BRAKES WERE WORKING FINE, COMING OFF FREEWAY, WAS COASTING THRU LIGHT, TRAFFIC STOPPED, BRAKES NO LONGER WORKED, BRAKE PEDAL WAS SUDDENLY FLUSH WITH FLOOR. REARENDED A CAR, CAR STARTED JUMPING FORWARD. HAD TO USE THE EMERGENCY BRAKE TO STOP THE CAR. CAR WAS TOWED AFTER ACCIDENT, NOT BECAUSE IT WAS NOT DRIVABLE, IT WAS NOT DRIVABLE DUE TO BRAKE PROBLEM. REPAIR SHOP SAID BRAKES FAILED TO VACUUM HOSE BREAKING, NO WARNING PRIOR TO LOSING BRAKES. *TR