The government-owned South Australian Railways started to build the broad-gauge Salisbury–Long Plains line as a branch off the Main North line in 1915, completing it in April 1917. The line was extended from Long Plains to Redhill from 1917 to 1925, and again from Redhill to Port Pirie in 1937. In the latter year, the Commonwealth Railways extended its standard gauge Trans-AustralianRailway line from Port Augusta south to Port Pirie. In 1980, the Federal and State Governments entered an agreement to convert the line from Adelaide to standard gauge, albeit altered to meet theTrans-Australian Railway at Crystal Brook. This allowed Adelaide to become the last mainland state capital to join the standard gauge network. The line opened in 1982. It runs on the western side of the same corridor as the Gawler railway line from north of Salisbury railway station to the triangle near Adelaide Gaol, and continues on the western side of the metropolitan broad gauge tracks to Adelaide Parklands Terminal. The new line allowed Australian National to operate The Ghan, Indian Pacific and Trans-Australian through to Adelaide without passengers having to change trains. In July 1998, it became part of the Australian Rail Track Corporation network. Until late 2017, this meant that the standard gauge trains had to cross the Outer Harbor railway line at-grade at Torrens Junction, north of the River Torrens. In 2017, this conflict was removed by lowering the suburban Outer Harbor line into a trench so it could pass under the standard gauge line. This would ease timetable and operational conflicts on both services.
Crossing loops
The maximum length of trains on this line is 1.8 kilometres, and almost all crossing loops are of this length. East of Mile End the maximum train length is 1.5 kilometres, though this is starting to be increased to 1.8 kilometres also.
Mile End
The crossing loop at the Adelaide Parklands Terminal at Mile End is of length 1,658m.
The first crossing loop north of Adelaide, of length 1,950m, is south of Dry Creek.
Bolivar
The Bolivar crossing loop is 1800 metres long, having been lengthened from 1200 metres in 2012, after the Taylors Road level crossing at the southern end was replaced by an overpass of the Northern Expressway. As a result, the overpass marks the approximate mid-point of the loop.
In 2007, it was proposed that an Intermodal Rail/Road facility be built in the Edinburgh Parks area. Accordingly, an area of rural/agricultural land in Penfield was rezoned in 2008. In the 2010s, SCT Logistics and another company started to develop an intermodal hub. The new facilities and trackwork commenced construction on the north-east side of the line, south of the Northern Expressway and north of Heaslip Road and RAAF Base Edinburgh, in 2011/2012.
The next crossing loop, of length 1,817m, is at Two Wells - the loop is between Gawler Rd and Tenby Rd.
Others
There are about a dozen other crossing loops north of Two Wells - refer to the infobox to the right.
Crystal Brook
includes the triangle junction with the main line to Broken Hill and Sydney. Then there is a 968m crossing loop and siding with provision to load grain at the silos in the town. The tracks converge to single track to cross a bridge over the Crystal Brook, then split into double track for the 20km to Coonamia. The western track is for northbound travel and the eastern track for southbound, except that there is a balloon loop for loading grain from the AWB silos which is accessed by proceeding a short distance north on the eastern track.
Coonamia
, comprising only a nameboard, is the former stopping place that coincides with the "0 km" datum point for routes to Port Augusta, Broken Hill and Adelaide. At this point ARTC train controllers in Adelaide hand over to controllers in Port Augusta ; the sign remains so that train crews can identify the change-over point. The location has a crossing loop 1638 m long on the south side of the double mainline from Crystal Brook. A further 2.25 km west is a triangle junction where the double track ends and from which single tracks go west to Port Pirie Yard and north to Port Augusta.
