Abstract: Employee #1, two other pile drivers, and a foreman were dispatched from union hall to a worksite to drive test piles. Having finished driving the first test pile, the crew now proceeded to set up the second pile site. While the other two pile drivers were rigging the concrete pile, Employee #1 was preparing the cut-off rope for the hammer and then approached the cage to tie one end of the chain link to one side of the cage. As he turned to walk away from it, the hammer suddenly dropped down and the protruding front side of it hit Employee #1 on the left clavicle. The equipment involved a crane used exclusively for pile driving operations. At the time of the accident, it was equipped with a 12-ton hammer. Employee #1 suffered a broken clavicle, broken right femur, right scapula, third rib, right hip and right tibia, and a collapsed lung. The causal factor/s of the accident is determined to be the absence of identification on the controllers of the crane.