The public transport fast track to Auckland Airport is likely to happen - but not any time soon.
It could be at least a decade before routes for trams or even driverless buses get settled, transport officials say.
The Auckland Transport board yesterday opted to drop trains as an option for a rapid and congestion-free network to the airport, backing the earlier decision by the New Zealand Transport Agency.
The board cited a report saying trains could cost up to $1.3 billion more than trams, though both could reach the airport from downtown Auckland in around 40 minutes.
AT members also elected to protect the route for trams and buses, but board chairman Lester Levy said the technology could change from the vehicles in use today.
"There's talk of platooning buses and that buses could travel with a 2cm gap between them at speed. If that's possible, we'd love to consider it."
The transport bodies are under pressure from Auckland Airport to decide on their preferred network. The company needs to know what to factor into its renovations.
The decision to protect the routes for light rail and buses buys Auckland Transport some time because the terminal at the airport would be the same in either case.
Mr Levy said the business case for heavy rail was so weak it had to be dumped.
According to the report, a heavy rail line along SH20A could cost between $2.6 billion and $3 billion while light rail offered similar benefits for $1.2 billion to $1.3 billion.
There has not yet been a business case for buses as it's not known what the technology would be, but the route would be the same as light rail.
Mr Levy said: "We have to look at value for money and we have to be realistic about that and when we look at heavy rail versus options, discounting heavy rail becomes a virtual no-brainer. We have to use funds in the best possible way so now we're moving forward to investigate these other options. Who knows if there's actually a bus option that's feasible but we should be able to work that out relatively soon."
Whatever the final decision was, it was likely to be at least a decade before the infrastructure was built.
However, Xero founder Rod Drury said a rapid transit network to the airport should be considered a priority as a national project.
"It's not just the cost for the Auckland commute, it's the cost for the entire country working with Auckland. If you look at the flight from Wellington to Auckland, getting from the airport into the city is often longer than the flight.
"It's kind of like the last mile - it's as important as the flight."
Green Party transport spokeswoman Julie Anne Genter said the growing number of people catching trains in Auckland shows that people will opt for public transport when it's efficient and affordable.
"It's ridiculous for John Key to dismiss rail as too expensive when he promised in January to spend a whopping $1.8 billion on a new East-West link motorway, a project that had not been fully assessed, and which has a very low benefit-cost ratio."