Mangamuka Gorge in Far North reopened after second slip in a week cleared

SH1 through Mangamuka Gorge has reopened after the latest slip site had concrete barriers put in place on Friday.

The highway through Mangamuka Gorge has reopened after contractors cleared the second of two slips that closed the road.

State Highway 1 through the gorge was closed on Sunday because of 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.

NZTA Waka Kotahi said contractors had done a great job clearing up the latest slip and the road was reopened at 2pm on Friday after concrete barriers were in place on the roadside.

The road has been closed since Tuesday evening, when a large slip came down at the southern end of the gorge. Contractors had been monitoring movement on the hillside following recent heavy rain and the slip was expected.

Contractors have worked over the past days to clear soil and vegetation from the slip and secure the hillside.

This slip that closed SH1 through the Mangamukas in the Far North on Tuesday has been cleared and the road reopened.

On Friday morning, concrete barriers were installed in the road shoulder at the slip site to stop any remaining material that could fall during future weather events from reaching the road, minimising the chance of future road or lane closures.

NZTA said it understood closure of the gorge was disruptive, especially for freight, local businesses and communities.

“However, the geology and varying terrain through the Mangamuka Gorge mean it will always be susceptible to some movement during severe weather, like what we’ve seen 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 because of the ground conditions in the Maungataniwha Range.

In a sign of just how vulnerable the Far North is to road closures, SH10 was blocked about 7pm on Wednesday after a serious crash between Taipā and Mangonui. The road was closed for more than 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.

NZTA reopened 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.

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