The state highway north of Kaikoura has reopened for the first time since last year's earthquake, with a long queue of traffic already waiting to take the first trip.

Drivers were warned to expect delays as soon as the stretch of State Highway 1 between Picton and Christchurch opened on Friday, one year, one month and one day after a 7.8 magnitude quake rocked the seaside town.

An "extensive queue" had built ahead of the 1.30pm opening, the NZTA said.

Earthquake recovery manager Tim Crow said it marked the achievement of 1700 crew members who had worked to piece back together the area's infrastructure.

"It's also been a long, tough year for the communities along the route," he said.

The new State Highway 1 at Kaikoura reopened today. (Photos / NZTA)

"They have been very supportive and welcomed our workers in to fix the transport corridor, while dealing with uncertainties about their own homes, jobs and access to family and friends."

A dawn service was also held north of Kaikoura on Friday to mark the occasion, attended by about 100 people, including mayor Winston Gray and Transport Minister Phil Twyford.

But drivers are being reminded two areas of the SH1 will still continue to close overnight from 8.30pm until 7am.

The closure areas are between Clarence and Mangamaunu (north of Kaikoura) and between Goose Bay and Peketa (to the south).

The re-opening gives drivers two viable options for travel around the upper South Island, including the alternate route through Lewis Pass.

It comes just in time for the area's economically important tourism season.

And while it was a significant moment for the area's tourism sector, farmers were also celebrating on Friday.

"It's so crucial to have this highway open again. While much of the focus has been on getting tourists back into the region, it's the rural sector too that relies heavily on this route," Federated Farmers north Canterbury provincial president Lynda Murchison said.