Boring, Installation, Tunnelling, Water

Sydney Metro prepares to start northwest tunnel

During the second stage of the project, five tunnel boring machines (TBMs) will be used to bore twin 15.5 km rail tunnels.

In preparation for the second stage, geotechnical surveys have been carried out on Sydney Harbour’s seafloor.

“One of the interesting things with starting to look at where these tunnels would go under the harbour is just how little information is actually already available to us,” said Sydney Metro Program Director Rodd Staples.

“So we’ve been out drilling holes into the bed of the harbour to see what the soil is like and where the rock is.”

Sydney Metro Principle Engineering Geo-Scientist Dr David Och has been leading the team conducting soil and rock tests on the seafloor in preparation for stage two works, utilising new investigation methods to access accurate data.

“Most recently, we’ve used the 13 t sonic draw rig on an anchor bloating barge to drill 30 m below sea level. This was the first time that this type of geotechnical investigation had been used in Sydney over water,” said Dr Och.

“With this research and investigation we’ve done we can now make sure we choose the right sort of tunnel machine, the right tool for the job to get this tunnel built under the harbour,” said Mr Staples.

Earlier this year, a John Holland joint venture was awarded the contract to tunnel underneath Sydney Harbour.

The first TBM is planned to be in the ground before the end of 2018, with Sydney Metro services starting in 2019 in the northwest. Services are anticipated to extend into the city and beyond by 2024.

For more information visit the Sydney Metro project website.

If you have project news you would like covered in Trenchless Australasia contact Managing Editor Nick Lovering at nlovering@gs-press.com.au

Image supplied by Sydney Metro

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