I ARRIVED AT DRIVEWAY TO MY HOME AND PUT THE CAR INTO PARK. I GOT OUT OF THE CAR AND CLOSED DRIVER DOOR TO UNLOCK CHAIN ON GATE IN FRONT OF DRIVEWAY. I PROCEEDED TO MANUALLY OPEN THE 25' METAL GATE. WHEN THE GATE WAS ALMOST COMPLETELY OPEN I TURNED TOWARDS THE CAR AND TO MY SURPRISE THE CAR WAS MOVING FORWARD WITH NO ONE IN IT. THE CAR TRAVELED APPROXIMATELY 15' AND WAS STOPPED BY A 3' DIAMETER METAL CYLINDER. THE CARS FRONT BUMPER WAS DAMAGED. LUCKILY, NO PERSONS WERE INJURED. *TR