DRIVER WAS AT TRAFFIC TIE U WHEN A VEHICLE STRUCK THE DRIVER FROM BEHIND, THE TRUCK WAS MOVING AT A HIGHT RATE OF SPEED, PUSHED THE DRIVER INTO A VAN THAT WAS STOPPED IN FRONT AND INTO THE CENTER CEMENT DIVIDE. DRIVER'S SIDE SEATBACK FELL INTO A SEMI-RECLINE POSITION AND THE SEAT SLID BACK, AIRBAG DID NOT DEPLOY, THE SEAT FALLING BACK CAUSED THE DRIVER'S LUMBAR SPINE TO BE INJURED.