Trains running between Picton and Christchurch are now using a new stretch of rail track that bypasses the oldest tunnel on the line, bringing greater resilience to the key freight and tourism corridor.

Rail track and sleepers are removed from Tar Barrel Tunnel, before it is filled with mudstone and permanently sealed off

KiwiRail, working with Waka Kotahi NZTA, has built one kilometre of new track and a new road overpass for State Highway One just south of Ward in Marlborough to bypass the 108-year-old Tar Barrel Tunnel.

KiwiRail’s Group Chief Executive Greg Miller says the work has strengthened the key freight route used to move domestic products from Auckland to Christchurch and beyond.

“With funding from the Government, we’ve been able to remove the tunnel from the route altogether, which is great news for our freight customers around the country who use this line.”

Due to its age and restricted width, trains had to slow down markedly to travel through Tar Barrel Tunnel. The tunnel was repaired after being damaged in the 2016 Kaikōura earthquake, but was still not up to modern standards and continued to cause operational constraints for KiwiRail.

“The new link strengthens the road and rail connection for the Marlborough region and New Zealand’s transport network. Building seismic resilience into our core freight routes is vital to ensure we can manage if there is another significant earthquake,” says Mr Miller.

The two-year construction project involved temporarily moving part of the state highway for 11 months, while the Ruakanakana Overpass was constructed. It opened to traffic in November 2020. The overpass was named in consultation with Ngāti Kurī hapū of Ngāi Tahu.

Approximately 400,000 cubic metres of material was cut out of the hillside alongside the tunnel to make a path for the new rail alignment. Tar Barrel Tunnel is being backfilled with some of this material and sealed at the portal entrances.

Mr Miller says at its peak more than 80 people were working on the project at one time.

“Some of the workers have been involved in earthquake recovery repairs in the region for over four and a half years and it’s a great moment to see this final piece of the rail repair story completed.”

Director Regional Relationships for Waka Kotahi Top of the South Emma Speight, says that the project has been well managed throughout.

“It has been great to work with KiwiRail and Marlborough Roads to improve safety, resilience and the reliability of our SH1 network in Marlborough for both rail and road users.”

Work on SH1 will be continuing through the rest of May and in June with roadside drainage and guardrails being installed. Temporary traffic management measures will be in place while this road work is carried out.

KiwiRail and Waka Kotahi NZ Transport Agency appreciate people’s careful driving through the site and thank everyone for their patience.

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