Work is being carried out on the A12 at Kessingland to repair a ridge in the road.
Police were alerted to the problem at 6.45pm yesterday, with reports of a large ridge in the road where the tarmac meets the concrete.
A police spokesman said the road is raised about eight inches.
It was reported after people using the carriageway said it was making a loud bang as they were driving along.
Police passed the incident over to Suffolk Highways, who have coned off the area. Work is expected to continue until next Monday, June 26.
A Suffolk County Council spokesman said the carriageway was raised due to an expansion on the bridge section of the road. However he said there is thought to be no structural damage.
The carriageway is affected from the roundabout with Whites Lane to the roundabout with London Road.
Traffic has been moved into one lane, with the southbound lane remaining open. Drivers heading northbound can take a signed diversion along the B1437 through Kessingland village.
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