Collins had the second question of the day and asked the Prime Minister: "Is she satisfied with her Government's record of delivery for new transport projects across the country?"
Ardern answered by first congratulating Collins for being elevated to National's leader before listing a range of transport projects from rumble strips to Auckland's City Rail Link.
As soon as Collins mentioned light rail and Labour's failure to get it across the line, Ardern shot back.
"I know the member is probably going to reference light rail to the airport, and I would say to the member as she would well know sometimes it takes a little longer to get what you want."
Following laughter from Government MPs, Ardern added: "And light rail would be an example of that for me and for the Labour Party."
Parliament's Speaker Trevor Mallard was forced to intervene and ask senior MPs to "keep their mouths zipped" as interjections in the chamber became louder.
Collins quizzed Ardern about funding for light rail, which Ardern said included $1.8b in seed funding, but the full cost to the Crown - estimated by Winston Peters to be $10b - depended on which course the Cabinet chose.
Ardern said light rail in Auckland had always been her intention, along with the Greens, but consensus had not been forthcoming.
She took a jab at Collins' infrastructure announcement from last Friday, saying it "raided" $7b from the Government's $50b Covid response fund.
Ardern said the Government fully costed its policies, highlighting that parts of National's announcement on Friday were uncosted.
Collins pressed Ardern about Peters' disparaging comments on light rail, and Ardern said those comments were unsurprising given NZ First's opposition to it.
National's new leader pressed Ardern on why she had committed to light rail, and she responded by saying that the light rail project that Cabinet considered was different to what she had campaigned on.
"We have made significant inroads on transport," Ardern said, adding that Collins was harping on about one project that Cabinet couldn't agree on.
Mallard then asked National's deputy leader Gerry Brownlee to withdraw and apologise for an interjection.
"You know there is a big difference between getting something wrong and making something up. The member should think about it," Mallard told Brownlee.
National MPs responded with laughter as Collins pushed Ardern on her previous comments about light rail starting immediately after the election.
Ardern again said a three-party Government meant that consensus was needed.
The Prime Minister then pushed back on the slow progress in National's roads of national significance.
Associate Transport Minister Julie Anne Genter tried to ask a question about public road safety, but Mallard stopped her short for trying to put "a centipede" onto a question that usually was only allowed "two legs".
Today's question follows National's $31 billion infrastructure policy over 10 years that Collins announced on Friday, with a major focus on transport in the upper North Island including a four-lane expressway from Whangārei to Tauranga.
Collins has been a very effective performer in the House, known for previously hounding Phil Twyford over KiwiBuild issues.
Her predecessor Todd Muller, who didn't want to be oppositional for opposition's sake, didn't cause Ardern too many concerns during Question Time before he resigned the leadership at the start of last week.
Collins won the subsequent vote and has since seen the resignation of Auckland Central MP Nikki Kaye, Selwyn MP Amy Adams and Rangitata MP Andrew Falloon.
The former two are choosing to leave politics at the election, but Falloon was forced to quit immediately following revelations that he sent pornographic images to women. The latest UMR poll, from before Collins took over as leader, had National on 32 per cent, down 2 percentage points and well behind Labour on 53 per cent support.
National was on 38 per cent support in the latest 1 News-Colmar Brunton poll on June 25, when Muller was leader, but the party's own internal polling at the end of June had National stagnating at about 34 per cent for the past three weeks.
Collins has reshuffled her shadow Cabinet, including bringing former leaders Muller and Simon Bridges on to the front bench, as well as Muller supporters Chris Bishop and Nicola Willis into the top 13.
She also stripped Michael Woodhouse of the shadow health portfolio for failing to inform the Health Minister that he had received private Covid-19 patient information from former National Party president Michelle Boag, and also for failing to tell Boag to stop sending him that information after the first occasion.
