en.Wedoany.com Reported - A tunnel boring machine (TBM) with a diameter of 4.1 meters has arrived in Adelaide for cross-passage excavation on the River Torrens to Darlington (T2D) tunnel project, Australia’s largest road infrastructure initiative. This is the first of two dedicated cross-passage TBMs serving the A$10 billion project.
The T2D project is South Australia’s first major underground road tunnel. Previously, the first mainline TBM, Mary, began its drive between Clovelly Park and Glandore, excavating the initial 4.5-kilometer southern tunnel. This 100-meter-long, 15-meter-diameter earth pressure balance machine (EPBM) advances approximately 8 to 10 meters per day, operating continuously.
The project is being delivered by the T2D Alliance, comprising John Holland, Bouygues Construction Australia, Arcadis Australia, Jacobs, and Ventia, using Herrenknecht TBMs for the Australian and South Australian governments.
The newly arrived cross-passage TBM has a diameter of 4.1 meters, with a second identical unit expected to arrive within weeks after completing factory acceptance testing in China. These dedicated cross-passage TBMs are a first for Australian tunneling, making T2D the country’s first project to excavate cross-passages solely with TBMs, abandoning traditional mining methods.
These compact machines are essentially scaled-down versions of the three mainline TBMs (Mary, Catherine, Elizabeth), designed specifically for Adelaide’s soft clay and soft ground conditions. They will excavate cross-passages at approximately 120-meter intervals, creating mandatory emergency escape routes, maintenance access, and space for electrical, communication, and signal infrastructure between the twin tunnels.
Project construction pace continues to accelerate. Following Mary’s launch, its sister machine Catherine has undergone a traditional tunnel engineering blessing ceremony at the Clovelly Park launch box and is about to begin excavating the second 4.5-kilometer southern tunnel. Another TBM, Elizabeth, will start from the central northern area in Hilton, excavating the twin 2.2-kilometer northern tunnel, with a blessing ceremony to follow.
Mary’s launch marked the culmination of months of assembly work. The machine’s components first arrived in Adelaide in October 2025, with a total weight of 3,500 tons. They were lowered piece by piece into the launch box using a 500-ton gantry crane and assembled underground.
The T2D project is Australia’s first underground road project to deploy three 15-meter-diameter TBMs simultaneously, enabling parallel excavation of the southern and northern tunnels. Scheduled for completion in 2031, the project will close the final 10.5-kilometer gap in Adelaide’s north-south corridor, forming a continuous 78-kilometer highway from Gawler to Old Noarlunga without traffic signals.
The project is jointly funded by the Australian and South Australian governments, each contributing A$7.7 billion.
