Police say a semi was traveling north on I-77, just before the Edens Fork exit, when the driver slammed on its breaks because a car stopped in the road.
It caused several metal posts on the flatbed to fall unto the road.
A car behind behind the semi swerved to miss the posts and landed on its top in a ditch.
Several other vehicles were damaged by the posts.
There were no injuries.
One lane of Interstate 77 was closed for a short time, but it has re-opened.