This Trains O Scale glossary covers the more basic terms you will encounter in model railroading. As you get deeper into this hobby you will run across additional terminology some of which is unique to the actual railroad industry itself.

Access area – An opening near the center of your train layout which allows you to get to areas which you can’t reach from the outside edges of the layout.

Articulated – A steam locomotive which has a pivoting joint allowing it to make sharper turns.

Ballast – In a model train layout this is a substance, like gravel, used to keep your train tracks in place.

Benchwork – The foundation and platform that supports your model railroad layout.

DCC (Digital Command Control) – With this type of controller each locomotive has its own ‘address’ so a different command can be sent to each engine separately thereby allowing multiple trains to run separately from others on the same track.

Extruded foam – Foam board used on top of plywood as your layout’s base.

Flextrack – A three-foot length of flexible track with the ability to be used either as a straight track or bent to any desired curve.

Freelance – Not modeling after any specific period of time or particular railroad.

Gauge – The distance between the two outside rails of a track.

Hand laid track – These are train tracks that you make yourself out of raw materials.

Helix – A circular track section that resembles a corkscrew used to move trains between different levels of track.

Homasote – Pressed paperboard typically used as roadbed.

Kitbashing – Taking one or more railroad kits to build a personalized structure. A practice that is very often used when, for example, specific models for buildings are not available.

Layout Design Elements (LDEs) – Using certain elements like towns or scenes, which were important aspects that identified the prototype.

Operation – The running of your trains on a layout in a purposeful manner.

Prototype – The full-size, real-life piece of equipment after which a scale model is created.

Pull the pin – Operating the uncoupling lever.

Pullman – A sleeping car, also known as a parlor car, operated by the Pullman Co. It is also the generic term for any sleeping car.

Puzzle switch – A railroad switch or turnout that guides trains from one track to the other.

Rail – The part of the track that the wheels of the train ride on.

Rail code – The height of the rails on a model track. It’s measured in thousandths of an inch. (Code 100 = 0.100 inches tall, code 83 = 0.83 inches tall)

Rail Diesel Car (RDC) – A passenger car that is self-propelled.

Rail joiner – A clip used to join two pieces of rail together.

Rail nipper – A pair cutting pliers use to cut rails.

Railfan – A person who enjoys anything connected with the railroad.

Railhead – The wider, top part of the rail on which the wheels ride.

Rectifier – A device to convert AC current to DC current.

Reefer – A refrigerated car used for hauling perishables.

Relay – A switching device used to control power and signal circuits.

Rerailer – A section of the railroad track dedicated to placing cars and locomotives back on the rails.

Return loop – A track section which reverses the direction of the train.

Reverse or “S” curve – Curved tracks which are connected end to end in the opposing direction.

Right-of-way – In model railroading it’s the track as well as roadbed and sub-roadbed.

RIP (repair-in-place) track – The area of a train yard where minor repairs to cars take place.

Riser – The vertical section of benchwork which supports the track board.

Roadbed – In model railroaders’ terms, it’s wood, cork or other materials which provides the foundation for the tracks.

Road switcher – Also known as a hood unit, this is a diesel train that can be used for road duty as well as yard switching.

Rolling stock – Any type of railroad equipment that rides the rails.

Roundhouse – A circular engine house, facing a turntable, to move a locomotive on and off the tracks.

Ruling grade – The area in a train’s run where the train pulls the hardest. It’s caused by a combination of curve resistance and the grade.

Runaround – It’s when the locomotive uncouples from its cars, goes forward, backs up past the train car while on an adjacent track, then moves ahead to couple itself at the very rear of the train.

Running board – The walkway along the sides or roof of train cars.

Scale – The ratio between the size of a model train compared to that of the real-life version. HO scale, for example, has a ratio of 1:87 or 1/87 the size of the prototype.

Scratchbuilding – Creating a model from raw materials without the use of a kit.

Sectional track – Short, rigid pieces of track which are joined together.

Spur or spur track – This is a track with no outlet, a track with a turnout at just one end.

Standard gauge – In North America and Europe, standard gauge is the distance between the rails which is 4 foot 8 ½ inches.

Styrene – Short for polystyrene that is used in modeling.

Subroadbed – The bottom layer of the platform that your layout sits on, typically made of plywood. It can also be made of Homasote, foam board or either of these in combination with plywood.

Superelevation – To raise up the outside section of a curved track to assist the trains in negotiating the curves at higher speeds.

Tangent – Refers to a straight track.

Tank engine – A type of steam locomotive which carries its own water supply in tanks alongside the boiler or at the rear but not in the tender.

Tender – A train car which carries extra fuel and water for the locomotive.

Third rail – Literally a third rail mounted along the running rails. It supplies current for electric locomotives or traction cars.

Throttle – In the terminology of model railroaders, a speed controller.

Track – Two parallel rails fastened to either wood or plastic which the train rides upon.

Trackboard – The horizontal support, typically wood, underneath the roadbed and track.

Trains O Scale – This website (just wanted to see if you were paying attention).

Transformer – Changes high-voltage AC current to low-voltage AC current in order to power the DCC system.

Truck – The wheel and axle assembly under a railroad car.

Turnout – A section of track with rails that move. Its purpose is to move a train from one track to another. Sometimes referred to as a “switch”.

Turntable – A revolving railway track which turns locomotives in an engine terminal.

Uncoupling lever – The device that raises the couplers locking pin allowing the cars to uncouple. Also known as a ‘cut lever”.

Unit – One diesel locomotive

Unit train – A freight train carrying only one commodity to one destination. It returns empty.

Varnish – Term used for a passenger train. Passenger cars at one time were made from wood and given a number of coats of varnish.

Walkaround railroad – A model railroad layout in which you can walk around while operating without the need to walk under any section of the benchwork.

Water column – A standpipe usually found next to the track which is connected to a water supply for the purpose of filling the tenders on steam locomotives.

Weathering – The process by which model railroaders make new models look old and worn for more realism.

Wheelset – A set of wheels on a railroad car connected to the axle.

Wye – A triangular track configuration, making the letter “Y”, used for directing a train car or locomotive to another track.

Yard – Tracks used solely to sort and store cars.

Yard engine – A locomotive used for switching railroad cars on storage tracks.

We will be updating the Trains O Scale glossary from time-to-time based on questions posted by our readers. If you don’t know what a certain railroading term means, just ask us.