Three TBMs set to tunnel simultaneously on Adelaide T2D project

All three main TBMs on Adelaide’s US$10.3bn River Torrens to Darlington (T2D) project are expected to be operational this week, marking an Australian first for a road tunnelling project. TBMs Catherine and Elizabeth are completing final preparations ahead of launch and will join TBM Mary, which has already excavated around 100m beneath South Road. The main works are being delivered by the Torrens to Darlington Alliance, comprising construction contractors John Holland and Bouygues Construction Australia, designers Arcadis and Jacobs, and operations and maintenance partner Ventia, working with South Australia’s Department for Infrastructure and Transport. The alliance contract was executed in September 2024. The three large-diameter Herrenknecht TBMs will excavate the project’s 4.5km-long Southern Tunnels and 2.2km-long Northern Tunnels concurrently. Each machine is approximately 100m long, 15m in diameter and weighs 3,500 tonnes, making them the largest pieces of construction equipment used in South Australia. The machines are designed to operate around the clock and advance approximately 8m to 10m/day. Mary was the first machine to launch, beginning excavation from the Southern Precinct at Clovelly Park towards Glandore. Catherine will launch from the same site to excavate the parallel 4.5km Southern Tunnel. Further north, Elizabeth will launch from the Central North Precinct at Hilton and drive approximately 2.2km north towards the Brickworks Marketplace at Torrensville. On completing the first Northern Tunnel, the machine will be dismantled into sections, turned around and reassembled before driving the southbound tunnel back to Hilton. The simultaneous operation of Mary, Catherine and Elizabeth will be the first time three large-scale TBMs have operated concurrently on the same underground road project in Australia. The machines are named after South Australian suffragists Mary Lee, Catherine Helen Spence and Elizabeth Webb Nicholls. Together, the three TBMs are expected to excavate around 5Mt of rock and soil during construction of the Northern and Southern Tunnels. Excavated material will be transported by conveyor from the machines to surface spoil sheds before being loaded into covered trucks and taken to a reuse site at Gillman. Around 7.5Mt of spoil is expected to be generated across the entire T2D programme, comprising approximately 5Mt from tunnelling and 2.5Mt from associated civil works. The three main machines will also be supported by two purpose-built 4.1m-diameter cross-passage TBMs. The smaller machines will excavate connections between the parallel running tunnels at approximately 120m intervals, in what the project says is the first Australian use of purpose-built TBMs for cross-passage excavation. Tunnelling is scheduled to continue for up to 24 months. Following excavation, the alliance will construct the roadways and install mechanical, electrical and tunnel safety systems before testing and commissioning. The T2D scheme forms the final 10.5km section of Adelaide’s North-South Corridor and will connect the existing motorway sections to provide a 78km traffic light-free route between Gawler and Old Noarlunga. The project is jointly funded by the Australian and South Australian governments, which have each committed A$7.7 billion. Completion and opening to traffic is scheduled for 2031. Herrenknecht Pioneering Underground Technologies - Herrenknecht AG is the technology and market leader in mechanized tunnelling. As the only company worldwide, Herrenknecht delivers cutting-edge tunnel boring machines for all ground conditions and in all diameters - ranging from 0.10 to 19 meters. More Information | [email protected] | +49 7824 3020 Comments: