at Ooldea on 17 October 1917. Under the aegis of the federal department of transport, the Commonwealth Railways was established in 1917 to operate the line. Once passenger trains started to run, maintenance staff found that the high mineral salt content of bore water available along the route was playing havoc with steam locomotive boilers: repairs to boilers at one time accounted for an extraordinary 87 per cent of all locomotive maintenance. The problem was only arrested with the introduction of barium carbonate water treatment plants at watering points. In 1937, the eastern end was extended south to Port Pirie. Soon afterwards, the South Australian Railways extended its broad-gauge line north to Port Pirie from Redhill. These two projects made redundant the indirect , narrow-gauge connection from Terowie via Peterborough and Quorn, resulting in a much shorter and more comfortable journey to Adelaide. These two projects eliminated one break of gauge in the journey across Australia, but they turned Port Pirie Junction yard into a complex three-gauge facility. Railway engineers, however, were able to construct the new yards with no more than minimal dual-gauge track and the complex signalling that would have been incurred. The long-anticipated conversion of the entire line between Sydney and Perth to standard gauge occurred in 1970. In 2004, the gap in standard gauge connections between the mainland state capitals was finally closed with a connection between Port Pirie and Adelaide, thence Melbourne, and by completion of the northern component of the Adelaide–Darwin railway line, which diverges from the Trans–Australian Railway at Tarcoola. In 2008, the engineering heritage of the railway was recognised by the Engineering Heritage Recognition Program of Engineers Australia when markers were installed on the platform at the Port Augusta station in South Australia and the ticket office at Kalgoorlie station in Western Australia. On 17 October 2017, centenary celebrations were held at Ooldea. Named services When the line was inaugurated, the passenger service was named as the Great Western Express. Later, the train became known as the Trans-Australian or, colloquially, "The Trans". After the Sydney–Perth route was converted to standard gauge in 1970, the railway was no longer flanked at both ends by narrow-gauge lines and an all-through service, called the Indian Pacific, was started. Although passengers no longer had to move to different carriages at change-of-gauge localities, Commonwealth Railways remained responsible for the service where it operated between Port Pirie and