A report on the outage that saw Wellington trains grind to a halt is due in April. Photo: RNZ / Rebekah Parsons-King
KiwiRail is investigating if new overhead lines in Wellington were badly installed, and whether they caused commuter trains to grind to a halt for hours in early January.
KiwiRail said at the time that the problem was caused by days of hot weather, but also that it was looking into whether there were faulty parts.
Documents released to RNZ under the Official Information Act also reveal heated conversations between KiwiRail staff about the breakdown.
The company says it is still looking into what happened and a report is due next month.
It said the staff conversations did not "take into account all of the facts or information", and were made in the heat of the moment.
Failures attributed to poorly installed overhead lines
On 10 January, three separate overhead line issues on the Wellington train lines saw services grind to a halt for eight hours, forcing thousands of passengers onto bus replacements and leaving some passengers stranded on the tracks.
At the time, KiwiRail told media that consecutive days of warm weather had caused the overhead power lines that run passenger trains to expand.
The company said there were faults related to insulator and weight tension mechanisms, and that they were conducting a full and detailed technical investigation into the cause of the faults.
Documents released under the OIA show that two days after the incident KiwiRail's track operations manager - who was not named in the documents - believed overhead lines failed in two places because design or installation work was "wrong" or poorly done.
The same manager also said KiwiRail did not have documentation of regular quality assurance checks of the installation program of the parts during the completion of its works.
"It is a requirement for the installer to hand all docs and sign offs over to asset owner this has not been done."
The manager could not confirm at the time that the installer of the track parts on the lines was qualified.
"To date I have not received any paper hand over or COC (certificate of certification).
"I believe this is being looked into deeper."
KiwiRail has confirmed the parts that are being investigated were installed between mid-2020 and Christmas 2021.
They were part of the Wellington Metro Upgrade Programme - a $700 million work plan that is currently upgrading existing track infrastructure in the Wellington region.
The work often means buses replaced trains in the weekend and on holidays.
KiwiRail chief planning and asset development officer David Gordon said until the incident the whole installation in the most complex part of the overhead network came into service and operated without any disruption, so it seemed inconceivable its design and installation could have been done by people not competent to perform the specialist tasks.
Gordon said a full and formal investigation of the January outage was underway and due for completion in April.
"We will have answers to detailed questions about what happened and why, along with any actions that may need to be taken once it is complete."
Heated exchanges by KiwiRail staff
In the days following 10 January, email correspondence flew between KiwiRail staff, although KiwiRail stressed the workers did not have all the facts.
The day after the disruption, an email from Transdev - which operates the trains - told KiwiRail it would be seeking to recover costs for things like replacement buses and evacuating carriages.
In a response to that email, a KiwiRail staff member sent the following:
"[Name removed] the content and timing of the email from [name removed] is less than helpful!
"Yes, the incident was extremely disruptive for our customers and came at a cost.
"Contractually I get it, but for [name removed] and the team to receive such an email, the day after a major event when he's absorbed in network investigations and reports is inconsiderate and disappointing.
"It appears we still have some work to do with our middle management relationships."
On 18 January KiwiRail's Wellington traction operation manager wrote frankly about the issues they believed caused the problems the week before.
"I invite any engineer to come down and get a first hand taste of the day to day running and issues we face, dealing with poor workmanship from 3rd party that isn't being handed over correctly even at all!"
They also said they were short of qualified staff with experience in the field, and that staff did not get enough time to work on the tracks.
They go on to say "if the equipment was installed correctly to correct design this wouldn't have happened and it's not the inspection teams issue to ensure basic construction is followed".
Emails were 'in the moment responses under pressure'
KiwiRail said the correspondents did not represent the professional conduct of their people and organisation.
It said they were "in the moment responses under pressure".
KiwiRail said the content in the email chain did not take into account all of the facts or information that they said will become clear from the investigation process.
"While we expect our people to be straightforward in communicating their views, we also expect them to be respectful and professional in their conduct with others."
Greater Wellington Regional Council chair Daran Ponter said he shook his head when he saw the correspondence RNZ sent to him.
Ponter said he would have expected to hear from KiwiRail itself about the details of the investigation and not from an OIA response to RNZ.
He said the emails suggested the problems facing the company were more widespread than council had been led to believe.