The EPB machine was built at Herrenknecht’s Guangzhou factory in southern China and underwent comprehensive factory testing prior to shipment. Having arrived packaged in pieces, it will now be assembled at Auckland’s Mount Eden station where work on the tunnel portal is well advanced. From there, the machine will drive 3.2km of twin parallel tunnels (2 x 1.6km) to central Auckland where it will connect with the existing cut-and-cover tunnel at Britomart Station – currently a ‘dead end’ but to become a through station on completion.

The CRL line will be bored mainly through the East Coast Bays Formation of sandstones and siltstones. At an anticipated advance rate of 32m/day, each tunnel tube is expected to take around nine months to bore.

In August 2019, delivery partner CRL and the Link Alliance signed a contract for the construction of a 3.45km railway which includes the tunnels and three new underground stations. The new stations will be at Aotea, Karangahape Road and Mount Eden and the tunnels will be driven at depths of up to 42m below the city centre.

The Link Alliance comprises Vinci Construction Grands Projets, Downer NZ, Soletanche Bachy International, and engineers WSP Opus, AECOM and Tonkin+Taylor. Working with the owner to an outline design prepared by the Aurecon Group, the Alliance is responsible for design and delivery of the underground work and railroad systems.

The total cost for delivering the CRL project is around US$3bn and is jointly funded by the NZ government and Auckland Council. Completion is scheduled for 2024.