Abstract: Employee #1, age 19, and a coworker were using a transport dolly/cart to move twelve 8 ft long by 4 ft wide by 5/8 in. thick sheets of cement board, each weighing approximately 132 lb. The boards were stacked lengthwise on their edges as they moved and positioned the cart in a bathroom. Employee #1 was walking backward, pulling and directing the cart's movement, when the front left wheel dropped into a floor drain. The boards started to shift and fall from the cart. Employee #1 was trying to steady them by pushing against the wall when his legs became trapped beneath the boards. He sustained a fractured right ankle and tendon damage to his left knee. The weight capacity of the cart was 3,000 lb, and the floor drain was not seen by either employee. The floor was unfinished concrete and had scattered pieces of loose insulation on it from an earlier job in which it had been sprayed on the ceiling but did not stick.