The rebuild of SH1: the second chapter

Rebuilding SH1.

The great push to re-open SH1 between Picton and Christchurch in time for the Christmas holidays was a warmly-welcomed success, but the work goes on. Hugh de Lacy reports on this project in the second of his articles.

THE VISITOR SPEND in Kaikoura over the Christmas holidays just past was quadruple that of the same period in 2016, topping $12 million and showing just how vital to the local economy was the re-opening of SH1 between Picton and Christchurch in mid-December.

Figures released in February by the Ministry of Business, Innovation and Employment showed the big recovery in Kaikoura’s tourist cash-flow, but also that it – like the road repairs – still has some way to go, given that the December spend in 2015 topped $16 million.

For the whole of that year tourism contributed $111 million to the whale-watch haven, while last year it managed only $68 million, even with the December surge.

Given the continuing boom in overseas tourism to New Zealand – visitor numbers in 2017 reached 3.7 million, equivalent to the entire population of the North Island – this year is likely to see Kaikoura’s 12-month tourism spend top $120 million.

Such a recovery could scarcely have been imagined by the locals after the shaking stopped that night of November 14, 2016, when the magnitude 7.8 earthquake narrowed the gap between the North and South Islands by six metres.rebuilding SH1

During the two minutes that it lasted, the earthquake created ruptures in no fewer than 21 fault-lines spanning 170 kilometres of the north-eastern South Island – and sent a tsunami along the Kaikoura coast that was seven metres high in places.

It took more than 1.5 million worker hours – 250,000 hours a month – over the following one year, one month and one day to get both the road and rail operating again by a workforce that had more than 4500 people inducted into it.

The euphoria that accompanied the road re-opening on December 15 has since waned, but the workforce led by the North Canterbury Transport Infrastructure Recovery alliance (NCTIR) is still battling to clean up the mess, and in mid-February the road north of Kaikoura was still being closed at night for safety reasons.

Slip Nine at Waipapa Bay, north of Kaikoura, was one of the biggest of the 85 that closed the road and the railway line that night, and it’s still a major focus of the ongoing work, according to Tim Crow, the NZ Transport Agency’s earthquake recovery manager.

“Slip Nine has been a big one for us: it’s a very large slip and we remain concerned about it because it’s still coming down,” Tim tells Contractor.

Rebuilding SH1Traffic is confined to a single lane through the bay, and there are other slips like it, albeit on a smaller scale, all along the coast that continue to threaten both the road and the railway line.

Tim says the broad strategy, from now until the clearing and rebuilding is expected to be finished sometime in April, is to push the road out towards the sea as far from the threatening cliff faces as possible, and in turn to cut the faces back as far as is practicable so they no longer threaten the highway and rail line.

A second major work site is Ohau Point where the seal colony used to sit at the bottom of a waterfall, charming tourists in their thousands.

The waterfall, which is on private land, is currently closed off and the seal colony is no more, while contractors focus on lifting the carriageway from its present five metres above sea-level to 10 metres.

This part of the repairs involves building one of the longest stretches of seawall out of a total of 2.8 kilometres that have to be rebuilt after the quake and subsequent tsunami damaged no fewer than 302 retaining walls, 97 of them along the coastline.

A total of 7000 five-tonne concrete blocks is needed for just the seawalls north of Kaikoura, where more than a third of the work lies in preparing the foundations.

Rebuilding SH1Even the seals, which returned to the battered coast soon after the quake, have required major relocation work, with no fewer than 11,000 adults and pups having to be moved by hand out of the way of the works.

By Christmas nearly one million cubic metres of spoil had been shifted off the road and railway along the 194 kilometre stretch between Cheviot and the Clarence River, where there were more than 1500 damaged sites, 200 of them requiring major work.

The Irongate Bridge has absorbed most of the 140 beams required for bridge repairs along the road, the longest of which was seven spans and 144 metres, and which was built in just 14 weeks.

Slips still moving, or likely to resume advancing towards the road, have so far been sluiced by a total of 152 million litres of helicopter-borne water.

Work is well advanced on repairing the hundred buildings that were damaged, nine of them severely.

All this is being done by a workforce halved from the peak of 1700 that brought the road to its tentative reopening before Christmas, and which temporarily boosted the population of Kaikoura by 30 percent.

The total bill to repair the key South Island transport corridor has settled at around $1.2 billion, of which $351 million had been spent by last September, and more than half by early this year.

Upgrading the alternative access routes to Kaikoura and to Christchurch for the temporary boost in traffic volumes has cost $60 million, with a further $231 million budgeted for additional improvements, most of which are still in the design stage.

For most of its length, the railway line is largely free of the threat of further inundation by slips and has been open mostly at night since last August, leaving the line free during the day to facilitate road repairs.

Traffic on the rail line is gradually getting back towards the million tonnes of freight it used to carry annually, thanks to repairs at 220 sites, including to major damage to 20 rail tunnels.

As work on the slips and roads winds up over the next couple of months, the focus will switch to environmental work covered by more than 30 approved consent packages.

One beneficiary will be the rare Ohau Point daisy from which seed was collected last April and 200 seedlings propagated for re-establishment later this year.

Tim Crow says work is continuing 24/7 and over the next few weeks will gradually move off the slips and into the upgrading of amenities like road barriers and rest-stops.

This article was first published in Contractor March 2018. 

Read the first article in the series, A milestone for contracting.

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