Demonstrations against the northern bypass have ramped up after campaigners gathered at Suffolk County Council – but a motion for work to cease failed to gain traction.
Stop the Northern Bypass demonstrators staged a protest at Endeavour House ahead of the authority's full council meeting, highlighting their concerns around pollution, finances and information published.
A consultation with proposals for three possible routes has been launched, but objectors fear that a decision has already been made.
Nick Deacon from the group said: "We are calling for all affected residents and other stakeholders to form one voice by this action being brought forward by Suffolk county council.
"Whilst this threat hangs over us all it's blighting billions of pounds worth of real estate.
"They had their chance in the '80s and '90s - it was squashed on environmental grounds. The environmental agenda has only increased over that time so we see no reason for it.
"Our belief is they have already made their mind up that they will find the business case for this road and push it further down the process, costing taxpayers a great deal of money."
Green councillor Robert Lindsay put forward a motion calling for work on a northern bypass to be halted immediately, and work pumped into sustainable transport options to meet the council's climate emergency declaration.
But the proposals failed to get widespread support, voted down by 53 votes to 12.
Conservative council leader Matthew Hicks said money spent on the consultation was cash pledged by Suffolk Public Sector Leaders, not the county council, and highlighted the growth and economic benefits it could bring.
"This is us all working together across Suffolk," he said.
"I would never be supportive of ceasing money today because the consultation process has now started - I believe we should absolutely keep to what we say.
"It's important that in order to support growth in the longer term we have to consider carefully what infrastructure is needed."
Labour group leader Sarah Adams said a northern route was "hugely needed" because Ipswich was "a medieval town built for the horse and cart".
Mr Lindsay said: "It's very disappointing that Suffolk County Council's Conservative administration voted to support a target of getting to zero carbon by 2030 and then failed at the first opportunity to back this up with a simple action that would have saved us money and improved the quality of life our citizens.
"Tackling zero carbon takes courage. The courage to look residents in the eye and say that walkers, cyclists, and users of public transport must take priority over car drivers.
"That means more road space in congested parts of Ipswich needs to be given to pavements and segregated cycle and bus lanes. If we do that, we create a liveable breathable town for all."
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