South Australia’s $15.4 billion Torrens to Darlington (T2D) Project has commenced in Adelaide after months of planning and machine assembly.
Tunnel Boring Machine (TBM) Mary is beginning to excavate T2D’s first 4.5-kilometre Southern Tunnel from the Southern Precinct at Clovelly Park to Glandore, marking a major milestone for the state’s largest infrastructure project.
Mary will operate 24/7, and is expected to progress approximately eight to 10 metres per day, with up to 20 specialised workers inside at any one time.
Mary’s first components arrived in Adelaide in October 2025, and were lifted into the launch box by a 500-tonne gantry crane before being assembled.
Measuring approximately 100 metres in length, 15 metres in diameter and weighing 3500 tonnes, Mary is one of three large-scale TBMs being used on the T2D project.
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The project’s second TBM, Catherine, will soon launch from the Southern Precinct to excavate the second parallel 4.5-kilometre Southern Tunnel.
Further north, the third TBM, Elizabeth, will launch from the project’s Central North Precinct at Hilton to construct the 2.2-kilometre Northern Tunnels.
Named after pioneering South Australian suffragists Mary Lee, Catherine Helen Spence and Elizabeth Webb Nicholls, the project’s three TBMs recognise the trailblazers who helped shape South Australia.
The use of three TBMs allows both the Northern and Southern Tunnels to be constructed concurrently, helping deliver a non-stop South Road by 2031.
The T2D project is the final 10.5-kilometre section of the North-South Corridor, and will complete 78 kilometres of non-stop, traffic light-free motorway between Gawler and Old Noarlunga.
“Once complete the project will allow motorists to bypass 21 sets of traffic lights between the River Torrens and Darlington, saving up to 40 minutes of travel time in peak hour traffic,” said Peter Malinauskas, Premier of South Australia.
“The scale of this project is extraordinary and I’m proud to be leading a government delivering such important infrastructure works for South Australia.”
The Federal and South Australian governments have each committed $7.7 billion towards the project.
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