KiwiRail says decades of under investment is behind the mammoth issues with Auckland's train network.
An urgent and disruptive six month programme is underway to replace more than half of the city's tracks.
“We have actually found that we have wear on our railway lines at a higher level than we'd anticipated”, said chief operations officer Todd Moyle.
1 NEWS got a close up look at work being done on the city’s Southern line today.
The route, which passes through Greenlane and Ellerslie on the way to Onehunga, has been shutdown for four weeks.
Rolling closures will continue across the network for the rest of the year, with all trains set to be halted for four weeks over Christmas.
Moyle said 500 workers will be hands on deck to “blitz” the network.
Commuters are also facing reduced frequency of services and slower trips as the speed limit for trains on the fatigued lines has been halved.
KiwiRail has been aware of the wear and tear since 2018, according to Moyle, who says the infrastructure has reached its life expectancy.
He says staff weren’t able to begin work until this year, because KiwiRail didn’t have the funding from Government.
“The money is about two to three years late,” he said.
“Over the last 10 or 20 years, there hasn't been the level of investment [needed]”.
KiwiRail staff have historically carried out maintenance on just three to four kilometres per year, just two per cent of the network.
Auckland Mayor Phil Goff acknowledged the funding issue.
“I think in almost every area of infrastructure I can think of, we needed to start work a decade before we actually get the funds to do that work, it's the story of this city," told 1 NEWS.
KiwiRail maintains the steel, sourced from suppliers around the world, isn't the problem.
“There is a specific type of failure, it’s called rolling contact fatigue, and it’s about the way the wheel interacts with rail," Moyle said.
“We have got new rolling stock, new stations, new overhead infrastructure, and we are running it on tracks that some of it's 40, 50, 60 years old."
Investigations continue into why the fatigue is so severe.
"That will help us make sure that it does not happen again and that is key for me. we are going to fix the issue now but we have to make sure that we have a reliable network for Auckland," Moyle said.
That’s crucial as Auckland commuters make more than 22 million train trips a year.