Auckland leaders are urging the Government not to frustrate a long-range transport blueprint they have produced for the region after almost two years of preparation.

Amid deep funding and political uncertainty, the Auckland Regional Transport Committee has met statutory requirements in developing the 30-year strategy as a legacy to pass to the Super City's council in November.

The committee proposes $46 billion of spending on public transport, roads and walking and cycling infrastructure between now and 2040. But it warns of a possible deficit of up to $13 billion, especially if the pattern of Government transport spending for the next three years is extended.

Although it proposes more than $24 billion for roads, that would mean just 9 per cent more lane kilometres, with an emphasis on making better use of existing tarmac and improving freight routes.

The document says that it is neither desirable nor possible to double the region's roading capacity to cope with the travel demands of almost two million people expected to be living in Auckland in 2040.

It is therefore proposing about $21.5 billion in spending on public transport and "active modes" such as walking and cycling.

That represents a far higher proportion than the Government's planned investment in public transport over the next three years, of 19 per cent of a national land transport fund of $8.7 billion.

"If a similar allocation were to be made over the 30-year life of the strategy," the document warns, "a significant shortfall in the funds required for Auckland's priority projects could result".