The Darlington Upgrade Project in Adelaide, South Australia, is having two new 180m-long bridges built off-site by Gateway South and moved into position at a later stage. 

The South Australia Department of Planning, Transport, and Infrastructure (DPTI) has selected the Gateway South consortium to design and build the Darlington Upgrade Project. 

The consortium includes companies such as Fulton Hogan Construction and Laing O'Rourke Australia Construction with design partners KBR, Jacobs, and SMEC.

The project consortium Gateway South has already started the construction of the first of two 3,000t bridges, which are part of the A$620m ($485.4m) North-South Corridor project. 

These bridges are currently being constructed on land between the Southern Expressway and Main South Road, near Marion Road, which will continue for the next few months.

Once the structures are complete, the consortium will move them to the site by using self-propelled modular transporters, which will be later manoeuvred into the exact place. 

The Darlington Upgrade Project is expected to support nearly 370 jobs a year during construction.

"While this type of bridge installation is common in Europe and America, this method has never been used on this scale before in Australia."

Constructing the bridge structures at other sites and moving them to the original site at a later stage eliminates the need for multiple closures of parts of the Southern Expressway and Main South Road, substantially reducing the impact on traffic.

Upon completion, the new Main South Road bridges will carry northbound traffic over the Southern Expressway, where one bridge will be connected to the 3.3km non-stop motorway, while the other will deliver traffic to local surface roads.

The consortium will be involved in building eight bridges as part of the Darlington Upgrade Project. 

Bridges will be constructed at Ayliffes Road, Tonsley Boulevard, Over the Sturt River, Flinders Drive, Sturt Road Mimosa Terrace and Sutton Road.

South Australia Transport and Infrastructure Minister Stephen Mullighan said: "This project will make the journey quicker and safer for almost 100,000 vehicles using the Main South Road and Sturt Road intersection every day, including the 73,000 vehicles using this part of Main South Road. 

“Building the bridges in this way means keeping disruptions to a minimum during construction for the many tens of thousands of vehicles which travel through this part of Main South Road every day.

"While this type of bridge installation is common in Europe and America, this method has never been used on this scale before in Australia.

"These new bridges will improve traffic flow at some of Adelaide’s top ten busiest intersections and will reduce travel times for drivers travelling both north-south and east-west.”