The A14 is closed in both directions with long delays following a serious crash involving a lorry and a car near the Orwell Bridge.
Emergency services were called about at about 09:00 BST after an accident between junction 56 at the Wherstead interchange and junction 57 for Nacton, said Suffolk Police.
The westbound carriageway is closed between the junctions for Seven Hills and Wherstead, and the eastbound carriageway closed at Seven Bridge.
The congestion is affecting the A12 at Copdock. Diversions are in place, external with the Orwell Bridge closed in both directions, according to National Highways.
