Abstract: At about 11:40 a.m. on May 30, 2000, Employee #1, a supervisor, and two coworkers were using a hydraulic excavator to dig an approximately 5 ft deep by 20 ft wide trench alongside a street. In the course of excavation, abandoned underground 6 in. wide utility pipes were cut into 100 ft long sections and placed by the excavator on the edge of the uncut trench top surface. There was an 8 ft tall fence about 3 ft from the excavated edge; between the fence and the excavation was a bundle of three steel pipes, chained to the fence in three places along its length. One coworker was operating the excavator, which was on the trench bed, while Employee #1 and a laborer were standing next to the pipe bundle at the top. The laborer opened one chain at the end of the bundle, and Employee #1 opened a second chain at the middle of the bundle. He was walking toward the other end of the bundle to open the last chain when he heard a sound indicating that the excavator had been actuated. The laborer saw the excavator bucket moving, but before Employee #1 could signal the operator to stop, one pipe came under the bucket and trapped his right leg against the pavement. He lost his balance and fell to the ground at the edge of the excavation, his right leg held by the pipe and his body hanging down inside the trench. The excavator operator, alerted by other workers, lifted the pipe. Employee #1 fell into the excavation, then dragged himself a few feet away from the excavation edge so that a pipe from the top would not fall on him. He suffered a compound fracture of his right leg and was transported to St. Mary's Hospital, where he was treated and released four days later. Subsequent investigation determined the accident was the result of 1) the way the pipes were stored in a narrow strip next to the fence, which created a hazard of tipping, falling, collapsing, or rolling; and 2) second, the excavator operator acting on his own without a signal from Employee #1, the appointed signalman.