Rail Transport Modelling Scales - History of Scale Standards

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 gauges became de facto standards 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 1950s and 1960s when many new model railway accessories manufacturers were born and to whom the standard conformity was vital.

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 that certain parts be made oversize. A typical example is the wheel flanges, which must be proportionally higher in smaller scales to ensure that lighter and smaller models do not derail easily as they would if universal flange proportions were used in all the scales. For instance, a Z scale wheel flange as defined in the NEM standard should be about 9% of the scale nominal standard gauge (6.5 mm/0.256 in), whereas the same standard gives only 5% for 45 mm (1.772 in) standard gauge I scale.

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 have developed alternative scale standards where prototype proportions are maintained to the extent possible. These alternative standards are called finescale standards. Finescale standards are very much restricted to discerning hobbyists since, by definition, finescale model railways are generally less reliable and more expensive to manufacture, which makes them unsuitable for mass-production products.