The Torrens to Darlington Project is the final piece of the 78-kilometre non-stop motorway between Gawler and Old Noarlunga.

The “southern laydown area” for the tunnel boring has been revealed at a site near the Tonsley Boulevard in Clovelly Park.

Transport Minister Corey Wingard said property acquisitions have started in the area where the tunnel boring will take place.

“When we announced this project we made a commitment to let the community know as soon as possible, when activities would begin in particular locations and which properties were likely to be impacted,” Wingard said.

“When we know, you’ll know and as soon as we get certainty on elements of the Reference Design, we’ll be engaging with impacted land owners directly, before information is shared with the broader public.

“By announcing that we’ve started property acquisitions in the southern laydown area, we’re ensuring everyone who has a stake in this project and in the local community is aware of the progress that’s been made and how the next steps will play out.”

The transport minister said the State Government’s plan for the overall project will require the acquisition of 390 properties.

Last month, the State Budget revealed the cost of the Torrens to Darlington stage of the project had blown out by $1 billion to $9.9 billion.

This was due to updated plans for the tunnels which included increasing the number of lanes from two to three to accommodate greater traffic volumes than first predicted.

The project is expected to be completed in 2028.