Evidence and analysis has convinced the government of the case for road tolls to tackle traffic jams in Auckland, the Transport Minister says.
The government had previously not been keen on making motorists pay for future transport needs, but has now backed the idea in a report written jointly with the Auckland Council.
Transport Minister Simon Bridges has confirmed tolls or road charges were likely to be introduced in Auckland the long term. He told Morning Report their main purpose would be to manage congestion rather than raise revenue.
"This isn't about ... revenue. This is about once you've done the network and you've still got the growth, you need more in the demand side tools in the tool kit - technology, but also pricing."
Under the current plan, there would not be toll gates on existing roads but motorists could be detected by satellite and charged automatically according to their time and location in the network, he said.
"There will come a point of time where you can't just keep adding lanes to the motorway.
"The network will be there, and then you need to find new things to deal with the growth that Auckland is seeing."
Mr Bridges did not accept the government was late to accept road tolls as an option, saying there had been a five-fold increase in transport investment in the region.
"The reason for, if you want to say there's a change here, the change is simply because ATAP, the Auckland Transport Alignment Project, was about getting Auckland and government on the same page, not by negotiation but by evidence and analysis."
Public support if tolls effective, but public transport use must double
The Automobile Association (AA) said Aucklanders would be more open to road tolls if it would directly reduce congestion.
However, AA principal adviser Barney Irvine told Morning Report there was a lot of work to do to make sure such charges would be fair.
"The survey we've done showed there is a growing openness to new forms of road pricing, so long as people see a direct benefit in terms of congestion."
However, he said there were concerns that people would be disadvantaged depending on where they lived, and whether they could afford the tolls.
He believed the report suggested motorists would pay to travel on existing roads at congested times, Mr Irvine said.
Transport lobby group Better Transport said public transport use in Auckland would have to double to affect road congestion.
Spokesman Graham East said road charges were inevitable, but people needed public transport to provide effective alternatives.
"At the moment the public transport system is ... about one in six people using mainly buses but also the trains and ferries," he said.
"We want to at least double that, which would basically just only absorb the growth in car travel."
Mr East said some European cities had more than half of commuters travelling by public transport, walking and cycling.
Mr Bridges has said it could take up to a decade to fully implement road charges.
But Auckland mayor Len Brown said road tolls must be introduced sooner rather than later or the city would face a funding gap.
Mr Brown said an agreement must be reached before an interim transport levy expired in two years.
"And therefore at that time we are going to have in place a very clear agreement as to how we are going to continue to invest in transport in a way that deals with the massive growth we've got at the moment and the booming economy, and the considerable increase in every year of visitor numbers coming into Auckland."