The $15.4 billion River Torrens to Darlington (T2D) Project has reached another major milestone, with the third and final Tunnel Boring Machine (TBM) cutterhead carefully craned into place at the Project’s Central North Precinct in Hilton. 

The cutterheads, each weighing more than 300 tonnes, have now been lifted into place for the mega-machines, which will make Australian history as the first road project operating three large-scale TBMs concurrently.

The Albanese and Malinauskas Labor Governments have each committed $7.7 billion towards the T2D project.

Safely lowered into the 20-metre-deep launch box by a 500-tonne gantry crane, the cutterhead sits at the front of the TBM and rotates to excavate rock and soil, known as spoil, from the tunnel face using cutting teeth and discs. 

With the cutterhead now in place, the remaining TBM components will be assembled, before final testing and commissioning ahead of tunnelling beginning in the second half of 2026. 

The third TBM will construct the Northern Tunnels by launching from Hilton and excavating 2.2 kilometres towards the project’s Northern Precinct near the Brickworks Marketplace in Torrensville, where it will be turned around before tunnelling back to Hilton. 

Once operational, each TBM will operate 24-hours a day, seven days a week, progressing approximately 8-10 metres per day, with up to 20 specialised workers inside at any one time.

Each TBM is approximately 100 metres long and 15 metres in diameter, roughly the height of the Thebarton Theatre or the goal posts at Adelaide Oval. 

The use of three TBMs will allow both the Northern and Southern Tunnels to be constructed concurrently, for the project to be delivered by 2031, if not before.

Quotes attributable to Federal Infrastructure, Transport, Regional Development and Local Government Minister Catherine King:

“The T2D Project will transform the way people move through and around Adelaide and progress is now really accelerating on this exciting project. 

“This is the city changing infrastructure that is achieved when Labor Governments at state and federal levels can work together to get things done.” 

Quotes attributable to SA Minister for Infrastructure and Transport Joe Szakacs: 

“The $15.4 billion T2D Project is not only the largest infrastructure project in South Australian history, but also the first road project in Australia to operate three large-scale TBMs concurrently.

“This historic first highlights the scale of what we are delivering. 

“For motorists driving past these sites every day, this milestone is another visible sign that we are moving closer to a non-stop South Road.

Quotes attributable to Federal Member for Adelaide Steve Georganas: 

“With the final cutterhead craned into place, this milestone marks another step forward on this game-changing infrastructure project.

“These tunnels will take thousands of cars off local roads, making it faster and safer for people travelling through our community.”