Lucia’s breakthrough came 29 days ahead of schedule with the team able to rein in the construction timeframe using the knowledge gained from work on the conveyor drift, which was tunnelled last year.

Grosvenor’s underground construction manager Adam Foulstone said: “From an industry perspective, we have achieved the highest levels of collaboration and production through tunnelling, which provided a safer environment than conventional tunnelling methods.

“On our best production day, we installed 18 concrete rings to support the tunnel, so about 25m, and our best week was 78 rings, or 110m.”

The milestone was celebrated by members of the Grosvenor team and tunnelling contractor Redpath.

Coal CEO, Seamus French, congratulated the team. "This great result is down to the outstanding commitment of the team who came to grips with the new tunnel boring technology last year, and applied our operating and engineering experience from underground mining to lift the TBM performance over the last 12 months,” he said.

"The use of this technology is a first, not just for coal mining in Anglo American, but for the Australian coal mining industry and the team can rightly feel proud that they are the pioneers of this new technology in coal.

"The team will keep building on the valuable lessons learned as they progress to the next project milestones, including extraction of the TBM and commissioning of the longwall at the end of 2016."

Once extracted from the drift, the TBM will go into storage for future projects.