Yesterday, the two politicians addressed an NZCID conference in Auckland to outline their infrastructure plans for the city.
Mr Joyce said the Government was investing $1 billion a year in the Auckland transport system.
He expressed concerns about the rail loop and said it should not proceed until there was a robust transport plan for the central city with a thorough analysis of the alternatives.
It was important all funding options were considered for the rail loop, he said, including existing revenue streams and the council's balance sheet "rather than leaping straight into adding another cost for a broad group like road users".
Mr Brown said the Auckland Plan, a 25-year blueprint for the city, outlined a vision and, as unpalatable as it would be for some people, tolls and congestion charges had to be considered to pay for infrastructure needs. Other options included public-private partnerships and selling surplus property.
"My top priority is the city centre rail link. This is a game changer for Auckland," he said.
Questioned by Mr Selwood about a broad-based network charge, Mr Brown said the lobby group was addressing the issue in a way that was simple and straightforward with technology in place to achieve it.
"If Aucklanders can get a sense of that clear, not-too-complicated solution then I think that the feedback ... will be positive," he said.
Later, Mr Brown told the Herald he was open to discussing all ideas to speed up expensive projects.
"We're currently in a process of consideration and consultation and it would be inappropriate for me to indicate a preference before the community has had a say on whether they want to go ahead with innovative solutions to fixing Auckland's transport problems," he said.
A discussion paper canvassing options and funding models is due next month.
Mr Selwood said Mr Joyce clearly had political apprehensions about funding options for the rail loop, but he admired the courage of Mr Brown for raising the question with Aucklanders.
Mr Selwood said he had visited 12 of the 21 local boards and sensed 60:40 per cent support for a network charge. Some of the 40 per cent were not opposed but "just not quite there yet".
"I think the mayor is sensing that willingness for a change."
PROPOSED CHARGES
$3 PEAK: 7am-9am and 4pm-6pm
$2 OTHER: 6am-7am, 9am-10am and 3pm-4pm, 6pm-7pm
$1 OFF-PEAK: