As the Super City's mayoral combatants argue over timing for trains to the airport, officials are planning a major study before securing land designations for a $1.5 billion rail loop.

Six organisations including the Transport Agency, KiwiRail, the Auckland Regional Transport Authority and Auckland International Airport Ltd are preparing to sign a memorandum of understanding to begin detailed planning investigations for airport rail services through both Onehunga and Puhinui.

Auckland Regional Council and Manukau City Council have also agreed to sign the document, even though they are about to be supplanted by the Super City.

Despite the gulf between leading mayoral candidates John Banks and Len Brown over when airport rail links should be built, both agree that preferred routes should be "future-proofed" early against encroaching land developments.

Mr Brown is campaigning for a railway line to the airport via Onehunga within 10 years.

But Mr Banks is accusing him of making hollow promises to buy votes, saying there is no way the Government would consider providing the money for such a venture in recessionary times.

Even so, he agrees with a need to protect potential rail routes - his preference being via Puhinui on the main trunk line - to support what he has described in a mailout to households as part of his "vision" for Aucklandtransport.

Which is just as well, as the memo of understanding is believed to be days rather than weeks away from signing, ready for the Super City's new Auckland Transport organisation to oversee the investigations.

The proposed study will include a business case on a cost-benefit analysis for airport trains, and is likely to take about 18 months to complete, a similar time-frame to a $5 million investigation into a preferred route for a $1.5 billion central Auckland rail tunnel.

Neither will it come too soon for more than 10,000 Aucklanders who signed a Campaign for Better Transport petition in 2008 for an airport rail link.

The idea was also endorsed by 53 per cent of 300 people interviewed in a two-week Herald survey last month who said they would be willing to pay higher rates to be able to catch trains to the airport.

That was more than for six other projects, including the rail tunnel, which was backed by 45 per cent but which Mr Banks and Mr Brown agree is more pressing than an airport link given capacity constraints on Britomart if it is not turned into an open-ended station on a circuit line before 2021.

In 2008, consultants recommended to the transport authority an airport loop costing about $1.5 billion and a $729 million heavy rail link between Onehunga and the western line at Avondale as offering greater connectivity than light rail or busways.

They estimated that a double-tracked railway from Penrose to Onehunga with bridges or tunnels replacing the sector's eight road level-crossings would cost $271 million, and that running a line to the airport - across Manukau Harbour and then parallel to State Highway 20 and George Bolt Drive - would cost $707 million.

A 6.5km link west to the airport from Puhinui Station would cost about $471 million, providing greater initial cost-effectiveness but longer trips from Britomart.

Although transport planners share the mayoral candidates' views that a central-city rail tunnel needs building first to enable Britomart to cope with major service extensions, Auckland Regional Council chairman Mike Lee says this month's reopening of the Onehunga branch line "changes everything."

He believes a 9km extension from there to the airport could start with the relatively low frequency of Onehunga trains to keep within Britomart's constraints and that the existing single branch track could cope with a fledgling service.


Manukau Mayor Len Brown wants a rail link to the airport in seven to 10 years, to be built straight after a loop tunnel to double rail access to the Super City's central business district.

A rail link under Waitemata Harbour to Albany would come about five years after that.

His urgent priority if elected to lead the Super City wouldl be to extend a line from Onehunga, although he would also consider adding a link to the airport from Puhinui or Wiri on the main trunk line at some later stage to form a circuit, as favoured by transport planners.

Asked whether the airport with its 13.5 million annual air passengers and about 12,000 people working within its territory could support a rail link, he said: "It's not just tomorrow that you're building for."

"We talking about extra business in 10 years - by that time we would have completed a second runway, added 400,000 to 500,000 people to our population and there would probably be up to 22 million or 23 million visitors [to the airport].

"You've got to plan these things with a vision in mind, in anticipation that growth is coming, which most assuredly it is."

Mr Brown said that although his chief mayoral rival, John Banks, began his campaign by supporting airport trains, he bailed out once Transport Minister Steven Joyce poured cold water on them.

His strategy would be to persuade the Government that if it wanted the Super City to succeed and follow Brisbane's lead, it must be prepared to make hefty investments in public transport, including airport rail.

"An airport link is critical - if it's anything from John it will be an excuse to not make progress in this city."


Auckland City Mayor John Banks says an airport rail link remains part of his transport "vision" for the Super City ... but not any time soon.

In a mailout to homes in his campaign to be Super City mayor, Mr Banks said: "My vision to improve rail includes an inner-city loop to improve CBD and western rail access and a rail line from Britomart to the airport."

Yet in subsequent mayoral debates he has said rail to the airport would "send us all broke", and he has accused t his leading rival, Manukau Mayor Len Brown, of promising anything from $8 billion to $40 billion including trains under the Waitemata Harbour and to Albany.

"There's not one OECD city where the airport link to downtown makes any money," Mr Banks said during one debate.

Although a study commissioned by Mr Banks' own council as well as others including North Shore City and the Transport Agency recommended four tunnels under the harbour costing $3.7 billion to $4.1 billion, two were for motorway traffic.

The inner-city loop tunnel and airport links are likely to cost a further $3 billion between them, but a 10km rail extension from the harbour to Albany is unlikely to exceed $1 billion.

Mr Banks said this week there was no way that a Government borrowing $240 million a week to shore up the Crown accounts would be prepared to "engage in a rail link to the airport".

He said it would be hard enough persuading it to back his top priority of a CBD tunnel to open up the otherwise constrained Britomart.

Asked why he had mentioned airport rail in his mailout, he said: "It's a vision - I haven't said I'm going to do this."