Rail gauge is the term used to measure the spacing of the rails on a railway track. This term is used in Australia. In the U.S., we use the term track gauge.

there is track width (measured from mid rail to mid rail) and track gauge (measured from inside rail to inside rail. As that is the most important size of track, that is normally the distances referenced to. normal distance for track gauge is 1435 mm

Standard Gauge. 4ft 8"

1.62 mt.

Most models designed to run on 3 rail "O" gauge track will work. Models designed to run on 2 rail will also probably work.

On the other hand models designed to run on three rail and having metal wheels and axles will not work on 2 rail track.