Any new generation of Auckland trams would likely start from the waterfront and head up the Dominion Rd commuter spine via Queen St, says the city's transport head.
Auckland Transport chairman Lester Levy told the Weekend Herald that link - stretching about 10km from an existing waterfront tram circuit in Wynyard Quarter - would be "the most likely candidate" for stage one of a network capable of extension as other isthmus routes become more congested.
Although costings had yet to be made in an investigation due to be reported back to his board in March, Dr Levy said: "We are talking about something we would expect not to exceed $1 billion."
The investigation has come as a surprise to Auckland Council members and appears to have irked mayor Len Brown, being announced the same day as he put a 10-year budget flagging deep transport spending cuts to public consultation.
But Dr Levy has indicated hope of attracting private investment to shield ratepayers from any extra financial burden for at least the first five years of a new era of electric trams, as successors to what were taken off 72km of city streets in 1956.
Council infrastructure chairman Mike Lee is delighted Auckland Transport is considering the Wynyard Quarter as its starting point.
"The best way I think to demonstrate the effectiveness of light rail is to get the Wynyard tramway connected to Britomart and run some very modern trams on it, to show Aucklanders what modern trams can do," he said.
Labour and the Greens have indicated support for the light rail investigation, as has the youth group Generation Zero and most Herald readers with views on the subject.
"Light rail can carry two or three times more people per hour than buses and at faster speeds," said Labour's Auckland issues spokesman Phil Goff.
Green Party transport spokeswoman Julie Anne Genter said operating costs would be lower than buses, and trams would provide "huge benefits for neighbourhoods in terms of noise and congestion reduction and property values".
Transport Minister Simon Bridges said decisions about replacing buses with light rail were for Auckland Transport rather than the Government, but a business case stacking it up against other public transport projects was essential.
Former Labour Party president Mike Williams, an Auckland Transport member until October, said efforts to attract private investment for transport projects in his time went nowhere and talk of funding up to $1 billion for trams from that quarter was "utterly pie in the sky".
He had been unaware of concern about isthmus roads becoming so congested that buses could no longer handle passenger loads, and believed double-deckers would provide enough extra capacity.
North Shore councillor George Wood liked the idea of light rail but believed Auckland had become "locked into" heavy rail.
"I think we've made our bed - we've got to sleep in it.
But Mr Lee said 87 per cent of Aucklanders who made submissions on a waterfront plan in 2011 favoured extending the Wynyard tramway to Britomart, and it was time to turn it into "a genuine light rail service rather than just a novelty".
"I think Aucklanders want to see a practical demonstration of a modern tram in operation."
Herald readers say
John Rudd: "Great idea - Istanbul, $2 a ride regardless of distance."
Ian Werder: "The sooner the better. I live in Sandringham Rd and it gets clogged in the morning and evenings because of the single lane and the number of buses. Dominion Rd is even worse."
Glen Stanton, Mairangi Bay: "These are a super-efficient, quiet and cost-effective way of moving people in any big city. The countries in Europe are light years ahead of New Zealand when it comes to transport."
T. Marinovic, Parnell: "It's time transport planners took the bull by the horns before Auckland grinds to a halt by 2020."
Fiona M: "No thanks to the train set. I live on the Shore so it's no good to me. Our rates are already going up higher than other parts of Auckland."
Brian, Howick: "Can't believe it has taken the planners so long to get around to considering this most efficient system of transport."
Mark Levene: "Has a cost/benefit comparison been done on using light rail instead of spending $2.5 billion on the City Rail Link?"
Allan: "I suggest they look at the light rail system in Adelaide - wonderful service."