SH1 expected to open by Christmas despite approaching winter, volume of work to be done

Last updated 19:41 10/03/2017

A helicopter crew sluice the Ohau Point landslide off the northern Kaikoura coast.

A landslide spotter monitors rockfall as a digger works halfway up a slip on SH1 north of Kaikoura.
While ground work has begun on most slips, sluicing is required for those where there is still loose debris.
Temporary access roads have been built on parts of the foreshore using debris from other slips.
A digger at work on one of the slips covering SH1 north of Kaikoura.
Sluicing continues on the Ohau Point slip, the largest of those blocking the highway.
Eight of the 10 slips have access tracks across the bottom of the debris, allowing work to begin on those further in.
Secondary slips which don't reach the road are still a threat, as wet weather will bring debris through the trees and across the road.
From the air, the colossal scale of work remaining on SH1 becomes clear, but officials are confident it will open by Christmas.
Much of the railway lines were protected by tunnels, but about 750 sites have been damaged.
The rail corridor was also badly affected by the quakes.

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Officials remain confident work to clear massive slips on State Highway 1 will be done by Christmas, despite the massive amount of work still to do as winter approaches fast.

The arterial road, vital to Kaikoura's tourist-driven economy and the key route between Picton and Christchurch, was badly damaged during November's magnitude-7.8 earthquake. 

An aerial survey on Friday showed 10 towering slips are blocking the highway north of Kaikoura. The tallest is 400 metres high.

The biggest by volume, covering Ohau Point in the middle of the slip sites, has 110,000 cubic metres of debris and is 300m tall, but very wide. On Friday, five helicopters worked to sluice loose rock down from the site.

* SH1 reopens as wet weather sets in across the South Island
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* New video shows just how damaged SH1 is after Kaikoura quake
Pressure builds on alternative State Highway 1
State Highway 1 rebuild critical for Marlborough and Kaikoura

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Work is progressing well, but the challenges of winter, and the wet weather it brings, are just around the corner.

NZ Transport Agency earthquake recovery manager Steve Mutton said winter conditions would "make it harder" for those working to reopen the highway.

Contractors were racing to do what they could "while the good weather was here".

South Island roads are notoriously weather-dependent at the best of times, and with State Highway 1 out of action for the year, most of the island could end up being cut off in a bad storm.

On average, the Lewis Pass (SH7) closes for five non-consecutive days a year, and Arthur's Pass (SH73) closes for six, often due to snow or heavy rain.

State Highway 6, which runs along the West Coast, also closes several times a year during flooding and slip events, particularly at the southern end.

SH1 has been open south of Kaikoura since December, but remains fragile. The road closed for two days this week because of wet weather and rockfall.

Mutton said some bad weather was "factored into the timeline" for reopening SH1, and the crews were "very experienced in working in winter conditions".

"It's going to be a challenge to work around but it's not going to affect our overall programme."

Access tracks have been built around the bottom of the debris at eight of the 10 slip sites. Another is in progress at the ninth using a remote-controlled digger. 

Once all of the access tracks are in place, contractors can work to clear all of the slips simultaneously. 

Up to 150 people are working on the ground daily, and more are expected to join the efforts in the coming weeks. About 100 people are simultaneously working on road design from Christchurch.

About 20 secondary slips, which do not reach down to the road, exist north of Kaikoura. When it rains, sediment and debris is washed down through the trees and onto the road in volumes that can cover sections of the highway. Managing these is an ongoing issue. 

Mutton said there were "huge logistics" involved in moving the volume of material that came down in the quake and coordinating the workers' efforts.

It was not possible to put more machinery on the slips because the weight would make it unstable.

"There's just not the room, in this beautiful environment between the coastline and the cliffs, to put lots of machinery."

There were no plans to bulldoze material into the sea, he said.

"It's a beautiful coastline around here, and it's a tourist attraction, so we need to make sure it maintains a beautiful environment for tourism and community."

KiwiRail earthquake recovery manager Walter Rushbrook said the railway along the coast was "better off" than the highway in some ways because it was protected by tunnels in many places.

For areas where the railway lines moved further, it was possible to cut the track up and "recycle it" to get the network going.

The number of damaged sites was the problem, with about 750 sections of rail damaged.

Rushbrook estimated the cost of repairing the rail network to be between $300 million and $500m.

About six return freight trains had used the line each day, as well as the tourist train from Picton to Christchurch.Losing the line had caused a big disruption to both domestic and international freight, he said.

The total cost for the SH1 road and rail rebuild is expected to be between $1.4 billion and $2b. 

- Stuff


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