Four Herrenknecht tunnel boring machines (TBMs) have been ordered for the construction of twin bore 9km tunnels on Melbourne’s Metro Tunnel project.
The first of the 7.2m diameter TBMs is expected to arrive on site early next year and are scheduled to complete tunnelling on the AUS$11bn (£5.95bn) scheme by 2021.
Two of the machines will be launched from 20m deep shafts at Arden and the other two from Domain to drive tunnels towards Kensington and South Yarra at depths of up to 40m below ground level. The TBMs will then be recovered, dismantled and transported back to the start point to complete drives towards the city.
Speaking at an event to announce the order, Victorian government minister for public transport Jacinta Allan said: “The TBMs will dig through a variety of ground conditions to link one side of the city to the other and its completion will represent a significant engineering feat.
“The Metro Tunnel will provide more trains, more often across Melbourne, meaning less time waiting on platforms or stuck on a train, and more time with your family.”