Two TBMs have been relaunched to build the next 11km section of Sydney Metro West.

TBMs Beatrice and Daphne were relaunched from Five Dock Metro Station site to build the new metro tunnels from The Bays to Sydney Olympic Park. Their next stop will be 2km away at the future Burwood North Metro Station site.

The two machines made tunnelling history in December last year when they arrived at Five Dock Station site minutes apart to achieve the first double TBM breakthrough in the southern hemisphere.

They then spent 10 weeks traversing the 200m-long station cavern at Five Dock and underwent maintenance, including the replacement of gear boxes and cutter discs.

Each double shield hard rock TBM is 165m long, weighs 1,300 tonnes and has 34 rock-cutting discs in its 7m diameter cutterhead. They will advance at a weekly average of 200m and are expected to complete their journey by the end of the year.

Now the TBMs have left Five Dock, work will continue to prepare the 30m-deep cavern for station construction.

The relaunch marks the start of a significant year of tunnelling for the 24km-long twin-bore Sydney Metro West.

Autonomous TBMs Betty and Dorothy are making good progress in building the tunnels between Sydney Olympic Park and Westmead and are more than 1.3km and 930m into their journey, respectively.

A further two TBMs to construct the metro tunnels below Darling Harbour will arrive at The Bays in the coming months for tunnelling to commence mid-year.

Sydney Metro West is expected to be complete by 2032. When it opens, it will double rail capacity between Greater Parramatta and the Sydney CBD.