Traffic thundering through four east Suffolk villages could rise by 30% by the time of the peak construction period for Sizewell C, according to a new report.

Consultants are predicting that daily vehicle flows along the A12 at Farnham, Stratford St Andrew, Marlesford and Little Glemham will rise from current levels of around 15,500 a day to more than 20,200.

Experts say that such a rise will mean a bypass is both necessary and viable and are hoping it will persuade Government and EDF Energy to come up with the cash – between £39million and £105m, depending on whether it is single or dual carriageway – to build one.

The report – to be considered this afternoon by members of Suffolk Coastal’s Sizewell C task group – is bound to add more weight to the campaign for the road scheme.

In the traffic study prepared by AECOM it is revealed vehicle flows on the A12 through east Suffolk have reduced slightly in the past few years, mainly due to the recession, and are currently around 15,500 a day, 89% of them cars.

However by 2024, analysis of predicted future flows plus using what information is available concerning Sizewell C traffic, the daily average figure is expected to be 20,210 vehicles a day going through the villages.

This would include around 1,795 Sizewell-related vehicles – nearly 1,200 of them lorries.

Extra lorries in particular will slow journey times with queues behind trucks along single-lane stretches.

AECOM says a pinchpoint at Stratford St Andrew is already suffering air quality problems and this is only liken to worsen. An Air Quality Management Area may have to be declared and measures introduced to improve air quality. This might include restrictions on certain vehicle types at certain times of the day.

The report says: “The assumed development traffic levels might be a significant underestimate of daily demand.

“The impacts of development traffic on the A12 are likely to raise serious concerns amongst stakeholders, particularly given perceptions over the weakness of the north east Suffolk economy.

“For nearly 20 years the need for the bypass, and its value for money, have not been in doubt – the problem has been prioritisation for funding. The impact of the Sizewell C traffic requires mitigation through the four villages, and the full bypass provides a clear solution.”

Debbi Tayler, speaking for the Four Villages Bypass campaign group, said: “Year on year the amount of traffic on this road will keep on increasing and the Sizewell C traffic will include heavy vehicles and construction will take ten years. It’s a nightmare now and it’s going to get so much worse.

“The Prime Minister was in Suffolk talking about our infrastructure. Well this road is the main route from Ipswich to Lowestoft, a green energy and enterprise zone, and its only single carriageway.”