Roads authority Highways England has said a major maintenance project on the A12 near Ipswich is running three months late and is now expected to be complete by the end of June.
The project, between junctions 31 and 33, started in December and was originally scheduled to finish at the end of March.
The roads authority has blamed operational issues for the delay, saying there were problems with materials supplies. The work involves resurfacing the road, renewing road signs, repairing drainage and upgrading safety barriers.
Highways England service delivery team leader Aran Nugent said: “I appreciate this will be frustrating news for drivers, but I’d ask them to bear with us while we complete this important work. By taking the extra time now and completing the job to a high standard, we can reduce the likelihood of future repairs.
“The work has taken longer than we anticipated because of various operational issues which has slowed down how quickly we can complete the work.
“Our contractors have had issues with the plant, which supplies the materials, and we also postponed work over the Bank Holiday to help drivers setting off for the half-term break.”