The probable cause, the report says, was the failure of the welding crew to detect the approaching train as they were backing across a grade crossing. The welding truck was backing toward a farm crossing on a dirt road, which crossed the railroad at a sharp angle, when it was struck by a westbound BNSF freight train. The train crew had seen the truck, sounded the locomotive horn constantly, and had put the train into emergency three seconds before the collision. The passenger in the truck told NTSB investigators he did not see the train until seconds before the collision, and the driver was using side-view mirrors to maneuver the truck into position for work. BNSF subsequently conducted a safety stand-down to review safety procedures and amended the rule to emphasize that a person on the ground or on-track safety must be used to guide a backup move.