On March 14, 2016, at 9:41 p.m. mountain daylight time, westbound Union Pacific Railroad (UP) freight train KG1LAC-13 (5718 West) traveled from the main track through a switch into a controlled siding and collided head on with stopped eastbound UP local freight train LCK41-14 (5155 East).1 At the time, UP was installing and testing positive train control (PTC) on the main track. While this work was in progress, UP employees suspended signals and established absolute blocks to ensure that trains could move safely through the areas without signals (the suspension). The collision occurred on a siding on the UP Evanston Subdivision near Granger, Wyoming. The engineer of the striking train received minor injuries; the conductor was not injured. The crew of the stopped train exited the locomotive before the collision and were not injured. At the time of the accident, it was dark with cloudy sky and light wind; the temperature was 20°F.