Rail Transport Modelling Scales

Model Railway scales are standardized worldwide by many organizations and hobbyist groups. Some of the scales are recognized globally while some others are less wide-spread and in many cases, virtually unknown outside their circle of origin. Globally the two dominating standard organizations are NMRA in North America and MOROP in Europe with its' NEM standard. The majority of commercial model railway equipment manufacturers base their offerings on NEM or NMRA standards in most popular scales. Worldwide the most popular scales are HO , N , O , G , TT and Z . In addition to these, there are several less well known scales, significant in their own speciality areas such as Live Steam Garden Railroad ing.

The terms '' Scale '' and '' Gauge '' are often confusingly misplaced in model railways, but there is an important difference. ''Scale'' means the ratio between a unit of measurement on a model compared with a unit of measurement in corresponding full size prototype. Gauge, on the other hand, is the distance between the two running rails of the track. In full size prototype, a railway may have tracks of normal gauge (1435 mm in most countries), but there are also narrow gauge railways and even narrower industrial railways. In a similar manner, a scale model railway may have several track gauges in one scale.

HISTORY OF SCALE STANDARDS

The first model railways were not built to any particular scale and were more like toys than miniature representations of the full size prototype. Eventually, the authenticity of models grew and benefits of standardization became more obvious. The most significant and the most basic area of standardization was the model Track Gauge . At first, certain Track Gauges became '' De Facto '' Standard s in hobbyist and manufacturer circles. While the first unofficial standard gauges made interchangeability possible, the rolling stock were still only a rough approximation of the full scale prototype.

Eventually the unofficial or manufacturer specific scale standards became more established and were adopted by various model railway standardization bodies such as NMRA and MOROP . However, despite of existing scale and gauge standards they were very often poorly implemented in design and manufacturing processes with commercial manufacturers before the World War II . The conformity to scale standards grew strongly in the 1950's and 1960's when many new model railway accessories manufacturers were born and to whom the standard conformity was vital.

It should be noted, that for most standardized model railway scales, the nominal scale reduction ratio is not applied systematically to all the components of a scale model railway and normally the standards give scale specific design guidelines for all the scales they cover. Reliability of operations requires certain parts to be designed oversized. A typical example are the wheel flanges which must be proportionally higher in smaller scales to ensure that lighter and smaller models do not derail easily which would be the case if universal flange proportions were used in all the scales. For instance, a Z Scale wheel flange as defined in NEM -standard should be about 9% of the scale nominal standard gauge (6.5 mm) whereas the same standard gives for 45 mm standard gauge I Scale only 5%.

While standards that put the emphasis on operational reliability satisfy most users and the industry, certain groups of dedicated hobby modellers who were dissatisfied with the scale inaccuracies in the name of reliability, developed alternative scale standards where the proportions of the full size prototype were maintained as much as possible. These alternative standards are called Finescale standards. Finescale standards are very much restricted to hobbyists circles since, by definition, finescale model railway is generally less reliable and more expensive to manufacture which makes it unsuitable for mass production marketed to consumers. However, there are some commercial finescale manufacturers that produce remarkably detailed and expensive handmade scale miniatures for connaisseurs in small series.

SCALES

SEE ALSO

EXTERNAL LINKS

http://www.spikesys.com/Modelrr/scales.html – Contains more specifics about some of the scales

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Rail Transport Modelling Scales