Lift off! Tunnel boring machines emerge from the ground at Westmead
11.12.2025
From mega breakthroughs to now mega lifts – retrieval of tunnel boring machines (TBMs) Betty and Dorothy has kicked off after their enormous effort building part of the Sydney Metro West tunnels.
TBMs Betty and Dorothy carved out the Sydney Metro West tunnels from Sydney Olympic Park, through Parramatta, and made their final breakthroughs at Westmead in September and October respectively.
The 9-kilometre journey was also the first in Australia to be completed by autonomous tunnel boring machines equipped with artificial intelligence software capable of automatically steering, operating and monitoring the machines.
Now the meticulous effort begins to dismantle and lift the 1,200-tonne TBMs piece by piece up and out to the surface using a 750-tonne mobile crane.
The process of retrieving these mega machines begins underground, as each TBM is taken apart and lifted out in pieces of varying sizes.
The larger components, such as the 100-tonne cutterheads and 110-tonne main drives, are lifted out using 750-tonne mobile cranes, while other pieces will be taken out over multiple loads using the gantry crane.
The TBMs are carefully dismantled, transported in sections through the crossover cavern to the station box, and lifted out in pieces of varying sizes – a process that will take around seven weeks.
Key components of the TBMs, such as the main drives, will be recovered for refurbishment and reuse on other TBM projects, while the remaining parts will be recycled.