CONTRACTOR WORKING ON RAILROAD TRACK. EE WAS REMOVING BOLTS FROM FROG WITH A PUNCH AND CO-WORKERWAS HELPING BY KNOCKING OLD BOLTS OUT WITH A HAMMER. A PIECE OF METAL FROM HAMMER STRUCK EE ON LEFT ARM JUST ABOVE ELBOW INSIDE ARM. EE WAS TAKEN TO HOSPITAL AND GIVEN TREATMENT. DR. AT E.R. CUT SMALL INCISION TO REMOVE BUT FAILED & REQUIRED 5 STITCHES FROM THIS.