The closures on State Highway 73 will start on Monday, December 4 - Westland Anniversary Day - and run through to Friday, December 15, each day from 10am to 6pm.
"Drivers will be able to use SH73 between Otira and Arthur's Pass village up to 10am each day and after 6pm at night, Monday to Friday," NZTA system manager Mark Pinner said.
West Coast motorists will need to be at Otira by 10am if they are heading east on SH73 and back at Arthur's Pass after 6pm to get home.
The route will be open throughout the weekend in the middle - December 9 and 10.
The closure has been met with disbelief and fury by the tourism sector.
"It seems beyond belief," he said today.
He understood the councils had pressured NZTA to change its plans.
Gerry McSweeney owns tourist lodges at Lake Moeraki and Arthur's Pass and said they would be full with international tourists throughout the closure.
The closure was "absolutely outrageous … destruction of the tourism industry at peak".
He understood NZTA had consulted with the trucking industry, which said it could work at night - "essentially destroying the tourism industry which uses Arthur's Pass".
Tourists would not travel in the dark or early morning, he said.
"It's a real test for Maureen Pugh and the new government - she (Pugh) lives on highway 73."
Greymouth Mayor Tania Gibson said the work had been pencilled in for January, so early December, when schools were still in, was better.
"It has to be done. May would have been preferable, but it needs to be done properly once."
But West Coast Regional Council chairman Peter Haddock was disappointed.
"I only hope Waka Kotahi takes the opportunity to do other maintenance so there are no other closures along that route."
Mr Pinner said they knew the closure would be "unwelcome" for many regular road users, businesses along the route and visitors to the West Coast.
"But this fortnight before the Christmas holidays has the least impact overall, compared to later options, and follows extensive engagement with travel, hospitality and freight operators."
The alternative route is State Highway 7 through the Lewis Pass via Reefton and Waipara, which adds 40 minutes to the three and a-half hour journey from Greymouth to Christchurch over Arthur's Pass.
"Our aim is to ensure that the highway remains safe and fit for purpose for many years to come," Mr Pinner said.
"We want to reduce the potential for more frequent short-term delays in the future due to failures in the road surface. It is now starting to crumble in places. This road is constantly under significant stresses from its grade (16%) and the alpine environment with seasonal weather extremes."
An average of 1500 vehicles a day use the Arthur's Pass route.
"This will be inconvenient for many people, but we believe this is the shortest and most efficient way to get this key piece of work, both sides of the highway, completed safely and successfully.
"We thank everyone for building in the extra 40 minutes if they need to take the SH7 Lewis Pass route during this time, or if they organise their trip around the closures times."
About 342 metres of the Otira Gorge section between the viaduct and the rock shelter will be re-surfaced with new asphalt. It was last fully resealed about 12 years ago, with just short-term repairs in more recent years.
Mr Pinner said the road is narrow in this part of the gorge, which meant the paving and sealing machines fill up the space and did not allow room for traffic to safely pass while work was under way.
NZTA said it consulted on a range of opening times and durations. Stopping the crews and machinery to enable a midday traffic convoy would reduce productivity significantly and more than double the length of time required to do the work.
It could not do it overnight as the rockfall risk could not safely be managed.
The asphalt surface needs a minimum air temperature, so the work needs to be done in summer.
A project page is being set up for the re-surfacing project, and in the meantime people can ask to be sent updates by emailing Otira@nzta.govt.nz .
• For people travelling from Greymouth to the road block point at Otira, they need to allow one and a-half hours from Greymouth to make the trip comfortably before 10am. (Leave Greymouth by 8.30am or earlier depending on weather).
• For Canterbury people aiming to get to the road block at Arthur's Pass before 10am each weekday of closure, they need to allow two and a-half hours from Christchurch. (Leave Christchurch by 7.30am or earlier.)
