Rail enthusiasts led by Auckland Mayor Len Brown have gained a confidence boost from a survey which has found hefty public support for trains to cross Waitemata Harbour.
An UMR Research poll, the results of which are out today, found 79 per cent of 241 Aucklanders in favour of installing railway lines across the harbour - whether on a new bridge or through tunnels - and 18 per cent against.
They were more evenly split over the form of a new harbour crossing, with 38 per cent opting for a second bridge and 41 per cent for tunnels.
Twelve per cent did not want any new crossing.
The small sample meant the difference between support for a bridge and for tunnels fell within a statistical margin of error of 6.3 per cent.
But UMR research director Gavin White said the "emphatic" preference of Aucklanders for a rail crossing was well outside the margin.
The harbour crossing questions were added at short notice to a list of unrelated issues, in an omnibus survey of 750 New Zealanders.
Only the 241 Aucklanders were asked the crossing questions, which were added the day a Transport Agency cost comparison the week before last between two motorway tunnels and a new bridge.
A bridge was estimated at $3.9 billion in 2010 dollars, compared with $5.3 billion for tunnels.
That led the agency to suggest that Aucklanders might have to help to pay the difference, if tunnels were what they wanted.
The report also included an estimate of $1.6 billion for two smaller rail tunnels, but said these would not be justified for 30 years, given the carrying capacity of the Northern Busway.
But the Campaign for Better Transport and the Forum for Auckland Sustainable Transport say rail tunnels would be far more cost-effective than a new motorway link, and would remove capacity pressure from the existing bridge by taking buses off it and encouraging more people to leave their cars at home.
Campaign convenor Cameron Pitches said it was ironic that almost 80 per cent of Aucklanders favoured a rail link, as that was about the same proportion as the Government said drove cars to work and should therefore receive most transport funding, despite growing concern about rising oil prices.
Forum spokesman Bevan Woodward said: "We find it extraordinary that the Government would seriously consider a road-only bridge to solve Auckland's future transport issues."
Mr Brown said the poll result reflected feedback he received every day from Aucklanders about rail projects including links to North Shore and the airport, and a central city tunnel.
"Aucklanders understand that we need to unclog our roads by fixing public transport - we need to future-proof the additional harbour crossing for rail to cater for Auckland's growth."
He said new figures showing that more people went through the Britomart railway station each day than through the airport's domestic terminal, and that public transport patronage had reached a 60-year high, "indicate clearly we have to plan and build for the future."
Auckland Transport estimates that 25,000 rail users pass through Britomart each week-day, compared with 14,000 travellers through the airport terminal.
Auckland Council transport committee chairman Mike Lee said the survey showed "the average member of the public seems to be somewhat ahead of your average politician, especially the National Party cabinet, when it comes to rail transport."
But Transport Minister Steven Joyce said the trouble with such polls was options were presented as costless, and he had received a rough estimate of $3 billion for a rail crossing from Gaunt St in the Wynyard Quarter to Takapuna.
Officials believed it could cost another $6 billion to $7 billion to run rail tracks to Albany, because of a need for more tunnelling, given that the busway corridor would be unsuitable for trains.
They had also told him that commuter rail for the North Shore would entail huge extra spending south of the harbour, for new underground stations.
"A lot of things sound like good ideas when we have no idea how much they will cost us, whether they be through taxes, big hikes in rates, or more likely both."