Australian engineering contractor John Holland has recently completed the Sydney Metro City and Southwest Tunnel and Excavation Works (TSE).
The contract includes the construction of twin 15.5 km tunnels and civil works for six new metro stations with John Holland’s joint venture (JV) partners: CPB Contractors and Ghella.
The company said that the trip deep under Sydney Harbour – from Sydney Metro’s new Victoria Cross Station in North Sydney to Barangaroo Station – will be just a three-minute journey for commuters when Metro trains start running through the harbour tunnels in 2024, extending to the North West Metro, into the city and beyond to Bankstown.
John Holland was awarded the contract to tunnel underneath Sydney Harbour back in 2017, as part of the $2.81 billion Sydney Metro project.
“Construction of Sydney’s first-ever under-harbour rail tunnels would not have been possible without our construction, tunnelling, safety and environmental teams and the mammoth effort of a specially designed mix shield tunnel boring machine (TBM) named Kathleen, which used state-of-the-art slurry technology,” a spokesperson for the company said.
Kathleen set off on its journey to build the first tunnel from Barangaroo to Blues Point on 28 June 2019.
It took the TBM four months to make the first crossing, digging through marine sediments, silt and clay. Once Kathleen finished the first tunnel, the cutterhead and shields were retrieved and barged back to Barangaroo where the machine’s support trailers manoeuvred the TBM into position to build the second tunnel, taking two months to excavate.
Approximately 174,800 t of material was removed to build the two tunnels, with all tunnelling on the twin 15.5 km tunnels from Chatswood to Sydenham, including through Sydney’s CBD, completed in March 2020.
Last year, the project received international recognition from the ITA Tunnelling and Underground Space Awards, an international competition that seeks to reward ground-breaking innovation and outstanding projects in the sector.
The John Holland JV took home the ‘Major Project of the Year’ award, being Australia’s biggest public transport project and the first Australian project to have five TBMs building simultaneously.
For more information, visit the John Holland website.