The work in Western Australia was predicated by an agreement entered into in November 1960 between the State Government and BHP for a standard gauge line to be built to allow iron ore from Koolyanobbing to be shipped to a new steel mill at Kwinana. A new dual gauge line was built through the Avon Valley from Midland to Northam on 1 in 200 grades instead of 1 in 40; and a new line was built from Southern Cross to Kalgoorlie though Koolyanobbing. The first wheat train ran from Merredin to Fremantle in November 1966 and the first iron ore train from Koolyanobbing to Kwinana in April 1967, with the line opened in full in August 1969. Kalgoolie to Perth freight train times were reduced from 31 hours to 13 hours, and passenger train times from 14 hours to 8 hours. A new line was built from Woodbridge to Kwinana and one of the tracks on the Fremantle line converted to dual track from Cockburn Junction to Fremantle Harbour. The Midland line in Perth was converted to dual gauge and a new terminus station built.