Work at Ohau point on State Highway 1 on Thursday. The site is one of the critical parts of the rebuild.

Authorities have back-pedalled on promises to have the highway north of Kaikōura fully functional by Christmas.

The NZ Transport Agency (NZTA) on Friday reinforced the earthquake-damaged State Highway 1 would open on schedule – but only during the day,and with unsealed surfaces, lane closures and stop/go traffic control. Temporary closures could be a possibility.

The announcement is in contrast to the agency's comments in May, when it claimed the highway would open with "two lanes, and with full functionality – it won't have stop-goes".

IAIN MCGREGOR/STUFF The highway is still expected to reopen before Christmas - but only during the day and with some unsealed sections.

Earthquake recovery manager Tim Crow said they "haven't hit that visionary goal" but got as close as they could.

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"We really did strive to achieve that, but with the weather that we had . . . we've not been able to achieve that. But I'm really pleased with the amount of work the team has done to get it into a safe state."

SUPPLIED A 3-D model of Ohau Point as it was in December shows the scale of the damage to the highway.

He said it would take about five-and-a-half hours to drive between Picton and Christchurch when it opened. This is an hour slower than before the November 14 earthquake, but an hour faster than the alternative route.

Crow said it was important people understood the full rebuild of the highway would not be completed in December.

"This work will continue well into 2018," he said.

"We had one of the wettest winters in recent history, so it really did affect the programme, but we made the promise we would open for Christmas and we're confident we will."

Ohau Point, where the largest slip came down in the earthquake, is one of the critical points of the project.

Crow said cliff face stabilisation was complete and seawalls were being built at the site.

He said an opening date for the road would be revealed in mid-November, about a year after the quake happened.