South Western Railway, Western Australia

The South Western Railway, also known as the South West Main Line, is the main railway route between Perth and Bunbury in Western Australia.

Construction
The South Western Railway was constructed for the Western Australian Government Railways (WAGR) by various private contractors from 1891. Among these was the engineer and magistrate  Owen.

Construction was completed in two parts. The first, East Perth to Pinjarra, was undertaken by William Atkins (former mill manager of the Neil McNeil company at the Jarrahdale Timber Station) and Robert Oswald Law (who built the Fremantle Long Jetty) from the end of 1891. Work began in 1892 but was slowed by difficulties with building the bridge over the Swan River. This section opened on 22 May 1893.

The second phase of construction was also completed by Atkins and McNeil, starting at Bunbury and working north to Pinjarra opening on 22 August 1893. Bunbury station was opened by John Forrest on 14 November 1894.

Post-World War II improvements
Prior to 1938, the WAGR determined that the South Western Railway would soon reach saturation point. During World War II, plans for its full duplication between P and were therefore included in an intended post-war improvement project.

A special committee later recommended, however, that the proposed duplication be replaced with centralized traffic control (CTC), and in 1944 that recommendation was confirmed by the WAGR's newly appointed Signal and Telegraph Engineer, who had gained experience with CTC while working for the New Zealand Railways Department.

In 1949, the plans for lengthy duplication of the line were shelved, and installation of CTC was approved. The incoming WAGR Commission later placed orders for the necessary materials.

Post-war improvements to the WAGR network as a whole also encompassed a major program for relaying track on various main and secondary lines with heavier, welded, rails; included in that program were rerailing, reballasting and ancillary works on the South Western Railway.

The first part of that line to be relayed was the 82 mi Armadale to Picton Junction section, on which work began in 1952 and was completed in 1954. Work on the 5 mi section between Picton Junction and Bunbury followed in 1960, and then the double track section in Perth's south eastern suburbs equivalent to 34 mi was relaid in 1961 and 1962.

Meanwhile, installation of CTC equipment began with the equipping of a pilot section between Armadale and Byford in 1958. The CTC was then extended progressively southwards, to North Dandalup by April 1959, and then to Pinjarra, including a crossing loop at Venn, by June 1959.

Proposals for a 4.9 mi extension of the double tracked Perth suburban portion of the line from Armadale as far as Byford, and installation of the CTC all the way to Brunswick Junction, both ended up being abandoned due to a shortage of funds. Even so, the truncated 39 mi project, when it entered fully into service, was the first large-scale application of CTC in Australia.

Alignment
As operated by the WAGR, the line was 115 mi from Perth to Bunbury. Since that time, the line has been shortened to 181 km as some stations have closed, moved or been replaced by passing loops.

The first 30 km of the line from Perth are served by Transperth's Armadale Line. This section is double-tracked and electrified using 25 kV AC. The line south of Armadale is not electrified and predominantly single-track, with passing loops at various locations. The section from Perth to Mundijong Junction is controlled by the Public Transport Authority, with the remainder of the line controlled by Arc Infrastructure.

The section controlled by Arc Infrastructure has been upgraded to accommodate 21 t axle loads, featuring concrete sleepers and continuous welded 50 kg/m rail.

Bridges
The Bunbury Bridge near Perth was the most significant engineering structure on the line. It was replaced by the Goongoongup Bridge in 1996. Other notable bridges include:
 * Jenna Bidi Bridge over the Canning River in Gosnells
 * Murray River Bridge south of Pinjarra
 * Harvey River Bridge north of Harvey
 * Collie River Bridge south of Roelands

Branches
The line connects with all Transperth commuter rail lines at Perth, with specific branches to the Midland Line at Claisebrook and the Thornlie Line at Kenwick.

In terms of key freight connectivity, the line branches to the Kwinana Line at Kenwick and Mundijong Junction. The Jarrahdale Branch was accessed at Mundijong, but this line is now out of service. A branch south of Pinjarra serves Alcoa and provides access to the Hotham Valley Branch. The Collie Branch connects at Brunswick Junction, providing access to Worsley Alumina and Collie. At Picton the line once continued 200 km south as the Northcliffe Branch, with further branches to Flinders Bay and Katanning, however only the first few kilometres of this line remain in use. A 10 km spur to Bunbury Harbour provides access to the port west of Picton.

Timber tramways
Several timber mills used to operate along the railway, each with their own access to the mainline. Many of these mills operated extensive timber tramways that fed significant quantities of timber to the railway.

Passenger
The Transperth commuter rail Armadale Line operates a frequent passenger service at the Perth end of the route.

Beyond Armadale the only passenger service on the line is The Australind. It traverses the entire length of the line from Perth to Bunbury twice a day in each direction, taking about 2 hours and 30 minutes each way. Other named trains that previously operated on the line were the Bunbury Belle and The Shopper.

Stations
There are currently 31 passenger stations on the line, of which 20 are served by Armadale Line services. Beyond the Armadale Line section, all stations meet Disability Discrimination Act standards. The stations at Brunswick Junction and Bunbury provide connections to Transwa coach services. A planned extension of the Armadale Line as part of Metronet would see a new station built at Byford.

Freight
Freight services on the line are operated by Aurizon and are primarily focused on bauxite and alumina mining and refining. Bulk bauxite is carried from Alcoa Pinjarra to Kwinana for export and bulk alumina is transported from Alcoa Wagerup as well as from Worsley Alumina to Bunbury port. Caustic soda is transported from Bunbury Port to Wagerup and Worsley for use in alumina refining and some coal from the Collie Branch is also carried on the line. Potential exists for the line to carry mineral sands, agricultural produce, lithium ore and containerised freight on the line in the future.