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The first freight train to travel on the Picton–Christchurch rail line since the Kaikoura earthquake was welcomed into Kaikoura on Friday morning 15 September by the community and special guests

Trains resume after ‘mammoth’ Main North Line rebuild – By Dave MacIntyre

What has been described as “one of rail’s biggest rebuilds in New Zealand since World War II” has taken a major step forward with the opening of the South Island’s Main North Line for its first freight services since last November’s Kaikoura earthquake severed the main road and rail link between Christchurch and Blenheim.

KiwiRail announced in early September that trains would begin operating restricted services on the Main North Line (MNL) on 15 September, just 10 months after the 7.8 magnitude earthquake that caused havoc to New Zealand’s freight supply chain. The event was marked by celebrations in Christchurch and Kaikoura as the first train travelled down the line.

The initial opening is a restricted one, with low-speed, low-frequency services. Freight trains will initially run at night, five nights a week, with two return services operating so that work on the rail and road networks can continue during the day. This equates to about 50% of normal capacity and is likely to take up to 2000 trucks per month off the South Island roads being used as alternative transport routes.

The link will not be fully operational until sometime in 2018. KiwiRail’s award-winning passenger service, the Coastal Pacific, will also remain on hold until 2018.

State Highway 1 remains closed to through-traffic from Picton to Christchurch. The highway is open between Picton and Clarence, and from Christchurch to Kaikoura during daylight hours four days a week. It remains closed between Clarence and Mangamaunu.

Road access was restored to Kaikoura before Christmas 2016, via the Inland Route 70 and on State Highway 1 south of the seaside town which is open with restrictions.

Damage and repairs

Returning freight to the tracks has been “a mammoth task”, says KiwiRail chief executive Peter Reidy. “There were close to 60 major damage sites, including tunnels, bridges and embankments, and the line had been buried under more than 100 slips and landslides. Approximately 60 bridges were damaged and repairs are being carried out at more than 750 sites,” he tells FTD.

“However, getting the line open, even on a restricted basis, will ease pressure on the alternative road, which has been the main route to shift freight south since the earthquake. I am proud of what has been achieved by the team and how our KiwiRail people have worked together with our partners in the North Canterbury Transport Infrastructure Recovery (NCTIR) alliance and have responded to what had been a devastating blow to the network.”

NCTIR is an alliance representing the NZ Transport Agency and KiwiRail on behalf of the government, charged with repairing the road and rail networks between Picton and Christchurch. It also includes Fulton Hogan, Downer, HEB Construction and Higgins as participants. Given the size of the job, a large number of subcontractors are involved in the reinstatement works.

Its task is not only to repair and rebuild the networks to be more resilient and safer, but to also manage the upgrade of the alternate highway route between Picton and Christchurch, along State Highways 63, 6, 65 and 7 (Lewis Pass), and Inland Route 70 (between Kaikoura and Culverden). Over 1500 workers have been involved in the project.

Sequencing of work

Walter Rushbrook is the project director for KiwiRail on the MNL rebuild, working on secondment from engineering and infrastructure consultants Aurecon. He says that the rebuild task has been approached by sequencing work from either end, with the goal of meeting in the middle.

“Given the narrow transport corridor and the close proximity of the road and rail, it has been essential for teams from both modes to work closely with each other,” he explains. “In some cases, the road and rail track have had to be shifted to new positions, when the original alignment was located too close to unstable slopes.”

The stabilisation task for the rock faces above the rail and road pathway has been approached using a number of techniques. First, the hillsides were sluiced using helicopters with monsoon buckets to get rid of loose material. Abseilers were then used to scale the slope to remove further loose material and undertake a detailed inspection of the slip faces.

In some locations, benches have been cut into the slope to help stability. Additionally, the benches cut into the hill face also act as a safety measure by helping catch any falling rock or debris. Excavators have then attacked the slips from the bottom, removing material and deconstructing the slip to a point where it is stable.

Other techniques used to stabilise the hillside and provide future protection for the road and railway include building bunds (embankments) with catch pits and special rock-catching fences so that any falls of material are intercepted. In some places, rock and mesh have been bolted onto the cliff face to give the slope greater resilience.

Sensors, trip wires, cameras and weather stations have also been installed along some parts of the rail line, connected to train control, so that the condition of the track can be monitored remotely.

Mr Rushbrook says that while the rail and road tasks were tackled side by side, the progress has been faster for rail. “While some tunnels were damaged – including one with a major fault rupture going through it – the tunnels elsewhere largely protected the track whereas the road was impacted by a larger number of slips,” he notes. “It is also easier to recreate one width of rail track than two lanes of road.”

However, the opening of the rail track also gives the opportunity to make faster progress on the State Highway 1 road rebuild. Trains will now be used to move materials to worksites along the route, including the large concrete blocks for sea retaining walls.

The wider story

Peter Reidy says that the MNL is a critical part of New Zealand’s transport network, carrying around 1 million tonnes of freight annually before the earthquake. “Reopening the line will help strengthen and make the transport links more resilient for customers moving freight between the islands. It will reduce greenhouse gas emissions as every tonne of freight carried by rail is a 66% emissions saving for New Zealand.”

The final weld to rejoin the Main North Line track was made in August

Walter Rushbrook says the MNL rebuild is more than just a construction story. “It is a wider land transport story. Getting rail moving again takes trucks off the alternative route. Taking pressure off the roads will be good for New Zealand. It adds to the diversity and resilience to our land transport system.”

He concludes by giving the human side of the story. “This triumph was a huge team effort. There have been numerous people working for months away from home and in shifts to get everything up and running. Those efforts need to be recognised and celebrated.”

Dave MacIntyre is an award-winning journalist who specialises in transport issues within New Zealand; he can be contacted at d.macintyre@xtra.co.nz

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