You’ve probably seen videos of tunnel boring machines (TBMs) breaking through rock with their cutter heads looming like something out of a sci-fi movie, but this one is particularly cool as it shows a bird’s eye view of the TBM tunnelling half-submerged as part of the Sydney Metro Northwest project.
TBM4 ‘Maria’ is one of four of the French-made NFM Technologies machines working on the project, which used to be known as the North West Rail Link.
Most of her work was done fully underground, but at the Cheltenham site — which will be used for fresh air tunnel ventilation and as an emergency access point to the tunnels below when metro trains start operating in 2019 — she just stuck the top 3m of her cutter-head out and kept on tunnelling.
This means that in this Transport For NSW video you can see how she inches her way forward while installing concrete tunnel segments behind her — more than 12,300 of them so far.
Overall Maria and her sister Isabelle (TBM3) will travel 6km from Cherrybrook to Epping. TBM1 ‘Elizabeth’ and TBM2 ‘Florence’ are digging 9km from Bella Vista to Cherrybrook.