A lorry carrying a refuse wagon collided with the central reservation early yesterday morning near Catterick.
Both carriageways were completely closed for 12 hours between Junction 51 at Leeming Bar and Junction 52 at Catterick.
Although two lanes in each direction are now open, one lane in each direction remain closed as repair work is continuing.
The lane closures will protect workmen working on the central reservation.
The lengthy complete closure was necessary because both vehicles were so badly damaged, specialist teams were needed to remove them from the road.
There was also a large diesel spill which had to be removed and significant damage to the road surface which had to be repaired before the road could be declared safe and reopened to the public.