Mangamuka Gorge to reopen on Friday after two slips closed the road

Contractors working to clear a slip that closed SH1 over the Mangamuka Gorge, in the Far North, on Tuesday. It was the second slip in three days to close the highway, with the road due to reopen on Friday.

Mangamuka Gorge should reopen to traffic on Friday after a large slip closed the road on Tuesday for the second time in three days.

State Highway 1 through the gorge was closed on Sunday due to a slip. It was cleared on Monday, but another slip on Tuesday evening again closed the road, after a previous $204 million repair job was required to fix more than 30 slips.

The latest closure left people having to detour through SH10 or via Broadwood.

But in a sign of just how vulnerable the Far North is to road closures, SH10 was blocked about 7pm on Wednesday due to a serious crash between Taipā and Mangonui. The road was closed for over an hour, with no detours possible, meaning traffic had to wait until the scene was cleared. Two people were seriously injured in the crash and taken to hospital.

NZ Transport Agency Waka Kotahi said SH1 through Mangamuka Gorge will remain closed overnight Thursday and is expected to reopen on Friday.

Contractors were on-site on Thursday, with specialist machinery removing loose material above the slip site in a safe and controlled manner.

“Contractors are continuing the clean-up of the slip site and removal of at-risk vegetation. Concrete barriers will be installed in the road shoulder at the slip site tomorrow [Friday] morning to stop any remaining material that may fall during future weather events from reaching the road and requiring road or lane closures. Following this, NZTA will be in a position to confirm when the road will reopen,” NZTA said.

People should continue to use the detour via State Highway 10 in the meantime.

“NZTA understands any closure of the gorge is disruptive, especially for freight, local businesses and communities. We appreciate everyone’s patience as we work to get the road reopened as soon as we are able to do so safely.”

NZTA opened the troublesome stretch of SH1 through the Mangamukas just before Christmas after more than two years and $204 million of work, following a closure caused by more than 30 major slips.

A one-in-500-year storm caused major slips and forced its closure in July 2020. The gorge opened in June 2021 and repairs cost $16.2m. The road was destroyed by slips during another major storm in August 2022, and yet another storm in 2023 delayed repairs and bumped up costs from $160m to $204m.

The road was rebuilt over 22 months, with more than 1300 piles and 300 anchors installed, the road resurfaced, guardrails upgraded and drainage improved.

NZTA said the geology and varying terrain through the Mangamuka Gorge mean it will always be susceptible to some movement during severe weather, as conditions have been in the area has over the past 2-3 weeks.

“While the risk of major slips through the gorge has been significantly reduced by recently completed recovery works, the area remains susceptible to occasional, less severe slips due to the ground conditions in the Maungataniwha Range. The recovery work was designed in a way that any future movement is expected to be much less severe, ensuring we can respond quickly and minimise disruption to the travelling public.”

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