EMPLOYEE WAS WORKING WITH ANOTHER DRILLING INVERT DOWELS. LOCATION APPROX 150' HEADING SIDE OF AIR DOOR #2. DRILLING PERFORMED WITH SINKING HAMMER POWERED BY AIR HOSE AND TUNNEL #1 AIRLINE, LO CI PUSHING FLATCARS WITH RAIL PANELS, STRUCK EE FROM BEHIND AND KNOCKED BOTH EE'S INTO THE INVERT BETWEEN THE RAIL. SHAKEN BUT NO VISIBLE INJURIES.