Railways in Melbourne
In February 2015, the State Government established the Melbourne Metro Rail Authority to oversee planning for new twin 9-kilometre rail tunnels through the central city between South Kensington station and South Yarra. The new Metro Tunnel will have five new underground stations and connect the Pakenham and Cranbourne lines with the Sunbury line, creating a new route through the CBD as an alternative to the City Loop. New underground stations will be created at Arden, Parkville, Domain and two new CBD stations, State Library and Town Hall. Enabling works were underway by 2016 and major construction work on the tunnel and stations began in 2017.The project has an estimated cost of $11 billion and is scheduled to be complete by 2025.
Railway tunnels in Victoria, Australia
The Melbourne–Echuca railway or Bendigo line was commenced by the private Melbourne, Mount Alexander and Murray River Railway Company, but when the company experienced financial difficulties it was taken over by the Victorian colonial government in 1856, with the Victorian Railways Department being formed to operate the new public railway system. The line opened in five stages from February 1859 to September 1864, and was at the time the largest engineering undertaking in the colony. More than 6,000 men were involved in construction of the Bendigo line with the main contractors Cornish and Bruce undertaking the works. The line served a strategic economic need of serving the important goldfields of Castlemaine and Bendigo (then called Sandhurst), and capturing for Melbourne the trade in wool and other goods from northern Victoria and the Riverina which were formerly shipped through South Australia via the Murray River. Two tunnels were built on the line. The Elphinstone Tunnel, long, was built in brick and bluestone as a double-track horseshoe profile tunnel, and was completed in 1860. The Big Hill Tunnel, located between Kangaroo Flat and Ravenswood, south of Bendigo. Like the Elpinstone Tunnel, it was double-tracked when built, but was singled as part of the Regional Fast Rail project. 
Cheviot tunnel was built for the extension of the Mansfield railway line from Yea and is located near Limestone, roughly halfway between Yea and Molesworth, where the line crosses the Black Range at McLoughlin's Gap. It was built in 1889, at a cost of £88,661/2/11, by contractors by Kenny Bros. as part of the Yea to Cathkin section, but construction was delayed by accidents.