Adelaide Ramps Up for Historic Tunnel Construction with $180 Million TBM Purchase

South Australia’s largest infrastructure project has reached a pivotal milestone with the formal signing of contracts to purchase five tunnel boring machines for the $15.4 billion River Torrens to Darlington Project. The September 30, 2024 agreement represents one of the biggest equipment purchases in the state’s construction history and accelerates the timeline for completing Adelaide’s long-awaited non-stop motorway.

Historic Equipment Purchase Advances Timeline

The South Australian Government and the T2D Alliance sealed contracts with German manufacturer Herrenknecht for three primary tunnel boring machines, valued at approximately $180 million total including two additional smaller machines. Infrastructure and Transport Minister Tom Koutsantonis finalized the purchase at Herrenknecht’s headquarters in Schwanau, Germany, just two weeks after the main construction contract was awarded to the consortium comprising John Holland, Bouygues Construction, Arcadis Australia, Jacobs and Ventia.

The acquisition represents up to double the number of machines originally anticipated for the project. The three main TBMs will excavate the twin tunnels concurrently rather than sequentially, potentially allowing completion ahead of the 2031 target date.

Machine Specifications Drive Construction Strategy

Each primary tunnel boring machine measures approximately 100 meters in length and 15 meters in diameter, comparable to the height of the Thebarton Theatre. The machines will operate continuously, progressing 8-10 meters per day through Adelaide’s varied geological conditions. Components will be manufactured in Germany and China before assembly and factory testing in China, with the first TBM scheduled to arrive in Adelaide by late 2025.

Two additional 4.1-meter diameter machines will excavate cross-passages between the main tunnels every 120 meters. These smaller TBMs replace conventional construction methods for the safety and operational passages, reducing construction time and complexity.

Construction Precincts Establish Foundation

Major construction activities commenced at the Southern Precinct in Clovelly Park during May 2025, marking the first permanent works on the project. The site will serve as the launch point for two TBMs constructing the twin 4.5-kilometer Southern Tunnels. Construction crews have begun excavating diaphragm walls up to 35 meters deep to form the TBM launch box where the machines will be assembled and begin tunneling operations.

A second construction precinct opened in Richmond between Sir Donald Bradman Drive and Keswick Creek for the Northern Tunnels. The Central North Construction Precinct features a bentonite plant with nine 14-meter tall silos capable of holding 810 cubic meters of bentonite slurry for ground stabilization during excavation.

Manufacturing Infrastructure Supports Demand

Construction has advanced on a specialized concrete manufacturing facility at Waterloo Corner that will produce over 55,000 precast tunnel lining segments. Heidelberg Materials Australia secured the segmental lining concrete supply contract, building a dedicated wet batch plant to meet the project’s substantial demand. The facility spans 285 meters in length and 25 meters in width, with the concrete slab foundation nearing completion as of June 2025.

The manufacturing approach reflects the project’s massive scale, with 8 million tonnes of spoil expected during construction and 189 contracts already awarded totaling approximately $350 million.

Employment and Economic Impact

The project will support approximately 5,500 jobs annually during peak construction, with 90 percent of labour hours performed by South Australians. The consortium committed to minimum 6 percent Aboriginal employment alongside more than 600 positions for apprentices and trainees, and opportunities for over 220 long-term unemployed individuals.

Up to 550 workers will be employed at the Southern Precinct during peak construction, with similar numbers expected at the Central North facility. The employment figures represent the largest single infrastructure workforce in South Australia’s history.

Minister Koutsantonis emphasized the project’s momentum during the TBM signing ceremony. “The ink is still wet on the T2D main construction contract, but already the project is moving forward by swiftly securing South Australia’s first-ever tunnel boring machines from world leader Herrenknecht in Germany,” he stated.

“These are seriously big pieces of kit, and today’s purchase represents one of the biggest purchases of building equipment in South Australia’s history.”

Final Thoughts

The concurrent tunneling approach enabled by three main TBMs provides reasonable expectation for completion ahead of the 2031 deadline. TBM works for the Southern Tunnels are planned to begin in the second half of 2026, following assembly and commissioning of the machines after their late 2025 arrival.

The project will complete 78 kilometers of non-stop, traffic light-free motorway between Gawler and Old Noarlunga. Motorists will bypass 21 sets of traffic lights between the River Torrens and Darlington, reducing peak hour travel times by up to 40 minutes.

Federal Infrastructure Minister Catherine King highlighted the project’s significance for South Australia’s transport network. “This is the last leg of a long journey to create the North-South Corridor – 78km of non-stop, traffic light-free motorway – and once complete, it will change the state for the better,” she said.

The T2D Project represents joint funding of $15.4 billion split equally between the Australian and South Australian governments, marking the largest infrastructure investment in the state’s history.