A second precinct for Australia’s River Torrens to Darlington (T2D) Project has been established ahead of construction of the Northern Tunnels.

At the Central North Construction Precinct at Richmond work has started on the diaphragm walls for the TBM launch pit. The third TBM will be launched from this site to build the twin 2.2km Northern tunnels.

Three Herrenknecht TBMs will work concurrently to construct the Northern and Southern Tunnels, and two 4m-diameter TBMs will excavate the cross-passages. These are located every 120m along the length of the main tunnels. The first TBM is expected to arrive in Adelaide later this year.

Work is already under way to enable the first two TBMs to be launched from the Southern Precinct at Clovelly Park to construct the 4.5km Southern tunnels. Excavation is scheduled to begin in the second half of 2026.

A bentonite plant has recently been built at Central North to produce and recycle bentonite slurry. Nine 14m-high silos have been installed in the bentonite plant, which can each hold 90m3 of bentonite slurry.

A water treatment plant is being built to treat and reuse water during the tunnelling process, as well as a 100m3 buffer pond to hold spare water produced by construction activities.

Construction is also under way on the manufacturing facility that will supply more than 55,000 segments for the tunnels. The precast plant is expected to start segment production later this year.

South Australia deputy premier Susan Close said the establishment of the Central North Construction Precinct was a significant milestone in creating a non-stop South Road that would ease congestion, improve safety and create more connected communities.

“Every step forward on the River Torrens to Darlington Project brings South Australians closer to a more modern transport network that strengthen our state and serve our community for generations to come,” she said.