Abstract: AT ABOUT 9:45 AM ON AUGUST 29, 1986, EMPLOYEE #1 WAS PACING OFF ROUGH MEASUREMENTS SO THAT A CURB UNIT COULD BE PLACED AT THE CENTER OF A 270 BY 90 FOOT ROOF AREA. TWO DAYS BEFORE, A MASONRY CONTRACTOR HAD PLACED SOME STYLOFORM SHEETS ALONG THE EDGE OF THE ROOF AT THE NORTHEAST SIDE TO PROTECT HIS MASONRY EMPLOYEES, WORKING BELOW, FROM RAIN. EMPLOYEE #1 HAD NOT BEEN ON THE ROOF SINCE THE MASONRY CONTRACTOR HAD PUT DOWN THE STYLOFORM SHEETS. EMPLOYEE #1 STARTED PACING AT THE SOUTH WEST SIDE, MOVING TOWARDS THE NORTH EAST EDGE. AS HE APROACHED THE EDGE HE PLACED HIS FOOT ON THE UNSUPPORTED STYLOFORM SHEETS AND FELL 17 FEET TO THE CONCRETE SIDEWALK. THE SIDEWALK WAS COVERED WITH MASONRY DEBRIS, BRICKS AND MORTAR PANS. EMPLOYEE #1 KNEW WHERE THE SHEETMETAL CORRUGATED ROOFING ENDED, BUT WAS DECEIVED BY THE OVERLYING STYLOFORM SHEETS. THE SKY WAS OVERCAST, BUT IT WAS NOT RAINING. EMPLOYEE #1'S ASSIGNED WORK AREA WAS 45 FEET FROM THE ROOF'S EDGE ON THE NORTHEAST AND SOUTHEAST SIDES.