A Treasury-led officials group is urging ministers and Auckland political leaders to employ aggressive "push" tactics to get people out of cars and on to buses, trains and ferries.
It says comparisons with overseas cities show that existing investment plans and public transport "pull" factors such as better reliability and seamless fares will at best only keep pace with Auckland's population growth, and will not ease congestion.
If Auckland is serious about rapid public transport growth between now and 2016, it must consider bold new tools such as road charges as well as greater use of existing measures such as parking restrictions and bus priority lanes, the group says.
That is despite stiff opposition raised by Aucklanders to several road-pricing or tolling schemes mooted by the Ministry of Transport and Transit NZ.
Transit has abandoned a scheme to toll the western ring route, but the ministry is continuing a study into charging motorists for using key Auckland roads, despite support from just 25 per cent of submissions for various models proposed last year.
The latest report from Wellington, presented to Auckland mayors and regional council leaders, has found a high degree of alignment between Government and local officials over transport strategy.
That includes recognition of a need for a substantial shift to public transport and is in contrast to a Government statement in July that Auckland and Wellington were "not well-aligned" on long-term regional transport planning.
Auckland Regional land transport committee chairman Joel Cayford said the report was encouraging but Aucklanders had been firm in telling the Government they would not tolerate road charges without better public transport alternatives.
Regional council chief executive Peter Winder said it was important not to characterise the exercise as a road-pricing debate, citing recent fuel price rises as an important "push" factor that had nothing to do with local policy decisions.
It is now up to the Government and Auckland political leaders to choose between steady or rapid growth in public transport over the first decade of a 30 to 45-year planning horizon.
The "strategic alignment" steering group, on which Government officials held the majority but which also included Mr Winder and Auckland City chief executive David Rankin, has refrained from recommending between those two rates of growth.
It says both scenarios represent a substantial increase in public transport services over current levels, and would see patronage rise from 7 per cent of peak morning travel to 15 per cent by 2051.
That would entail 100 public transport trips a year by the average Aucklander, compared with 40 now.
But a steady-growth scenario would see public transport accounting for just 9 per cent of the morning travel peak by 2016, compared with a rapid-growth goal of 11 per cent envisaged by the 2005 Auckland regional transport strategy.
The officials' report, which the Auckland mayors are taking back to their councils for decisions, estimates the rapid-growth path would cost about $1 billion more than the steady option. An earlier report estimated that about $12 billion in available funds would still leave a $4.4 billion shortfall for Auckland's overall land transport needs over 10 years.
Firmer Government funding commitments to a state highway programme of about $4.3 billion and to a $600 million basic rail upgrade have since narrowed the gap to $3.3 billion, without reliance on tolls or some other form of road charges.