A Model Railroad Glossary


Model Railroading, like any hobby, has terms specific to it that can create a bit of a barrier to outsiders who want to join the hobby. There are also regional variations in terminology that can be confusing in a global market, even if you’re used to your local model railroading terminology. I’ve created this page to capture some of the terms I use on my site, but I don’t make any pretense to it being complete.

Some “prototype” terms, meaning terms used by real railroads, are included here for clarity or to describe subtle differences between prototype and hobby usage.

3-pole, 5-pole - In describing the motor used in a model train, the number of armature winding sets is referred to as a “pole”. This is hobby jargon, and DC motor suppliers who aren’t familiar with the hobby won’t understand you if you use the term (“pole” has a different meaning for DC motors and applies to the stator, not the armature). High-quality DC motors used in HO scale have been “5-pole” designs because this offers more even rotational speed at lower voltages (effectively, smoother low-speed operation), and so this has come to indicate “quality”. In N-scale, the lower torque produced by 5 sets of windings (less wire used at any given instant means a weaker magnetic field) may be an issue. Additionally, it doesn’t have the same connotation in Japan, so N-scale models sold for that market are usually 3-pole designs and packaging never calls it out as a feature. See my posting on this topic for more details.

ballast - a prototypical term for the gravel spread around the ties of railroad track to hold them in place and promote drainage. In a model railroad ballast may be small stones glued in place, or a plastic casting attached to the ties (or incorporating the ties) to which the rail itself is attached.

bank engine - the U.K. or Australian term for a pusher or helper engine; an extra locomotive, often on the rear but sometimes in the middle of the train. The term “banking” comes from this, and shouldn’t be confused with the structure of a raised fill (an embankment).

banked - another word for superelevated.

canted - another word for superelevated. Kato uses “cant track” in Japanese to describe their superelevated tracks, and this will sometimes appear in translated website text.

DCC - Digital Command Control is a method used for controlling trains that allows precise control of individual trains. Both trains and command systems must be “DCC” for this to be used to its full capabilities (and using non-DCC trains with DCC controllers, or vice versa, has a number of limitations beyond the scope of this page).

diamond - a place where two tracks cross at the same level (meaning the tracks touch) without connecting to allow trains to move from one to the other (there may be a connection nearby). See slip switch.

dry-brushing - to paint after wiping most of the paint off the brush (e.g., onto a paper towel). This is a technique used for adding paint in a way that accents or modifies the base color, rather than covering it.

easement - in track work, an easement is a section of transitional track. A “spiral easement” is used entering/exiting a curve to gradually change the radius of curvature. This can help with longer cars and tighter curves, although since Unitrack uses a constant radius curve it can’t be done without using flex track. A “vertical easement” is used when going from level track to uphill/downhill track, or gradually change the slope. This can prevent longer cars from uncoupling (or hitting the track) on steeper slopes.

electrofrog - a powered metal frog or a turnout equipped with one. The term is a trademark of Peco, a manufacturer of model railroad track, but is often used generically. The converse is an insulfrog. These can be a problem when wiring a layout, as the polarity of the frog needs to change when the route through the turnout changes, and when the turnout itself does this, it is often unreliable.

embankment - a raised area of soil used to support a road or railway, or to hold back water.

feeder - a wire connected to track on a model railroad that provides power from a DC power-pack or DCC command-station/booster (power to run trains in either case) is called a feeder or track feeder.

fill - another word for embankment.

finescale - modeling involves making a number of compromises between appearance (trying to look like the prototype) and function. Mass-produced models need to make more compromises than hand-made ones (although that’s less true today with computer-controlled machinery to make models). This has given rise to modelers who go beyond the average in trying to create models and whole layouts with fewer compromises. This kind of modeling is called “finescale” because it uses dimensions that a more precise, and have less tolerance for variation (e.g., dimensions are “finer”). There are a number of standards in different scales for such models.

FineTrack - Tomix’s line of sectional N-scale track, which has several sub-classes (such as Wide Tram).

flex-track - short for “flexible track”, which is a section of track, usually sold in 3-foot or 1-meter lengths, with molded-on ties that have the webbing holding the ties at a constant spacing underneath the rail cut on alternate sides. This allows the track to be bent into a curve (or curves) without the ties shifting out of place. Flex-track needs to be attached to a roadbed surface (typically using glue) and ballast material (loose gravel) applied by hand and glued in place, but produces much more realistic track than usual sectional track elements.

foam - this word can mean several things, but usually refers to rigid insulation foam sold in home improvement stores in large sheets. This is not “styrofoam”, but extruded polystyrene (XPS), which can be cut or carved into shape and used to form landscape on a model railroad. The term is confusingly also used for flexible (rubberized) foam used as roadbed.

frog - a prototype term meaning the place on a track switch where the left rail from one route crosses the right rail of the other. On a prototype switch this is a metal casting. On a turnout it may be metal or plastic. The name actually derives from the “V” shape of part of a horse’s hoof, which probably made a lot more sense to people in the nineteenth century who saw horses every day. See insulfrog, electrofrog. Other types of track crossing than switches (i.e., diamonds) have frogs too.

gauge - on the prototype, gauge refers to the distance between the rails, with “standard gauge” meaning 4’ 8.5” (1435mm). Model track usually approximates standard gauge, but not always. There are many different gauges in use in the real world. In modeling “gauge” can also be used to refer to the type of model track used (e.g., “HO gauge”). This is really a confusion of gauge with scale. And not a very good one, since a 1/87 scale HO train could use standard gauge track (normal HO track) or narrow-gauge track in a variety of sizes, sometimes simulated using 1/160 N-Scale track (which isn’t any exact gauge in HO scale, but is close to 30” gauge). A more specific terminology actually refers to the gauge within the scale, e.g., On30 means “O Scale, Narrow Gauge 30-inch track” and HOn2 means “HO scale, Narrow Gauge, Two-foot track”.

grade - a prototypical term meaning the slope (up or down) of a track, usually expressed in percent. A 4% grade would rise four inches vertically for each 100 inches along the track (4/100 = 0.04 = 4%). Prototypical railroads are rarely steeper than 2% on mainlines (branch lines and special purpose railroads may be several times that, but with severe limitations). Model railroads are often steeper, but 4% is a practical limit and may cause problems with some trains. In some countries this is expressed in rise or fall per thousand (“per mille”) rather than per hundred (“per cent”) and a symbol much like a percent sign but with two zeros on the lower portion is used.

hand-lay, handlaid - handlaid track is track composed of individual wooden ties (typically very soft wood) with individual rails attached to them with nails or specialty staples, and with granular ballast glued between the ties. If that all sounds like a lot of work compared to sectional track or flex track, it is, but the results can be worth it for a serious modeler.

helix - a helix is a track structure (usually used on hidden track) to raise track from one level to another by having the train turn one or more complete circles, going up by just a few inches each circle. Since it takes a long time to move a train through a helix, these can also be used to simulate longer distances on a layout by delaying a train moving from one area to another.

insulfrog - an insulated frog (typically made of plastic) or a turnout equipped with an insulated frog. The term is a trademark of Peco, a manufacturer of model railroad track, but is often used generically. The converse is an electrofrog.

kitbash - to make something by modifying a kit or merging two or more kits, see scratchbuilt.

layout - a complete model railroad, with track, scenery, buildings and the necessary electrical systems is called a layout. The term can be used in a general sense, but typically means one semi-permanently or permanently installed in one location. See modular railroad.

modular railroad - a modular railroad is a model railroad constructed individual sections, called modules, usually of the same or similar dimensions, which are individually portable in a car or similar vehicle, and can be put together to form a larger railroad. Modular railroads are often displayed at train shows by clubs whose members each construct their own module, or modules.

number - applied to a switch this is a reference to the angle of the frog, expressed as the ratio of separation to length (a number 6 switch is one foot apart six feet from the frog). This is a common North American prototype reference, other places use different terminology. The same terminology is used on both prototype and model railroads, but on the prototype numbers are quite large (e.g., 22) whereas on a model railroad a number 8 turnout is considered a very gentle curve, and number 6 or even number 4 turnouts are in common use.

prototype - applied to practices, structures and other things used by real railroads, or to real equivalents of models (“a prototype hopper car”).

rail - although “rail” can be used generically to mean “track”, it usually refers more specifically to a single rail. People who hand-lay track buy rail in bulk and assemble it themselves to wooden ties.

rail joiner - a small folded sheet of metal that slips over the base of two rails where they connect, to hold them in alignment and provide an electrical connection. Kato’s Unijoiner is a rail joiner in a plastic surround that helps align the track when two sections are pushed together.

roadbed - the thing on which track is placed, modeling the ground immediately below the track, which is typically slightly raised on the prototype to enhance drainage of rainwater. Sectional track may include built-in roadbed (as Unitrack does), while flex-track is usually placed on cork or flexible foam roadbed. Track is typically glued or nailed to roadbed. See subroadbed.

scale - Scale is the ratio of a model to the prototype (e.g., HO is 1/87 scale, meaning 1 foot on the model equates to 87 feet in the real world). It can be written with either a slash (1/150) or a colon (1:150) and the two representations mean exactly the same thing. There are a number of standard modeling scales, but sometimes the same label is used for slightly different scales. For example, “N Scale” means 1/160 scale in the U.S. and Europe, 1/148 scale in the U.K., and 1/150 or 1/160 scale in Japan, depending on the type of train being modeled. See gauge.

scratchbuilt - to create something from raw materials, rather than a kit. See kitbash.

sectional railroad, sectional layout - a sectional model railroad is similar to a modular railroad, except that it’s usually semi-permanently installed and divided into sections to allow it to be relocated. Individual sections may be built to any shape or size required, as there is no need to interconnect with sections built by someone else.

sectional track - track comprised of standard size elements that go together is called sectional track (see flex track). Beginner’s train sets have typically used this, while “serious” hobbyists tend to want a more prototypical look, and use flex-track or even hand-lay their own track (a very difficult proposition in N-scale). Kato’s Unitrack is a sectional track system.

shelf layout - a model railroad small enough to fit on a shelf, or a sectional layout whose individual sections can be stored on shelves. A shelf layout can be installed on a shelf along a wall or walls of a room, or a shelf in a bookcase or similar article of furniture.

slip switch - a switch located where two tracks cross (which would otherwise be called a diamond, but that term is never applied to a slip switch). A slip switch may be a half-slip (connecting only two of the four tracks) or a full slip (connecting on both sides of the intersecting tracks). Slip switches are common in yards and multi-track passenger stations, where lack of space prevents more spread-out individual switches and diamonds (which are simpler to build and maintain and thus preferable).

staging, staging track - track used for storing complete or partial trains waiting to be run into the scenic portion of the layout, or holding them after being run off (or both). Staging track is usually simple bare track out of sight (often called “hidden staging”).

subroadbed - the physical supporting structure below roadbed. On many layouts this is made of plywood, but rigid insulation foam or other materials may be used. Roadbed is typically glued to subroadbed.

superelevated - a prototype term for curved track with the outside rail elevated to ease passenger comfort at high speed (by letting trains lean into a turn like a motorcycle rider, although not as sharply) and to reduce rail and wheel wear. See banked and canted.

switch - see turnout.

switcher - a prototype term for a small locomotive used for moving individual cars or small strings of them, often in a yard.

switching layout - a small layout, possibly a shelf layout, where the intended operation is to move freight cars, or passenger trains, between sidings on the layout or to and from staging.

tail chaser - a model railroad layout with at least one track arranged in a continuous loop. The term is often used disparagingly by modelers who feel such layouts are “not prototypical”. My layouts are tail chasers, and one of the prototypes I model (Tōkyō’s Yamanote commuter line) is too, so thphtpt!

track - the assembly of rail and ties (and optionally roadbed) is called “track”, as distinct from an individual “rail” (although “rail” is sometimes used in a collective sense to mean “track”). See sectional track.

track-feeder - see feeder.

T-Track - a set of rules (actually there are at least two incompatible sets of rules) for creating small sectional (or modular) layouts using Unitrack.

turnout - on a prototype railroad, the track assembly that lets a train take one of two (or more) diverging routes is called a “switch” or “track switch”, but model railroads use the term “turnout”, likely to avoid confusion with electrical switches. However moving train cars around is still called “switching”. The British term is “point” or “points”. See also number.

Unijoiner - Kato’s version of a rail joiner.

Unitrack - Kato’s sectional N-scale track system.

weathered - means painted or otherwise made to look like a structure or vehicle that didn’t come straight from a paint shop. This can be done with rub-on chalks, airbrushing, dry-brushing or other techniques. Usually a sealer of a non-glossy transparent paint will be added when done to hold the material in place and remove any “shine”.

wye - a switch (turnout) that has two curved routes (normally switches will have one straight through route and one curved diverging route.