Auckland Transport, Mayor Phil Goff and the Labour-led Government all seem hell-bent on getting trams ("light rail") brought back in Auckland. Their flagship project is for a $2.3 billion line from the Wynyard Quarter up Queen St and out along Dominion Rd to the airport.

The grand plan extends trams to West Auckland, and has an estimated cost of $5 billion.

The case for these trams seems to be that the number of workers heading into downtown Auckland at the morning peak will exceed the capacity of the city centre to provide bus terminuses by the early 2020s.

But there is a much more fitting and future-proof solution to Auckland's pubic transport problems than trams.

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The OECD International Transport Forum has modelled shared urban transport using 8- and 16-seat taxi-buses and 4-seat taxi-cars. Their model has an online dispatcher from which users request service, a scheme familiar to users of Uber and Lyft.

They propose two classes of service: a cheaper minibus with a maximum walk of 400 metres at the user's origin and destination, and a more expensive door-to-door shared taxi. Their modelling is so-far published for Lisbon, Helsinki and, yes, Auckland. It works.

For Auckland the improvements in congestion, traffic flows, journey times and cost are apparent when only 20 per cent of the current car journeys are replaced by shared services, and the model incorporates a number of scenarios up to the complete replacement of current private car and bus transport which would halve the current congestion.

The model is also run for projected 2046 population and transport needs, and shows even greater benefit then because the greater population density improves its performance.

This modelling does not depend on battery-powered electric or autonomous (driverless) vehicles, although it allows those as possibilities and estimates the improvements in pollution and cost they would bring.

Both of these technological advances will certainly be here during the expected economic life of a tram service, if not already with us before it can begin.

The shared mobility modelling in its most comprehensive scenario indicates Auckland's peak transport needs would be met by 22,000 taxi-cars, 3500 8-seat and 22,000 16-seat taxi-minibuses at a current capital cost of about $3.5 billion.

That is within the ballpark of the tram costings, and yet as well as replacing the trams it provides for a complete replacement of the current bus fleet and all of the private cars used for commuting.

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More moderate scenarios that are modelled by the International Transport Forum involve retaining core bus services or all current bus services, and have correspondingly lower capital costs.

The modelling indicates the operating cost of shared mobility, without subsidy, is about 50 per cent of current Auckland public transport fares for the taxi-bus service, and twice the current fares for the door-to-door shared taxi.

Further attractions of the shared-mobility proposal are that its implementation can begin immediately, without disrupting current traffic flows or services, and that its introduction and development can be gradual, evolutionary and flexible, responding to changes in demand and in demographics.

If as it develops it should turn out in practice to have been a mistaken move, then alternative public transport developments are not precluded by financial exhaustion.

A fixed tram service by contrast, is a sunk cost, planned in haste, causing great disruption during construction, unable to be used until completed, and then to be regretted at leisure.

Auckland has narrow main streets, and many people live and work more than 500 metres from a main arterial route. It has few radial arteries and many workers whose daily commute runs across them.

If those commuters use the current public transport system they must travel into the centre on one arterial route and continue their journey out on another.

As the International Transport Forum's modelling shows, Auckland's needs are well met in both near and far future by a shared mobility solution of taxis and taxi-buses that can provide these point-to-point cross-town journeys or, where appropriate, deliver passengers to rail and bus stations for onward travel, making better use of the investment we have already made in trains and busways.

We need leaders and planners who can help our city advance into the 21st century, not regress to the 19th with an expensive, inflexible and limiting solution predicated on trams.

But if they insist on pursuing their tram plans, then let us be very clear at the outset whose idea this is and who supports it. In the unlikely event that the future proves Auckland's trams to have been a success, then we shall need to know where to sheet home the credit.

• Ross Boswell is a pathologist and physician in the public hospital system. He lives in the central city and regularly uses public transport.