Emergency repair work to underpin the A14 at Rougham, which had subsided after a £12 million project to improve the Rookery Crossroads, will start at the end of the month.
After investigations, the Highways Agency found cavities in a drainage crossing trench, 3m below the road, which they intend to fill with grout as a temporary fix while investigations into a permanent solution continue.
Officers hope the grout will stabilise the road, which suffered repeated subsidence after the completion of the Rookery Crossroads scheme in 2006.