From 1 May, Metlink will operate a reduced timetable. Photo: RNZ / Richard Tindiller
It will be a slower commute for Wellington train passengers in May, with lower speeds and a reduced timetable.
The equipment - the only one of its kind in New Zealand - that evaluates the train tracks is broken, so safety inspections on the Kapiti, the Hutt Valley and Wairarapa lines cannot be carried out, KiwiRail spokesperson Siva Sivapakkiam said.
From 1 May, Metlink will operate a reduced timetable, although Wairarapa services will run as normal. Trains will be limited to 70km/h.
Shuttles will replace Melling Line trains between Melling and Petone. Capital Connection and Northern Explorer timetables would also be affected, Sivapakkiam said.
KiwiRail said it would be hugely disruptive to many, apologising for the unplanned inconvenience and the late communication of the information.
"To comply with engineering standards, every four months we run a Track Evaluation Car across the Wellington network, which makes very exact measurements of the tracks - important for trains to operate safely," Sivapakkiam said.
"It is a highly specialised machine that inspects rail lines across the country, doing the kind of fine detailed work that cannot be done by our staff using hand-held equipment.
"Due to unforeseen technical issues with the Track Evaluation Car, we have been unable to undertake the necessary inspections due on the Kāpiti Line by the start of May. The machine also needs to assess the Hutt Valley and Wairarapa Lines by 7 May. As a result, these lines will no longer be compliant and we need to put temporary speed restrictions in place to meet our regulatory requirements.
"It's similar to the warrant of fitness on a car expiring."
Greater Wellington Regional Council chair Daran Ponter said it showed "an abysmal lack of accountability and management".
"This is a monumental failure by KiwiRail. The poor maintenance of this essential piece of equipment is holding the entire North Island's rail network hostage.
"If ever there was a perfect example of a lack of prudent management and accountability for critical rail infrastructure in this country, here is exhibit A."
He said it was not clear how long KiwiRail has known about the equipment failure, and warned other centres' rail services could be affected if repairs did not happen soon.
"Greater Wellington, Metlink and Transdev are doing all we can to run as many services as possible under these unexpected speed restrictions… . I expect the Transport and Infrastructure Select Committee will be keeping a watching brief for an investigation into the cause of this failure and the response."
A member of that committee, National Party transport spokesperson Simeon Brown, said it would "cause chaos".
"The government needs to move heaven and earth to do whatever it takes to fix this problem and then urgently order an independent inquiry to get to the bottom of what has happened."