Early days

In 1856, the first steam train ran between Adelaide and Port Adelaide, stopping at Bowden, Woodville and Alberton.^[3] Soon after, a 40 km (25 mi) line was built from the Gawler to Adelaide to cater for the agricultural and mining industries.

The South Line, through the Adelaide Hills, opened to Aldgate, then Nairne in 1883, and extended to Bordertown in 1886. The first through train between Adelaide and Melbourne – The Intercolonial Express – ran on 19 January 1887, and was the first intercapital rail journey in Australia without changing trains at a break-of-gauge station.

A map of Adelaide's rail lines c.1970s

Most of the lines around Adelaide were built before 1900.

The Webb Era

Despite the earlier geographic expansion, by 1920 the infrastructure and rolling stock of South Australian Railways (SAR) had become run down, inadequate and outdated. Many of the operating practices, such as train control and signalling, were backward by the standards of the time.

However the 1920s saw substantial and expensive improvements in most facets of the SAR's operations under the leadership of Railways Commissioner William Webb. Webb was an American who had substantial operational experience with US railroads, and served as Commissioner between 1922 and 1930.

During his reign, track, bridges, railway workshops, rolling stock and especially steam locomotives were all modernised and upgraded along essentially American lines. Adelaide station was rebuilt with a handsome sandstone building as a showpiece of the city on North Terrace. The building still stands; the lower level remains as the railway station, but the upper levels have been converted into a casino.

In 1929, one of the original broad-gauge steam railways to the beach-side suburb of Glenelg was transferred to the Municipal Tramways Trust, electrified and converted to a tramway. The Glenelg tram line is still in operation.

SAR, STA and AN

From early colonial days up until 1978, the SAR had built and operated most of the railway system within the state.

The Commonwealth Railways (CR), owned by the Federal Government, also had a significant role in the northern part of SA, with lines from Port Augusta across the Nullarbor Plain to Kalgoorlie, and to Marree and Alice Springs. None of its lines came close to Adelaide.

During the early 1970s, the Whitlam Federal Government proposed a strategy to nationalise and standardise the various state rail systems around Australia. South Australia and Tasmania were the only states to participate in this initiative and negotiations were long and drawn out. The result was that in March 1978 the SAR became defunct and South Australia's railways were split between Commonwealth and State Government ownership.

A new Commonwealth Government organisation, Australian National Railways Commission (ANR), took over all the former SAR and CR track in South Australia outside the metropolitan area. Other rail facilities such as property and workshops were also transferred to ANR. ANR become Australian National (AN) as it refined its corporate identity.

The State Government retained ownership and control of tracks and trains in the Adelaide suburban area under the auspices of the State Transport Authority (STA). The STA had been created in 1974 to co-ordinate all public transport in South Australia.

In 1994, the STA was abolished and reformed as the government-owned corporate body TransAdelaide as a prelude to competitive tendering for operation of bus and rail services in metropolitan Adelaide. TransAdelaide subsequently lost all its bus services to private operators, but has retained the contracts to operate train and tram services.

In November 1997, AN was broken up and sold as part of a Federal Government privatisation agenda. Track, workshops, depots and passenger and freight operations were sold to various private organisations, which has led to today's operational structure described in an earlier section.

Noarlunga and Tonsley Line electrification

In 2008, the South Australian government announced, in collaboration with the Federal government, a plan to upgrade and electrify the Noarlunga line (now Seaford line) and Tonsley line (now Flinders line); the Belair line was also partially electrified as far as Goodwood to allow for electric train movements. Work on electrification began in January 2013 with the Belair line completed in mid-July 2013,^[4] and electric train services beginning in February 2014 on the recently-extended Seaford Line.^[5]

Gawler Line electrification

Previously cancelled in 2013, electrification of the Gawler line was announced in 2018. Though Stage 1 electrification as far as Salisbury was initially planned,^[6] a $220 million grant from the Federal Government also allowed for Stage 2 electrification on the remainder of the line to proceed.^[7] Works commenced in November 2019, and after many delays electric train services began on 12 June 2022.^[8]

Port Dock railway line extension

In 2022, the Department for Infrastructure and Transport announced that train services would be reinstated to Port Dock on the Outer Harbor line with the construction of a new spur line and station to begin in late 2023.^[9] Despite the project only delivering one additional station, which spurs off from the Outer Harbor line after Alberton station, the opening of Port Dock will bring Adelaide Metro's total number of lines up to seven, and will be the first new railway line constructed on the network since the opening of the to Flinders Link extension in 2020.

Seaford line extension to Aldinga Beach

In 2019, Renewal SA delivered a Draft Structure Plan of a 94 hectare area of land in Aldinga which is set to include a new school and a railway station as an extension of the Seaford line.^[10]

Underground city centre link

Infrastructure SA intends to complete electrification of the Gawler line, and analyse feasibility of an underground rail link in the CBD between the northern and southern railway lines.^[11]

Closed lines

The Coast to Vines Rail Trail, built on the route of the former Willunga line.

Adelaide's passenger rail network decreased in size during the later half of the 20th century, with the closure of several lines and branches, including:

• Dry Creek–Port Adelaide line: opened 1868 (last passenger service in 1988; now freight only)
• Finsbury line: Woodville to Gillman Junction, 1940–1978
• Northfield line: Dry Creek to Northfield, 1857–1987
• Penfield line: Salisbury to Penfield 3, 1941–1991
• Semaphore line: Port Adelaide to Semaphore, 1878–1978
• Willunga line: Hallett Cove to Willunga, 1915–1969 (now the Coast to Vines Rail Trail)