Curtis Thompson, 43, of Layton, was heading east on the highway about 20 miles southwest of Park Valley when apparently dozed off and then over corrected, said Utah Highway Patrol trooper Cameron Roden.
"There was a pretty steep lip that caused him to roll," Roden said. "The driver was not wearing a seat belt and was ejected out of the semi."
Another driver came across the wreckage about 7:30 a.m. Officials believe the crash happened an hour or two before that.