New Zealand’s largest transport infrastructure project is celebrating a significant milestone – Auckland’s City Rail Link (CRL) has formally accepted ownership of its big Tunnel Boring Machine (TBM) after extensive factory tests in China. 

“The successful factory assessment tests and the handover of the TBM to the Link Alliance is a very clear and strong indication that the CRL project can meet critical milestones in a Covid-19 world,” says Dr Sean Sweeney, Chief Executive of City Rail Link Ltd. 

The tests were conducted on the fully constructed TBM by the German manufacturer, Herrenknecht, at its factory at Guangzhou in southern China.  

“The TBM successfully underwent more than 500 tests to make sure everything works as it should.  There is now great excitement that we are ready for the next step – to bring the TBM to Auckland,” says Francois Dudouit, Project Director for CRL’s Link Alliance.    

Rigorous checks tested the TBM’s three big jobs underground: excavating the tunnels, transporting tonnes of excavated spoil to the surface, and installing the thousands of concrete panels that will line the tunnels. 

“It is a unique, world class machine – an underground factory -  purpose built to carve its way through Auckland’s sticky soil,”  Mr Dudouit says. “Just about everything that moves was tested to make sure it can do the transformational job it’s been designed for. ” 

The TBM will be used by the Link Alliance - the group of New Zealand and international companies building the substantive tunnels and stations contract for City Rail Link Ltd - to excavate two tunnels side by side between Mt Eden and central Auckland to connect with cut-and-cover tunnels already constructed from Britomart Station.

The Link Alliance describes the TBM as big by international standards for rail projects.  The revolving cutter head at the front of the TBM is 7.15 metres – slightly taller than one of Auckland Zoo’s adult giraffes – weighs 910 tonnes – that is roughly the equivalent of nine blue whales, the largest animal ever known to have existed - and at 130 metres stretches the length of a rugby field. 

The TBM is now being dismantled and will be shipped in pieces to New Zealand.  It is due to arrive in October.  The arrival has been delayed by the Covid-19 pandemic which forced the closure for several weeks earlier this year of the factory in China.  

The TBM will be reassembled at CRL’s Mt Eden site, where it will undergo further testing and be officially blessed for safe journeys before it starts the first of its two excavation drives next April.  Both tunnels are one-point-six kilometres long and each TBM drive will take about nine months.  

Mining tradition will be observed before the start of tunnelling when the TBM is formally named after an inspirational woman.  Earlier this year New Zealanders voted for the TBM to be named in honour of the Māori rights champion, Dame Whina Cooper.