Model Railroading has been successful as a hobby for many reasons, not least because it is complex and challenging (and fun!). But one of the reasons for its success is that you can buy your locomotives, cars, track and power supply from any number of manufacturers and be confident that they will work together. This doesn’t happen by coincidence. It’s the result of hard work by many people over decades of time. And like most things that work well, the majority of us take it for granted until something goes wrong. But I think it’s worth mentioning a bit about where our standards came from, why they exist today, and why it matters.

And I’ll freely admit, this is something of a U.S.-centric view, because that’s where I live and so my information sources are likely somewhat biased. I’ve tried to call out where I know things were developed elsewhere first, or independently, but I’m sure I’ve missed many of those.

Early History

Model Railroading as a hobby traces its roots back to the toy trains of the middle 1800’s, not long after the first real ones appeared. Some of these could be quite complex, and wind-up and even steam-powered models existed, but every manufacturer did things their own, and incompatible, way.

The first multi-vendor standards (for gauges 1-5) were introduced by Märklin in Germany in 1891, and they soon became international standards. Use of 1 Gauge continues to this day, and the track standard is used by G Scale (in 1 Gauge at 1:32 scale the track is standard gauge, in G scale at 1:22.5 it is meter gauge and suitable for many European railroads).

In the U.S., “Wide Gauge” was introduced by Lionel in 1906, and became multi-vendor. This remained in use until around 1942, although popularity declined significantly in the 1930’s following the rise of O scale as a popular scale in the 1920s, and the increased popularity of HO scale in the 1930s.

Both of these were manufacturer-defined standards. They were made by companies who wanted to sell products, and saw an advantage in being compatible with other manufacturers to enlarge their potential market.

In 1909, Model Railways and Locomotives, the first journal dedicated to model railroading began publishing (in Britain). This, I think, marks the beginning of the hobby becoming aware of itself, with modelers discussing things with each other, rather than merely buying what was available and using it alone or with a few close friends. And the title points out that even then, it was the railway (or railroad as an American would say) and not simply the train that was being modeled.

Formal Standards

Industry standards set by one vendor and adopted by others, tended to be concerned with fairly basic interoperability issues: How far apart are the rails? What scale is the model?

Real railroads have standards for all sorts of things, from the height of trains to the weight per unit length of rail. These are required for the railroad to operate safely and reliably. Once the hobby moved from making and running models of trains to modeling a railroad, it’s not too much of a jump to move beyond basic standards needed to sell interoperable trains, to standards needed to accurately replicate the prototype and to make operating a railroad, as opposed to running one train, a practical pursuit.

Informal standards set by hobbyists addressed the problem of modeling a railroad. These began with club-level activities. Identifying the first is problematic. In the U.S., the New York Society of Model Engineers (formed 1926) lays claim to being the first club, and produced standards. Many of its members went on to be active in the NMRA. But informal standards only go so far. They dictate limits on what a club member should do (and to an extent what products they should buy), but don’t address how a manufacturer should build products, except very indirectly.

Formal standards, issued by some body recognized by both modelers and manufacturers, are what are needed to define what characteristics are important to the majority of modelers. Manufacturers aren’t obligated to conform to such standards in the usual case. They meet them because they see a financial advantage in meeting the defined needs of a majority of modelers. To be successful, there needs to be wide agreement on such standards. They can’t simply reflect the views of modelers in one club or one geographic region. Standards need to exist on a national or supra-national level, and they need to be inclusive. Standards that only meet the needs of a subset of modelers (e.g., finescale standards) are much less interesting to a manufacturer looking to sell products to the largest audience possible.

Standards are, as a result, an exercise in compromise. This is why most model railroad standards are about “good enough”, not “exact”, replication of the prototype. That doesn’t mean that standards about niche issues, like finescale standards, aren’t important. But it’s why these will always exist alongside more relaxed standards serving a wider audience.

Standards and Standards Bodies for Model Railroading

The National Model Railroad Association (NMRA) was formed in the U.S. in 1935, and one of its early proponents was Al Kalmbach, publisher of Model Railroader magazine, which gained the organization widespread visibility and an interested and active membership in the formative years of scale model railroading. This, I’ll argue, was a key to its success: it represented modelers across an entire country (and later continent, and still later even beyond that). The NMRA was a membership organization, open to modelers. But it also had close ties to many of the early manufacturers as well. Its standards today need to be ratified by the membership, and this was likely true in the beginning as well.

The NMRA, unfortunately, is an organization that seems to live in the present, with no published organizational history and no history of changes to their standards that I’m aware of (and I’ve been a member for two decades, so if they’ve got one, it’s a well-kept secret). I haven’t even been able to find out when they published their first standards, although it appears that at least some were in place by the end of the Second World War in 1945. Nor do I know exactly what those standards covered, although it is likely that they were mostly about matters of track and wheel dimensions, since those had the most direct and immediate effect on operation, and even today those seem to be the standards most often mentioned. That said, there’s probably a lot of documentation of the early work in their library and if I really cared I could ask.

I do know, from a Model Railroader Clinic article from their December 1947 issue that sometime prior to that the NMRA had standardized motor power to 12 Volts DC or 16 Volts AC for HO, OO, S and O scales (the popular scales of the day). They’d eventually back away from that, and in the current (S-9, August 1984) standard there’s no specific voltage mandated, only a minimum applicable to all scales (“not less than 12 volts DC”).

The British Railway Modelling Standards Bureau (BRMSB) published a booklet of standards for “Rails - Track - Wheels - Buffers - Conductor Rails” in 1950. The publisher was the Model Engineering Trade Association, so this may have been an association of manufacturers rather than a hobbyist association. The standards, regardless of origin, were influential, although some manufacturers continued working to their own designs. From comments I’ve seen, some perceived these standards as too narrowly-defined, and not serving the wider industry, and this may be why that body seems to have been less successful over the long term than others.

Although I’ve seen online information that the BRMSB was founded in either 1948 or 1941, and in the latter case that they had published standards by 1944, it would appear that the organization was actually formed in 1936 (Harrington article, citing an editorial in Model Railway Constructor magazine, volume 3, number 26, April 1936, pg. 85). This makes it essentially as old as the NMRA. However I can’t find any definite reference to published standards before the 1950 booklet (which I don’t have a copy of, but have seen in an Amazon used book listing). The organization seems not to have survived, although I can’t find anything specific about its end either.

The Australian Model Railway Association (AMRA) formed in 1951, and using local manufacturers’ information, as well as referring to the NMRA and BRMSB standards, codified and published their own member-approved standards in 1952.

The European Union of Model Railroad and Railroad Friends (MOROP) was formed in 1954 in Genoa Italy, and today publishes the NEM (Normes Européennes de Modélisme) standards, more formally known as “The Norms”. It drew on some pre-existing national standards within Europe, as well as on the BRMSB and NMRA standards, and likely also from AMRA as they were in communication from 1953 (per AMRA history). I don’t have an exact date for the first publication, but it was probably not long after 1954.

Today the NMRA and MOROP continue to work closely to ensure that their standards remain compatible, although they each publish their own standards and there are some minor differences in the way things are defined. AMRA also continues to publish their own standards for certain things, referencing (at least in some of them) MOROP’s NEM standards.

These are hardly all of them. Many specialist groups publish standards for single things, like modular railroads in a specific scale, or “finescale” standards that are intended to more accurately model the prototype rather than simply being interoperable in the manner of NMRA and NEM standards. These kinds of standards, however, more often apply to behavior by modelers rather than behavior by manufacturers (although there are manufacturers of products that, for example, conform to specific finescale standards).

And note that standards in model railroading are for the most part voluntary. Some of them may reflect local laws (such as those for allowable voltage on exposed rails), but companies remain free to ignore them if they don’t think following the standards is in their best interest. Despite N-scale being widely defined as 1:160 scale, Japanese manufacturers use 1:150 scale for models of domestic trains, and British manufacturers use 1:148 scale, both likely for historical reasons, meaning so that new models will remain compatible with ones their customers already own.

Creating Standards

Often formal standards were little more than existing practice by one or more manufacturers, formalized for all to follow. But in many cases work was done to improve the common practice to avoid problems, and standards are often tightly interwoven (e.g., the space between rails in a track switch needs to be coordinated with the tread size and flange depth of model train wheels to avoid derailments). It is not enough to simply rubber-stamp one manufacturer’s design, although that has been done.

Often something entirely new would be introduced by one manufacturer, and largely adopted as a standard, but only after careful review and often with minor changes to improve reliability or compatibility. This is essentially what happened with both N-Scale trains (today’s standards are largely based on early models from Arnold) and DCC control systems (Lenz’s system was adopted, although not without modifications).

Without this kind of review and adjustment a manufacturer’s standard isn’t necessarily going to be the best solution for modelers. Take, for example, British OO scale (1:76 scale), which uses HO (1:87 scale) track: this is what the 1920’s model-making companies used, to avoid creating yet another track size. It met their need for interoperability at a low cost, and there wasn’t any standards body at the time to say “no, it does’t meet our need for trains to look ‘right’ relative to the track they are on”.

One typical aspect of the hobbyist-organization standards is that proposed standards must be approved by a member vote before final adoption. This ensures, or at least is supposed to ensure, that standards meet the needs of the hobbyists. Widespread apathy about the value of standards tends to undercut this.

Standards are a crucial part of our hobby. Even if you don’t participate in forming them, you can join a standards-making hobbyist organization serving your part of the world and vote on proposed standards published by your organization. And if you do that, then you’ll be making the hobby just a little bit better for modelers who come after you.


AMRA (Australian Model Railway Association) website.

AMRA - It’s [sic] formation and progress to May 1954, by Tim Dunlop, originally published in the AMRA Journal No. 97, May-June 1972 (per online text)

History of the New York Society of Model Engineers (website)
The NYSME was the first U.S. model-railroading club, and its members went on to become prominent in the larger hobby. It developed early standards before the formation of the NMRA.

Miniature Railways and Cultural Microcosms, by Ralph Harrington (online copy)
This is a very academic essay about the sociology of model railroading, but it contains some interesting details of early British modeling history.

MOROP Website (English), and particularly NEM 001 (French edition).

NMRA (National Model Railroad Association) website.

The Railway and Modernity: Time, Space, and the Machine Ensemble edited by Matthew Beaumont, Michael J. Freeman (page found via Google Books), pg 65 gives BRMSB formation date.

WISE Division (of the NMRA) History website.

Wikipedia article on Gauge One.
Wikipedia article on N-Scale.
Wikipedia article on Standard Gauge (Toy Train). (aka Wide Gauge)