Phil Twyford says National left a $9.7 billion "fiscal hole" in Auckland's transportation budget, describing it as "another hand grenade in the bottom drawer that we've inherited".
The Transport Minister on Thursday teamed up with Auckland Mayor Phil Goff to reveal a $28 billion plan to fix the city's congestion over the next decade. It shifts much of the focus of the previous plan, developed by Auckland Council and National, from roads to public transport.
It's a couple of billion dollars more than National was planning to spend, paid for by an upcoming fuel tax for the Auckland region.
"We have closed the funding gap," Mr Twyford told The AM Show on Friday. "The programme of investment we announced yesterday is fully funded."
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He says the extra spending will allow infrastructure to be built before it's needed.
"For so long in New Zealand, infrastructure... has followed along behind the growth. We subject people to years and years of sitting in gridlock, and then we expensively retrofit after the fact. What we've got to do is get ahead of the growth."
While National spokeswoman for urban development and planning Judith Collins agrees with the idea, she doesn't have confidence Labour's execution will be up to standard.
"I quite like the fact that Phil is thinking about the future for when we're in Government and we have to fix it," she said.
One road that is getting some attention in Labour's rejigged transport plan is Mill Rd in Papakura, Ms Collins' own electorate. She had been collecting signatures for a petition to fund the road's expansion, which under National's plan would have cost close to $1 billion. The new plan allocates about half that.
"Phil knows I have a great petition and he understands Mill Rd is very important. It's incredibly important, which is why it's disappointing you're not giving me all of Mill Rd - you're only giving me half of Mill Rd... but half is better than none."
Ms Collins and Mr Twyford sparred over the Waterview Connection project, which saw a tunnel built through Mt Albert, linking the Southwestern and Northwestern motorways.
The decision to build a tunnel was made by Labour when Helen Clark was Prime Minister. National was uncomfortable with the cost, and looked at a surface-only motorway as well as a combination surface road and tunnel option, which ended up being what was built.
Ms Collins said Labour had a poor track record on roading infrastructure under Ms Clark, and opposed the Waterview Connection during the 2009 by-election for Ms Clark's former seat of Mt Albert.
"Your lot were against it."
Mr Twyford said that wasn't true, because Waterview was actually planned under Labour, which also oversaw the finishing touches on Spaghetti Junction (opened in 2006) and the Northern Busway (2008).
AM Show host Duncan Garner suggested National only backed the Waterview Connection because, as Mt Albert by-election candidate infamously Melissa Lee put it, it would divert south Auckland criminals away from the electorate.
"There aren't any because we've already sorted them out and locked them up," said Ms Collins.
Ms Clark sought to clear up any confusion of who was to thank for the Waterview tunnel, taking to Twitter last year to say it was her Government that decided on a tunnel "rather than wreck the suburb with a motorway".
NZTA says the Waterview Connection has been a success, drastically cutting commute times.