The tunnel boring phase of the City Rail Link (CRL) project in Auckland, New Zealand, has been completed after the tunnel boring machine (TBM) Dame Whina Cooper broke through at Te Waihorotiu (Aotea) Station.

This phase involved boring twin 1.6km tunnels up to 42m under the country’s largest city.

The City Rail Link tunnels were constructed using more than 64,200m³ of concrete.

By travelling more than 3.2km, the TBM placed 2,118 segment rings, as well as removed 260,000t of spoil during the boring of the twin tunnels from Maungawhau/Mount Eden Station to Te Waihorotiu Station.

With a length of 130m and a diameter of 7.15m, the Dame Whina Cooper TBM weighs 910t.

This TBM will be dismantled and lifted above the ground, as the tunnel boring is now concluded. It will be sent to the port for shipping back to its manufacturer, Herrenknecht

In a statement, Auckland Mayor Phil Goff said: “The final tunnel breakthrough is the culmination of 13 months of hard work by the tunnelling teams.

“When complete, City Rail Link will make it faster and easier to get into and around central Auckland, immediately doubling the capacity of heavy rail and ultimately carrying up to 54,000 passengers per hour in peak times.”

Link Alliance is a group of companies responsible for the contract of main tunnels, stations, and rail systems for CRL.

Link Alliance project director Francois Dudouit stated that “the swifter finishing of the second tunnel reflected operational improvements and efficiency gains.”