While driving in stop & go traffic traveling at speeds less than 15mph, when I stepped on the brake pedal to slow / stop my RAM, the brake pedal failed to activate the brakes and the vehicle continue in a forward motion causing my RAM to collide with the vehicle traveling in front of me. After the collision, my RAM pushed the vehicle I hit into the center shoulder of the freeway. My RAM continued its forward motion (up an shallow grade) for another 1/4 mi. My constant stabbing and continual pressure failed to stop or slow my RAM. I eventually I brought my vehicle to a stop by depressing the "emergency brake pedal". While I was attempting to stop my RAM in appeared the throttle continued to deliver the engine power even though my right foot was on the brake pedal.