EMPLOYEE WAS USING BACKHOE AROUND NEW QUICKLIME STORAGE LOADOUT FACILITY WHEN HE BACKED MACHINE TO NEAR RAILROAD TRACK AS THE COMPANY LOCOMOTIVE WAS MOVING SOME CARS INTO POSITION FOR LOADING AT THE FACILITY...TRAIN WAS MOVING VERY SLOWLY BUT CORNER OF CAR STRUCK THE BUCKET OF THE BACKHOE...BUCKET AND SWING ARM ABSORBED MOST OF THE IMPACT BUT ENOUGH ENERGY REMAINED TO TIP IT OVER.