The new underground station would be built either under or adjacent to the new terminal, he said.
"We don't know when the city will make the decision for rail to the airport but we need to enable it," he said.
The railway station and terminal land is now partly pasture and at the southern end of the international terminal. Littlewood said the two corridors for the rail lines had been created in the airport's spatial master plan not necessarily because both would be built but because options must be kept open.
"We have set aside enough land for a rail corridor through the airport precinct to the terminal and for an underground station at our new combined domestic and international terminal building," he said.
The airport was working with the Government and Auckland Council to ensure transport infrastructure was developed to cater for the massive expansion forecast, from 14.5 million passengers last year to 40 million by 2044.
"We have also designed space for an additional express bus service, created extra bus lanes and improved facilities for local buses and shuttles.
And the airport might need a longer second runway in the next three decades, he said.
The airport had 7,000 carparks now but plans to build two multi-story mega-parking blocks with pedestrian walkways to the new terminal, he said. Littlewood said those buildings could be about three levels, but no final decision had been made.
On dissatisfaction with high parking fees, Littlewood defended the charges but said 22,200 new carparks would be developed directly opposite the new terminal, of which 15,900 would be for the public and 6,300 for staff.
"Public transport is a critical part of the future and a central part of our long-term vision. We need to make sure we have the right number of car parks for passengers and you can get $5/day to $40/day parking."
Chris Gaskin of Devon Funds Management which holds a stake in the company, praised the business.
"The stock is probably the best single asset on the NZX you can invest in for the very long term. It's very expensive right now, but then it's always expensive - price tends to run well ahead of earnings/cash flow. We are in the free cash flow sweet spot right now where they don't have any major capital expenditure projects under way," Gaskin said.
Littlewood said the airport's new James Lord-designed entranceway, with 9m high rock-covered mounds of earth and extensive landscaping, would soon be highlighted with LED lights, turned on in the next month.
The new northern runway was expected to be built by 2025 and was given resource consent 12 years ago.
Auckland mayor Len Brown said the airport's 30-year expansion strategy supported the council's southern initiative and was great for the people of Auckland, especially South Aucklanders.
Manukau East MP Ross Robertson said the plan provided employment and economic growth opportunities.
Kim Campbell, Employers and Manufacturers Association chief executive, said the plan would boost the city's economy and Auckland Chamber of Commerce chief executive Michael Barnett said exporters and the wider business community needed the airport to manage its rapidly rising passenger and freight loads.
Video turns 30-year airport vision into reality
Vast tropical gardens sporting mature swaying nikau palms, two railway lines converging on the airport with an underground station, a stylish new air traffic control tower and a huge new curved uniquely themed international-domestic terminal are displayed in Buildmedia's sophisticated "fly-through" video of Auckland International Airport by 2044.
A double-height glazed viewing hall looking across to the Manukau Heads, two huge new carparking buildings with pedestrian accessways directly into the terminal, a new northern runway and grand sweeping lawns near upgraded and expanded public transport interchanges are all displayed in the short film made to present the airport after its ambitious 30-year makeover.
Airport chief executive Adrian Littlewood said: "We got it done because when you're talking 30 years, it's very hard to articulate all the different elements and people can't get a sense of it when they look at a top-down plan.
"But the video really makes it real."
