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 9km journey was also the first in Australia to be completed by autonomous TBMs equipped with AI software capable of automatically steering, operating and monitoring the machines.
Now the 1,200-tonne TBMs are being dismantled and lifted to the surface using a 750-tonne mobile crane.
The TBMs are being 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 projects, while the remaining parts will be recycled.
The cavern wall lining is also complete – a process that required construction of the largest formwork system of its kind in the southern hemisphere.
In an 82-hour operation crews jacked and winched the temporary arch into position with millimetres to spare. Once the structure was in place, the team completed a 1,941-tonne concrete pour to create the cavern’s 2.5m-thick walls.
It took almost 12 months of planning and collaboration – along with multiple crawler cranes – to construct the 21m-high structure.
With the formwork operation now complete, the tallest cavern on the Sydney Metro network is fully lined, standing around 26m high. Tunnelling at the eastern end is approaching its final breakthrough to Hunter Street in Sydney’s CBD, with TBMs Ruby and Jessie now less than 550m from completing the 24m twin tunnels.
