KiwiRail's identified the cause of a power outage at its National Train Control Centre which caused havoc for Auckland rail users yesterday.
CEO Jim Quinn says it was a faulty uninterruptible power supply unit, which feeds the Auckland network control desks.
He says the faulty unit was immediately removed from service and a replacement is being installed today.
Mr Quinn says the existing power system design wasn't robust enough, and they're taking immediate steps to further minimise the chance of this type of incident happening again.
He says an independent review of the system will be undertaken.
Mr Quinn says it's the first time an outage like this has occurred.
And Auckland's Mayor is questioning whether the system which controls the city's train network should be moved from Wellington.
Len Brown wants to know if it's appropriate to shift the control desk given the investment in Auckland rail.
"Now that's a discussion that we'll have with KiwiRail but it may be timely to do that. We cannot have any UPS' failing Auckland rail commuters anymore in the future."
Photo: NZ Herald