The Bendigo and Geelong-Ballarat mainlines were both built as double track in the 1860s, but were singled in the 1930s and first decade of the 21st century respectively.
On the interstate railway corridors there are independent sections of track due to the use of both broad and standard gauges in the state, these sections being from Melbourne to Seymour and on to Albury (constructed in the 1960s), and Melbourne to Geelong (completed in 1995).