A woman died when her car aquaplaned on the M4 and crashed into the central reservation.
The eastbound motorway, between junction 35 for Pencoed and 37 for Pyle, in Bridgend county, was shut for more than five hours after the crash.
South Wales Police said the driver of a Renault Clio died at the scene following the crash at about 07:40 GMT.
The road reopened by 13:00 and police investigating the cause of the crash said her family was being supported.
The Welsh Ambulance Service said there were reports the car aquaplaned before crashing. Three fire crews were also sent to the scene.