SH1 Mangamuka Gorge slip repairs

Update on the slip that occurred on Tuesday 29 April 2025

1 May 2025

Cleaning up material and vegetation from the slip site

SH1 Mangamuka Gorge expected to reopen tomorrow

Kia ora koutou,

State Highway 1 (SH1) Mangamuka Gorge will remain closed overnight and is expected to reopen tomorrow (Friday 2 May).

Contractors are continuing the clean-up of the site from Tuesdays slip and removal of at-risk vegetation.

The slip occurred in a natural gully feature that's reforming. Due to dry conditions from last year through to March, the clay-based terrain across the Maungataniwha Range has cracked and dried out. This has made the already slip prone material more susceptible to water, especially following the sustained heavy rainfall we've seen over the past 2–3 weeks and throughout April - one of the wettest on record.

Tomorrow morning, concrete barriers will be installed on the road shoulder at the slip site to stop any remaining material that may fall during future weather events from reaching the road and requiring road or lane closures. Following this, we’ll be in a position to confirm when the road will reopen.

Please continue to use the detour via State Highway 10 in the meantime. Allow additional time for your journeys and plan ahead.

We know any closure of the gorge is disruptive – thank you for your patience as we work to get the road reopened as soon as we are able to do so safely.

Visit the NZTA Journey Planner website for the latest information on the closure: www.journeys.nzta.govt.nz

Ngā mihi nui.

More information

For more information on the SH1 Mangamuka Gorge slip repairs, contact us at northlandproject@nzta.govt.nz or 0800 4 HIGHWAYS (0800 444 449)

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