SH1 Mangamuka Gorge slip repairs

23 May 2025

Slip A7 – The final slip repair for the project is now complete, and the team have demobilised from site.

Final project update – May 2025

Kia ora koutou,

We’re pleased to let you know that all of the final finishing works for the Mangamuka Gorge slip repairs are now complete. This will be our final update from the project team.

The repairs were a major undertaking, involving more than 1,300 people and 190 companies with the majority of the workforce coming from Northland. Over 1,300 piles were installed, fastened deep into the mountain with over 300 anchors, alongside improved drainage systems to manage water and reduce future slip risk.

We’d like to extend a heartfelt thank you for your patience, support, and interest throughout the process. A massive shout-out to everyone involved in the repair work – your efforts have helped reconnect the Far North.

April slips update

The two recent slips caused by April’s record rainfall were fully cleared and concrete barriers installed along the road shoulders at these locations. These barriers are designed to catch any minor debris that may fall during future weather events, reducing the risk of future road or lane closures.

While the risk of major slips through the gorge has been significantly reduced, the area remains prone to occasional minor ground movement due to the natural conditions of the Maungataniwha Range. Thanks to the stabilisation work completed, any future movement is expected to be much less severe, allowing us to respond quickly and minimise any disruption.

Plan before you travel

For up-to-date information on the state highway network, please check the NZTA Journey Planner.

You can also stay informed by subscribing to our Northland state highway maintenance updates.

Ngā mihi nui,

The SH1 Mangamuka Gorge slip repairs project team

Thank you from the whole Mangamuka Gorge slip repairs project team.

More information

For more information on the Northland state highway network, contact us at northlandproject@nzta.govt.nz

Visit our website www.nzta.govt.nz/projects/northland-state-highway-maintenance-programme/