MARSHALL TWP, Allegheny County — Northbound traffic on Interstate 79 was slowed after a van rolled over Tuesday afternoon. The accident occurred just before 1:30 p.m. in the northbound side, about a mile from the Butler County and Cranberry Township lines. Traffic backed up as fire and emergency crews responded to the scene. A blue van was seen with damage to its roof and sides, though it was sitting upright by 1:50 p.m. One lane of traffic was closed as crews worked to clear the scene.No additional information on the accident or any injuries was immediately available.