The government has given its first clear sign that Aucklanders will eventually have to pay road tolls to help fund the city's transport system.
It has previously been cool on the idea, but now backs it in a report jointly written by Auckland Council (PDF, 2.1MB), which is already committed to the charges.
The report is the second stage of a move by the government and council to agree on a 30-year bundle of major transport projects, and new ways to fund it.
Transport Minister Simon Bridges said, in the longer term, road pricing would be part of the toolkit.
"We've got to change the way we think about this - it's not just going to be supply. Yes, we will need to do something on that side. We will need more roads, we will need more public transport."
Mr Bridges refused to say road tolls would be imposed, calling it "variable network pricing" instead.
He told Checkpoint with John Campbell the government had ruled out road charges in the past, but now needed to consider a new approach.
"There will come a point in our network, in the not-to-distant future, and we're not there yet, where we just can't keep adding lanes to the motorways," he said.
"Ultimately, variable network pricing - we're not talking tomorrow, we're not talking next month, we're not talking next year - is directly charging for road use and varying charges by location and time."
Sophisticated modelling and further investigation needed to be carried out, but he suspected charges might be introduced in the next decade.
Mayor Len Brown described the report showing road pricing was part of the answer as good news.
Any agreement on road pricing would need to be agreed upon sooner, rather than later, he said.
"We would need to have that finalised, I would suspect by 2018/19 and therefore the community engaged and a debate concluded by that time."
The council had previously hoped to introduce charges from 2018, if the government agreed.