Ownership of tunnel-boring machine accepted for $4.4b City Rail Link job

The business building New Zealand's largest transport infrastructure project now controls a new tunnel-boring machine after extensive factory tests in China.

Sean Sweeney, City Rail Link chief executive, said assessments were conducted on the machine, named Dame Whina Cooper, which will cut through ground to complete the $4.4 billion scheme.

"The successful factory assessment tests and the handover of the machine to the Link Alliance is a very clear and strong indication that the CRL project can meet critical milestones in a Covid-19 world," Sweeney said.

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

Francois Dudouit, Link Alliance project director, said today: "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."

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.

Giant cutting head on the new TBM. Photo / supplied

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

The machine will be used by the Link Alliance, the global and local companies building the tunnels and stations. It will 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 machine is 7.15m, slightly taller than one of Auckland Zoo's adult giraffes. The machine weighs 910 tonnes, equivalent to nine blue whales. At 130m long, the machine stretches the length of a rugby field.

Tests were carried out on the new machine. Photo / supplied

The machine is now being dismantled and will be shipped here in bits, due to arrive in October.

That was delayed by the Covid-19 pandemic, which forced the closure for several weeks earlier this year of the factory in China.

The machine will be reassembled at the 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 1.6 kilometres long and each TBM drive will take about nine months.