The Gorge will open tomorrow

Concrete being poured into the last supporting pile needed to open SH1 through the Mangamuka Gorge before Christmas. Photo / NZTA

State Highway 1 through the Mangamuka Gorge will open to light traffic at midday tomorrow, as promised by Waka Kotahi / NZTA.

Motorcycles, private cars and other class 1 vehicles, travelling north or south, will be allowed through, with traffic lights at the slip on the northern side that has closed the highway since July. There will also be a single lane past another slip a couple of hundred metres further south, with Give Way signs. A 50km/h speed limit will apply throughout the Gorge.

"Drivers are advised to plan ahead, keep to the temporary speed limit, and allow extra time for the journey through the Gorge," Waka Kotahi's Northland system manager Jacqui Hori-Hoult said.

There may be delays getting past the slip site, but that will depend on the amount of traffic."

"Waka Kotahi understands the importance of the holiday period to the local economy, and we're very pleased to ensure the Far North is open for business over Christmas and the local community and holidaymakers can travel by the shortest route to Kaitaia and beyond," she added.

"We understand the inconvenience and extra cost of having to travel on the recommended detour route (SH10), and we thank the local community and businesses on both routes for their patience and understanding while we worked as quickly as possible to fix the road."

On Friday last week the repair team had celebrated the completion of the 31 piles needed to support the road so it could safely open to traffic tomorrow. They would be back in the New Year to complete the piling work and realign the road, restoring it to two lanes.

They were spending this week tidying up the site and preparing the road for tomorrow's opening, including the installation of a guard rail, signage and new lane markings. New asphalt was also being laid.

"It's been a great effort by the team, working in a difficult environment to get to this stage," Hori-Hoult said.

"They've worked double shifts (20 hours a day) and shaved more than four weeks off the work schedule to achieve the December 18 deadline.

The road would be closed again on January 11to complete the piling and begin Stage 2 of the repairs, which would involve cutting into the hillside to realign the road and restore it to two lanes.

The drilling rig and other equipment used on the big slip would move a few hundred metres up the road to fix the second slip, where the road had dropped, reducing it to one lane.

"The repair work at both slips takes up the full width of the road, so we have to balance opening the road to let traffic through with just getting on and completing the repair as quickly as possible," Hori-Hoult said.

"We are asking our contractors if we can keep a lane open part-time as we finalise our building methodology to see what is achievable and practical. At this stage we plan to have the road restored to two lanes at both slips by mid-2021, but it could be sooner, depending on the weather and work progress. We're committing all available resources to getting it done."

Until then, trucks and buses would have to continue using SH10.