WAS INVOLVED IN A TRAFFIC ACCIDENT WHERE VEHICLE WAS AT A COMPLETE STOP WAITING TO EXIT FREEWAY: BACKUP ON FREEWAY EXIT, WAS REAR ENDED AT HIGH SPEED BY ANOTHER VEHICLE. CAUSING CHAIN REACTION CRASH, VEHICLE WAS SANDWICHED BETWEEN TWO VEHICLES. VEHICLE FLOORING BECAME DEFORMED WHICH MAY HAVE CONTRIBUTED TO DRIVER'S SEAT COLLAPSING AND MOST IMPORTANTLY FOR THE SEAT BELT TO FAIL CAUSING ME TO BANG MY FACE INTO THE STEERING WHEEL. I FOUND THE SEAT BELT WAS UNBUCKLED AFTER THE CRASH. AIRBAGS DID DEPLOY. *TR