Work has entered a new phase on South Australia’s largest infrastructure project, with tunnelling now underway on the $15.4 billion River Torrens to Darlington (T2D) project as construction moves below ground.
Tunnel Boring Machine Mary has begun excavating the first 4.5-kilometre southern tunnel between Clovelly Park and Glandore, marking the first major underground road tunnelling project undertaken in South Australia.
The T2D project will complete the final 10.5-kilometre section of the North-South Corridor, creating a continuous motorway between Gawler and Old Noarlunga. Governments say the completed route will allow motorists travelling between the River Torrens and Darlington to bypass 21 sets of traffic lights, with peak-hour travel times expected to improve.
Operating around the clock, Mary is expected to advance between eight and 10 metres each day, with up to 20 specialised workers inside the machine during excavation. The tunnel boring machine measures about 100 metres in length, 15 metres in diameter and weighs approximately 3,500 tonnes.
Mary is one of three tunnel boring machines being used on the project. A second machine, Catherine, is expected to begin excavating a parallel southern tunnel from Clovelly Park, while a third machine, Elizabeth, will later construct the 2.2-kilometre northern tunnels from the project’s Hilton site.
The three machines are named after South Australian suffragists Mary Lee, Catherine Helen Spence and Elizabeth Webb Nicholls, recognising their contribution to the state’s history.
The Australian and South Australian governments have each committed $7.7 billion towards the project, which is scheduled for completion in 2031.
South Australian Premier Peter Malinauskas described the start of tunnelling as a major milestone after years of planning and preparation.
“After all the careful planning and machinery assembling, tunnelling is now underway to deliver South Australia a non-stop South Road,” he said.
Federal Infrastructure, Transport, Regional Development and Local Government Minister Catherine King said the project would improve connections across Adelaide while reducing traffic on local roads.
“As we reach another important milestone for the River Torrens to Darlington project, we are a step closer to taking thousands of cars off local roads, making it safer and faster for commuters travelling across the state,” she said.
South Australian Minister for Infrastructure and Transport Joe Szakacs said construction was entering a new chapter as work shifted underground after months of visible activity along South Road.
Federal Member for Boothby Louise Miller-Frost said the completed project was expected to provide a faster route for through traffic while reducing pressure on surrounding local roads.
Members of the public will be able to follow the progress of tunnelling through an online tracker, which will provide updates on the approximate location of each tunnel boring machine as work continues over the coming years.
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