Three enormous tunnel boring machines are set to operate beneath Adelaide at the same time this week, marking an Australian first for the $15.4 billion River Torrens to Darlington Project.
TBMs Catherine and Elizabeth are undergoing final preparations and are expected to begin excavating within days, joining Mary, which has already carved around 100 metres beneath South Road.
It will be the first time three large-scale tunnel boring machines have operated simultaneously on the same underground road project anywhere in Australia.
Each machine stretches about 100 metres, weighs 3,500 tonnes and ranks among the largest pieces of construction equipment ever used in South Australia.
Federal Infrastructure and Transport Minister Catherine King said the milestone represented another major step forward for the nationally significant project.
“The completed T2D project will transform access to Adelaide Airport, Port Adelaide, the national highway network and more,” she said.
Mary was the first machine to begin tunnelling from the project’s Southern Precinct at Clovelly Park. Catherine will soon join her, with the pair excavating twin tunnels along a 4.5-kilometre route towards Glandore.
Further north, Elizabeth will depart from the Central North Precinct at Hilton and excavate the first of the 2.2-kilometre northern tunnels towards Brickworks Marketplace at Torrensville.
Once she reaches Torrensville, Elizabeth will be turned around and reassembled before making the southbound return journey to Hilton.
The use of three TBMs means work on the northern and southern tunnels can progress concurrently, helping keep the project on track to deliver a non-stop South Road by 2031.
Together, the machines will remove about five million tonnes of rock and soil, known as spoil. The material will travel from the TBMs to a spoil shed by conveyor before being loaded into covered trucks and transported to a reuse site at Gillman.
Around 7.5 million tonnes of spoil is expected to be generated across the entire project, including approximately five million tonnes from tunnelling and a further 2.5 million tonnes from civil works.
South Australian Infrastructure and Transport Minister Joe Szakacs said the scale of the operation was enormous both above and below ground.
“One TBM alone weighs about the same weight as eight or nine jumbo jets. At the completion of tunnelling for this project, 30,000 jumbo jet equivalents in soil weight will be moved,” he said.
Tunnelling is expected to take up to 24 months, although substantial work will continue after the machines complete their journeys.
This will include constructing the road inside the tunnels, installing mechanical, electrical and safety systems, testing and commissioning, and completing the open motorway section, bridges and footpaths.
The T2D Project will complete the final 10.5-kilometre section of Adelaide’s North-South Corridor, creating 78 kilometres of non-stop, traffic light-free motorway between Gawler and Old Noarlunga.
