The 7mm Narrow Gauge Association aims to encourage the modelling of
narrow gauge railways at a scale of or around 7mm to 1 foot (1:43)



Modelling the Narrow Gauge

Narrow Gauge v Standard GaugeSo what is Narrow Gauge? Technically, anything less than the 4 feet 8 ½ inches of the standard gauge is "narrow", but this ignores the fact that in many parts of the world, main line railways are operated on track gauges significantly less than standard. Prime examples are the South African and New Zealand Railways main lines, with a gauge of 3 feet 6 inches. On the other hand, a South African Railways narrow gauge locomotive, such as the NGG16 class of their 2 feet narrow gauge, dwarfs many of the smaller UK standard gauge locomotives. A general rule, though there are exceptions, is any gauge of 3 feet or less is a true narrow gauge, and greater than 3 feet is main line.  The drawing on the right compares the UK standard gauge with some of the narrow gauge railways.

Most narrow gauge prototypes were either industrial feeder lines, such as the Festiniog Railway, and initially the Talyllyn, or provided rail services to sparsely populated rural communities, as did the Irish narrow gauge railways and the Welshpool and Llanfair Railway. This pattern was repeated overseas, with many British locomotive and rolling stock manufacturers providing the infrastructure. Later on, tourist oriented narrow gauge railways started to emerge, such as the Groudle Glen on the Isle of Man, and narrow gauge railways also played a significant role in the logistics systems on both sides of the front line in the World War 1. Since the end of World War 2, many former industrial and rural lines have been preserved, and are now purely tourist in nature. From a modelling perspective, narrow gauge has a distinct advantage over main line in that many narrow gauge lines were short, so in the Comparison of standard and narrow gauge modelssmaller scales it is quite possible to model an entire railway. Narrow gauge lines were also no strangers to tight curves, some would say notorious, so what looks so out of place on a main line layout is prototypically normal on a narrow gauge layout.  The drawing below shows how narrow gauge models in 7mm scale compare to standard gauge models in the most common scales.

So where does the would-be narrow gauge modeller start? Almost anywhere, is the unhelpful but realistic answer. As recently as 25 years ago, there was very little trade support for narrow gauge railway modelling, although PECO™ were early pioneers, offering body kits in 4mm and 7mm scales, as well as track. Most modellers embarking on a narrow gauge project invariably scratch built most of their stock. Alternatively, they heavily modified locomotives, track and stock from the next scale down using, for example, a Triang™ 4mm scale "00" dock shunter as a basis for a 7mm scale narrow gauge diesel locomotive, often involving no more than a new cab of appropriate dimensions. In 7mm scale, "00" track at 16.5mm gauge is very close to a scale 2 feet 4 inches, particularly useful for modelling the Talyllyn, Corris and Welshpool railways. Modellers wishing to work in 4mm scale would adapt N Gauge prototypes in the same way. The 9mm N Gauge track is a scale 2 feet 3 inches. These were, and remain, the two dominant scales to work in, simply because there is so much trade support for track, accessories, buildings and figures; a 7mm scale vicar and church is equally at home on an O Gauge layout as it is on a 7mm scale narrow gauge layout.  The drawing above shows the track gauge in 7mm scale for a sample of narrow gauge railways.
 
I have already mentioned the two dominant scale/gauge combinations, known as 0-16.5 and 00-9, but there are many others. For many modellers, these over-scale gauges were unacceptable to those wishing to accurately model a 2 feet gauge prototype. They had two choices: either increase the scale to suit the commercially available track, or make their own track to the correct scale gauge and both alternatives have been tried. There has been 8mm to the foot scale scratch built stock running on 16.5mm track and more successfully, 14mm gauge track built for 7mm scale. Similarly, in 4mm scale, 8mm gauge track and stock has been built, and I believe at least one layout built to a scale of 4.5mm to the foot, in order to utilise N Gauge track. Confusing isn't it?

Building one's own track is not particularly difficult, but may appear daunting to those who have never done it before. So in migrating from main line railways to narrow gauge, most modellers opt for the commercially available track, and picking a suitable scale for the prototype they find most interesting. PECOâ„¢ manufacture track specifically for narrow gauge in 9mm, 16.5mm and 32mm gauges, for respectively: 4mm scale, 7mm scale and 16mm scale, although it is perfectly possible to adapt track, designed for a main line scale, to a larger narrow gauge scale. Some of the possible combinations, using commercially available track, are shown in the table below, and I have also included suitable prototypes where possible.

 

Track

Narrow Gauge Scale

Approximate Prototype Gauge

Potential Prototypes

Remarks

 

 

6.5mm Gauge

4mm

18 inches

1. Groudle Glen, Isle of Man

2. Beyer Peacock Works Tramway

Would involve converting “Z†locos and rolling stock chassis to take 4mm scale bodies, etc.

7mm

10 ½ inches

Fairbourne Railway as running today

As above, but converting to 7mm scale

 

 

 


9mm Gauge

4mm

2 feet 3 inches

1. Talyllyn


2. Corris


3. Welshpool & Llanfair

Lots of trade support for the main 00-9 combination

7mm

15 inches

1. Ravenglass & Eskdale (The Ratty)


2. Romney, Hythe & Dymchurch

Good trade support

 


12mm Gauge

4mm

3 feet

Irish narrow gauges and Isle of Man

Some trade support

7mm

21 inches

 

 

 

14mm Gauge

7mm

2 feet

1. Festiniog


2. Welsh Highland


3. Many quarry tramways

Track components available, to make accurate scale 2 feet gauge track in 7mm scale

"00/H0"

16.5mm Gauge



7mm

2 feet 4 inches

1. Talyllyn


2. Corris


3. Welshpool & Llanfair

Lots of trade support for the main 0-16.5 combination

1/4 in (On30)

2 feet 6 inches

US Logging Rail Roads

Good trade support

"EM"

18mm Gauge

7mm

2 feet 6 inches

 

 

21mm Gauge

7mm

3 feet

Irish narrow gauges & IoM

Scratch built track, if true scale

32mm Gauge

16mm

2 feet

1. Festiniog


2. Welsh Highland


3. Many quarry tramways

Still possible to create an indoor model in this scale, but we are now heading into the garden!

 

I hope the foregoing has displaced some of the mystique surrounding the modelling of narrow gauge prototypes. If I have been successful in this, and you are tempted to explore further, you will find much more on this web site, and on the 00-9 Society on: www.009society.com both of which also provide additional links to other related sites.