South Australian Railways (SAR) was the statutory corporation through which the Government of South Australia built and operated railways in South Australia from 1854 until March 1978, when its non-urban railways were incorporated into Australian National, and its Adelaide urban lines were transferred to the State Transport Authority. The SAR had three major rail gauges: 1600 mm (5 ft 3 in); 1435 mm (4 ft 8+1⁄2 in); and 1067 mm (3 ft 6 in).