T2D Project makes an Australian first with new construction milestone

The delivery of the $15.4 billion River Torrens to Darlington (T2D) Project in South Australia is progressing well and continues to achieve major milestones.

Tunnel Boring Machines (TBMs) Catherine and Elizabeth have now joined TBM Mary, which has already excavated about 100 metres beneath South Road. All three massive diggers are now operational and tunnelling simultaneously, a first in Australian history.

"With TBM Catherine and Elizabeth getting underway, this is the first time in Australian history that three large-scale TBMs are tunnelling simultaneously on the same underground road project.

"This is yet another exciting milestone in this nationally significant infrastructure project, which will connect Adelaide from north to south.

"The completed T2D Project will transform access to Adelaide Airport, Port Adelaide, the national highway network and more," Federal Minister for Infrastructure, Transport, Regional Development and Local Government Catherine King said.

As the TBMs continue their journey beneath South Road, millions of tonnes of excavated material will also make their way to the surface. Approximately five million tonnes of rock and soil, also known as spoil, will be excavated collectively by the three large-scale machines as they build the northern and southern tunnels.

Spoil will be transferred from the TBMs via a conveyor to a shed before being loaded into covered trucks, which will be transported to the re-use site at Gillman.

In addition to the five million tonnes of spoil from the tunnels, a further 2.5 million tonnes are also expected to be generated from civil works, bringing a total of 7.5 million tonnes across the T2D Project.

Each TBM is around 100 metres in length and weigh 3,500 tonnes, making them the largest pieces of construction equipment ever used in South Australia.

"One TBM alone weighs about the same as eight of nine jumbo jets. At the completion of tunnelling for this project, 30,000 jumbo jet equivalents in soil weight will be moved.

"Together, the three TBMs will excavate around five million tonnes of rock and soil known as spoil as they construct the Northern and Southern Tunnels, so there's an enormous operation happening both below and above ground," SA Minister for Infrastructrure and Transport Joe Szakacs said.

Project map (source: T2D Torrens to Darlington)

TBM Mary began its journey from the project's Southern Precinct at Clovelly Park to dig underneath South Road. TBM Catherine has now joined her on the 4.5-kilometre journey towards Glandore to build the twin southern tunnels.

Meanwhile further north, TBM Elizabeth commenced its journey at the Central North Precinct at Hilton to excavate the first of the twin 2.2-kilometre northern tunnels towards the Brickworks Marketplace at Torrensville.

Upon reaching the end, TBM Elizabeth will be turned around and reassembled for a return journey to Hilton, building the second northern tunnel.

Utilising three massive TBMs will allow both southern and northern tunnels to be constructed concurrently, enable the delivery of a non-stop South Road by 2031.

Tunnelling works across the project are expected to take up to 24 months. Significant work will continue after the TBMs conclude their journeys, which will include building the road within the tunnels, installing safety, mechanical and electrical systems, testing and commissioning, and completing compliance checks.

Works on the open motorway that connects to the tunnels will also be completed, including the delivery of bridges and footpaths.

"The hard work continues on this massive project, with these incredible machines now carving a new north-south road link beneath Adelaide.

"This project will mean faster journeys across our city and take pressure off surrounding roads. There's so much for our community to look forward to as we reach this exciting new stage," Federal member for Boothby Louise Miller-Frost said.

The T2D Project is the final 10.5-kilometre section of the North-South Corridor, and it completes the 78-kilometres non-stop, traffic light-free motorway between Gawler and Old Noarlunga. Once up and running, it will enable motorists to bypass 21 sets of traffic lights as they travel through two separate tunnels that are connected by an open motorway.

The River Torrens to Darlington Project is comprised of:

• Southern Tunnels
  • Run between the open motorway at Darlington to just south of Anzac Highway in Glandore and provide key connectivity to Anzac Highway
  • Includes about 4.5 kilometres of twin three-lane tunnels
• Open motorway linking the tunnels
  • Connecting key routes such as Richmond Road and James Congdon Drive, it will provide critical east-west connectivity and links to key destinations such as the airport
  • Just over 2.7 kilometres in length
• Northern Tunnels
  • Run between James Congdon Drive and the existing motorway south of Grange Road
  • Includes about 2.2 kilometres of twin three-lane tunnels

Source: Minister for Infrastructure, Transport, Regional Development and Local Government; We Are SA – News; T2D Torrens to Darlington