Hiwa-i-te-Rangi our giant Tunnel Boring Machine broke through into a shaft in Western Springs as she builds the 16.2-kilometre Central Interceptor tunnel from Māngere to Point Erin, Herne Bay. ... the TBM ‘s arrival was on target, after travelling 13-kilometres from Māngere. ... The Tunnel Boring Machine is currently lying 25m below ground just south of MOTAT. Hiwa-i-te-Rangi began tunnelling in August 2021. Since then, she has crossed under the Manukau Harbour and passed through the 110m-deep Hillsborough Ridge (the deepest section of the route). The 4.5m diameter tunnel has a 1:1,000m gradient, so that wastewater will flow downhill by gravity all the way from central Auckland to Māngere Wastewater Treatment Plant for processing.

...Ghella Abergeldie JV project director Francesco Saibene says the successful TBM breakthrough is testament to the skill and expertise of the tunnelling team.

... The Central Interceptor project is due for completion in 2026.

https://www.watercare.co.nz/home/about-us/latest-news-and-media/tunnel-boring-machine-hiwa-i-te-rangi-passes-three-quarter-mark-for-central-interceptor-tunnel