Auckland Airport says passenger growth rates took it by surprise, putting a strain on infrastructure and leading to accelerated capital spending not seen since it opened more than 50 years ago.
The company stressed how much it was spending on terminal and airfield developments when it released its half-year results, which showed underlying profit rising by 18.6 per cent to $123.9 million.
Chief executive Adrian Littlewood said the aviation environment had changed totally in the past two years due to the flood of tourists into New Zealand and the wider region.
"It's happened much faster than we would have expected. The major airports around Australia are all going through a similar thing."
The airport has been criticised for a slow response to the travel boom as it returned more than $2 billion to shareholders in the 12 years to June last year. Problems with traffic around the airport prompted urgent action with transport authorities to try to alleviate traffic snarls.
Significant highway projects are nearing completion and Littlewood said ways of unclogging the airport campus were being investigated.
About 20,000 people work in the wider airport area and more public transport, cycleways and walkways were being investigated.
Littlewood said capital spending of $1 million a working day this year was four to five times what it was as recently as two years ago.
Upgrades of the international terminal "were just around the corner" and the domestic terminal would be replaced within the next five years.
Auckland Airport raised its capital expenditure guidance for the full year to between $370m and $400m, from a previous range of $330m to $370m.
The company has 42 capital expenditure projects worth more than $1m underway.
Construction is well underway on the new international departure area and the airport will open a new and expanded security screening and processing area, as well as the first half of the new stores for two anchor duty-free operators, by the middle of this year
The remainder of the new duty-free stores and the first half of the new passenger lounge will be opened by the end of December this year, with the project due for completion by mid-2018.
Construction of the international terminal's Pier B extension is also underway to provide additional gate lounges and airbridges to accommodate the increasing number of double decker A380 and Boeing 787 Dreamliner aircraft using the airport.
The first new gate lounge and air bridges ̶ Gate 17 ̶ will be opened before the 2017/18 summer peak season and the second gate lounge and air bridges ̶ Gate 18 ̶ will be completed by early 2018.
It has committed to accelerating work on a new five-star hotel , has completed airfield stands including those that can accommodate the new generation of jumbos such as the A380, is making progress on plans for a second runway and has installed infrastructure required for its new builds, including water, wastewater, electricity and fuel.
In Auckland Airport's first half, international passenger numbers (arrivals and departures) climbed about 13 per cent to 5.1 million, while domestic passengers rose 12 per cent to 4.3 million.
The airport welcomed four new airlines and five new services in its first half and now has a stable of 27 airlines, 44 international and 19 domestic destinations. New additions Hong Kong Airlines, Tianjin Airlines and Hainan Airlines will contribute to growth in the second half of the year.
Littlewood said there were signs the airline growth was levelling off, as would be expected after such a strong increase in the number of flights.
Airfield income showed the fastest growth in the first half, rising about 18 per cent to $59m, while its passenger services charges rose about 14 per cent to $85.9m. Investment property rental income rose 17 per cent to $32.5m.
The weakest growth came from retail income, up 2.7 per cent to $80.7m, with disruptions during terminal refurbishments taking much of the blame.
The airport said that following its performance in the six months to December 31, the company had tightened its guidance for the full year to be between $235m and $243m.
The company lifted its first-half dividend by about 18 per cent to 10c a share.