The South Australian government and the T2D Alliance have signed a contract to purchase three initial TBMs from Herrenknecht and infrastructure and transport minister Tom Koutsantonis confirmed plans to purchase two additional, smaller TBMs – with another likely to follow – to excavate the cross-passages between the main tunnels. The total cost of all TBMs is expected to be around A$180m (£93m).
The purchase of the three initial TBMs comes just two weeks after the main construction contract was officially signed by the T2D Alliance of John Holland, Bouygues Construction, Arcadis Australia, Jacobs and Ventia.
The TBM components will be manufactured in Germany and China, before being assembled and factory assurance tested in China and then delivered to Adelaide. The first is expected to arrive in late 2025.
The TBMs used to construct the T2D tunnel will be approximately 100m in length and 15m in diameter.
The additional smaller 4.1m-diameter TBMs will construct the cross-passages –saving time on conventional construction methods.
The procurement of three initial TBMs for the major tunnelling work means the northern and southern tunnels can be constructed concurrently.
Main construction works are scheduled to start in 2025, with TBM works for the southern tunnels planned to begin in the second half of 2026.
The project is due to be completed in 2031.
The T2D project, which is being jointly delivered by the Australian government and the South Australian government, is the final section of the North-South Corridor and South Australia’s largest infrastructure project. Two sets of twin, three-lane tunnels will account for more than half of the 10.5km stretch of road.
