In Australia, tunnel boring machine (TBM) Betty has broken through into a cavern deep beneath Westmead to complete the first tunnel at the western end of the 24km Sydney Metro West line.

This landmark breakthrough brings major tunnelling for the project that will link Westmead to the Sydney CBD to 93% completion.

TBM Betty spent 24 months working round-the-clock to construct a tunnel from Sydney Olympic Park, via the future Parramatta metro station. During its dig, the machine moved 790,000t of earth and installed 30,000 concrete segments along the way to line the new tunnel walls.

Fittingly named after Olympic sprint champion Betty Cuthbert, TBM Betty is the first to finish its tunnel at both ends of the line. There is now just 3.5km of tunnel left to build to bring a marathon 30-month tunnelling programme by six TBMs across the finish line.

The remaining sections of tunnel are being worked on by three TBMs: TBM Dorothy is 1059m from its final breakthrough at Westmead, where it is due to arrive in the coming weeks. At the opposite end of the alignment, TBMs Ruby and Jessie are making their way under Sydney Harbour to reach the Hunter Street terminus in the Sydney CBD by the end of the year.   

With Betty's mission complete, crews will now dismantle the TBM before it is lifted out of the station box piece by piece over the next seven weeks.  A crew of up to 150 workers at a time have spent three years constructing the 500m underground structures at Westmead.

Along with having the deepest station on the Metro West line, at up to 39m below ground, the Westmead site is made up of a crossover cavern for future trains to switch tracks if required, a station cavern and turnback tunnels to allow trains to turnaround to head back towards the Sydney CBD.