A collision between a tractor-trailer and a pickup caused a big traffic backup Thursday afternoon on I-64. It happened at the Route 15 intersection at Zion Crossroads. State Police say a pickup driven by 33-year-old Thomas Flynn of Waynesboro came off the ramp heading to westbound 64 when he hit a tractor-trailer. The truck kjack-knifed in the left lane and overturned in the median. Flynn was taken to UVA Hospital with minor injuries. He was charged with making an unsafe lane change. The tractor-trailer driver was not injured. That happened shortly before 2:30 p.m. There was a traffic backup on the westbound side of 64 for about two miles.