SH1 will be rebuilt but it will take many months: Simon Bridges

The ruined State Highway 1 along Kaikoura's pulverised coast will be rebuilt - with the prospect that huge rockfalls will be bulldozed into the sea.

Transport Minister Simon Bridges - who flew over the disaster zone yesterday - said that reconstructing the vital road artery could take "many months" but not years. The Government was "absolutely" committed to reopening the route, he said.

"Clearly in light of the earthquake we'd want to look at our options and examine them closely in terms of where that State Highway is. My view is that that is going to lead us back to the coastal route that it is currently on, because it is the most direct route and it has very significant tourism appeal."

Transport minister Simon Bridges on an aerial tour of earthquake-affected highway 1 near Kaikoura. Photo / Kurt Bayer

Bridges toured the Kaikoura region again yesterday and told the Herald roading was "top of mind" with potholes already emerging in the main alternative route, via the Lewis Pass and Murchison.

There are serious concerns for public safety with the alternative route already taking four times as many heavy trucks as normal, and police putting 10 extra highway patrol officers on the road to try to bring down speeds.

Contractors are using heavy machinery to clear the rubble and debris, while helicopters with monsoon buckets are sluicing gouged-open hillsides. Cracks and crevasses in the road are being filled with shingle and dirt as a stop-gap measure, as aftershocks continued to rattle the region.

Last night there was a 5.7 magnitude shake, and a 4 over M4 in the space of 10 minutes.

To take the load off the roads, cargo is expected to be diverted to a sea route between Auckland and the Port of Lyttelton.

Bridges said: "I think shipping can be a real hero over summer for us," adding that the Government could give the industry "nudges" to make sure that capacity was being used.

Asked if limiting the number of heavy vehicles on roads could be one of those "nudges", Bridges said: "There are measures we could take but we wouldn't do that lightly."

The national body representing the road freight industry will today ask the Government to consider splitting the alternative routes between Christchurch and the top of the South Island between heavy vehicles and other transport.

Heavy vehicles could be banned from the narrow Wairau Valley, for example, and instead go through Nelson.

Road Transport Forum head Ken Shirley said the group also wanted a station at Springs Junction to check truck drivers' logbooks.

"That will deter those from cheating on their logbooks and trying to do a return trip from Christchurch in a day, which you cannot do. It is an eight-hour journey now [one way]. We have anecdotal reports that some are [doing return Christchurch to Picton trips]. Those who are transgressing need to be hit and hit hard."

Shirley hoped the Government would not be "sensitive" about SH1 and bulldoze rubble into the sea.

"What you've got there is mountains meeting the sea - that material wants to go into the sea, that's gravity, to try and truck it away ... would add to the cost and time massively. They might need some special environmental powers."

Bridges said it was too early to make that call, but the New Zealand Transport Agency (NZTA) was currently working on options to present to Government. "And we don't want to muck around on that, because we appreciate livelihoods ... are seriously affected."

Damage to the railway and state highway 1 near Kaikoura. Photo / Supplied

At a briefing at the Beehive's civil defence bunker yesterday, NZTA regional performance manager Mark Owens said the scale and complexity of slips on SH1 are "unprecedented and the task ahead of us is huge".

The agency's chief executive, Fergus Gammie, told Kaikoura residents the agency had been working on roading issues immediately after learning of the damage. "This is an unprecedented damage on a state highway in New Zealand."

Gammie said in the 15km north of Kaikoura there were six major and nine minor slips.

Six of those slips are as big or bigger than the Manawatu Gorge slip in April last year. One of the slips is three times as big.

"These slips cannot be dealt with in a normal way. It's a very very big exercise to deal with those."

SH1 toward Kaikoura from the south is a wild ride over cracked seal and gaping holes. Photo / Mike Scott