the Kalgoorlie to Perth line was completed and in 1969 the Broken Hill to Port Pirie standard gauge railway were opened, completing Sydney–Perth railway. The Whyalla line was opened between Port Augusta and Whyalla in 1972. In October 1980, a new standard gauge railway was completed from Tarcoola to Alice Springs, replacing the former narrow gauge railway. Adelaide was connected to the standard gauge network with the opening of the line to Crystal Brook in 1982 and the Melbourne–Adelaide railway was converted to standard gauge in 1995. Meanwhile, the Tarcoola to Alice Springs railway was extended to Darwin in 2004 to complete the Adelaide–Darwin rail corridor. Private railways There have always been niches for private railways in most colonies, such as: timber – private timber lines have occurred in most forested areas of Australia since the late 19th century mining – private iron mining railways alone now account for most Australian rail freight by tonnage, but private coal railways have been important since the early years of coal mining in the mid 19th century quarrying major factory sites, such as steel works temporary lines at construction sites agriculture, especially the sugar industry Timber railways Most timber railway operations across Australia were transitory, only existing for the time that timber was extracted. Some lines were moved regularly to the areas of forest to be exploited. A few 19th century operations were horse hauled, but most were steam powered. Very few timber railways lasted into the 1960s with the advent of more versatile and stronger road based haulage. Mining railways Starting in the 1960s, four heavy duty railways were developed in the Pilbara region of the far north of Western Australia for the haulage of iron ore from several mines to the nearest ports. These railways are isolated from each other and from the national system, carrying no other traffic. The very heavy traffic on these lines, up to 100 million tonnes per year, push wheel/rail technology to its limits, and has resulted in considerable research and development that has been of value to railways worldwide. These iron ore railways are all gauge, and started off using American standards for track, locomotives and wagons. In 2008, the Fortescue Metals Group (FMG) commenced operating a fifth iron ore railway in the Pilbara. The railway lines are: Hamersley & Robe River railway (Rio Tinto) Mount Newman railway (BHP) Goldsworthy railway (BHP) Fortescue railway (FMG)