Meet the big Tunnel Boring Machine (TBM) that will excavate the City Rail Link tunnels. It arrived from China in late 2020 to be assembled at the Mt Eden station construction site.
The TBM was named by public vote after Māori rights activist Dame Whina Cooper.
The TBM has three jobs:
Excavating the tunnels
Removing tunnel spoil
and installing concrete segments to line the tunnels
Specialist German manufacturer, Herrenknecht built the TBM at its factory in Guangzhou, China. Herrenknecht earlier designed and built Alice, the TBM used to construct Auckland’s Waterview motorway tunnel.
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In December 2020, 5000 Aucklanders obtained tickets to see the TBM up close at the Mt Eden construction site.
TBM blessing
Our Tunnel Boring Machine (TBM) was blessed by Dame Whina Cooper’s daughter, Hinerangi Puru Cooper, and her wider whanau at the Mt Eden construction site in December 2020.
They were joined by Deputy Prime Minister Grant Robertson, Transport Minister Michael Wood, the city’s Mayor Phil Goff, Ngāti Whātua Ōrākei and other Auckland Iwi who sit on CRL’s Mana Whenua Forum, and community, transport and CRL representatives.
The TBM was named by public vote after the famous Māori rights champion.
CRL CEO Dr Sean Sweeney said: “Dame Whina’s legacy is one of determination and the importance of working together, values that fittingly apply to this project and our journey ahead to build a world class railway for Auckland.
Hinerangi said she was honoured and humbled to be present at the unveiling.
BLESSING: From left, Auckland Mayor Phil Goff, Dame Whina Cooper’s daughter, Hinerangi Puru Cooper and deputy Prime Minister Grant Robertson
LEARN MORE ABOUT OUR BIG MACHINE
Commonly asked questions
TBM looks huge. How long is it? 130 metres (a rugby field is up to 120 metres long).
When does it start operating? It is being assembled and then tested. It starts excavating next April.
Who built it? A German tunnel machine company, Herrenknecht, at their Chinese factory.
Is it the same TBM that was used for the Waterview tunnel? No but the TBM for the Waterview Tunnel was also built by the same company at the Chinese factory. TBMs are built for specific jobs.
How much does the TBM cost? $13.5 million.
How fast will it travel? TBM can travel 32 metres a day.
What about the spoil? Where will it go? Up to 1,500 tonnes of spoil can be excavated each day. Spoil from Mt Eden will be a mix of cleanfill, managed and contaminated. We won’t know how much of each until tunnelling is underway. The spoil will be either wet spoil extracted by the TBM or a clean, dry type of spoil removed during initial tunnelling operations.
Cleanfill will be disposed of at the Three Kings Quarry in Mt Eden. All other spoil – managed or contaminated – will be trucked to various disposal sites at Mercer in Waikato.
Does the TBM also line the tunnel walls? Yes, besides excavating the tunnels and removing dirt and rocks to the surface, it will be installing precast concrete panels that will line the tunnel walls.
How many people will be in the TBM? Up to 12 people.
At one stage, it’s going under the southern motorway. If you’re on the motorway will you feel it? No. This is because it is what is called an Earth Pressure Balanced TBM. This means it controls and balances the pressure of the earth it excavates which stabilises the tunnel face and reduces any possibility of settlement occurring.
When the TBM reaches the Aotea Station area, does it turn around again? No, the TBM will be dismantled and returned to Mt Eden in sections then reassembled again to excavate the second tunnel.
When does that happen? Excavation of the second tunnel is planned to start in March 2022.
What hours will it work? 24/7.
Who chose the name? Dame Whina Cooper was chosen after a nationwide competition for a name of a ground-breaking woman. Dame Whina at the age of 80, led a land march from Northland to parliament and devoted her life to fighting discrimination.
Why call the TBM something? Traditionally, TBMs are given female names in honour of Saint Barbara, the patron saint of miners and those who work underground. This tradition is said to bring good luck to the work ahead.
What sort of rock will it encounter? The expected ground conditions for the TBM alignment is East Coast Bays Formation rock of the Waitemata group https://en.wikipedia.org/wiki/Geology_of_the_Auckland_Region
