The Wellington Regional Council says the city's trolley bus lines are likely to be pulled down and the buses replaced with more modern vehicles by 2017.
Trolley buses make up about 20 percent of the council's fleet, and were upgraded at a cost of $40 million seven years ago.
But the public transport portfolio leader, Paul Swain, says it will be more cost-effective to replace the buses than pay for their maintenance and upgrade the 50-year-old power system.
Mr Swain says the council has not decided what the fleet will be replaced with, but options include environmentally-friendly hybrid, electric or modern diesel buses.
He says the plan will be out for public consultation on Wednesday and a decision will be made by June.
The Green Party says it is concerned that phasing out Wellington's trolley buses will result in a less environmentally-friendly public transport system for the city.
The Greens' transport spokesperson, Julie Anne Genter, says the National government is putting pressure on the regional council to cut public transport costs.
She says the clean-burning and quiet trolley buses may be replaced with diesel buses - the cheapest but most environmentally damaging option.
