A proposal to create a park-and-ride site on water meadows on the edge of Bath has been backed by the city’s Conservative cabinet despite claims that the project would put its world heritage status at risk.

During a special meeting on Wednesday evening, opponents claimed it was a costly white elephant that would wreck the meadows and precious views of the city. One leading Tory councillor even called the project “evil”.

But following a meeting lasting almost four hours, the cabinet concluded that an 800-space park and ride to the east of the city was necessary to cope with growing congestion and decided the site at Bathampton Meadows was the best option.

Anthony Clarke, Bath and North East Somerset council’s cabinet member for transport, said that every day more than 73,000 people travelled into the city by car and the figure was expected to grow by 2029 to 96,000.

He said new homes and jobs were planned and visitor numbers were also on the rise, adding that without positive measures, the city “will not last very much longer” without becoming gridlocked.

Council leader Tim Warren said the site had also been chosen because it might also be possible to create a rail link there. “It is near to the city and well-located,” he added.

But Martin Veal, a Tory councillor and a member of the cabinet, said the proposal to tarmac the meadows was “evil” and urged his colleagues: “Do not have this as a dead albatross hanging around your necks.”

Traffic in Bath, one of Europe’s most popular tourist destinations, has troubled politicians and local people for decades. The geography of the city, nestling in a valley surrounded by hills with the Avon river running through, has made it difficult to find a way of getting millions visitors a year – on top of commuters and residents – in and around its Georgian streets.

Labour councillor John Bull reminded the meeting that centuries ago Daniel Defoe had complained about the traffic problem – then horses and carriages. But Bull said the city’s congestion problems could not be solved by “a single park-and-ride magic bullet”.

Liberal Democrat councillor Alison Millar, who represents a ward the meadows fall in, told the cabinet: “This is a terrible, terrible decision. If I were in your position I couldn’t inflict something of this magnitude on a whole section of the community who are so vehemently opposed.

“If a solid business case had been presented with indisputable facts, then there would be nowhere near this level of opposition and residents would have had no choice but to accept it for the good of the whole community.”

Millar argued that up to £21m of public funds was going to be spent without having any real impact on congestion and pollution levels. She added: “A fully integrated transport policy for the 21st century is what is required for this city and this Tory council has failed to produce it. Instead, purely for short-term political reasons, it has come up with a rehashed version of an utterly discredited scheme that has huge drawbacks and nothing going for it.”

The leader of the Liberal Democrats in Bath, Dine Romero, described the scheme as a “costly white elephant” but suggested that a it might never be built. “You are going up against a community that is organised, resourceful and stubborn.”

Caroline Kay, the chief executive of the Bath Preservation Trust, called for the council to think again, arguing the move could harm the city’s Unesco world heritage status. She reminded the council of the 1930s’ Bath bill, a plan for radical alterations that included driving a new road through the Georgian heart of the city and led to a national scandal. “You risk falling into your predecessors’ trap,” she said.

Before the meeting, farmer Steve Horler, who has land at Bathampton, pointed out that he had been refused permission to build two shepherd’s huts on the meadows because such a development was not deemed appropriate. “You could not make this up,” he said. “They told me these two small huts were inappropriate but they’re proposing to build a park-and-ride here.”

The campaigners argue that as well as ruining the meadows, which are mentioned in 1086’s Domesday Book, a park and ride will put bus services for the wider public at risk. They claim people will drive to the park-and-ride rather than use local buses, which will then be cut.

Campaigners vowed to fight on. Before the scheme comes to fruition it will have to go through a stringent planning process. The use of the preferred site is also subject to purchase of the land and securing agreement from Highways England over access.