Temporary piles are installed at a major slip on SH1 through Mangamuka Gorge.
Photo: Supplied / Waka Kotahi

Waka Kotahi is revealing “a timeline to reopening” State Highway One over the Mangamuka Gorge on Friday as the road undergoes a $100 million repair job.

The critical Far North main access has been shut since huge August 2022 rains brought down slips above and below the highway, once again cutting the essential main arterial route into Kaitāia and the Far North that had not long before reopened following a previous shutdown.

Waka Kotahi would not reveal exactly what would be brought to light on Friday or a potential opening date for the route.

“We expect to share more information of a timeline to reopening SH1 Mangamuka Gorge by the end of the month,” the transport agency’s regional manager maintenance and operations Jacqui Hori-Hoult said.

Mangamuka Gorge’s SH1 closure has added huge amounts of extra travel time for truckers and others travelling into the Far North, who are having to use the alternate SH10 around the Far North’s east coast.

Trenching alongside SH1 at the end of a slip at the northern end of Mangamuka Gorge.
Photo: Supplied / Waka Kotahi

Northland Mayoral Forum chair Vince Cocurullo said recently the SH1 Mangamuka Gorge closure was costing truckies taking freight north to Kāitāia from Auckland an extra $1000 each way on their journeys.

The Mangamuka Gorge state highway closure has added half an hour onto car trips north into the Far North and added major traffic loading onto alternate SH10.

The closure has been exacerbated by Cyclone Gabrielle reopening old wounds further south on SH1 over the Brynderwyns, which has had restricted access since February 11.

The $100m for the Mangamuka Gorge repairs was aimed at restoring the route to its original condition.

The gorge was also hit by major slips in July 2020 with repairs taking almost a year and costing $13.8m.

Drainage work being undertaken on the Mangamuka Gorge SH1 route.
Photo: Supplied / Waka Kotahi

Work on the road over the Mangamuka Gorge is being done in three phases. The first was to protect the road from further damage, the second stage was fixing slips and returning the route to its original condition, and the third was to future-proof the road so it could withstand weather events.

There have been fears since Cyclone Gabrielle that Mangamuka Gorge repairs would suffer, with attention instead shifting to SH1 over the Brynderwyns, and putting huge pressure on alternate bypass diversions over Whangārei and Kaipara District Council roads.

The Brynderwyns will be open over Easter for two-way traffic for the first time since Cyclone Gabrielle.

Local Democracy Reporting is Public Interest Journalism funded through NZ On Air.