He said the new track would be purpose built for the demands of open-wheel speedway and there would be other facilities such as a museum.
"Speedway needs to grow as a sport," he said. "This will allow us to do that."
Mayor Goff said, "Speedway has been constrained at the current site to 12 meetings a season. At the new site, away from any population centres, it should be able to do far more."
With Speedway agreeing to go, the council will extend its lease by one year to allow time for the new site to be developed.
Stock cars, which require a different kind of track from speedway, are expected to remain at Waikaraka Park in Onehunga.
RFA boss Chris Brooks called the agreement "a really great outcome".
Goff said the council would make a "big contribution" to the cost of moving speedway, which was "probably $12 or $13 million". He said around $5 million would come from RFA and $5 million from council directly.
Turning Western Springs into a cricket venue will require extra funding. "Properly
developing the site for future use will require a new budget request," confirmed Brooks.
Cr Clow said, "There's nothing in the budget for the development of an oval playing field. Government will have to help with that."
There are no cost estimates for Western Springs at this stage, although concept plans have been developed. New cricket facilities at the park would probably include a stadium for 15,000 to 20,000 people. "About the size of Hagley Park," said Clow.
He said that's a good size for most international cricket matches, although they could get bigger crowds for some Cricket World Cup games and perhaps some short-form internationals with Australia and India.
NZ Cricket has long been keen on moving to Western Springs. RFA head of the venue development strategy, Paul Nisbet, told the Herald, "NZ Cricket is strongly in support of an oval ground being developed at Western Springs."
But Auckland Cricket, which is based at Eden Park and uses the No 2 ground, is opposed to shifting. That disagreement will need to be resolved.
Clow said Speedway Promotions' decision to move "unlocks the stadium strategy". That strategy was developed by RFA with a focus on four venues. Western Springs is one of them. In addition to cricket, it would host Australian Rules Football, which is keen to expand into New Zealand.
Eden Park is limited in its ability to host concerts, but with cricket gone, says Clow, "we hope it would become easier to use for major musical events".
That hope is shared by the Eden Park Trust Board, which launched a campaign in March this year to get public support for more concerts at the park.
"We want fans of Adele, Sir Paul McCartney, the Edinburgh Tattoo, Andre Rieu, opera, eSports and the arts to enjoy Eden Park," trust CEO Nick Sautner told the Herald on Sunday at the time. He added that they had the support of 850 local households.
But Eden Park Neighbours' Association president Mark Donnelly said his group, representing about 450 households, would continue to oppose concerts at Eden Park.
"It's really just not a suitable ground for it - completely residentially surrounded, four schools within the immediate environment."
But staging more concerts at Eden Park is an interim step. The park is not one of the four stadiums in the RFA strategy. Instead, RFA favours a new "international stadium" which would have a "central city location" and "ideally be located in proximity to the City Rail Link, bus and ferry transport hubs, other public transport networks and supplementary car parking".
This is the downtown stadium Goff has been promoting. It would become home to rugby, perhaps league, major concerts and other events. Once the new stadium is built, Eden Park would be sold and the land used for housing.
The RFA strategy does not identify any funding for such a stadium. Nor does the council's 10-year budget.
Goff told the Herald that new stadium funding could be introduced to the next version of the 10-year budget, to be drawn up in 2021, but that's not certain either.
"We're talking with the private sector," said Goff. "It's quite a way off at the moment but I want us to keep our eye on the horizon. If there's a decision to build a new stadium, we want to make it before anyone spends hundreds of millions on Eden Park. And we want to do it in a timely fashion, not be rushed like happened with the waterfront stadium proposal in 2008."
The RFA strategy acknowledges that an alternative to a brand-new stadium is to redevelop Eden Park.
Mt Smart is the third stadium in the strategy. It's destined to remain home to the Vodafone Warriors and to keep being used as an outdoor concert venue, at least "until such time as a new international stadium is available".
The fourth stadium is the QBE Stadium in Albany, home to NZ Football and North Harbour Rugby. It's developing a high-performance sports hub and will also be available for the Australian Baseball League.
Meanwhile, Speedway is gearing up for its last two summers at Western Springs, while cricket is preparing for an internal showdown between the national and Auckland bodies.
Residents near the Western Springs will be happy. Residents near Eden Park remain divided.