What does “gauge” mean ?
Gauge is the distance between the inside faces of the two rails of a railroad. In the US, most of Europe, and most of the British Commonwealth, the normal or standard gauge is 4’8.5″ (1.435 meter). Common smaller gauges in the US are 3′ and 2′, while in Europe one finds 1.0 meter as well as 0.75 meter.