KiwiRail is working to clear and repair sections of the Main North Line between Picton and Christchurch along the Kaikoura coast, after it was hit by Cyclone Gita last week.
Heavy rainfall – exceeding 200mm over 18 hours in some areas – caused approximately 300,000 cubic metres of material spreading across 60 sites between Parnassus and Clarence in landslips. This has led to the shutdown of both the rail line and the state highway.
KiwiRail’s Main North Line project director, Walter Rushbrook, said that teams were currently clearing and repairing track, but that no trains would be able to run this week between Blenheim and Christchurch.
“We will get the line open again as soon as we possibly can, and we are already working on getting the freight rolling again by extending operating hours at our Blenheim Freight Hub to support transport of freight through the South Island,” Rushbrook said.
“In the meantime, we are in close contact with our customers keeping them updated on the situation. An update on the target rail reopening time will be provided next week.”
Rushbrook indicated that sections of track repaired after the damage wreaked by the Kaikoura earthquake in November 2016 fared better than others.
“A lot of the areas where work had been done after the 2016 earthquake have held up well in the face of the severe weather that hit the area,” he said.
Geological scientists have speculated that the major slips that occurred during the heavy rainfall could have been made more likely by the 2016 earthquake.
A research project was established by GNS Science late last year to develop predictive tools for managing the landslide risks and sediment hazards after earthquakes.
“The debris generated by the Kaikōura Earthquake, when mobilised, will create new hazards, including further landslides, landslide dams and dam failures, rapid aggradation, and increased river channel instability, as the debris cascades from hill slope to sea,” the project research outline reads.
“These hazards may persist for decades and therefore represent a prolonged risk that must be considered by the impacted communities and stakeholders.”