Abstract: A concrete pump truck had 60 ft of boom plus 40 ft of 4 in. hose extending from the ground level over the roof edge guarding to pour concrete onto corrugated metal decking and mesh-covered roof surface. The roof edge guarding consisted of nylon rope between 3 in. by 3 in. wood posts clamped to the side of the structural steel 45 ft apart at heights of 15 in. and 34 in. Average deflection at the center of the spans was 15 in. No toeboard was provided. A string of red and white pennant flags was also strung from post to post at the same height as the top rope. Employee #1, the job site superintendent, elected to act as signalman for the concrete pump operator. To be seen by the pump operator, Employee #1 had to stand no more than 2 ft from the edge of the roof. The exact circumstances that precipitated the fall are unknown; no one was aware of his activity just prior to the fall. He was wearing cowboy-type boots. It is possible that the heels of his boots caught in the mesh, causing him to fall first to the roof surface, then off the edge, 51 feet to the ground. Employee #1 was killed.