KiwiRail's boss has admitted to dropping the ball in their handling of Wellington track maintenance.

Over the past three days, a 70 kilometre speed limit has been slapped on Wellington train lines, roughly cutting the frequency of services in half.

It's due to issues in scheduling maintenance outside of the track's compliance period and their only specialist track evaluation car breaking down last week.

KiwiRail Chief Executive Peter Reidy says the problem hasn't been caused by a lack of money.

"The core issue here is- this wasn't funding, this was just our own goal."

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