Road crews work round the clock to reopen Nelson-Blenheim highway

With less than two weeks until State Highway 6 between Nelson and Blenheim is due to reopen, contractors are working long hours to complete repairs along the flood damaged highway.

The repair bill is estimated to cost more than $15 million and there are more than 100 contractors working on the road, 24 hours a day, with restored access promised by 18 December.

Waka Kotahi top of the South regional manager Mark Owen said heavy rain caused dropouts beneath several sections of the highway during the severe weather event in August and once work started, it became clear it was a bigger job than expected.

"As the crews have been working, it's almost like a design build. As you go that dug down and found a more complications, the scale of the workers got a bit larger."

Contractors are working on five key sites, and at the largest and most complex, pouring concrete behind structural steel columns before the road surface can be rebuilt again.

"We had a metre of rain, so when you think about that volume of water hitting a key lifeline between Marlborough and Nelson, that's pretty significant.

"A lot of the network wasn't directly impacted but these sites we're working on now were severely impacted, particularly where we've lost the lane large underslip and it's taken quite a significant sort of geotechnical design to put a retaining wall back in that's going to be resilient for the future."

Emergency management minister and associate transport minister Kieran McAnulty said the full closure of the road wasn't a decision made lightly.

"We could either close it for seven weeks - do it once, do it right and prepare for the future - or do it slowly with severe disruption over a number of months. The call was made to do it in seven weeks; it's on track to meet that timeline and I'm sure that people here and the Nelson Tasman and Marlborough regions will be grateful for that.

"We know there'll be more severe weather events, we know they'll be more frequent, there's no point doing a patch-up job."

This year, there have been seven states of emergency declared around the country due to severe weather, causing millions of dollars of damage to the road network.

"My focus as emergency management minister is not only to oversee a response, but in the good times to plan, how we can be more resilient and how we can help our communities when they are affected either by a natural disaster, or a severe weather event.

"We are a country of isolated rural communities of small towns, many of them don't have the resources to do it themselves."

Nelson mayor Nick Smith said the highway linking Nelson to Blenheim was the city's most important infrastructure link and its closure had been disruptive.

"Most of the community are very accepting of the roadworks, the part we are really pleased about is that Waka Kotahi are not just doing the job of fixing it, but actually building it more resiliently and that gives us confidence that not only are we going to get a job well done, but there's less chance of another storm locking out this main route."

Many were hanging out for the road's reopening, he said.

"There will be a huge sigh of relief on December 18 with the highway re-opened and us re-linked with Marlborough, particularly for Nelson that has a really important January and February of tourism, those businesses are feeling it and if that date is achieved as I'm confident it will be, it's really a shot in the arm for a visitor industry that's had two and a half years of hell with Covid."

Waka Kotahi said the road will open late evening on 18 December, with the exact time to be finalised on 16 December.