Two 1266 tonne, 165 m long double-shield, hard rock, gripper-type TBMs have been ordered to build the city’s next metro rail tunnels as part of the Sydney Metro West project, with the first machine set to be in the ground before the end of this year.  

The two TBMs are part of the EUR 1.24 bn (AUD1.96 bn) Central Tunnelling Package awarded in July to the Acciona Ferrovial Joint Venture, who have contracted world-leading manufacturer Herrenknecht to design, build and deliver the TBMs following a global tender process.  

Each TBM, designed to excavate through sandstone and shale, will tunnel an average of 200 m/ week and will be operated by a team of 15 workers per shift as they dig the 11 km twin tunnels from The Bays to Sydney Olympic Park. These will be the first of six TBMs being used to build the 24 km tunnels from the Sydney CBD to Parramatta.  

Meanwhile geotechnical investigations are being done along the length of the Sydney Metro West alignment to inform the final design of the tunnels and station boxes: more than 50 bore holes are being drilled, ranging in depth from 10 m to 100 m. Geotechnical work has also been done at the White Bay Power Station, including inside the turbine hall and boiler room. Data captured from each borehole includes the depth of each layer of soil and rock, the properties and strength of the soil and rock and the type of soil and rock in each location – for example, determining if its Ashfield Shale, Mittagong Formation or Hawkesbury Sandstone. 

The Sydney Metro West tunnel alignment runs about 22 m under the power station, which was built in 1917 and decommissioned in 1983. Click here and au/11 for more about the project in the tunnelbuilder archive and also visit https://www.sydneymetro.info. 04/22.