S-3.3, r. 2 - Regulation respecting rail safety

Full text
61. Rail gauge must be more than 142.24 cm (4 ft. 8 in.) and not less than 147.32 cm (4 ft. 10 in.).
Rail gauge is measured between the heads of the rails at right-angles to the rails in a plane 1.59 cm (5/8 in.) below the top of the rail head.
O.C. 1401-2000, s. 61.