SH1 Mangamuka Gorge slip repairs

Project update

28 April 2025

Sunday 27 April slip – The road has reopened and the clean-up is ongoing with traffic controls in place.

Update on the slip that occurred on Sunday 27 April 2025

Kia ora koutou,

State Highway 1 Mangamuka Gorge has reopened after a slip closed the road during heavy rain on Sunday 27 April.

Contractors have cleared a significant amount of material, and one lane is now open with traffic controls in place. Clean-up crews will continue working to stabilise and clean up the area around the slip site over the coming days.

This new overslip is in a new area, uphill of the large cut at Slip A11 on the southern side of the gorge and was not part of previously completed recovery works.

Additionally, a section on Slip A11 cut face has shown further signs of movement after recent heavy rain. This is a natural gully feature that is reforming. This is expected, and the majority of any material or vegetation that comes down is expected to be within the safety buffer zone. The lane closure has also been extended past this area as a precaution. With more wet weather forecast this week, we are continuing to monitor this area carefully to keep traffic moving safely through the gorge.

Other recovery work, including the piled slip repairs and drainage improvements, held up well to the weekend’s wet weather.

While the risk of major slips through the gorge has been significantly reduced, the area remains susceptible to occasional minor movement due to the ground conditions in the Maungataniwha Range. However, because of the stabilisation work we’ve completed, any future movement is expected to be much less severe, helping us respond quickly and minimise disruptions.

We understand that any closure of the gorge can be disruptive, especially for freight, local businesses, and communities. We are working hard to keep the route open and minimise disruption while ensuring the gorge remains safe.

Our contractors are continuing to respond to a range of weather-related issues on the network, including fallen trees, potholes and surface flooding.

Please drive with care, allow extra time for your journeys and treat our contractors with kindness and respect, as they work to keep the state highway network open and safe.

Check the NZTA Journey Planner website for up-to-date information on the state highway network.

Ngā mihi nui.

Before - The recent slip on 27 April that closed the gorge.

After - The slip has now been cleared, and the road reopened.

More information

For more information on the SH1 Mangamuka Gorge slip repairs, contact us at northlandproject@nzta.govt.nz

Visit our website www.nzta.govt.nz/mangamuka