A419 road noise has 'doubled since 1998'
Campaigners claim noise levels on a concrete stretch of road linking the M4 and M5 doubled when it was built.
A road noise expert, acting for the A419 Noise Action Group (NAG), took measurements replicating those taken for a survey carried out in 1998 when the link was built.
The results from Latton in Wiltshire and Cerney Wick in the Cotswolds show the noise level peaked at 75 decibels.
Operator Road Management Services, said it would not comment on the findings.
The survey was conducted by Ray Brassington, the then environmental health officer at Cotswold District Council who carried out the original survey on the road.
The operating firm receives payments from the Highways Agency on behalf of the Department for Transport based on the number of vehicles using the route.
Cotswold District councillor Paul Hodgkinson, who chairs the A419 NAG, said the decision to use concrete, rather than asphalt, was "financial" and "has brought misery to thousands" since it opened in 1998.
Mr Hodgkinson said the new figures give "firm evidence that action should be taken at last".
The increase in noise, he said, was primarily down to the use of the road by 35,000 to 45,000 vehicles a day.
He wants the Department for Environment, Food and Rural Affairs (Defra) to designate the route as one that suffers noise pollution.
"If Defra designates the dual carriageway as important for noise pollution purposes under its Environmental Noise Directive, action would be taken to reduce noise levels," he said.