VICTIM WAS A PASSENGER IN A PICKUP TRUCK ON THE HAULAGE ROAD. A ROCK APPROX. 31/2 SQUARE FOOT CAME OFF THE HIGHWASS & STRUCK THE TOP OF THE CAB (PASSENGER SIDE) RESULTING IN SERIOUS INJURIES T O VICTIM (A VISITOR, NOT AN EMPLOYEE). HE SUFFERED FRACTURES TO THE LEFT TIBIA & FIBULA, RIGHT FEMOR & PELVIS, AND A CONCUSSION.