People complaining about the cost of a new car-free bridge across the Waitemata Harbour would probably also complain if it wasn't built, and a lane on the Harbour Bridge was used instead, a Green MP believes.
The new crossing for cyclists and pedestrians is tipped to cost $785 million, but Waka Kotahi's initial assessment of the project's benefit-to-cost ratio (BCR) is just 0.4 to 0.6 - meaning for every dollar spent, there'd be a 40-60 cent loss.
Julie Anne Genter, former Associate Minister of Transport, says it would have been much cheaper to just take one of the Harbour Bridge's lanes off cars.
"Obviously we could do it cheaper and faster on the existing bridge. Lots of cities around the world are doing that - they're taking car lines off bridges," she told Newshub Nation on Saturday morning.
She and host Simon Shepherd rattled off some of the cities where it's been a success, including London, San Francisco and Vancouver.
"Before it happened there were lots of people predicting 'carmageddon', and afterwards most of those people have been absolutely convinced of the success of the policy."
Cyclists took over a lane of the bridge last month, demanding at least a trial of the idea. Less than a week later, Transport Minister Michael Wood unveiled the new bridge plan, which will run alongside the existing one.
Appearing on Newshub Nation before Genter, he defended the project's poor BCR.
"You're not asking me that about any of the roading projects which often have similar BCRs," he told host Tova O'Brien, who suggested giving cyclists a lane on the existing bridge instead.
"I suspect if we did that, we'd be sitting in this interview and you'd be telling me how outraged motor vehicle users are. There are always trade-offs and choices."
Genter said either way, we need more cycling and pedestrian options, especially linked up.
"The cost of the bridge is not the cost of walking and cycling - it's the cost of keeping all eight lanes on the existing bridge for cars. If that's what people want, they should be prepared to pay for it," she said.
"The people complaining about the cost of the bridge would also probably oppose opening a lane for active transport."
Wood said the recent report from the independent Climate Change Commission made it clear action has to be taken now.
"It is different to what we've been doing in the past, but we're going to have to make different investments if we want to be up to that challenge, and don't have our kids in 30 years' time looking back at us and saying that we failed and we led to runaway climate change that made our world worse.
"So I stand by these investments - I know that they'll be tough sometimes, but this is the challenge of governing in a time of change. We're up for it."