Railway modelling or model railroading is a hobby in which rail transport systems are modelled at a reduced scale.
G scale or G gauge, also called large scale, is a track gauge for model railways which is often used for outdoor garden railways because of its size and durability. G scale trains use a fixed track gauge of 45 millimetres (1.75 in) to accommodate a range of rail transport modelling scales between narrow gauge (~1:13‒1:19‒1:20), metre gauge (1:22.5), Playmobil trains (~1:24), and standard gauge (~1:29–1:32).
OO gauge or OO scale is the most popular standard gauge model railway standard in the United Kingdom, outside of which it is virtually unknown. OO gauge is one of several 4 mm-scale standards, and the only one to be marketed by major manufacturers. The OO track gauge of 16.5 mm corresponds to prototypical gauge of 4 ft 1+1⁄2 in, rather than 4 ft 8+1⁄2 in standard gauge. However, since the 1960s, other gauges in the same scale have arisen—18.2 mm (EM) and 18.83 mm (Scalefour)—to reflect the desire of some modellers for greater scale accuracy.
O scale is a scale commonly used for toy trains and rail transport modelling. Introduced by German toy manufacturer Märklin around 1900, by the 1930s three-rail alternating current O gauge was the most common model railroad scale in the United States and remained so until the early 1960s. In Europe, its popularity declined before World War II due to the introduction of smaller scales.
HO or H0 is a rail transport modelling scale using a 1:87 scale. It is the most popular scale of model railway in the world. The rails are spaced 16.5 millimetres (0.650 in) apart for modelling 1,435 mm standard gauge tracks and trains in HO.
N scale is a popular model railway scale. Depending upon the manufacturer, the scale ranges from 1:148 to 1:160. Effectively the scale is 1:159, 9 mm to 1,435 mm, which is the width of standard gauge railway. However the scale may vary to simulate wide or narrow gauge rail. In all cases, the gauge is 9 mm or 0.354 in. The term N gauge refers to the track dimensions, but in the United Kingdom in particular British N gauge refers to a 1:148 scale with 1:160 track gauge modelling. The terms N scale and N gauge are often inaccurately used interchangeably, as scale is defined as ratio or proportion of the model, and gauge only as a distance between rails. The scale 1:148 defines the rail-to-rail gauge equal to 9 mm exactly, so when calculating the rail or track use 1:160 and for engines and car wheel base use 1:148.
S scale is a model railroad scale modeled at 1:64 scale, S scale track gauge is 22.48 mm (0.885 in). S gauge trains are manufactured in both DC and AC powered varieties. S gauge is not to be confused with toy train standard gauge, a large-scale standard for toy trains in the early part of the 20th century.
Protofour or P4 is a set of standards for model railways allowing construction of models to a scale of 4 mm to 300 mm (1 ft) (1:76.2), the predominant scale of model railways of the British prototype. For historical reasons almost all manufacturers of British prototype models use 00 gauge. There are several finescale standards which have been developed to enable more accurate models than 00, and P4 is the most accurate in common use.
OO9, often also denoted as 009 or 00-9 and commonly pronounced as Double-Oh Nine, is a model railway scale and gauge combination of 4 mm scale and 9 mm gauge tracks, which models a prototype track gauge of 2 ft 3 in. It is a common choice in the United Kingdom for the modelling of narrow-gauge railways whose prototype gauges lie approximately between 2 ft and 2 ft 6 in. The 9 mm track gauge is used by N gauge model railways, a common commercial scale, which means that a selection of wheels, track, and mechanisms is readily available.
Z scale is one of the smallest commercially available model railway scales (1:220), with a track gauge of 6.5 mm / 0.256 in. Introduced by Märklin in 1972, Z scale trains operate on 0–10 volts DC and offer the same operating characteristics as all other two-rail, direct-current, analog model railways. Locomotives can be fitted with digital decoders for independent control. Model trains, track, structures, and human/animal figures are readily available in European, North American, and Japanese styles from a variety of manufacturers.
4 mm scale is the most popular model railway scale used in the United Kingdom. The term refers to the use of 4 millimeters on the model equating to a distance of 1 foot (305 mm) on the prototype (1:76.2). It is also used for military modelling.
PECO is a UK-based manufacturer of model railway accessories, especially trackwork, based at Pecorama, Beer in South Devon, England.
On30gauge is the modelling of narrow gauge railways in O scale on HO gauge track in 1:48 scale ratio by American and Australian model railroaders, in 1:43.5 scale ratio by British and French model railroaders and 1:45 by Continental European model railroaders.
O14 is a set of model railway standards for accurately modelling 2 ft narrow-gauge railways in 1:43.5 using 14 mm (0.551 in) gauge track.
Rail transport modelling uses a variety of scales to ensure scale models look correct when placed next to each other. Model railway scales are standardized worldwide by many organizations and hobbyist groups. Some of the scales are recognized globally, while others are less widespread and, in many cases, virtually unknown outside their circle of origin. Scales may be expressed as a numeric ratio or as letters defined in rail transport modelling standards The majority of commercial model railway equipment manufacturers base their offerings on Normen Europäischer Modellbahnen (NEM) or National Model Railroad Association (NMRA) standards in most popular scales.
Gauge conversion is the changing of one railway track gauge to another.
3 mm scale, also known as 3 mm finescale, is a model railway scale of 3 mm : 1 ft (305 mm) used for British prototypes. Introduced as British TT gauge, it sits approximately halfway between British N gauge and OO gauge but is not as popular as either and there is no longer any mass manufacturer ready-to-run support. When TT gauge model railways were developed for British prototypes, in order to fit the small British prototypes, the scale was enlarged but without altering the 12mm gauge. The result, British TT gauge, is too narrow. This led to the development of 14.2 mm gauge 3mm finescale. Thus two finescale standards were developed. By far the more common of these is 14.2 mm gauge track, which is accurate. Some modellers choose to use slightly narrower 13.5 mm track due to the necessary oversize motion of outside-cylindered steam locomotives.
In automobiles, the axle track is the distance between the hub flanges on an axle. Wheel track, track width or simply track refers to the distance between the centerline of two wheels on the same axle. In the case of an axle with dual wheels, the centerline of the dual wheel assembly is used for the wheel track specification. Axle and wheel track are commonly measured in millimetres or inches.
