UNINTENTIONAL ROOF FALL OCCURRED ON THE MAIN NORTH TRACK AT 41X CNT(#4 OF MN 2 CROSSCUTS OUTBY OLD 4 WEST TRACK SPUR)CAUSE OF THE FALL WAS THE DETERIORATION OF THE ROOF AROUND THE EXISTING ROOF BOLTS. THE FALL WAS 30X20X8 FT. THE AREA WAS BOLTED WITH 8' LONG POINT ANCHOR ROOF BOLTS. HEADER BLOCK PLANK AND WIRE SCREEN WERE USED ALSO. FALL RESTRICTED THE PASSAGE OF MATERIALS