SH1 Mangamuka Gorge to open to light vehicles before Christmas

4 MinutesBy NZ Trucking magazineNovember 27, 2020

Reinforcing steel is lowered into a steel casing as another pile is drilled to support the road on SH1 in the Mangamuka Gorge.

The NZ Transport Agency says State Highway 1 through the Mangamuka Gorge will open to light vehicles and camper vans before Christmas, with a single lane past two slips on the northern side of the gorge.

A single lane past the big slip that has kept SH1 closed since July will be open in time for Christmas and remain open for at least three weeks to accommodate holiday traffic, says NZTA senior system manager Wayne Oldfield.

SH1 will also be reduced to one lane just a couple of hundred metres up the road where the northbound lane slumped after the heavy rain in July.

There will be traffic management in place past both slip sites.

“NZTA understands how much opening the road will mean for the local economy and holidaymakers planning a trip to the Far North over Christmas. Local businesses and visitors can now plan ahead with some certainty. SH10 has been the alternate route north since the gorge was closed in July, but over the holiday season motorists will be able to choose between SH1 and SH10.”

Oldfield says the repair teams have done a great job, working safely and efficiently to achieve the critical Christmas deadline.

“They‘ve been working double shifts (20 hours/day) to accelerate the work and keep to the tight schedule and so far, the weather has been favourable.

“We set an ambitious target of drilling enough piles to stabilise support for the road in time for a Christmas opening. The road past the slip is safe for light vehicles and camper vans but trucks and buses will have to wait until we‘ve completed all of the piling and the full re-alignment of the road. This work should be completed by the middle of 2021.” 

SH1 through the Mangamuka Gorge will be reduced to one lane past this second slip when the road opens at Christmas.

Oldfield says that around 11 January the road will be closed again so the works team can cut into the hillside to realign the road and restore it to two lanes. In designing the work, the team will be looking for opportunities to open the road to traffic at times where possible.

The Mangamuka Gorge has been closed since heavy rain across Northland in July brought down eight significant slips in the gorge. When the road reopens, regular travellers on SH1 will see that maintenance crews have used the gorge‘s closure to repair the road surface, replace roadside guard rails, improve drainage, and generally tidy up the roadside.

“NZTA acknowledges the impact of the road closure on local communities and businesses and the extra time and cost of travelling on the recommended detour route – SH10 – which adds 20 to 30 minutes to the journey.

“We thank people for their patience and understanding while we‘ve worked as quickly as possible to reopen the road.”