VEHICLE WAS IN MOTION AT ABOUT 30-35 MPH IN A HIGHWAY CONSTRUCTION ZONE, AND I HEARD A BANG, VEHICLE LOST CONTROL AND WAS SENT OFF THE ROAD. WHEN I INSPECTED THE VEHICLE AFTER THE VEHICLE CAME TO A STOP, I NOTICED THE FORE LINK/FORWARD CONTROL ARM WAS LOOSE. THE STUD THAT HELD THE BALL JOINT TO THE STEERING KNUCKLE HAD BEEN SHEERED OFF.