A new one-way road system is being introduced on some of the busiest city centre roads in Swansea to accommodate a new "bendy bus" service.
Work could start in June to make the Kingsway one-way
The Kingsway, Mansel Street and Orchard Street are among those to be altered for the 110-seater passenger vehicles.
The changes would help the 18.7m (61ft) StreetCar, dubbed a cross between a tram and bus, to negotiate the roads.
The council said there was widespread backing for its plan but others have warned of disruption and problems.
The Welsh Assembly Government has provided £2.2m funding to help launch the Swansea Metro, the first of its kind in Wales.
The StreetCar vehicles, which are set to hit Swansea's roads in early 2008, will carry passengers along a specific route, made up of existing roads and dedicated lanes, between Morriston and Mumbles.
Swansea Council has described the vehicles as a cross between a tram and a bus because they run on wheels but have two separate compartments.
Work could start in June on the one-way system which will be introduced along the Kingsway, Mansel Street, De La Beche Street, Alexandra Road and Orchard Street.
Swansea's opposition Labour group said it was "unimpressed with the proposal as it stands".
"Turning a major cross-city arterial road into a one-way street is going to have a major impact and we hope that it will be put out to wider consultation before any action is taken," said a spokesman.
The Civic Society has also raised concerns, saying it could make the city less pedestrian-friendly as the main Kingsway roundabout and its under-passes would be lost.
The society's Phillipa Watkins said the system would also force drivers to travel further to reach certain parts of the city and it did little to connect the different cultural and commercial areas.
The StreetCars are set to hit Swansea's roads in early 2008
"We are totally in favour of public transport - we are just not sure the bendy bus is the right thing for Swansea," she said.
Swansea environment cabinet minister John Hague said: "A widespread consultation took place in November to highlight the plans linked to the Swansea Metro transport scheme - this included the proposal of a one-way system along the Kingsway.
"The three-day event was well attended by many different user groups including cycling groups, transport operators, disability groups, emergency services and major retailers in the city centre.
"All who attended were supportive of the scheme. Feedback received from the consultation process was noted and some changes have been made to the original plans to incorporate these ideas.
"The council is committed to providing a fully integrated transport system than will not only provide 21st Century public transport for residents and visitors. It will also help to reduce traffic congestion in the city centre."