It’s the $15 billion project that’s reshaping how we travel across Adelaide. Discover everything you need to know about the River Torrens to Darlington (T2D) Project.
It’s South Australia’s biggest road project, and things are ramping up.
You might have seen footage of huge pieces of machinery moving along South Road in the middle of the night.
They were the first components of what will become the state’s largest-ever construction machines, the Tunnel Boring Machines (TBMs), and their arrival marked a major milestone for the River Torrens to Darlington (T2D) Project.
The TBMs will excavate the northern and southern twin tunnels of the T2D Project, paving the way for a non-stop South Road and a safer, easier way to travel across Adelaide.
Two TBMs will launch from Clovelly Park to build the 4.5km southern tunnels, while a third will begin its underground journey from Richmond to excavate the 2.2km northern tunnels.
Here’s what’s happening, why it matters, and what it means for your drive.
What is the T2D Project?
The T2D Project is the final 10.5km piece in Adelaide’s North-South Corridor, connecting Gawler in the north to Old Noarlunga in the south.
Once it’s complete, motorists will be able to travel beneath South Road on a continuous, non-stop motorway – bypassing 21 sets of lights and improving travel times by up to 40 minutes during peak hour.
It’s a $15.4 billion project – jointly funded by the Australian and South Australian Governments, with each contributing $7.7 billion – combining two major tunnel sections with an open motorway in between and linking to the other motorway sections already in place.
What’s happening to South Road?
When the tunnels are finished, South Road isn’t disappearing – but it will feel very different.
For much of the 10.5km stretch between the River Torrens and Darlington, the tunnels will run beneath the existing South Road, carrying through-traffic underground. The road above will stay in place for local access, connecting nearby suburbs, shops and businesses.
Here’s how it works:
- Underground: The new motorway will handle most of the through-traffic – three lanes each way, completely free of lights and intersections.
- Above ground: South Road will stay open for local trips, public transport, cyclists and pedestrians.
- In between: An open motorway section will connect the northern and southern tunnels, sitting below the surface but providing ramp connections from the motorway to other key roads.
That means most cars, trucks and commuters will travel non-stop underground, while the surface level becomes quieter, safer and easier to navigate for people moving around their local area.
Meet the mega-machines
Three large Tunnel Boring Machines (TBMs) will be used to excavate the northern and southern twin tunnels of the T2D Project.
Purchased from world-leading manufacturer Herrenknecht, each large-scale TBM measures approximately 100m in length and 15m in diameter – longer than a Boeing 747 and roughly the height of the Thebarton Theatre or Edwardstown Bunnings. They’ll be the largest pieces of construction equipment ever used in South Australia.
Shipped to Adelaide in numerous pieces, each TBM takes around six months to assemble and commission at purpose-built launch sites before tunnelling begins.
You might have seen footage of the 9m-wide centrepiece of the cutterhead, which goes at the front of a TBM to excavate soil and rock, on its journey from Port Adelaide on a specialised truck and trailer. It’s now on site at the project’s Southern Precinct in Clovelly Park.
Two TBMs will launch from this precinct to build the 4.5km southern tunnels, which will run from Clovelly Park to just south of the Glenelg Tramline in Glandore. The third TBM will start at Richmond to construct the 2.2km northern tunnels.
The TBMs will operate continuously, moving about 8–10m a day, and have up to 20 specialised tunnel crew members working inside.
In addition to the three large TBMs there will be two mini-TBMs (around 4m in diameter), that will excavate the cross passages linking the twin tunnels for maintenance and safety access.
What’s happening now?
If you’ve noticed more detours and roadworks around South Road lately, that’s because major construction is underway. While crews are working hard to keep disruptions to a minimum, things are getting busier as the project progresses north.
- Southern Precinct (Clovelly Park): The first permanent works began in May this year, ahead of tunnelling works starting in the second half of 2026. Two of the project’s TBMs will be launched from the Southern Precinct to construct the twin 4.5km southern tunnels, which will run between the motorway at Darlington to just south of Anzac Highway in Glandore. A section of open motorway will also be built here, linking the T2D Project with the Darlington motorway.
- Central Precinct (on South Road between Sir Donald Bradman Drive and Cross Road): A second purpose-built precinct where the T2D Project’s open motorway will be built. This is also where a third TBM will be launched to excavate the northern tunnels, from Richmond, and where the TBMs constructing the southern tunnels will be retrieved at Glandore.
- Northern Precinct (Torrensville near the Brickworks Marketplace): Work is well underway to prepare the area for future tunnelling activity. Demolition has begun to make way for construction, including the entry and exit points for the northern tunnels. Once the TBM finishes excavating the northbound northern tunnel, it will be turned around here at this site to construct the southbound northern tunnel. A section of open motorway will also be built here, linking the T2D Project with the Torrens Road to River Torrens motorway.
Why the T2D Project matters
The River Torrens to Darlington (T2D) Project will upgrade the final section of one
of Adelaide’s most important transport routes, the North-South Corridor. This is the last vital link in the 78km non-stop motorway between Gawler and Old Noarlunga.
The T2D Project will improve Adelaide’s transport network, enabling safer, faster and more efficient transport connections across Adelaide. The non-stop South Road will help to stimulate economic growth while enhancing liveability and delivering long-term benefits for all South Australians.
Once finished, the project will:
- Allow motorists to bypass 21 sets of traffic lights between the River Torrens and Darlington, improving travel times by up to 40 minutes during peak hour traffic.
- Reduce the amount of stop-start traffic on South Road, resulting in about 200 fewer crashes per year on this section of the road network.
- Provide better access to travel gateways including Adelaide Airport, Port Adelaide and the national highway network.
The project will support around 5,500 jobs per year during main construction, with 90 per cent of labour hours to be undertaken by South Australians.
The timeline
Here’s how the T2D build is tracking:
- Late 2024: Site set up and early works began.
- First half 2025: Establishing works for the Southern and Central Precincts, including building the Norrie Link Road, relocating utility services and other works to ready the site for tunnelling.
- Late 2025: The Northern Precinct is currently underway and the first TBM components have arrived in Adelaide.
- Second half 2026: Tunnelling is expected to begin.
- By 2031: The T2D Project is scheduled to be complete.
You can learn more about the T2D Project, explore maps, and sign up for construction updates here.
