AN UNINTENTIONAL ROOF FALL OCCURRED AT 85+70 ENTRY #4 ON THE 6TH NORTH BELT LINE. THE FALL MEASURED 85' LONG X 19' WIDE X 5' THICK. THE FALL DID NOT IMPEDE TRAVEL OR IMPAIR VENTILATION. THE FA LL CAUSED DAMAGE TO THE BELT & BELT STRUCTURE AT THE ABOVE LOCATION. THE 4-WAY INTERSECTION WAS SUPPORTED BY 4' FULLY GROUTED ROOF BOLTS.