Tunnel boring machine (TBM) 3 Isabelle is the first Sydney Metro Northwest tunnel boring machine to reach the end of her tunnelling journey after breaking through at Epping on Friday 18 September 2015.
Isabelle completed her journey from Cherrybrook after digging almost 6 kilometres of Australia's longest railway tunnels and will now be dismantled. The TBM was one of four mega tunnelling machines delivering the 15 kilometre twin tunnels from Bella Vista to Epping and her achievement coincided with the project completing more than 75 per cent of tunnelling. During her 10-month journey, Isabelle dug the deepest section of the new railway tunnels, 58 metres below Thompson's Corner at West Pennant Hills.
She also set a cracking pace – achieving a tunnelling trifecta in June with best tunnelling day of 79.90 metres, best tunnelling week of 246.5 metres, and best tunnelling month of 848.3 metres.
Isabelle was named after four-year-old Isabelle Andersen to represent all the tunnel builders.
During her journey TBM3: • Excavated more than 515,000 tonnes of crushed rock, both sandstone and shale • Installed more than 20,000 concrete segments to line the new rail tunnel • Had 650 hardened steel cutters on her cutter head replaced • Had her conveyor belt extended by 11 kilometres from Cherrybrook • Was home to tunnelling crews of 15 workers who spent more than 90,000 hours underground since launching from Cherrybrook on 3 November 2014.