It is fair to say that tunnelling is an extremely complex and process-oriented activity. While it is the massive tunnel boring machines (TBM) doing the bulk of the hard work, it's important to remember the thousands of civil engineers who are setting new standards in tunnelling around every turn.

With this in mind, it is these professionals who need to be recognised following the breakthrough of the second TBM along the Sydney Metro Northwest project. In late October, TBM 4, named Maria, reached the end of her journey as she spun through the last of the concrete at Epping.

Maria – by the numbers

The amount of work that Maria has got through since launching from Cherrybrook on January 13 is simply staggering. According to an October 30 media statement from Transport for NSW, Maria excavated over 550,000 tonnes of crushed rock and installed more than 20,000 concrete segments which will line the new rail tunnel.

Covering close to 6km at a pace of around 135m a week, Maria was operated by 15 workers who spent over 75,000 hours underground solving difficult issues and ensuring the project remained on track.

While Maria's work in the tunnel is complete for now, civil engineers will quickly dismantle the TBM and then bring the individual pieces to the surface before it is removed from the Epping site.

Sydney Metro Northwest progress report

Minister for Transport and Infrastructure, Andrew Constance, explained that now that TBM Isabelle and Maria have completed their sections of the tunnels, the focus is now on the remaining two.

"Tunnelling is now almost 90 per cent complete as we count down to finishing the twin 15km railway tunnels from Bella Vista to Epping," he said.

"Just over 26km of the 30km tunnelling work is now complete."

Focus on Florence

With the trains not expected to get up and running until 2019, the focus turns to the two remaining TBMs. One particular machine made the headlines in early October when TBM 2 Florence entered the site for the future Castle Hill station for the first time.

After a 6.6km dig on Australia's longest railway tunnel project, Florence is now undergoing maintenance before starting on the final journey to Cherrybrook station. TBM 1 Elizabeth is currently on this final leg already.

With Bluey supplying key products for waterproofing and ground support on this project, we look forward to letting you know more about the progress on this important infrastructure effort.

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