An employee was giving hand signals to the operator of a telehandler to place a trash hopper loaded with tools onto a roof. The employee was standing between a wall and the trash hopper attached to the telehandler when the telehandler encountered rough terrain and the trash hopper moved, striking the employee and causing him to become caught between the wall and the trash hopper. The employee suffered a laceration above the right eye, three fractured ribs on the right side, and a fractured sternum.