A close look at ground level destruction to State Highway 1 north of Kaikoura following the 7.8 earthquake.

As work continues on the inland route to Kaikoura, up to 15 crews have started clearing the slips on State Highway 1.

NZ Transport Agency regional performance manager Pete Connors said work was "well under way" to clear some of the smaller slips and make repairs to SH1, where it was safe to do so.

As of Tuesday, up to 12 crews were working between Parnassus and Oaro, south of Kaikoura, to clear slips and rockfalls to improve access for local residents and emergency services along the route.

The highway remains closed to the public north of Parnassus.

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On the north side of Kaikoura, three crews are working south of Ward, aiming for less restricted road access as far as Clarence by the end of the week.

ROSS GIBLIN/STUFF Work has begun clearing slips on State Highway 1.

Over the weekend, they cleared a four-wheel-drive track from SH1 to the Glen Eaton settlement on the Clarence River north of Kaikoura.

That allowed escorted access for Marlborough Lines to reconnect power to Waipapa Bay on Sunday.

It was hoped the lines company would gain access to Clarence Valley on Wednesday.

LAWRENCE SMITH/FAIRFAX NZ Up to 15 crews are working to clear SH1 to provide access to local residents of small communities.

Connors said clearing SH1 was a huge job that would take some time to complete.

"The scale and complexity of the slips on State highway 1 are unprecedented in New Zealand, and the task ahead of us is huge."

Conditions were still too unstable for geotechnical engineers to get onto the largest slips to carry out inspections, but that would be done as soon as it was safe, Connors said.

IAIN MCGREGOR/FAIRFAX NZ The larger slips on SH1 are still too unstable to be inspected.

Meanwhile, on the Kaikoura Inland Road, 25 crews are working to clear up to 60 slips from the 100-kilometre route. Geotechnical experts and structural engineers are on site daily.

Connors said the crews had been working 12 hour days to clear the thousands of tonnes of material that came down during November 14's earthquake.

Eleven excavators, 24 truck and trailer units and a variety of other specialist machinery were being used to help clear the road, as well as helicopters to sluice and remove rock from slips in the Conway and Whalesback areas.

BRADEN FASTIER/FAIRFAX NZ Contractors work on repairing the inland road between Kaikoura and Waiau which they hope to open by permit only on Thursday.

Connors said all of the 20 bridges on the route had been checked and a temporary Bailey bridge had been installed across the Wandle River, as the permanent bridge sustained major damage.

The Bailey bridge was not ready to be used yet, but an update was expected on Wednesday.

It was unknown when the full inland route would be opened to the public.

"The inland road is still a fragile and hazardous route, but good progress is being made with controlled access for military vehicles, essential services and local residents to date," Connors said.

BRADEN FASTIER/FAIRFAX NZ Part of the damaged inland road between Kaikoura and Waiau.