Mined tunnelling completed on NZ rail project

7 June 2023

Link Alliance has completed mined tunnelling on Auckland’s City Rail Link (CRL) project.

Tunnelling crews completed the final 99.5m mined tunnel section, known as the cavern, adjacent to where the TBM broke through on its second CRL tunnel drive in 2022.

The latest milestone marks the end of all tunnelling from Maungawhau Station, which has used three types of tunnelling – excavation by the 7.15m diameter Herrenknecht TBM Dame Whina Cooper, which was completed in September last year, cut-and-cover tunnelling and SCL mined tunnelling.

During the 2.5 years of mining 296m of tunnels, crews excavated approximately 15,000m3 of spoil, used about 10,000m3 of concrete and shotcrete and installed around 250 tonnes of steel and 4,500m2 of waterproofing membrane.

Work is now beginning on the fit-out of the mined tunnels, including electrical works, signalling, ventilation and installation of the rail tracks.

CRL is New Zealand’s first underground rail network. It comprises a 3.45km twin-tunnel underground rail link up to 42m below Auckland city centre. It will transform the existing downtown Waitemata Station into a two-way through-station that better connects the city’s rail network.

The Link Alliance of City Rail Link Ltd, Vinci Construction Grands Projets, Downer NZ, Soletanche Bachy International NZ, WSP NZ, Aecom New Zealand, and Tonkin + Taylor is delivering CRL’s main tunnels, stations and rail systems contract.