An employee used a step ladder to get onto a flat trailer and then climbed onto a precast plank. At the same time, a crane was lowering clamps onto a nearby plank to lift it. As the crane lifted the plank off of the truck, the plank came toward the employee. He jumped from the precast plank and trailer to the ground and landed on large rocks. His left leg rolled, breaking his left ankle. He was hospitalized and had surgery.