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Banner Module 4  Scale v Gauge.PNG

The Concept of 'Scale' as opposed to 'Gauge"

As outlined in Module 1: Introduction the concept of scale as opposed to gauge can sometimes prove hard to grasp, even for some experienced members of the G Gauge community, never mind beginners. Many people manage to get huge enjoyment out of the hobby without having much regard for scale and gauge as long as they can just run trains and this is no bad thing. It is not something you should develop a complex over but if you can come to terms with these key words it could help you avoid some costly mistakes.


As we have already mentioned, unlike our fellow modellers in the smaller scales such as OO, HO and N, where each scale appears to have individual and clearly delineated standards to work to and share a common "scale" or proportion to the actual prototype.




















Despite the simplicity of the above graphic the world of G Scale is a far more complex affair with a plethora of different scales all running on the identical 45mm gauge track (or 32mm gauge track so even here their is an anomaly). Railway modelling enthusiasts tend to refer to 0, 00, H0, or N 'scales' but the largest model trains are generally referred to as G 'gauge' rather than G scale as the width of track is often the only common denominator.


This is due to the fact that over the years competing companies have chosen to manufacture their models in different scales to the actual prototype, particularly if they are reproducing a standard gauge prototype rather than a narrow gauge one.


The Size of G 'Gauge'  

As a result, all trains made for large scale tend to get grouped under the same generic title and the indiscriminate use of the term "G Scale", often wrongly as an interchangeable synonym for "G Gauge" - only serves to complicate matters further. I am often guilty of this offence myself and will probably continue to do so in this manual!


In many hobby outlets, especially those which only carry a limited range of large-scale models, everything in this category can be lumped together creating a potential trap for the unwary. You really do need to do your research beforehand and keep your wits about you if you are striving for prototypical perfection. I shall be discussing how to go about sourcing your trains in more depth in a later module.


However, provided one is not a stickler for absolute accuracy (and possibly compromising the integrity of your railroad layout) it is sometimes better to go with the flow on the age-old adage that "if it looks right it is right" or as some old railroad geezers are prone to say ”it’s my railway and I'll run whatever I d**n well like, when I like” or some similar more aphorism (sometimes referred to as Rule 8 although i am uncertain as to the origin).


Indeed many manufacturers (even including the legendary LGB who have never adhered rigidly to its stated scale ratio of 1:22.5 ever since Lehmann Brothers introduce G Scale Narrow Gauge as far back as 1967) appear to have taken considerable liberties with their published scales ( I say ‘published’ but one or two manufacturers appear reluctant to even disclose the scale of their products at all) and adopted this rather more pragmatic approach ’selectively compressing' their models to fit an average size so that they will not look out-of-place when run together. When you think about it, this practical approach makes a lot of sense but it would be a lot more helpful if they were more forthcoming as to the exact scale of their products.


This 'laissez-faire' attitude is viewed as a compromise too far by some ardent rivet-counters (who would probably be happier constructing their own scratch-built models anyway - no offence intended) but for the majority of average modellers who are prepared to tolerate such practices, their enjoyment of the hobby is largely unaffected by such considerations.


So, let us return to the vexed question of scale versus gauge. As someone once said, two deceptively simple terms but extremely important in the world of model trains. Knowing the distinction and what to look for when selecting your very own train could be the difference in making a costly, time-consuming mistake or getting on the fast track to countless hours of enjoyment!

To put it simply "scale" is the proportion of the model relative to the actual prototype it represents in real life. Thus, if a model is built to 1:24 scale every 1" of the model will be equivalent to 24" on the real thing and so on. It is the same ratio in metric measurement where each 1mm of the model will represent 24mm of the prototype on which it was based. Note that scale can also be expressed as a fraction e.g. 1/24th.

This size of train is ideal for building a railroad through your garden or landscaping, though you can use it inside if you have enough space. They may cost more than smaller trains, but G gauge allows you to have a lot of fun designing a track while integrating a variety of natural scenery and features into the layout.





















By the way. I should have mentioned earlier that the term "gauge" is merely the measured distance between the inside head of the two rails which form the track which in G Gauge, or perhaps more accurately Gauge #1, is 45mm. You can learn more about rail sizes (codes) in a later Module 9 devoted to track systems.



To summarise I think I can do no better than to present the following drawing by Scot Lawrence from the USA which I believe goes a long way towards encapsulating, in a clear and comprehensible manner, this entire module:


























There you have it! Hopefully, the foregoing explanation has not served to confuse you even more but it is essential to have a proper understanding of the meaning of these basic terms to get the best out your hobby. In fact, it is quite amazing that these terms can create so many altercations and much *head-scratching".


(Note: the first recorded use of this term, meaning puzzled contemplation, apparently only dates back to 1926 but I suspect that a lot of it probably went on in prehistoric times as well.)


The multiplicity of scales and gauges in popular use around the world for model and miniature railways is quite mind-boggling but some further information may help you in choosing the right mix for your own large-scale layout - whether located indoors or more likely in the garden.

Below is a table showing some of the most common scale/gauge combinations but there is always some individual, or even a group of like-minded enthusiasts out there, who have chosen to model in a unique format which may have escaped attention. The smallest scales generally considered suitable for outdoor use are SM32 and G Gauge but some intrepid modellers have successfully created al fresco layouts in 0 Gauge and even 00 so if you fancy a challenge don't be put off.


On the next few pages, I have appended a table showing some of the more common modelling scales to be found in the world that are found outdoors (usually in a garden or park environment).

Model Railway Gauge Comparison EXcellent
Train Size Comparison.PNG
Table 5.PNG
Table (4).PNG
Table of Scales (3).PNG
Table of Scales (2).PNG
Table of Scales (1).PNG

Note:  Some of the scales shown in the above table are recognised around the world whilst others are little known outside their country of origin.


So, Who is in Charge of Codifying all these Scales & Gauges?


Step forward the NMRA (National Model Railroad Association) and MOROP (Normen Europäischer Modellbahnen), the two organisations that probably have most influence on the world of model railways.

NMRA Logo large.jpg
MOROP Logo.jpg

These two organisations, with Headquarters based in the USA and Europe respectively, are the principle quasi bodies that set the standards that are followed in most countries around the world. These associations are the custodians of rail transport modelling standards in an attempt to bring some standardisation across the globe.


Observance is not necessarily universal as in many parts of the world the hobby of model railways is not as widespread. For example, in Japan, where living accommodation is normally confined, there is a natural predisposition to model in the smallest scale possible in order to occupy as little space as possible. Consequently, compact N Gauge (made to a unique scale of 1:150 rather than 1:160 customary in Europe) and HO (1:87 scale), HOn2½ (1:80), 13mm (1:80) and HOj or #16 (1:80) scale layouts are the norm.


I have to say that I have found both organisational websites somewhat difficult to try and navigate, indeed the MOROP site frustratingly so, and at times it appears impenetrable to English speaking visitors. There is rather too much technical and scientific ‘technobabble’ for the average layman.  I feel sure that a lot of useful information is contained within its vaults if you are prepared to persevere.


To be perfectly honest I had never heard of MOROP before researching this book and this could be due to my own ignorance or possibly the minimal impact it seems to have had on the UK modelling fraternity.


If I may be a little controversial, I would speculate that both organisations are in some danger of becoming ‘talking shops’ for highly informed ‘geeks’ (or is it ‘nerds’?) and are not necessarily serving the needs of the modelling fraternity as well as they might. For example, many of the standards established by MOROP are available only in German and occasionally French text even after many years of existence.

Even the NMRA have tended to make it difficult to follow their standards unless you are directly involved in their discussions - for example helpful advice on tunnel clearances etc. that used to be found in Section S7 appears to have been subsumed into to some other regulation or disappeared altogether.


At least one good thing to have come out of the NMRA is the harmonisation and regulation of *DCC (Digital Command Control)* which prior to their involvement had developed into a very messy proliferation of numerous proprietary systems that were largely incompatible with each other.

*incidentally there are at least 219 different definitions for this acronym. Bet you can't name them all!


I must stress that these are solely my own personal view and I have had no direct communication with either body. You may have had quite different experiences. There is certainly plenty of room for all opinions.

Choosing a Scale   

Now you are probably saying to yourself "that's all very well but I had no idea how many scales were available for large-scale modelling so how do I choose which one to model?

The truth is that only you can really decide which code to pursue. Given the wide choice of scales available it can prove a very difficult choice but in reality no scale is fundamentally better than another - it's just that that each have their individual characteristics and potential advantages and disadvantages depending on your viewpoint.

Of course, It does help help if you have a clear idea as to what you expect to gain from your new hobby. Everyone is different and each will have a personal view. No one can really decide for you but try to avoid "mixing" scales too much as any mismatch will tend to stand out "like a sore thumb". In this context it means something which not only looks or sounds or feels out of place but which very obviously looks or sounds or feels out of place.


Note: I have never quite understood the origins of this idiom as sore thumbs do not normally stand out as being especially noticeable or obvious?  According to most references the phrase was popularised  by the author Erle  Stanley Gardner in the 1930's and 40's but I have a feeling that it may date back a long way prior to then. In this context it means something which not only looks or sounds or feels out of place but which very obviously looks or sounds or feels out of place.

An appropriate example is probably mixing rolling stock in both 1:22.5 Scale (e.g. LGB) with Finescale 1:20.3 (e.g. Bachmann Spectrum Range) as they both run on 45mm gauge track (Gauge 1). This can sometimes work if the original prototype coach or wagon were of different dimensions but model representations of the same passenger car from the same era can look mismatched and jar in terms of length, height, width or even appearance depending on the amount of detail present.

Much the same goes for mixing mainline trains (1:29 or 1:32 scale) with narrow gauge (1:19, 1.22.5, 1:20.3 or 1:24) where the latter can appear much larger than the former due to the wide range of ratios involved.

As manufacturers do not always stick rigidly to the scale ratios themselves opting for 'selective compression'  (or indeed reveal their actual scales at all) different interpretations of the same passenger car, such as a Jackson- Sharp Passenger Car (manufactured in their works from the late 1880's), can vary significantly as these images of a Piko (1:27?), Bachmann (1:22.5), Accucraft /AMS (1:20.3) and LGB (1:22.5) versions serve to illustrate:












































































In fact the first three are all interesting examples of the "selective compression" techniques employed by nearly all model train manufacturers to ensure that their products look compatible with their other lines and are capable of negotiating the very tight curves on a model layout compared to the real thing. All four companies have chosen to optimise their own realisation of essentially the same Jackson-Sharp Clerestory Passenger Car. Needless to say the Accucraft / AMS interpretation is by far the most accurate (but still not strictly so as coaches of this period tended to have 12 to 15 windows or even more) but it should be as it costs around 3-4 times the  price of the competing  versions. To be fair I also believe the Accucraft cars to be based on the later factory rebuilt versions from the 1920's onwards which incorporated many improvements.

If it is your intention to model the USA railroad scene and are looking for historical accuracy on such matters I heartily recommend "The American Railroad Passenger Car"  by the esteemed John H. White Jr. which comprises a two volume tome and must surely constitute  the definitive work on the subject.

It is also worth pointing out that the track clearances necessary can vary considerably depending on the type of rolling stock you decide to run on your layout (and the degree of selective compression used)

In the final outcome whether or not a layout looks "right" is in the eyes of the observer. We all see things differently and my wife's assessment of colours is invariably different to my own - but as you may know men are far more likely to suffer from red-green colour blindness than women due to their inherited


If in doubt you can always fall back on the railway modeller's maxim - "If it looks right it IS right".

In practice it is far more likely that you will prefer a particular manufacture's brand of equipment and by doing so automatically adopt the scale proffered by that particular manufacturer. It is then a case of being very selective when contemplating a purchase from an alternative manufacturer to ensure visual consistency of approach - particularly if you seek to pursue historical accuracy tn your recreation of the prototype.

If you have a clearer perception of the type of railway you wish to model (see Module 5 for help) you can probably narrow down the choice quite a bit. For example, if you like the idea of a smaller, narrow gauge branch line operated by old-time steam locomotives with mining, logging or industrial trains you are likely to be attracted by product ranges currently offered by LGB (1:22.5), Piko (1:27)*, Accucraft/AMS (1:20.3) and Bachmann (1:22.5 and 1;20.3) although you may also come across  second-hand items from historical USA suppliers such as Hartland Locomotive Works (HLW), Aristo-craft (Classic), and Delton who have all largely fallen by the wayside.

On the other hand, if you are far more interested in mainline standard gauge action then your first port of call is much more likely to be USA Trains (1:29), Accucraft/AMS (1:29,1:32), Aristo-craft (1:29) - the latter now sadly discontinued and MTH (1:32) - which has just recently announced it's impending closure so hurry.

* This is the scale given to me by Piko Germany many years ago but estimates range widely from 1:20.3 up to 1.32!)

It would be nice to add here that should your preference be British outline mainline or narrow gauge operations your choice of solutions would be equally expansive but regrettably this is not the case. With the odd exception there are no mass-produced trains available from UK or Overseas sources so your choices are likely to be limited.  Such products as there are tend to be short-runs and development costs have to be recovered over fewer volume sales so prices inevitably reflect this.

If you limit your investment in stock (say just one or two narrow gauge locos, a few passenger cars and appropriate goods vehicles ) you might find the financial outlay affordable over a year or so but anything as regards a mainline concept will demand deep pockets even second-hand. In fact second-hand prices could even be higher than the original selling price due to scarcity. You will find that manufacturers in the UK tend to limit production runs to "orders in hand" which can take quite a while to accumulate to the point where they represent an economical batch.

The next Module 5 - "Choosing a Theme" should also give you a better steer of which railway or railroad to build.

LGB 3080 D&RGW.jpg

LGB 9 Window Version

Piko 7 Window Version


Bachmann 12 Window Version

AM54-015 Jackson & Sharp Coach - D&RGW B

AMS 12 Window Version

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