Inspection Detail

Inspection: 304268709 - Austin Bridge & Road Co.

Inspection Information - Office: Fort Worth Area Office

Investigation Summary

On January 16, 2002, a Manitowoc crane was used to lift a concrete beam when the back left side of the crane dipped down into the cribbing causing the boom to go backwards and hit the concrete barrier. Two employees were using a Terex aerial lift removing sections of the crane boom. A 175-ton Krupp crane was used to stabilize the crane. The crane was unhooked and hooked to the boom. A Manitex boom truck was also being used to stabilize the Manitowoc crane. The Manitowoc crane uprighted itself, causing the Manitex boom truck to topple over the I-35 overpass along with Employee #1. The Manitex boom truck struck the boom of the Terex aerial lift knocking the main basket with the Employees #2 and #3. The Manitowoc crane was being used at its maximum boom angle and rated capacity for the load radius. The lattice boom was 110 feet. The boom angle was about 82 degrees. The load radius was about 21 feet. The concrete beams weighed approximately 74,100 to 75,900 pounds. The rigging and load block weighed about 3,009 pounds. The total weight is approximately 77,109 to 78,909 pounds. The load chart shows for a load radius of 21 feet or 21.5 feet to use a boom angle of 80.3 degrees and maximum capacity is 78,860 pounds (the load chart does not have a 21 foot designation but has 20 feet for a boom angle of 81.4 degrees and load capacity of 88,230 pounds). No measurements of the slope were indicated. Interviews indicated that the load after the pick drifted out indicating a slight slope. Also, interviews indicated that the mats were level north to south, not west to east. Indications are the grade of the slope was more than one percent. All three employees were hospitalized to treat fractures.

Keywords: FRACTURE, COLLAPSE, CARPENTER, OVERLOADED, CRANE