U.S. Air Force Senior Airman Bobby Chambers, left, and Staff Sgt. James Terrell, students attending the Engineering Installation vehicle training class, rig a maintenance hole cover to be hoisted by an excavator Dec. 13, 2017, at the Air National Guard Schoolhouse, Fort Indiantown Gap, Pennsylvania. Airmen utilized rigging techniques they learned in class to maneuver maintenance holes for underground installation. (U.S. Air National Guard photo by Staff Sgt. Tony Harp/Released)