The train was carrying logs and pulp from Kawerau to Mount Maunganui when it derailed in Te Puke. Photo: Bay of Plenty Times / Tyson Smith
Transport investigators have found a communication breakdown led to the derailment of a KiwiRail train during bad weather.
Eleven of the freight train's wagons, carrying mostly logs, overturned while travelling from Kawerau to Tauranga in the early hours of 29 January.
A report by the accident investigation commission says flooding on the line undermined the tracks.
The issue was noted the day before, but not effectively passed on, and an inspector assessed the wrong area.
Chief investigator Naveen Kozhuppakalam told Morning Report there were communication issues.
"The rising water washed away the crushed stones, they're also called ballast... under the rail track so without adequate ballast under the track, the track was no longer able to support the weight of the train.
"So as the train went over the tracks, the track gave way and the train derailed."
Train derailment could have been as bad as Tangiwai
It came down to how information was passed on and how it was received, he said.
"If you do not provide information that's accurate than those that are responding to that information may not be able to respond effectively.
"KiwiRail, look, they are onto it, there's lots of evidence that KiwiRail is well aware of what needs to be done and we're seeing definitely some signs of them reacting and acting on it and...at the end of the day, floods, washouts, landslips, they're not new things.
"There is a clear need for the railway industry to manage its infrastructure effectively."
This was about minimising damage and mitigating the effects of weather events, weather normal or extreme, he said.
Weather events were one of the most important issues facing New Zealand's railway industry.
KiwiRail was aware of the risks and gaps in its response, and was working on improvements in the face of increasingly severe and frequent storms, he said.
KiwiRail spokesperson Paul Ashton said the company was committed to safety, and events such as the Te Puke derailment have underlined the importance it already places on preparing for bad weather.
KiwiRail admits poor communication before train derailment
Ashton told Morning Report it was a really serious incident.
"On this particular night ... the train crew were on an earlier train running from Mount Maunganui to Kawerau, they noticed water levels on that bridge were getting somewhat high, they reported this to our train control centre. But, unfortunately, the actual kilometrage of the point where the water was, was not very clear in the communication between the train crew and our train control centre.
"That information was then passed onto our track control inspector who actually inspected the wrong area, they inspected east of Te Puke, rather than west of Te Puke."
Ashton said the weather on that night was more than what was forecast but KiwiRail has strengthened its reporting from meteorological expert which is then reviewed every day "even to the extent that nine o'clock each morning we have a managers review of our issues that may face us for the next 24 to 36 hours and weather is the first item that we look at".