Adelaide T2D project reaches milestone with three simultaneous tunnel boring machines

The $15.4 billion River Torrens to Darlington (T2D) project in Adelaide has reached a significant milestone. For the first time in Australian history, three large-scale tunnel boring machines (TBMs)—named Mary, Catherine, and Elizabeth—are simultaneously excavating beneath the city.

Each TBM weighs approximately 3,500 tonnes and is equipped with a 300-tonne cutterhead. Once fully operational, the machines are expected to excavate between eight and 10 metres per day. The project aims to complete the final 10.5-kilometre section of the North-South Corridor, eventually creating a 78-kilometre motorway between Gawler and Old Noarlunga.