Abstract: At approximately 1:19 p.m. on July 31, 2012, Employee #1, a flagger, was performing flagging operations and controlling the flow of traffic at site. He stopped five vehicles at the south end of the work zone. A coworker stopped traffic in the northbound lane and in a single lane closure. There were five vehicles stopped in front of Employee #1, when a semi-truck approached from behind at a high rate of speed (estimated to be approximately 52.5 mph) and struck the rear car at high speed. The truck skidded off of the road and back onto the road. The truck rolled over at some point and also lost its load of drilling pipe. The trailer struck Employee #1 and killed him. The driver of the truck was also killed after he was ejected from the truck cab.