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Adelaide’s massive River Torrens to Darlington Project is expanding its underground fleet, with the first of two specialised tunnel boring machines arriving to excavate critical safety passages between the twin tunnels.
The two machines will bring the $15.4 billion project’s total fleet to five and mark the first time an Australian tunnelling project has used two dedicated machines to excavate cross passages.
Standing 4.1 metres tall, the smaller machines have been purpose-built to create connecting tunnels every 120 metres between the parallel northbound and southbound tunnels.
These cross passages are a mandatory safety feature, providing evacuation routes between the main tunnels in the unlikely event of an emergency. They will also provide maintenance access and contain important electrical and signalling infrastructure.
The machines are essentially scaled-down versions of the three enormous tunnel boring machines being used to excavate the project’s four main tunnel drives.
Each of the larger machines measures approximately 100 metres long and 15 metres in diameter and weighs about 3,500 tonnes.
Mary and Catherine will excavate the twin 4.5-kilometre Southern Tunnels, while Elizabeth will dig the twin 2.2-kilometre Northern Tunnels.
The first specialised cross-passage machine has now arrived in Adelaide after passing factory acceptance testing in China. The second is expected to arrive in the coming weeks.
The milestone comes as Catherine was officially blessed at the Clovelly Park launch box on Saturday before she begins tunnelling alongside Mary.
The ceremony was led by Father Joseph Wales Raja George from nearby St Bernadette’s Church, continuing a longstanding international tunnelling tradition.
Further north, Elizabeth will also be blessed before beginning work on the Northern Tunnels from the Central North Precinct at Hilton.
Acting Premier Kyam Maher said the project had made remarkable progress since contracts were signed less than two years ago.
“Since we signed on the dotted line less than two years ago, we’ve seen these machines designed and manufactured, pass rigorous factory acceptance testing, travel halfway around the world, transported piece by piece from the Port, meticulously assembled and now tunnelling.
“And in another Australian first, we’re adding two new TBMs to the mix to dig the project’s cross passages.
“Each day we are getting closer to delivering a non-stop South Road where South Australians will be able to bypass 21 sets of traffic lights between the River Torrens and Darlington and save up to 40 minutes of travel during peak hours.”
The T2D Project is the first underground road project in Australia to use three large-scale tunnel boring machines at the same time.
Using three machines will allow construction of the Northern and Southern Tunnels to progress concurrently, with the completed non-stop South Road expected to open in 2031.
The project will complete the final 10.5-kilometre section of the North-South Corridor, creating 78 kilometres of traffic light-free motorway between Gawler and Old Noarlunga.
The Australian and South Australian governments have each committed $7.7 billion to the project.
