Reference

Scales and gauges

The scale says how many times smaller the model is than the real railway. The gauge says how far apart the rails lie. The two belong together but are not the same thing: at one scale there are narrow-gauge variants with a smaller gauge.

TRAX uses the scale to size everything that has a real measurement: trees, buildings, platforms, the scale figure and the loading gauge. The gauge is carried by each track library, because it belongs to the track system.

The scales TRAX knows

These are the icons you see again in the editor, in the scale list on the Project tab and beside the track libraries.

T 1:480. The smallest there is, on 3 mm track.
Z 1:220, 6.5 mm track.
N 1:160, 9 mm track. In Japan 1:150 and in Britain 1:148, all three on the same 9 mm.
TT 1:120, 12 mm track.
H0 1:87, 16.5 mm track. The most used scale in Europe.
OO 1:76, also on 16.5 mm track. A British scale; the model is bigger than H0 but the track is the same width, which is how history left it.
S 1:64, 22.4 mm track.
O 1:48 in North America and 1:45 in Europe, around 32 mm track.
I 1:32, 45 mm track. Also called gauge 1.
G 1:22.5, on 45 mm track as well. Garden railways.

Narrow gauge

A scale sometimes carries a letter after it. That says the model is at that letter's scale but runs on narrower track, exactly as in real life. The model stays the same size; only the rails come closer together.

m is metre gauge, a thousand millimetres. H0m is 1:87 on 12 mm track.
e is narrow gauge around 750 to 800 mm. H0e is 1:87 on 9 mm track.
f is field railway, narrower still. H0f is 1:87 on 6.5 mm track.
n3 is three feet, 914 mm, the American counterpart. H0n3 is 1:87 on 10.5 mm track.

The same track under another name

Where Europe puts a letter after the scale, the Americans count in feet and the British have names of their own. It is exactly the same thing: a model at one scale, running on narrower track. Meet one of these names in a catalogue and you now know where it belongs.

12 mm under H0 is H0m in Europe. Americans write H0n3½: three and a half feet, that is 1067 mm, the Cape gauge of South Africa, Japan and New Zealand.
9 mm under H0 is the European H0e. In America it is called H0n30 or H0n2½, after thirty inches, 762 mm.
9 mm under OO is the British OO9, also written 009: 1:76 on nine millimetres, for two-foot track.
10.5 mm under H0 is H0n3, the American narrow-gauge classic from Colorado.
16.5 mm under 0 is On30: a model at 1:48 running on ordinary H0 track. The European 0e comes to the same thing.
6.5 mm under N is Nn3: N models on Z track.

And the other way round, one gauge often carries more than one scale. On 16.5 mm run H0, OO and On30; on 45 mm run I and G; on 9 mm run N, H0e and OO9. A track library therefore always belongs to a scale and a gauge, never to one of the two.

What the scale does in TRAX

Your project's scale is on the Project tab. As long as you leave it on automatic, TRAX takes the scale of the first track library you use. Set it yourself and your choice holds for everything with a real measurement: a tree of twenty metres, a platform 550 millimetres high, the scale figure of 1.75 metres and the clearance the train has to pass through.

The page The track libraries says which scale and gauge belong to each library.