Rail transport modelling

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Model railroading (US) or Railway modelling (UK) is a hobby in which rail transport systems are modeled at a reduced scale. The modeled world includes rail vehicles (locomotives and rolling stock), tracks, signalisation, scenery (roads, buildings, vehicles, model figures and natural features such as streams, hills, canyons, etc.). The earliest forms of model railways are the 'Carpet Railways' which first appeared in the 1840s. Model trains are more realistic than toy trains.


General description

Involvement in the hobby can range from the possesing a train set to spending many hours and large sums of money on a large and exactingly executed model of a railroad and the scenery through which it passes, called a "layout." Hobbyists, called "model railroaders" or "railway modellers," may even maintain models large enough to ride (see "Live steam"). Model railroaders may find enjoyment in collecting model trains, building a miniature landscape for the trains to pass through, or operating their own railroad, albeit in miniature.

Some older scale models reach very high prices.

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An HO scale model railroad

Layouts vary from the very stylistic (sometimes just a simple circle of track) through to the 'absolutely realistic', where scale models of real places are modelled.

One of the largest of these is in the Pendon Museum in Oxfordshire, UK, where a OO model of the Vale of The White Horse as it appeared in the 1930s is under construction. The museum also houses one of the earliest scenic models ever made - the 'Madder Valley' layout built by John Ahern. This latter layout was built in the late 1930s to late 50s and brought in the era of realistic modelling;coverage in MODEL RAILWAY NEWS, and MODEL RAILROADER[!],'40s, & '50s. Bekonscot in Buckinghamshire is the oldest model village, and also includes a model railway,1930s onw. The largest model railroad track (in scale HO) in the world is Miniatur Wunderland in Hamburg, Germany [1] (

Model railway clubs exist for model railway enthusiasts to meet. Clubs sometimes put on displays of models for the general public. One rather specialist branch of railway modellers concentrates on larger scales and gauges, most commonly using track gauges from 3.5 to 7.5 inches. Models in these scales are usually hand-built and are powered by live steam, or diesel-hydraulic, and the engines are often powerful enough to haul even dozens of humans as passengers.

One particularly famous model railway club is the Tech Model Railroad Club (TMRC) at MIT, which in the 1950s pioneered the automatic control of track-switching amongst hobbyists by using advanced technology for the time -- telephone relays.

The Philosophy of Model Railways

(a simple, non-technical guide, avoiding 'railway jargon')

Whether it is a simple clockwork train on a circular track, or a huge detailed layout run to a timetable with historically accurate signals and train formations, the essence of a model railway is that it presents the appearance of a working railway. It is essentially the pursuance of this appearance which causes people to spend varying amounts of time and money creating a model railway, sometimes making it a lifetime’s project. Anyone intending to make a model railway, however, must sooner or later confront not the similarities between their model and the real thing, but the differences. Unless these differences are accepted and accommodated in some way, the model is unlikely to be successful or satisfying.

Generally speaking, the purpose of a model railway is to be interesting to see and to operate, whether the ‘interest’ depends on historical accuracy, fidelity to the appearance of the original, or complexity of operation. Those models which contain more detail, more track and rolling stock, are generally more interesting. But it is important to remember that this is not the purpose of a real railway. If the railway companies of the past could have implemented a ‘Star Trek’ method of transporting passengers and goods instantly from A to B they would quickly have abandoned the use of trains, which was always an expensive method of transport. They would never have used more locomotives or coaches than was essential to maintain their traffic, and certainly they would never have built and maintained ‘interesting’ and complex track formations, which were notoriously expensive, without first making every effort to simplify them.

There is another essential difference to be dealt with. Even the largest model railway cannot model an entire line, unless it be a cliff or miniature line. Most if not all interesting lines would ‘go off’ somewhere to connect with the rest of the system. Even a very large layout must compromise, therefore with the need to ‘disappear’ off the edge of the modelled world.

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Model Railroaders can also freelance their own locomotives and freight cars. TVS 802 is painted for the Trewsville Southern Railroad. Jason Trew photo

Many modellers begin with the urge to see trains running as soon as possible, and rush into the first type of layout that occurs to them. Many of them find too late that they have committed themselves to a design which is not going to interest them for long, or they see when halfway into construction that they would have been better to adopt a different plan, even to model a different railway altogether. Successful and satisfying layouts are almost always the result of a considerable amount of planning involving compromise and tradeoffs. This can be frustrating at first, though it can become an enjoyable pursuit in itself, but the results of a well-planned layout are usually well worth the time and effort involved.

The first stage in planning is to decide what sort of layout is wanted. All is not what it seems here, for though a large layout may seem more interesting to a beginner, it is likely to prove too exhausting in its construction and operation to be truly satisfying. On the other hand, someone who is determined to be historically accurate above all may spend an enormous amount of time in the construction of a layout which in reality had only three or four trains per day, using at the most two locomotives. It is therefore very important to decide first what one wants from a layout. Common themes include historical accuracy, detailed modelling, and operations. One popular approach is to choose a locale and a period in history, for example Virginia in the 1940s or New Mexico in the 1960s.

For many years the most popular form of layout was the ‘continuous run’, evolving from the simple ‘trainset’ or ‘toy train’ circuit of track. The advantage of this layout is that the trains do indeed run continuously, and a train can be seen running for a period of time not greatly reduced from that of a real train journey. It also avoids the need to have a ‘rest of the world’ located offstage somewhere. The disadvantage, however, is that it is most unrealistic. No real train appears again from the same direction after a few seconds! Modellers who really wish to see main line trains run for lengthy periods, however, may suspend their disbelief, or compromise with this aspect of the model, in the interests of getting what they want.

The other extreme from this type of layout is the ‘branch line terminus’, also known as a point-to-point line. The advantage of this layout is that while simple to operate and requiring few locomotives, it is realistic in operation. The trains arrive and depart like a real branch-line train. Much satisfaction can be gained from the inclusion of a small goods yard and the visit and shunting of the daily goods train. The disadvantage is that all the rolling stock must have an ‘elsewhere’ to go to, off the layout, representing the ‘rest of the system’. This is commonly known as a ‘fiddle yard’ where all traffic intended to run onto the layout is assembled by hand, and of course this requires extra space, often as much as the ‘real’ or modelled part of the layout. Another disadvantage is that the operation can become very unvaried after a while. Modellers whose urge to start a layout came from watching long expresses racing by will not find this very satisfying.

Many layouts follow a middle course, and model a stretch of line with ‘rest of the world’ at both ends. This is both realistic and satisfying to watch. Here too, though, there are disadvantages: two ‘fiddle yards’ are required, one at each end, and the amount of rolling stock required to represent a realistic selection of traffic is considerable. The modeller with time and space to spare will, however, find this a source of satisfaction.

To decide which layout to build requires some decision as to the 'philosophy' of one’s railway, and time spent thinking over the alternatives and their relative merits will be a good investment. The design, size and character of a layout can be very different according to what aspect of railways interests the modeller. Some are interested mainly in highly detailed scenery and buildings, realistic trackside vehicles and figures, others may be interested in signalling, and will want a fully signalled layout. Others will be happy with no signals at all, however unrealistic this appears. Most modellers seem to prefer locomotives in action above all else, and the other aspects of the model take a backward place. Whatever it is, much time and effort will be saved in construction if this is decided in advance of starting.

Methods of power

Model railway engines are generally operated by low voltage DC electricity supplied via the tracks, but there are exceptions, such as Märklin and Lionel Corporation, which use AC.

Although DC power with the positive and negative charges on the two rails is the most common method of power, Märklin and Lionel use AC power on a three-rail system where the middle rail is powered and the outer rails act as a common, or ground. To eliminate the unrealistic appearance of the third rail, Märklin conceals the rail as studs in the track. American Flyer is another exception, which used AC power on two-rail track.

Early electric trains ran on battery power, because few homes in the late 19th and early 20th centuries were wired for electric power. Today, inexpensive train sets running on battery power are once again becoming more common, but these are generally regarded as toys and are seldom used by hobbyists. Battery power is also used by many garden railway and larger scale systems both because of the difficulty in obtaining reliable power supply through the rails when outdoors and because the high power consumption and thus current draw of large scale garden models is more easily and more safely met with lead acid batteries

Model railways in the early twentieth century ran using wind-up clockwork or miniature steam engines instead; and steam or clockwork driven engines are still sought by collectors.

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Mamod live steam locomotive and train on a garden railway layout

Live steam is often built in large, outdoor gauges, and is also readily available in G scale, 16mm scale and can be found in O and H0 scale. Hornby Railways produce a live steam locomotive in OO scale, development of work by some very dedicated modellers who hand-built live steam models in HO/OO, OO9 and N, and there is even one in Z in Australia.

Occasionally the topic of gasoline-electric models, patterened after real-life diesel-electric locomotives, comes up among dedicated hobbyists, but these locomotives are not commercially available. Larger scale petrol-mechanical and even petrol-hydraulic models are commercially available but these are unusual and significantly pricier than the more usual electrical power.


The first clockwork[spring-drive] and live steam locomotives simply ran until they ran out of power, with no way for the operator to stop and restart the locomotive or to vary its speed. The advent of electric-powered trains, which first appeared commercially in the 1890s, allowed one to control the train's speed by varying the current,by altering the voltage. As trains began to be powered by transformers,& rectifiers more sophisticated throttles appeared, and soon trains powered by AC started containing mechanisms that caused the train to change direction and/or even go into a neutral gear when the operator cycled the power. Trains powered by DC can change direction simply by reversing polarity.

Electric power also permits control by dividing the layout into electrically isolated blocks, where trains can be slowed or stopped by lowering or cutting the power to a block. Dividing a layout into blocks also permitted operators to run more than one train on a layout with much less risk of a fast train catching up with and hitting a slow train. Blocks can also trigger signals or other animated accessories on the layout, adding more realism (or whimsy) to the layout. Three-rail systems will often insulate one of the common rails on a section of track, and use a passing train to complete the circuit and activate an accessory.

Many modern day model railways use digital techniques and are computer controlled. The industry standard command system is called Digital Command Control, or DCC. Some less-common closed proprietary systems also exist.

Scales and gauges

The size of the engines depends on the scale being used. The four major scales used are: G scale, O, HO (in Britain, the similarly sized OO is used), and N, although there is growing interest in Z. Somewhat different scales are used in Continental Europe. Engine sizes can vary from around 700 mm (28") tall for the largest ridable Live steam scales, down to matchbox size for the smallest ones in Z-scale. A typical HO engine is around 50 mm (2") tall, and 100 mm to 300 mm (4" to 12") in length.

G scale because of its larger size is most often used for outdoor modelling. It is easier to fit a G scale model into a garden landscape and still keep the scenery proportional to the size of the trains running through. O, HO, and N gauge are more delicate due to their size and are used more often indoors.

The words scale and gauge seem at first to be used interchangeably in model railways, but their meanings are different. Scale is the model's measurement as a proportion to the original, while gauge is the measurement between the two running rails of the track.

At first, model railways were not to scale. Manufacturers and hobbyists soon arrived at de facto standards for interchangeability, such as gauge, but trains were only a rough approximation to the real thing. See NEM and NMRA. Official scales for the various gauges were soon drawn up, but the scales were not at first at all rigidly followed, and were not necessarily correctly proportioned for the rail gauge chosen. O (zero) gauge trains, for instance, operate on track that is too widely spaced, while the British OO standards operate on track that is significantly too narrow. Most of the commercial scales also have standards that include wheel flanges that are too deep, wheel treads that are too wide, and rail tracks that are too large.

Later on, groups of modellers became dissatisfied with these inaccuracies, and developed finescale standards in which everything is correctly scaled. These are used by dedicated modellers but have not generally spread to mass-produced equipment in part because the inaccuracies and overscale properties of the commercial scales are neccessary to ensure reliable operation in the hands of consumers as well as experts, and also to allow for shortcuts neccessary for cost control.

The most common scales and gauges in Europe and the USA are:

Name Scale Gauge
in mm
Live steam1:24 to 1:863 to 190 Ridable, outdoor gauges, named according to their gauges in inches, and scale in inches per foot, for example 7-1/4" gauge, 1.5" scale. Private and public (club) tracks exist in many areas. Locomotives and rolling stock are almost exclusively handcrafted by the hobbyists themselves, who may spend many thousands of hours on a model. Kits and castings are available from a few manufacturers.
Wide gauge1:26.59 or 1:28.2553.975 Called Standard Gauge by Lionel, who trademarked the name. Other manufacturers used the same gauge and called it Wide Gauge. Not widely produced after 1940. Gauge No. 2 using track of gauge 2" (50.8 mm) was one of the standard model gauges in 1909.
16 mm scale1:19.0532 This scale was first developed in the UK in the 1950s to depict 2 foot narrow gauge prototypes utilising 32 mm or "O gauge" track and wheels, but really took off in popularity during the 1960s and 70s. Originally, it was mostly used as an indoor modelling scale, but has also developed as a popular scale for garden railways of narrow gauge prototypes. Some manufacturers that produce models depicting North American 2 foot narrow gauge prototypes have also adopted this scale for use alongside the near-compatible Fn3 (15 mm) scale on 45 mm track already popular in the US. Both electric, battery and live steam propulsion is used to power model locomotives in this scale, and is supported by a growing range of commercially available ready-to-run models, kits and parts.
Fn3 scale1:20.345 Similar to G Scale below, this scale also 45 mm gauge track, and used for both indoor and garden railways of narrow gauge prototypes. The scale of 1:20.3 was developed to depict North American 3 foot gauge trains in exact proportion to their correct track gauge whilst using 45 mm gauge model track. It equates to 15 mm = 1 foot scale. Increasingly popular for both electric and live steam propulsion of model locomotives, with an ever growing range of commercially available ready-to-run models, kits and parts. Fn3 scale, together with G scale and ½" scale, are commonly and collectively referred to as "Large Scale" by many modellers.
G scale1:22.545 Name derived from 'G'ross, which means "big" in German. G is generally used for garden railways of narrow gauge prototypes, and uses the same track gauge as Gauge 1 below. The scale of 1:22.5 scales the trains correctly for the European narrow gauge standard of 1 metre. The gauge 3 scale on gauge 1 track.
½" scale1:2445 Similar to G Scale above, this scale also runs on 45 mm gauge track, and is generally used for both indoor and garden railways of narrow gauge prototypes. The scale of 1:24 in combination with 45mm track is an attempt to model North American and UK 3 foot or 3 foot 6 inch narrow gauge trains in better proportion to the rails they run on.
Gauge 1 or I scale
3/8" scale
1:3245 This large scale, once rarely seen indoors in modern use but frequently used for modelling standard gauge trains outdoors, is making a come-back. The Japanese firm of Aster offers ready-to-run gas-fired livesteam models. Gauge 1 has seen something of a remarkable revival in recent years after decades of near extinction commercially, with a growing number of smaller UK manufacturers offering electricly powered locomotive and rolling stock kits and parts for (mostly) indoor layout use. Some manufacturers offer so-called Gauge 1 items in 1:30.48 scale (10 mm = 1 foot) that also run on 45 mm gauge track.
O scale1:43.5 or 1:45 (Eur)
1:48 (US)
32 Name originally was '0' (zero), '1' through '6' were already in use for larger scales. In the US, this is frequently a 'toy train' scale rather than for exact scale modellers.
Proto:481:4829.90 These are to the same scale as US O gauge but are accurate scale models in all dimensions including track and wheels.
ScaleSeven1:43.533 Exact scale version of British O gauge.
S gauge1:6422.42 Originally called "H-1" because it was half the size of Gauge 1 (1:32), the "S" name is derived from 'S'ixty-fourth. In the US, American Flyer toy trains are to this scale, but it is also used for more precise modelling and supported by several manufacturers. In the UK, S scale modelling is largely the preserve of a dedicated few hand-building models or using a small number of available kits and parts, mostly depicting standard gauge prototypes but also narrow and broad gauge subjects too. The UK-based S Scale Model Railway Society is the oldest scale support society in the world, being first established in 1946. This scale is also popular in North America to depict 3 foot narrow gauge prototypes (using dedicated 14.28 mm gauge track and known as "Sn3"), and elsewhere to depict the 3 foot 6 inches narrow gauge railways (using HO 16.5 mm gauge track and known as "Sn3½") of South Africa, Australia and New Zealand.
OO gauge1:76.216.5 This scale is today the most popular modelling scale in the UK, although it once had some following in the US (on 19 mm gauge track) before WW2. OO or "Double-Oh", together with EM gauge and P4 standards are all to 4 mm scale as the scale is the same, but the track standards are incompatible. OO uses the same track as HO (16.5 mm gauge), which is not correct for this slightly larger scale, but it is the most common British standard for ready-to-run trains. In Britain there exists The Double O Gauge Association to promote this scale. Narrow gauge modelling of 3 foot prototypes ("OOn3" on 12 mm track) was once popular although now less so, but the depiction of approximately 2 foot or 2 foot 6 inch prototypes ("OO9" on 9 mm track) has a greater following with a flourishing supply of kits and parts from many small UK-based suppliers.
EM gauge1:76.218 EM gauge was an earlier attempt in the 1950s to improve the inaccuracies of OO gauge, with wider, more accurate track at 18 mm between the rails, but still narrower than the correct gauge. Many early finescale modellers in the UK used this standard and it is still in use (albeit with the gauge now slightly adjusted to 18.2 mm), although P4 has superseded it for most. The UK-based EM Gauge Society exists to supports modellers of these standards.
P4 Standards1:76.218.83 During the early 1960s a group of British modellers evolved a finescale standard at 4 mm to the foot with near exact scale track and wheels. This was later formalised by the founding of the Protofour Society which attempted to exercise strict control over the manufacture of specialised parts to these standards. A separate group, the Scalefour Society, was formed in the 1970s promoting an even finer exact scale standard called S4, but encouraged a wider group of manufacturers to support its aims. Later, in the 1980s, sanity prevailed and both societies merged, adopting the original P4 standards by which it continues to be known (and not S4), but encouraging a wide manufacturing base and retaining the society name of Scalefour. The "P" stands for "Proto[type]" and these standards are intended to be applied to any prototype gauge in 4 mm scale, which for standard gauge track happens to work out at 18.83 mm. P4 standards have also been used to depict narrow and broad gauge railways on a variety of model gauges. In the UK many kits include parts to enable them to be built to OO, EM or P4 gauges and there is a flourishing "cottage industry" of small business kit and parts suppliers. EM gauge was an earlier attempt to improve OO with the more realistic (but still inaccurate) gauge of 18 mm (later 18.2 mm).
HO scale1:8716.5 This is the most popular model railway scale in the world (except in the United Kingdom). The name is derived from 'H'alf 'Zero', and the Normen Europäischer Modelleisenbahnen (NEM) define the scale as exactly 1:87, the US NMRA as 1:87.1 (3.5 mm : 1 ft). Not surprisingly, there is a vast selection of ready-to-run, kits and parts for locomotives, rolling stock and scenic items from many manufacturers depicting trains from all around the world. Narrow gauge modelling of North American 3 foot gauge ("HOn3" on dedicated 10.5 mm track) and 2 foot gauge ("HOn30" - actually 30 inch gauge - on 9 mm track), European metre gauge ("HOm" on 12 mm track) and 750/760 mm gauge ("HOe" on 9 mm track) has become very popular. In Britain, HO was popular before WW2 but lost out to OO and it virtually disappeared from the modelling scene, except for those modelling European and North American prototypes. A few commercial models depicting British prototypes were manufactured during the 1970s (usually in error or ignorance by foreign firms), which, together with a few items suitable for conversion to British outline, prompted some modellers to revive British HO modelling in the 1980s, culminating with the establishment of the British 1:87 Scale Society in the mid-1990s. Today, British HO is making a modest come-back.
Proto:871:8716.5 An alternative finescale standard for HO, with wheels and track that correspond with the prototype's, taking its lead from the establishment of P4 standards in the UK.
3 mm scale1:101.112 and 14.2 A UK version of TT introduced by the firm Tri-ang in the late 1950s (then known as "TT-3") and supported by several other firms offering kits and parts. Commercial production by Tri-ang petered out in the late 1960s, but "The 3mm Society" was established in 1965 and a dedicated membership has kept this UK scale alive. TT-3 was originally designed to run on TT's 12 mm gauge track, but latterly the more accurate gauge of 14.125 mm (popularly known as "14.2") has been adopted by some seeking more accuracy. Like the intermediate EM gauge standard in 4mm scale, some modellers in 3 mm scale developed 13.5 mm track gauge, but this has largely been superseded by 14.2 mm gauge. Both 3 foot narrow gauge (using 9 mm gauge track) and Irish 5 foot 3 inch broad gauge (using 15.76 mm gauge track) are also modelled in 3 mm scale in the UK.
TT scale1:12012 Name stands for 'Table Top' - no longer widely used but making a come-back. There is a small following in the US, and a large following in Germany, especially in the former DDR.
N scale1:148
9 As with 1:160 N scale below, name derived from 'N'ine millimeter track gauge, but the scale is a slightly larger at 2 1/16th mm = 1 foot. Developed as a UK commercial version of N scale in the late 1960s, models are restricted to depicting UK prototypes. Although nominally to 1:148 scale, some manufacturers took significant liberties with exact scale to suit production limitations. Despite the collapse of Graham Farish and its subsequent sale to Bachmann there is a growing choice of ready-to-run models available. A few commercial kits and parts to fit Z scale loco mechanisms and wheels are offered by the UK firm Peco to enable narrow gauge prototypes to be modelled.
N scale1:150
9 N scale in Japan is normally built to this scale, even though most rail lines are narrow gauge (3'6"). Because the Bullet train lines are standard gauge (4'8 1/2"), models of these are usually built to the scale of 1:160.
2 mm scale1:1529.42 British finescale standard, older than N scale, being first used as long ago as 1927 with photos and articles published in the model press. Became more popular in the 1950s, with The 2mm Scale Association established by 1960 to promote and support modellers in this tiny scale, and it remains very active in the UK to this day. In recent years the finer track and wheel standards of 2 mm scale (but not the gauge) have also been adapted for use in 1:160 N scale (on 9 mm gauge) in Europe and called "fiNe", and is supported by the FREMO modelling organisation. Since the 1950s, incredibly, 2 mm scale has been used to depict narrow gauge prototypes on various track gauges down to 4 mm, but almost everything has to be hand-made, unless some Z scale parts are used.
N scale1:160
9 Name derived from 'N'ine millimeter; this is the second most popular scale worldwide. N scale developed by the German firm of Arnold Rapido in the early 1960s, and was rapidly adopted worldwide as the most popular small-scale modelling choice. In recent years, finer profile wheels and track have been developed by some manufacturers (although the gauge and standards have remained the same). Huge range of ready-to-run models available as well as supporting kits and parts. With the introduction of an even smaller Z scale in 1972, the modelling of narrower gauge prototypes has been possible using that scale's locomotive mechanisms, track and wheels. In North America the depiction of 3ft gauge railroads in N scale using Z scale track is known as "Nn3"; in Europe, metre gauge modelling in N scale is known as "Nm".
Z gauge1:2206.5 The smallest commercially available model railway scale, introduced by the German firm of Märklin in 1972 depicting German and other European prototypes. In North America the firm of Micro Trains and others has introduced a range US prototype models. On both continents, a growing range of kits and scenic accessories has become available to help increase its popularity. In Europe a few enterprising manufacturers have developed even smaller metre gauge models (but still in 1:220 scale) known as "Zm" on 4.5 mm gauge track, in this smallest of commercial scales.

Model railway manufacturers

Famous model railroaders

See also

External links

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