Model Railways: Scales & Gauges

Posted by Rohit Nyss on

model train scale comparison

The history of model trains probably goes back as far as the days of the Invention of Trains & the Railroad Industry itself. The first models were not constructed to any particular scale or standard and were more like toys.

As standards were set for toy trains, manufacturers chose to build to common scales.

Model trains come in many different sizes, called “Scales” as many of you might be familiar with, as is the case with Model Cars and vehicles.
The scale of a model is its relative size in proportion to the real thing (called the “prototype”)

For instance, HO Gauge models are 1/87th (Scale) the size of the real thing. So if you had an HO scale model of a forty-foot Locomotive, you would need 87 of them to match the length of the real one.

The distance between the rails is the "Gauge".
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Rail Gauges

The gauge of a railway track is defined as the clear minimum perpendicular distance between the inner faces of the two rails.


The different gauges can broadly be divided into the following four categories:
Broad Gauge: width 1676 mm to 1524 mm or 5’6” to 5’0”
Standard Gauge: width 1435 mm and 1451 mm or 4’-8⅟2”
Metre Gauge: width 1067 mm, 1000 mm and 915 mm or 3’-6”, 3’-33/8” and 3’-0”
Narrow Gauge: width 762 mm and 610 mm or 2’-6” and 2’-0”.



Following are the factors affecting the choice of a gauge:
Traffic Condition: If the intensity of traffic on the track is likely to be more, a gauge wider than the standard gauge is suitable.


Development of Poor Areas: The narrow gauges are laid in certain parts of the world to develop a poor area and thus link the poor area with the outside developed world.

Cost of Track:
The cost of railway track is directly proportional to the width of its gauge.
If the fund available is not sufficient to construct a standard gauge, a metre gauge or a narrow gauge is preferred rather than to have no railways at all.

Speed of Movement:
The speed of a train is a function of the diameter of wheel which in turn is limited by the gauge.

The wheel diameter is usually about 0.75 times the gauge width and thus, the speed of a train is almost proportional to the gauge.
If higher speeds are to be attained, the broad gauge track is preferred to the metre gauge or narrow gauge track.

Nature of Country:
In mountainous country, it is advisable to have a narrow gauge of the track since it is more flexible and can be laid to a smaller radius on the curves.
This is the main reason why some important railways, covering thousands of kilometers, are laid with a gauge as narrow as 610 mm.

Advantages and disadvantages of different track gauges

Narrow gauge railways usually cost less to build because they are usually lighter in construction, using smaller cars and locomotives (smaller loading gauge), as well as smaller bridges, smaller tunnels (smaller structure gauge) and tighter curves. Narrow gauge is thus often used in mountainous terrain, where the savings in civil engineering work can be substantial. It is also used in sparsely populated areas, with low potential demand, and for temporary railways that will be removed after short-term use, such as for construction, the logging industry, the mining industry, or large-scale construction projects, especially in confined spaces.

Broader gauge railways are generally more expensive to build, but are able to handle heavier and faster traffic.

Now that you've understood Gauges, back to the world of Model Trains though.
Model Trains are usually based on the real world, Standard Gauge which are four feet, eight and a half inches. Measured from inside-to-inside between the rails. In the model world, HO trains run on track gauge that is only .625″ wide, scaled down from the real thing.

With the continued popularity of model railroading, hundreds of manufacturers have contributed thousands of different trains and accessories. All in a variety of scales and price ranges.

As the manufacturing process became more sophisticated. Modelers began to demand trains that more resembled the real thing.

The most popular Gauge Today is HO (1:87) but N Gauge (1:160) is also popular because of limited spaces in cities. While OO Gauge (1:76) is more a

British Standard for the popular HO Gauge (using the same track gauge). For model railroaders with large outdoor spaces, G Gauge is the way to go.

Whatever scale you choose … today’s model railroader can enjoy a detailed model that is “ready to run” right out of the box. Accurate down to the last rivet. Less expensive models allow the modeler to add more detail as desired.

You don’t need to spend a lot of money to get the greatest enjoyment from the hobby of model railroading! You might be surprised how good looking the most affordable models are today.

Hornby is a popular Brand for 00 Gauge

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