Both carriageways of the A14 were closed at junction 46 near Thurston following a ‘police incident’.
A police spokeswoman said: “Officers have stopped traffic on the eastbound carriageway and the westbound carriageway.”
The road was closed at around 5.30pm and reopened at around 7.30pm.
The incident related to a man standing close to the edge of a bridge over the carriageway.
The police safely dealt with the incident.
Tail backs were back to the A1101 junction 43 at Bury St Edmunds eastbound and Woolpit westbound but are now clearing.