Karl Freadhoff Jr., 79, from New Salem died in the crash. His retarding vehicle was hit from behind by a Ford Escape, powered by John Soward, 37, from Hazen, on Interstate 94 about 10 miles east of New Salem just before 6:30 PM.
Freadhoff's vehicle then went into a ditch and rolled, said the North Dakota Highway Patrol. All accusations against Soward are still under investigation.
Both men wore seat belts and airbags in both vehicles, the patrol said.
New Salem is located about 32 miles west of Bismarck.