I WAS TRAVELING ON A TWO-LINE ROAD NEARING THE CITY AND NEAR THE TOP OF A HILL WHEN A LINE OF CARS SLOWED QUICKLY IN FRONT OF ME. I HAD TO GET ONTO THE BRAKES QUICKLY TO MAINTAIN A SAFE FOLLOWING DISTANCE, BUT WHEN I DID THE PEDAL WENT COMPLETELY TO THE FLOOR. HAVING VERY LITTLE TIME TO REACT, I NOTICED THE TRAFFIC IN THE ONCOMING LANE HAD STOPPED OR SLOWED GREATLY ABOUT 100 YARDS IN FRONT OF ME, SO I WAS ABLE TO SWERVE INTO THE LEFT LANE TO AVOID REAR ENDING AN ENTIRE LINE OF CARS WITH MY 6000LBS TRUCK. FORTUNATELY THE DRIVER AT THE FRONT OF THE ONCOMING TRAFFIC SAW ME AND STOPPED. I WAS THEN ABLE TO BARELY MANAGE MY WAY BACK INTO THE RIGHT LANE AS SOME OF THOSE CARS STARTED MOVING AGAIN. AT THIS POINT I WAS JUST CRESTING A LARGE HILL AT APPROXIMATELY 40MPH. A POLICE OFFICER IN THE ONCOMING LANE HAD ALREADY SEEN ME AND ACTIVATED HIS LIGHTS AND THEN STARTED WORKING TO TURN AROUND IN THE ROAD TO CHASE ME. WHEN I WAS BACK IN THE RIGHT LANE I FINALLY HAD A SECOND TO TRY TO LOCATE THE PARKING BRAKE, BUT ACTIVATING IT HAD ABSOLUTELY NO EFFECT. I COASTED NEARLY 1/2 MILE DOWN THE ROAD AND FORCED THE TRUCK INTO A PARKING LOT, OVER A LARGE SET OF RAILROAD TIES AND INTO A YARD WITH AN UPSLOPED HILL. IF I COULDN'T HAVE GOTTEN IT STOPPED THERE I COULD HAVE COASTED DOWN AN EVEN STEEPER HILL AND INTO A VERY BUSY MULTI-LANE INTERSECTION AND KILLED SOMEONE. THE POLICE OFFICER ENDED UP BEING UNDERSTANDING OF MY SITUATION AND CALLED A TOW TRUCK FOR ME AND I HAD IT TOWED TO A SHOP. THE SHOP SAI