noun
railroad track gauge
Technical term for the distance between the inner sides of the two rails on a railway track.
日本の在来線の軌道間隔は1067ミリメートルです。
The track gauge of Japan's conventional railway lines is 1067 millimeters.
Compound of 軌道 (kidō, 'track') and 間隔 (kankaku, 'interval, spacing').