No-one was hurt in the accident on a straight section of road.
The driver and sole occupant of the Christchurch-based TNL truck and trailer unit declined to comment to the media yesterday. He was conveying a large consignment of crated milk south from Christchurch to Central Otago.
The trailer appeared to have slid about 100m on its side in its lane before spinning around and blocking both lanes.
The truck did not roll. No other vehicle was involved.
Traffic was directed off the road to get around the trailer unit.
A small amount of grit was poured on top on the milk to make the road safe and a crane from Alexandra was called to right the trailer.
Cromwell commercial vehicle investigation unit member Constable Allan Trow said yesterday he would be better able to comment on the cause of the accident today.
Constable Tyron Wall, of Cromwell, said no fuel had been spillt and the accident was "not too bad".
