The M40 has reopened northbound between junction nine for Bicester and J10 for the A43 after an overturned caravan, but long delays remain for motorists.
Drivers were urged to avoid the area while the caravan was recovered after flipping at around 10.30am, with three lanes initially closed.
Traffic is queued back to Hinksey Hill interchange on the A43 as people could not use the M40 at the J9 roundabout.
A diversion was in place along the B430 through Weston-on-the-Green.
No one is thought to be injured in the incident.