Abstract: At 12:20 p.m. on March 13, 2003, Employee #1, a mechanic, working for MPM Concrete Construction, came to the jobsite to transport a "Bobcat" back to the shop. A trailer was hitched onto the back of a pickup truck, which was parked on a hill facing the bottom. Another employee drove the "Bobcat" onto the trailer as Employee #1 stood near the front of the pickup truck watching. The weight of the "Bobcat" lifted the rear of the pickup truck. The trailer and pickup truck rolled downhill. Employee #1 was pinned against the curb of the sidewalk. Medical assistance was called. The San Francisco Fire Department and the San Francisco Police Department responded to the scene. The ambulance took Employee #1 to San Francisco General Hospital, where he was hospitalized and treated for a broken clavicle and a sprain knee. The investigation concluded the trailer and the pickup truck did not have its wheels chocked to prevent accidental movement.