One Rail Australia was an Australian rail freight operator company. Founded by a United States short line railroad holding company, Genesee & Wyoming Inc, in 1997 as Australian Southern Railroad, and successively renamed Australian Railroad Group and Genesee & Wyoming Australia, it was renamed One Rail Australia in February 2020 after the American company sold its remaining shareholding. In July 2022, assets from the South Australian, Northern Territory and interstate operations of the company were sold to rail operator company Aurizon Holdings Limited. The remaining assets, relating to coal haulage in New South Wales and Queensland, were sold in February 2023 to Magnetic Rail Group.
 Genesee & Wyoming Inc was one of several US regional railroad companies to take advantage of the privatisation of Australian rail freight operations in the 1990s. In 1997 its Australian subsidiary (named Australian Southern Railroad at the time) acquired the South Australian rail freight assets of Australian National from the Australian federal government, which included a 50-year lease on the South Australian network from the state government. Operations commenced in November 1997 under the Australian Southern Railroad brand.
 In 2000, Australian Railroad Group, a 50–50 joint venture between Genesee & Wyoming and Wesfarmers, took over the Westrail freight business in Western Australia and branded it as Australian Western Railroad. As part of the joint venture agreement, ownership of Australian Southern Railroad passed to the Australian Railroad Group. In 2002, Australian Southern Railroad, Australian Western Railroad and Australian National Railways were brought together as the Australian Railroad Group.
 In 2006, Australian Railroad Group sold its Western Australian operations to Queensland Rail and WestNet Rail. Simultaneously, Wesfarmers sold its 50% interest in the remainder of Australian Railroad Group to Genesee & Wyoming Inc, and the business was rebranded Genesee & Wyoming Australia (GWA).
 In 2010, GWA purchased the assets of FreightLink from that company's receivers and took over its operations. As a consequence, under a build–own–operate–and–transfer ("BOOT") agreement it became the lessor of the Alice Springs to Darwin section of the Adelaide–Darwin rail corridor until 2054, when ownership was to pass to the Australian federal government. It also became the lessee (from the Australian Rail Track Corporation) of the Tarcoola to Alice Springs sector until 2047. After this acquisition, GWA became the largest of 11  regions around the world in which Genesee & Wyoming Inc operated.
 After Freightliner Group was purchased by Genesee & Wyoming Inc in 2015, Freightliner's Australian operations were integrated with those of GWA.
 By 2016, GWA had been operating Glencore Rail's assets with fellow Genesee & Wyoming Inc subsidiary Freightliner for some time under a 20-year contract. In conjunction with Macquarie Infrastructure & Real Assets, the company acquired Glencore's Hunter Valley business. Concurrently, Genesee & Wyoming Inc acquired a 49% equity stake in GWA.
 In 2019, when the US parent Genesee & Wyoming Inc was sold to Brookfield Infrastructure Partners and GIC Private Limited, GWA was not included. Because Brookfield already had other rail assets in Australia that could well have led to the companies regulator, the Australian Competition and Consumer Commission (ACCC), to block the purchase, the 51% shareholding that Genesee & Wyoming Inc had in GWA was sold separately to PGGM. On departure of its US parent, the company was rebranded as One Rail Australia.
 In October 2021, Aurizon agreed on terms to purchase One Rail Australia. To ameliorate an expected concern of the ACCC about dilution of competition in the Hunter Valley and Queensland coal haulage market, in which the company already operated, Aurizon made a court-enforceable undertaking to divest the coal haulage part of its business. The ACCC did not oppose the company's sale, which took effect on 29 July 2022. 
 Assets assigned to be divested included 51 locomotives, 1468 freight vehicles, leases to four depots and offices, and two maintenance facilities.: 49–50   Assets acquired by Aurizon through ownership or leaseholding were 3700 kilometres (2300 miles) of track, 60 locomotives, 770 freight vehicles, five terminals, and six maintenance facilities.  About 400 employees transferred.
 At the time of the sale, the South Australian, Northern Territory and interstate haulage operations were carrying about 10 million tonnes annually. The divested part of the business conveyed 45 million tonnes of coal annually. Its disposal was arranged by a business unit operated separately from Aurizon, with an independent board and management and an ACCC-approved independent manager. Magnetic Rail Group purchased the assets in February 2023.
 The sale price of the divested assets was AUD2.35 billion.
 In 1999, Australian Railroad Group started operating services from Adelaide to Melbourne for Patrick Corporation. In that year the company also contracted with Liberty House Group to operate iron ore trains on its line from Middleback Range to Whyalla.
 In 2001, the company began operating services from Adelaide to Sydney via Broken Hill and Cootamundra. In 2003, it started operating within New South Wales when it was awarded a five-year contract to haul flour, grain and starch for the Manildra Group.
 In 2004, when the Alice Springs to Darwin section of the Adelaide–Darwin rail corridor was completed, the company commenced operating intermodal train services between Adelaide and Darwin supported by freight and passenger facilities owned and operated at Alice Springs, Tennant Creek, Katherine and Darwin.
 In 2008, as Genesee and Wyoming Australia, the company signed a five-year deal with ABB Grain to haul grain trains in Victoria.
 In 2010, when the company purchased the lease of the Alice Springs to Darwin section of the Adelaide–Darwin rail corridor and leased the Tarcoola-to-Alice Springs section, it also undertook train control for both lines. As of 2019, the weekly traffic on the line (in each direction) was six inter-modal, long-distance freight trains and The Ghan, an experiential tourism train.
 The company's market was expanded in 2020, when a coal hauling contract was started in Queensland.
 As of 2021, One Rail Australia leased 3700 km (2300 mi) of 1435 mm (4 ft 8+1⁄2 in) standard-gauge and 1067 mm (3 ft 6 in) narrow-gauge track. They were in two categories, since the company owned or leased some trackage and utilised some provided by other entities; three were narrow-gauge:
 The adjacent map summarises rail access arrangements for lines in South Australia and the Northern Territory, which formed the initial core of the company's operations. In South Australia, under a state government lease ending in 2047, the company operated and managed the non-metropolitan railway network except for routes to other states, and made it accessible to other companies. It also managed some yards and sidings attached to the ARTC main lines.
 The South Australian open-access regime included lines serving grain silos in the Murraylands and on Eyre Peninsula: respectively 1058 kilometres (657 miles) of broad gauge and 814 kilometres (506 miles) of narrow gauge. Viterra, the monopoly grain handler in South Australia, progressively closed most silos served by the Murraylands lines, resulting in rail haulage ending in the period 2002–2015. Viterra also moved to road transport on the Eyre Peninsula in 2019, resulting in the peninsula network becoming dormant except for the gypsum haulage line from Lake MacDonnell to the port of Thevenard near Ceduna. The Murraylands and Eyre Peninsula networks were the last remnants of the lightly built lines that had been crucial in establishing agriculture in South Australia. 
 As of November 2021, One Rail Australia's locomotive fleet totalled 132, including 16 in storage, of 24 different classes, as shown in the following table.  The table also shows the 51 locomotives of the 2200, GWA, GWN, GWU and XRN classes that were included in the divested assets eventually purchased by Magnetic Rail Group in February 2023.: 49