The City Rail Link project continues to chalk up milestones with the completion of mined tunnelling at Maungawhau Station in Mt Eden last week.

The tunnelling crews successfully completed the final 99.5m mined tunnel section, known as the cavern, adjacent to where the Tunnel Boring Machine slid through on its second CRL tunnel drive in 2022.

This marks the end of all tunnelling from Maungawhau Station which has used three types of tunnelling – the Tunnel Boring Machine Dame Whina Cooper, cut-and-cover tunnelling and mined tunnelling.

Mined tunnelling, which has been taking place at Maungawhau Station since 2020, involves creating a tunnel with machinery such as a jumbo drill, excavators, and a shotcrete machine to stabilise the ground. The area is then waterproofed and concreted with tailormade self-travelling formwork.

During the 2.5 years of mined tunnelling, 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 in creating mined tunnels extending 296m, about the height of the Empire State Building.

Link Alliance project director Francois Dudouit says the completion of mined tunnelling is a significant achievement.

“These people have been on a long journey, literally and figuratively speaking,” Dudouit says. “The team has faced many technical and environmental challenges and have shown both fortitude and innovation in overcoming those obstacles.

“The completion of this stage of the project is a cause for celebration and a source of great pride,” he added.

The occasion was marked with speeches, awards and flags showcasing the multinational team that has delivered this essential part of the CRL construction.

Work is now beginning on the fit-out of the mined tunnels, including electrical works, signalling, ventilation and installation of the rail tracks upon which the new CRL trains will run.

About the City Rail Link

The City Rail Link (CRL) is New Zealand’s largest ever transport infrastructure project, involving construction of a 3.45km twin-tunnel underground rail link up to 42m below the Auckland city centre. It will transform the downtown Waitematā Station (Britomart) into a two-way through-station that better connects the city’s rail network and more than doubles rail capacity across Tāmaki Makaurau. Two new stations Te Waihorotiu Station and Karanga-a-Hape Station are being constructed as part of the new modern urban railway link, while Mt Eden Station is being rebuilt and renamed as Maungawhau Station. When complete and fully operational, the CRL will carry up to 54,000 people per hour, an equivalent capacity to three Harbour Bridges or 16 extra traffic lanes in the city at peak travel times.

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