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The shining star of the City Rail Link project is due to arrive in Auckland next spring – a 130 metre feat of modern engineering that will bore twin tunnels under the city centre.
The $13 million Tunnel Boring Machine (TBM) will arrive on our shores in pieces later this year and be assembled in front of the Link Alliance Mt Eden portal site.
Once assembled, tunnelling is scheduled to begin in February 2021. It will take 9 months to complete the first 1.6 kilometre-long journey from Mt Eden to the Aotea Station site in central Auckland.
The TBM will have three jobs: excavating the tunnels, removing spoil and installing concrete segments to line the tunnels walls behind it.
Once it reaches the Aotea site, the TBM will be hauled out of the ground, dismantled and trucked back to Mt Eden to do it all again for the second tunnel. Excavation of the second tunnel is planned to start in January 2022.
The diameter of the machine’s rotating cutter head will be 7.15 metres. The whole thing will weigh 1600 tonnes, or the equivalent of 490 Asian elephants.
At peak operation the TBM will travel 32 metres and excavate up to 2,600 tonnes of spoil every day – just over a hundred truckloads.
Spoil will be transferred from the TBM by conveyor belt to the Mt Eden site and then transferred to disused quarries.
The TMB is being built by German company, Herrenknecht, at the company’s factory in China. Herrenknecht also built Alice, the TBM which dug Auckland’s Waterview Tunnel.
A crew of approximately 12 will operate the TBM underground. After tunnelling the TBM will be returned to Herrenknecht.
Auckland Mayor Phil Goff said the project’s TBM would be the “star of the show, providing the mechanical muscle required to get the job done as quickly as possible”.
“The CRL will be a gamechanger for Auckland, allowing 54,000 people an hour to travel into the city at peak times. It adds the capacity equivalent to three Harbour Bridges or 16 extra traffic lanes into the city at peak travel times.” Mr Goff says.
The Link Alliance is a group of seven companies working together to deliver the main section of CRL tunnels and stations.