available in a wide range of lengths and colours.
Styrene Sheet:
A strong durable plastic sheeting, easy to cut and shape when heated.


Tag Strip:
A means of joining several wires to a common conductor, such as in a common return system. The wires must be soldered to the tag strip.
Terminal Block:
A means of joining two wires with screw terminals, useful to avoid soldering.
Tin Plate:
Equipment once designed to be sold to children, most often running on 3 rail track. Cars and locomotives are often shortened to allow them to negotiate sharp curves. Originally pressed from thin sheet steel (ie: tinplate). Detail is usually coarser than scale and often exaggerated. In modern times most often sold to collectors.
Track isolation:
Track isolation is particularly important with modern controllers. You should always ensure it is not possible for more than one controlled output to be connected to the same circuit or section at the same time. You should similarly ensure that A.C. and uncontrolled outputs are not connected to a controlled circuit.
A device designed to change the voltage of an A.C. supply. All transformers deliver A.C. current and this is converted to D.C. (see also primary and secondary winding). Transformers are often used to power accessories on a layout (e.g. Point Motors).
Another word for track points and the one most commonly used by modellers.



A roofed railway goods-vehicle.
The area at the end of corridor and saloon coaches, from which access may be gained to the side corridor or central passageway, outside doors, W.C. (if any), and corridor connection to the next coach (if any).
A railway structure which is used to carry railway tracks above the general level of the ground and is usually made up of a continuous series of bridges or trestles.
A unit of electrical pressure. Commonly, 0 to 9 volts of DC are used for Z scale model railroading, 0 to 14 volts DC for N, HO and 00 scale, and 0 to 20 volts DC for large-scale model railroading.


Wagon Tippler:
A mechanical device which is able to lift up a whole wagon and tip out its contents.
Wagon Turntable:
A short-length turntable consisting of a round plate on which two tracks at right angles to each other are located. These devices are used for manoeuvring individual wagons between tracks which are at too obtuse an angle to each other to be connected with points.
Waist (Panel):
The area of a carriage body about half-way up the body-side; specifically the narrow panels below the windows on a traditionally panelled coach.
Water Column:
A standpipe adjacent to the track and connected to a water supply for filling steam locomotive tenders.
Water Crane:
A water column on top of which an additional hinged horizontal pipe is attached.
Water Scoop:
To save having to stop to take on more water, many steam locomotives were fitted with water scoops which could pick up water with out stopping from long troughs laid along the track between the rails.
Water Tower:
An elevated water-storage tank.
Water Troughs:
Longitudinal troughs of water laid between the rails of a train track, for the purpose of a locomotive picking up water without stopping.
Making shiny new models look more realistic by dirtying them up to simulate road grime, the action of sun and rain, and general evidence of use.
Weathering Powder:
A means of selectively dirtying the model to make it seem as if the model has seen years of active service!
Welded Rail:
Real rail sections that have been welded together to eliminate track joints. Also called continuous rail.
Well Tank:
Some steam locomotive carry their water supply in a tank set between the locomotive frames. As this greatly restricts the tank size, many locomotives with well tanks also had small side tanks.
Well Wagon:
A goods wagon in which the portion between the two axles or bogies is lowered so as to provide room within the loading- gauge for a high load.
Wheel Base:
The distance between the centres of the first and last axles of a vehicle.
White Glue (PVA):
Generally a water based adhesive primarily used for joining wood, paper and card materials.
Wing rail:
The portion of the closure rail which is bent to extend past the frog.
Wireless Cab:
A handheld cab that has no cable connection to the layout. Wireless cabs use infrared or radio waves as a method of transmitting information.
Working Timetable:
A time table used by railway operators, which includes the times of all regularly-run trains (not just passenger trains).
Type of turnout where the two legs curve away equilaterally, forming a Y. Also a triangular track configuration for turning a locomotive or a train or for joining a branch to a main line for operation in both directions.




Z scale:
Models built to a scale of 1:220. These are the smallest practical models in mass production at the time of this writing. .055" (1.39 mm) = one foot and the track gauge is approximately 1/4".