A walk along State Highway 1 north of Kaikoura reveals the extent of earthquake damage to the road.

A timeframe for reopening the South Island's main highway remains unclear, however the transport minister says he doesn't think it will take years, only "many months".

Roading crews are working around the clock to restore restricted-access on State Highway 1 from Cheviot to Kaikoura by Christmas, but an opening date for the northern stretch of the boulder-strewn road is less clear.

While work takes place on the southern part of the highway, the Marlborough roading authority, Marlborough Roads, has been told to prepare for three years of maintenance on State Highway 63 - the alternative route between Christchurch and Picton.

GEORGE HEARD/FAIRFAX NZ The 7.8 earthquake has left parts of State Highway 1 unrecognisable, though the transport minister says he doesn't think it will take years to repair the spine of South Island roading.

The highway is part of the bypass route, comprising state highways 7, 65, 6 and 63, that has become the defacto main transport line, through the Lewis Pass.

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Transport Minister Simon Bridges shot down any suggestion this meant SH1 would be out of action for three years, although he declined to provide a precise estimate.

DEREK FLYNN/FAIRFAX NZ A section of State Highway 1, near Kekerengu, lies deserted following the 7.8 magnitude earthquake.

From Kaikoura to Ward, in southern Marlborough, the New Zealand Transport Agency listed 11 moderate and six major slips, creating a far more complex repair job than the southern stretch.

"It's a much longer-term, more major job given the size of the slips and the complexity of what we're dealing with geographically," Bridges said.

"That being said, I don't think it's anywhere like three years.

MARLBOROUGH CIVIL DEFENCE A slip over State Highway 1, near Kaikoura.

"I think it's a period of many months but I'm loathe to put a more precise timeframe on it because I want to be realistic and I don't want to provide a false picture."

An NZTA spokeswoman said until geotechnical engineers were able to safely assess all the slips on the northern stretch of the highway, it was too early to say how long the work would take, or how much it would cost.

"Restoring full access on State Highway 1 north of Kaikoura will be a huge job that will take some time to complete," she said.



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

GEORGE HEARD/FAIRFAX NZ One of the slips blocking State Highway 1 north of Kaikoura.

Bridges said the Government had explored alternative locations for SH1, including the current bypass route, but it would be expensive to upgrade and faced comparable geographic risks.

"We're absolutely committed to repairing and rebuilding SH1, it's a critical piece of national infrastructure, it's the spine of our transport network," he said.

"It's much more likely, almost certain to be on that coastal route, because the inland option looks to be much more expensive and less positive environmentally and in terms of resilience."

GEORGE HEARD/FAIRFAX NZ Rocks on the highway.

He said it was inevitable parts of the highway would be re-routed because of the danger posed by slips, which meant the road could be moved closer to the sea.

There had been limited work clearing rockfalls on SH1 north of Kaikoura, but the priority was opening the Inland Rd and clearing the southern part of the highway to Cheviot.

After access was restored, the Government also wanted to improve the safety and resistance of SH1 to help it withstand future events, however Bridges said this was a longer term project.

The cost of repairing all damaged transport infrastructure would make up a significant proportion of the overall cost of the earthquake, which Treasury put between $2 billion to $3b, he said.

The Government had already committed between $50 million to $100m maintaining and upgrading the inland route from Christchurch to Picton, through the Lewis Pass.

KiwiRail did not respond to questions about the future of the main trunk line between Christchurch and Picton, which was severely damaged by the earthquake.