Projects

Tunneling Toward a More Connected South Australia

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Until now, Adelaide was the only mainland Australian capital without a continuous, non-stop motorway — creating growing congestion and safety concerns as traffic and population increased. The missing link in the city’s North-South Corridor, the River Torrens to Darlington (T2D) section, posed the greatest technical challenge: a 6.5-mile (10.5 km) stretch cutting deep through established residential areas.

To overcome this, the South Australian Government turned to an alliance, including Jacobs, to design and deliver the final piece of the 48.5-mile (78 km) corridor. Once complete, this infrastructure project will allow drivers to bypass 21 traffic lights and reduce travel times by up to 40 minutes.

Jacobs brings extensive experience in holistic infrastructure delivery, including global leadership in both tunneling and transportation solutions, to bring this transformational investment to life.

By easing congestion and improving traffic flow, the project is expected to unlock $153 million (AUD $230 million) in annual productivity gains for South Australia — making it a cornerstone of the region’s long-term economic growth.

As part of the T2D Alliance Jacobs is involved across all design disciplines, including roads and civil, stormwater, civil structures, geotechnical and buildings, as well as leading tunneling design, transport planning and construction integration for the corridor — and working to accelerate delivery. The project features two sets of three-lane twin tunnels — the southern tunnels and northern tunnels — linked by an open motorway.

Massive tunnel boring machines (TBMs) have started arriving, marking a major milestone in South Australia’s largest infrastructure undertaking. Each machine measures about 328 feet (100 meters) long and 49 feet (15 meters) wide — making them the largest pieces of construction equipment ever used in the state. Two TBMs will launch from the southern precinct to create twin 2.8-mile (4.5-kilometer) tunnels, while a third will deliver the twin 1.4-mile (2.2-kilometer) northern tunnels. Procuring all three machines allows crews to work concurrently on both tunnel sections, ensuring efficient delivery of this landmark infrastructure project. The project also includes upgrades to local infrastructure, including walking and cycling paths, and revitalizing green space exemplifying our ability to deliver transformative outcomes while investing in community resilience and sustainability.

“This critical transport corridor will transform the region. Most importantly, reducing the amount of stop and start traffic can result in fewer collisions – making Adelaide’s transport system safer and more efficient.”

Keith Lawson

Jacobs Senior Vice President

48.5 mi

(78 km) Length of Adelaide’s North-South Corridor motorway
$ 10.3 B

(AU $15.4 billion) Total project cost
5500

Estimated jobs supported annually during construction
40 mins

Peak-hour travel time saved by bypassing 21 traffic lights
6 %

Final stretch of the corridor to be completed
3

Tunnel boring machines building twin tunnels simultaneously

The first TBM arrived in October 2025 to be assembled at the Southern precinct
Industry engagement event for the T2D Project at the Adelaide Convention Centre

Images courtesy of South Australia Government

In June 2025, the T2D Alliance hosted an industry engagement event at the Adelaide Convention Centre, drawing over 700 attendees. The event showcased upcoming work packages and reinforced the commitment to supporting local businesses.

Jacobs is also supporting local workforce development and inclusion initiatives. With more than 300 South Australian businesses expressing interest, the project is creating a supplier legacy for the state.

Meet the team

Nick Monaghan, Alliance Leadership Team Member

Provides strategic leadership for the T2D Alliance, guiding project governance, collaboration and delivery aligned to shared objectives.
David Felton, Project Manager

Responsible for commercials, program, resourcing, quality and safety in design across a global team of 500+.
Dean Coutts, North Precinct Design Manager

Leads a multi-disciplinary team of engineers, architects, landscape and urban designers to deliver the detailed design for the surface works and northern tunnel.
David Gallagher, Operations Lead

Leads operations and delivery across the design function, including onboarding 700+ personnel, establishing satellite offices and achieving key project outcomes.
John Steele, Global Bridge Principal – Civil Structural Lead T2D

Leads the teams designing the cut and cover tunnels, bridges, retaining walls and miscellaneous structures which include drainage structures, signs, road furniture and screens and drainage structures.
Peter Chon, Technical Director - ANZ Delivery Partners Portfolio – Tunnels & Portals Precinct Design Manager – T2D

Managed the design of tunnels, cut-and-cover sections and entry portals for the T2D project. His role involves coordinating civil / structural works, safety systems and ventilation, while working closely with multiple teams to ensure the structures are safe, practical and well-integrated with the motorway and surrounding infrastructure.
Cheyne Bird, Digital Engineering Discipline Lead

Oversees digital engineering, including model coordination, systems integration, clash detection and data deliverables for construction and asset handover.
Juliana Mosquera, Zone Design Manager

Responsible for multi-disciplinary integration of the surface works designs in the central north area of the project.