South Australia’s largest ever road project has achieved a major milestone, with the first of three TBM cutterheads being lifted into place
The first of three 300-tonne tunnel boring machine cutterheads are being lifted into place on South Australia’s $15.4 billion River Torrens to Darlington works to create a non-stop South Road.
In a carefully coordinated operation, a 500-tonne gantry crane will safely lower the cutterhead into the 20-metres-deep Southern Precinct launch box at Clovelly Park.
Around 120,000 cubic metres of material weighing more than 343,000 tonnes has already been excavated in preparation for this milestone to form the TBM launch box, which measures 120m in length, 50m in width, and 20m in height.
The first and second TBMs are being assembled alongside each other at the Southern Precinct. They will soon be tasked with carving out the twin Southern Tunnels, excavating through soil and rock, known as spoil, on the 4.5-kilometre journey towards Glandore and Black Forest.
All components for the third TBM, which will dig both of the 2.2-kilometre-long Northern Tunnels, have now arrived in South Australia.
Once the first cutterhead has been attached to the front of the TBM, other major parts of the machine will then be assembled, with the completed TBM to undergo final testing and commissioning before tunnelling begins.
“River Torrens To Darlington is South Australia’s biggest ever road project, and the final piece of the road corridor that will link Adelaide’s north to the south,” federal infrastructure minister Catherine King says.
“The new underground tunnels will allow cars to skip 21 sets of traffic lights, and shave almost 40 minutes off some daily commutes.”
Tunnelling is expected to commence in the second half of 2026. Once operational, each of the mega machines 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 will be approximately 100m in length and 15m in diameter and weigh approximately 3,500 tonnes.
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.
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