Motorists were told to find alternative routes after a four-vehicle crash on the A19.
Cleveland Police said it was called to deal with the collision on the southbound route near the A689 turn off at Wolviston at 7.40am today.
Traffic was backed up for several miles.
Officers had also warned there were delays due to the ongoing protest at Hunstman Driver at Port Clarence, which was likely to cause disruption.
A spokesman said: "Please use alternative routes if possible until further notice and thank you to everyone for their patience."
Highways England has said the vehicles have now all been removed and the route is now reopen.