UNITED STATES
DEPARTMENT OF LABOR

Abstract: A crane operator was operating a 23.5-ton truck crane with a telescoping boom. The operator arrived at a residential construction site (a two-story frame home), parked his truck crane in the street and set the crane outriggers. The operator extended the boom to the full length which was 92 ft at a boom angle of approximately 53 degrees which corresponds to a lifting radius of 50 ft. The lifting capacity or load rating at this boom angle and boom height is 3,025 pounds. The distance from the point where the plywood was to be landed to the centerline of the crane turret was approximately 58 ft to 60 requiring a boom angle of 49 degrees with a load rating of 2,425pounds. The operator cabled-down to lift a bundle consisting of 87 sheets of 4-ft-by-8-ft-by-0.5-in. x 1/2" plywood. Each sheet of plywood weighed approximately 49 pounds each. The total load of the bundle at the site according to the shipping invoice was 4,303 pounds. Two synthetic web slings were attached to the load in a choker method and attached to the crane hook by the framing foreman. The operator cabled-up to clear the second floor of the structure and as the crane rotated clockwise toward the driver's side of the truck it started to tip over. As the crane tipped over the boom structure came down through the second story of the structure coming to rest on a supporting beam on the first floor. Employee #1, from the framing company, was standing on the second floor in order to guide the load in place, and had to jump from the back of the structure to avoid being struck by the boom. Employee #1 stated that the crane boom just glanced off his right shoulder pushing him off the structure. Employee #1 fractured his leg severely when he fell into the back yard. The crane operator was shaken but uninjured. According to the crane operator the crane is equipped with an override safety system that monitors the boom angle, length, lifting radius and load with an audible alert that beeps if the crane is overloaded. The operator stated that the audible alarm went off as the crane was tipping which did not give the operator time to cable down or raise the boom. Employee #1 was hospitalized.