TRAFFIC SLOWING DOWN IN FRONT OF ME, I APPLIED THE BRAKES AND THE PEDAL WENT SLOWLY TO FLOOR AND THE BRAKES DID NOT WORK CAUSING ME TO HIT THE CAR IN FRONT OF ME, REAPPLIED THE BRAKES AND THEY DID WORK CAUSING ME TO HIT THAT CAR AGAIN. THOUGHT THAT MAYBE MY FOOT WAS DEPRESSING BOTH THE ACCELERATOR AND BRAKE SO II USED MY LEFT FOOT, RESULT THE SAME. I DID THIS MANY MORE TIMES AND THE BRAKES DID NOT WORK. I APPLIED THE PARKING BRAKE AND PULLED OFF TO THE LEFT SIDE OF THE ROAD WHEN I WAS SURE IT WAS SAFE. THIS HAPPENED IN A CONSTRUCTION ZONE, I MANAGED TO AVOID HITTING ANY OF THE WORKERS AND THE 3 TRUCKS THAT THEY WERE USING. ONE OF THE WORKERS ASKED WHAT HAPPENED, I EXPLAINED TO HIM AND HE TRIED THE BRAKES, THEY WENT WERE SPONGY AND WENT SLOWLY TO THE FLOOR. CHECKED TO SEE IF THE DRIVER OF THE VEHICLE TO SEE IF SHE HAD ANY INJURIES, SHE SAID SHE WAS ALRIGHT. THE IMPACT WAS NOT HARD BECAUSE WE WERE BOTH GOING THE SPEED. CALLED THE MICHIGAN STATE POLICE (REFER TO INCEDENT # 31-10985-16 AND CRASH REPORT S/N 228890) NO TICKET ISSUED. CALLED FOR WRECKER TO TAKE THE VEHICLE TO THE NEAREST CHRYSLER DODGE JEEP RAM DEALERSHIP. THE DEALER WAS GARBER, 5330 BAY ROAD, SAGINAW MICHIGAN 48604, PHONE # 989-399-8550, SERVICE ADVISOR LARRY COOK. THEY COULD NOT FIND A PROBLEM, THEY CONTACTED CHRYSLER ENGINEERING. LEFT VEHICLE OVE NIGHT, CAUSE COULD NOT BE DETERMINED. BRAKES WORKED FINE, BROUGHT VEHICLE HOME AFRAID TO DRIVE IT AGAIN.