Auckland's population threatens to soar past two million by 2031 on its relentless flight path - two decades earlier than planners thought just five years ago.
Regional council strategic policy director Craig Shearer disclosed yesterday that more than 100 newcomers crammed into the region each day on average for the past 18 months, on a 3.1 per cent annual growth spiral.
The region's growth strategy, signed by all Auckland local bodies in 1999, envisaged adding 900,000 newcomers by 2051 to a population of 1.1 million.
That has since swollen to 1.3 million, after recent increases of 750 to 800 people a week, Mr Shearer told the regional land transport committee.
He said half of Auckland's growth was driven by immigration, which planners had no way of knowing would continue at present levels.
A younger population, especially among large Polynesian families, is another big cause.
With a 2.2 per cent annual growth, Auckland's population would not hit two million until 2041.
A high-level projection of 2.6 per cent would see it reach that figure in 2031.
But the present curve exceeds even this.
It compares with growth of 1.4 per cent in Sydney, where Mr Shearer said planners were "horrified" to learn about Auckland.
"They said, how on Earth do we cope with all these people and the pressure they put on infrastructure - housing, sewerage, transport. It's a major increase in population."
Mr Shearer told the committee that the regional council was under pressure from developers to expand Auckland's urban limits, in which there was enough land for only about 15 years of development.
The committee was reminded it needs to confine 70 per cent of new development to existing boundaries.
The Government had made this a condition of granting the region an extra $1.6 billion over 10 years for its transport needs.
Mr Shearer said after the meeting that a schedule would be added by March to the regional policy statement identifying areas where intensive development should occur.
Local bodies would also be encouraged to produce higher urban design standards to promote more multi-unit residential developments.
About 25 per cent of Aucklanders live in the desired development zones, although 43 per cent of new housing was in multiple units.