Perth commuter trains network is outstanding in terms of high frequency of services and high average speeds. Some lines average as high as 90 km/h and run with 4 min headway. Almost all CBD remains in short walking distance from underground train stations.
Unlike most European cities, commuter railways in Perth were created relatively late, the first electrified lines were opened in 1991. That has allowed Perth to develop fully modern commuter rail system that corresponds to today's highest world standards.
Perth had Diesel Multiple Units before electrification (from the 1960s till the 1990s.) They sold them to Auckland when the electrics came in and it completely rebooted Auckland's system. Maersk.146, the extra track is part of the dual gauge track (1067 and 1435) to/from East Perth station where the Indian Pacific and Prospector passenger trains arrive and depart from.