Police and the Highways Agency are warning drivers that the A14 westbound in Northamptonshire could be closed for much of the day following a serious crash involving three lorries and a tractor.
The westbound carriageway is blocked between junctions 7 and 3 after the crash at Rothwell.
One lane of the eastbound carriageway has been re-opened.
The Highways Agency says drivers should avoid the area if possible as there are significant delays.
A signed diversion is in operation with all traffic advised to leave the A14 westbound at junction 7 and follow the hollow circle diversion symbol via the A43, A6003, A427 and the A6 to rejoin the A14 at junction 3.