The first of five mega TBMS designed, built and to be delivered by Herrenknecht, will be in the ground before the end of this year to drive the twin 15.5km metro rail tunnels between Chatswood and Sydenham in  Sydney.

Four TBMs will be double-shield, hard rock, gripper-type designed to excavate through sandstone and shale: two TBMs will dig 6.2km from Chatswood to the edge of Sydney Harbour and two TBMs will travel 8.1km from Marrickville to Barangaroo; One TBM will be a specialised mixed-shield which will use slurry technology to build the twin tunnels under Sydney Harbour. About 93 per cent of the tunnelling will be will be through sandstone.

A specialised precast concrete factory at Marrickville will deliver more than 99,000 concrete segments which will line the inside of Sydney’s new metro railway tunnels. The factory is expected to make an average of 280 concrete segments a day, with up to 120 workers employed at the site.

Tunnel builders John Holland CPB Ghella will reuse the equipment and plant from the precast concrete factory they built at Kellyville in 2014, which produced 98,184 segments for the Sydney Metro Northwest tunnels.

108 giant moulds, originally used to deliver the twin 15km Sydney Metro Northwest tunnels between Bella Vista and Epping, have arrived on site and are being recycled for the next stage of Sydney Metro tunnelling. The moulds are designed to cast segments which each weigh about 4 t and measure 3.5 m long and 1.7 m wide. Some new moulds will be needed for segments under the harbour and for a few tighter bends. Click here and au/11 for tunnelbuilder archive. Visit https://www.sydneymetro.info. 11/18.