Why We Need Standards
When train sets were first manufactured in the late 19th Century, each manufacturer built the models the way that they wanted to. There was no such thing as standards back then and no guarantee that two models produced by the same manufacturer would be made even approximately to the same scale. As time went on people started to gain an interest in the hobby of Model Railways (or Railroad Modelling as the American modellers call it) and the concept of being able to build a miniature railway world was born.
Early model railways were for operating. The idea was to be able to run a sequence of trains across the model railway to some approximation of the timetables run on the prototype. The fact that the stations were hand written on the board, there was no scenery, and all of the locomotives sat on an 0-4-0 chassis didn't matter. The main thing was to run trains, operation was the thing. Standards were important only in so far as ensuring that all of your trains could run on your own track.
Around about the 1930s some modellers came up with the idea of not just running the trains but also attempting to model the scenery to some sort of "scale" that the hobby as we know it today started to come into existence. The biggest problem that modellers wanting to follow this new approach had was that they needed models that were closer approximations of the prototype than the manufacturers of the time produced. They had no choice but to build their own because the items produced by the various manufacturers bore only a slight similarity to their supposed prototype.
At this period of model railway history all of the manufacturers still produced models to whatever scale suited them and although you could run a variety of stock from the same manufacturer on that manufacturers track, stock from other manufacturers used different dimensions that made it as likely as not that it would fall off the track as soon as you tried to take it around a curve or through points. The campaign began to try to get the manufacturers to adopt common standards.
A number of Clubs and Associations around the world were formed to push to have the manufacturers produce models that were more closely to scale and also to produce models that used common standards so that stock from the different manufacturers would be able to be run together. These organisations included BRSMB in England, MOROP/NEM in Europe, NMRA in North America, and AMRA in Australia.
The early successes were in getting manufacturers to produce models more closely to scale. No longer would the manufacturers build models to whatever scale that suited them and sit them on a common chassis. The models began to look more like the real thing and were built to a more consistent scale.
Next came the introduction of something called "fine scale". A new set of standards was produced and promoted to the manufacturers in the attempt to get them to produce models that were closer to true scale than the prevailing models of the time. One example of a fine scale product that was introduced in the early 1960s by Triang was the code 140 Super 4 track that was introduced to replace their older and coarser series 3 track. That this fine scale track is considered was too coarse to be used by any serious modeller today shows us just how far the standards have come since.
The next step was to get the manufacturers to adopt the same standards so that we could run rolling stock from a range of manufacturers on the same track. By the 1970s some track manufacturers had produced what they called 'universal track' which meant that it was built to a compromise standard that allowed a variety of stock using different back to back measurements to run together. Before this you either only ran stock from one manufacturer, you laid separate tracks for the stock from the different manufacturers, or you reworked all of your wheels to a common standard that was compatible with your chosen track.
The process of adopting still finer standards continued with better tools allowing finer standards to be achieved and the various standards organisations pushing the manufacturers to produce models to finer standards through the use of these tools. Of course they also encouraged modellers to adopt these finer standards so that the manufacturers would have to change to meet their market. By the mid 1970s the models produced by most manufacturers had progressed to the point where most modellers could no longer produce models themselves to the same standard as produced by the manufacturers. Compare this to 40 years earlier where almost anyone could produce a model from scratch that was closer to scale than they could buy in the shops.
The modellers themselves in the search for models that were more closely to scale introduced more accurate scale/gauge ratios and new scales such as P4 and Scaleseven were introduced as variants of OO and O gauge respectively. The improvements to what could be achieved as led to a range of finer and finer scales corresponding to each of the popular scales and each of these now has its own appropriate set of standards.
Also during this time, success was had in convincing the various manufacturers to adopt identical standards so that we no longer needed to use universal track to allow us to run stock from different manufacturers but could instead use a still finer scale track knowing that most of what we would buy would run on it with little or no work. Today, even the coarsest scale that anyone can buy is super fine scale by 1960s standards.
For the most part, the issue of scale standards such as flange sizes and back to back measurements is pretty much resolved and while the NEM standards are somewhat coarser than the others most manufacturers now produce all of their rolling stock and track to meet the standards of their local standards organisation.
Of course there are some modelling gauges such as 45mm where we have yet to get the manufacturers to adopt even a modicum of uniformity. Even allowing for the different prototype gauges modelled, as well as recognising that scale has little, if anything, to do with rail profiles or track dimensions, we are confronted with the following chaos: Scale 1:32 (Marklin and a foreshadowed American manufacturer) is exactly correct for standard gauge; Scale 1:29 (Aristocraft and USA Trains) is over scale for standard gauge; Scale 1:24 (Aristocraft and Delton) is incorrect for 3' gauge; Scale 1:22.5 (LGB and Bachman) is exactly correct for metre gauge, but incorrect for 3' gauge; Scale 1:20.3 (Bachman and increasingly, several smaller American manufacturers) is - the American pundits assure us - exactly correct for 3' gauge. Moreover, recently LGB has offered models built to several scales other than any of the above, while to accommodate the wishes of modellers of industrial narrow gauge lines, several other scales - notably 16mm = 1ft - are in use.
It may appear that some, at least, of these scale/gauge relationships are logical; nevertheless the wheel profiles of virtually all of the manufacturers named differ slightly from one another, as do the dimensions (notably flange clearances, rail heights, and back-to-back measurements) of their competing track ranges. It is true that most will run on one another's track, but this is not always the case, while none, except Marklin and a number of specialized British manufacturers, comply with the Standards of the Gauge 1 Model Railway Association.
While many argue that all this points to the need for, at least, two sets of Standards to meet the differing requirements (coarse and fine), it is clear that workable Standards are urgently needed in this most rapidly growing aspect of railway modelling.
Unfortunately the scale of the models is not the only place where we need standards and somewhat less progress toward achieving standards has been made with some of the other aspects of the hobby.
Couplings are yet another area where standards are needed so that you can run rolling stock from different manufacturers together. In the early days this wasn't very important because you couldn't run items from different manufacturers on the same track anyway. Once universal track was introduced, the issue of couplings became more important. There were two solutions to this problem. The first was to get manufacturers to produce couplings as a separate item that modellers could purchase and use to replace the existing couplers on all of the stock that they bought (for example kadee couplers). The second was to convince the manufacturers to make their couplers more compatible with one another (for example some variant of the loop and hook coupling first introduced by Triang is now standard on most British OO scale stock) or to even adopt using the same coupler as other manufacturers were using (for example the Arnold-Rapido coupler that most N gauge manufacturers use). There are still a number of different and incompatible coupling systems in use but most stock is now designed to allow us to change the couplings for our own standard ones if that is not what is already fitted. Unfortunately, you may still come across the occasional item of rolling stock that might be perfect for your model railway except for having incompatible couplings that are permanently attached in such a way that they are impossible to remove without damaging the model. (Of course you can always purchase several models and a locomotive that use that coupling and run them as a block train.)
A kadee Coupler
Let's move on and discuss electrical systems next. Early on 24 volts was adopted for use and this was continued when smaller scales such as O gauge came in. These larger scales still sometimes use 24 volts today. When even smaller scales were introduced and more efficient smaller motors were produced to run them 12 volts became the popular voltage to use for the smaller scales and some stock in the larger scales has also been produced that will run on this voltage. The smallest commercial scale (Z gauge) introduced an even lower operating voltage and runs on 9 volts.
Over the years, the power required to run the motors that are used in our model locomotives has also come down as the manufacturers have found more efficient motors that they can use. As a result the control units produced today have much lower power ratings than earlier controllers did (perhaps only a fraction of an amp compared to several amps in earlier units). This can mean that newer controllers cannot output sufficient power to operate some of the earlier locomotives that can still be purchased on the second hand market.
The introduction of electronics to model railways presented us with the possibility of doing away with the artificial track sectioning that is used to control the train by feeding power to the appropriate section of track and to instead place a module within the locomotive that will respond to the specific signals from the controller intended for that locomotive wherever it is situated on the layout while ignoring signals from the controller intended for the other locomotives and accessories. Of course, initially every such Command Control system introduced has implemented a different method of achieving this so that, having spent your money, if you wanted to run your locomotives on someone else's layout you couldn't unless they used the same system. That problem was partly solved when the NMRA promulgated a new set of Standards requiring that, for example, ALL locomotives be fitted with identical DCC ports, allowing interface between competing systems from various manufacturers. Some of the earlier systems have come and gone, but the uniformity of application now so widespread has been achieved because 'market forces' have compelled manufacturers to comply with a very sensible set of Standards. (Of course there is still the problem that you can't run your loco at the same time as one of your friend's that is coded the same and that problem can only be solved between yourselves by adopting your own standards for how you will each encode your locos).
In the last 100 plus years much progress has been made in producing standards and convincing the manufacturers to use them. Just about anyone with an interest in model railways can walk into a hobby shop, buy a variety of equipment based on their chosen prototype made by a number of different manufacturers, take it home, and assemble an operating model railway with that equipment without having to think much about standards. As time goes on still further progress can be made in producing standards to cover all aspects of model railways.
It is not the place of any modeller to tell other modellers what standards they should use to build their own model railway. Each modeller can select their own standards to suit themselves and is free to adopt standards totally different from those produced by any of the organisations I mentioned earlier. Of course if they select their own standards then they will probably have to build everything themselves as the manufacturers now only produce models that (at least nominally) comply with the standards of their local organisation.
Modellers who has purchased a range of equipment of their chosen prototype and are ready to move on to start manufacturing equipment themselves rather than purchasing it ready made or in kit form will need to (at least nominally) comply with the same standards as the manufacturers of their other equipment use in order that their 'scratchbuilt' stock can be run alongside their bought stock. To allow modellers to do this the organisations that set the standards not only promote their standards for use by the manufacturers but also publish the standards for use by their own members. If the Australian manufacturers follow the AMRA standards in constructing the ready to run models and the kits that we can buy of Australian prototypes then we can produce compatible items of our own by following those same AMRA standards (which every AMRA member gets as part of their 'new members kit').
I wish to thank AMRA Journal editor Neil Riches for the rewrite and expansion of the paragraphs on 45mm gauge to correct the errors I made in the original text and also the corrections to the information on DCC to bring it more up to date.