Four giant tunnel boring machines (TBMs) will start arriving early next year to build the two 9km tunnels which make up Melbourne’s $11 billion Metro Tunnel project.
The Metro Tunnel will create a new end-to-end rail line from Sunbury to Cranbourne/Pakenham and five new underground stations, allowing more frequent, reliable trains to run between the city and suburbs each day.
Each TBM is 100 metres long with a diameter of 7.2 metres, and weighs up to 1,000 tonnes. The machines are large enough to include offices, kitchens and bathrooms to support crews of up to 14 people.
They will operate like moving factories in a round the clock operation beneath the city’s surface, . The giant cutterheads burrow through around 10 metres of soil and rock each day. The soil is then transported via pipes to the surface. At the same time, the TBMs progressively install watertight concrete lining.
Each TBM's cutterhead weighs 175 tonnes, and can tunnel through rock six times harder than concrete. The deepest tunnelling point, under Swanston Street near the new State Library Station, is around 40 metres below the surface.
Work is now underway to build a huge tunnelling hub shed in Yarraville to reduce noise and dust during construction of the Tunnel. The hub shed will be bigger than the Altona Bunnings, and will process more than 1.5 million cubic metres of dirt and rock excavated from the tunnels, enough to fill the MCG.
More than 800 people are already working on the West Gate Tunnel Project, which will create more than 6000 jobs for Victorians.