A third Sydney Metro Northwest tunnel boring machine (TBM) has now finished work on Australia’s longest railway tunnels, which are now 97 per cent complete. TBM1 Elizabeth arrived at Cherrybrook in a rare night-time breakthrough on December 1, ending her role in building the twin 15 km metro tunnels from Bella Vista to Epping. Elizabeth was the first TBM to start digging on Australia’s biggest public transport project in September last year, and was in the ground four months ahead of schedule. She dug 9 kilometres from Bella Vista to Cherrybrook. More than 29 of the 30 kilometre tunnelling task is now complete. The only remaining mega machine, TBM2 Florence, has about 850 metres left to dig and is also on its way to Cherrybrook. In her 15-month journey, TBM1 Elizabeth:
- Excavated more than 700,000 tonnes of crushed rock, both sandstone and shale;
- Installed just over 28,000 concrete segments to line the new rail tunnel;
- Had 735 hardened steel cutters on her cutter-head replaced;
- Was home to tunnelling crews of 15 workers who have spent more than 100,000 hours underground;
- Achieved an average weekly tunnelling distance of 171 metres.
Sydney Metro Northwest was the first transport infrastructure project in Australia’s history to use four TBMs. TBM1, which was named after colonial pioneer Elizabeth Rouse, will now be dismantled and brought to the surface at Cherrybrook in a series of precision operations expected to last several weeks.