Ground has broken on South Australia’s biggest infrastructure project.

Tunnelling has commenced on the $15.4 billion River Torrens to Darlington Project.

Set to open in 2031, the project will deliver the final section of the 78km North-South Corridor project.

Once complete, motorists will be able to travel non-stop, traffic light free on the motorway from Gawler in Adelaide’s northern suburbs to Old Noarlunga.

The project consists of two twin tunnels at each of the northern and southern ends, which are linked by 2.5 kilometers of open motorway.

Each tunnel will feature three lanes in each direction.

Tunnels were needed in order to avoid disruption as this final stage travels through highly developed residential and heritage areas.

As a result, this will be the most complex section of the 78-kilometer project.

(image source: South Australian Government)

All up, three tunnel massive boring machines will be used to excavate the two tunnels.

Each machine measures around 100 meters in length and weighs around 3,500 tonnes.

The first TBM – known as TBM Mary – launched at the project’s southern end on July 1.

It is now working on the 4.5 kilometer southern tunnel section that will run from the Southern Precinct at Clovelly Park to Glandore.

Operating 24/7, it will progress approximately 8-10 metres per day, with up to 20 specialised workers inside.

After its first components arrived in Adelaide last year, each component of the machine has been lifted into the launch box by a 500-tonne gantry crane before being assembled into the machine which it is today.

The Project’s second TBM, Catherine, will soon launch from the Southern Precinct to excavate the second parallel 4.5-kilometre Southern Tunnel.

Further north, the third, TBM, TBM Elizabeth, will launch from the Project’s Central North Precinct at Hilton to construct the 2.2-kilometre Northern Tunnels.

(image source: Infrastructure Australia)

The use of three TBMs allows both the Northern and Southern Tunnels to be constructed concurrently.

This will help to deliver the project on time by 2031.

The three TBMs were named after pioneering South Australian suffragists Mary Lee, Catherine Helen Spence and Elizabeth Webb Nicholls.

The names recognise the contribution of these women in helping to shape South Australia.

The project is being delivered by the T2D Alliance.

This involves the consortium of John Holland, Bouygues Construction, Arcadis Australia, Jacobs and Ventia – which is working with the South Australian Government.

The project is being funded jointly by the Australian Government and the South Australian Government.

Aurecon served as the lead master advisory and engineering consultant during the earlier master planning and community integration phases of the project.

Additional partners and subconsultants have included Woods Bagot, Modus Forma and Tract Consultants (architecture and urban design), Karl Winda Relfa (cultural advisor) and Bowhill Engineering (steel fabrication).