A U.S. Air Force member of the 90th Civil Engineer Squadron uses an asphalt compactor to level an asphalt patch of a simulated bomb impact crater on a concrete training runway at the North Dakota Air National Guard Regional Training Site, Fargo, N.D., Sept. 29, 2021. The visiting engineers are using the Rapid Airfield Damage Recovery (RADR) system for training to repair damage to a 150 feet by 750 feet concrete simulated runway, sectioned off in 20 foot by 20 foot squares for training craters. It is specially designed for making holes in the concrete squares that simulate bomb impact craters that can be repaired with fill and capping material. The Fargo civil engineer training site is one of four in the Air National Guard, and is the first one of those to provide new system for RADR training. (U.S. Air National Guard photo by Chief Master Sgt. David H. Lipp)