WHILE BRAKING TO SLOW THE VEHICLE TO A STOP BEHIND TRAFFIC AT A RED LIGHT, AFTER COMING OFF A HIGHWAY EXIT RAMP, THE BRAKES FAILED TO RESPOND TO ADDED PRESSURE APPLIED TO BRING THE VEHICLE TO A COMPLETE STOP. THE BMW X3 KEPT MOVING FORWARD, AND COLLIDED, AT VERY SLOW SPEED, WITH THE STOPPED VEHICLE AHEAD. I QUICKLY CHECKED TO ENSURE THAT MY FOOT WAS PROPERLY ON THE BRAKE PEDAL AND DEPRESSED THE PEDAL AGAIN, WHICH AGAIN FAILED TO BRING THE VEHICLE TO A COMPLETE STOP, RESULTING IN SECONDARY CONTACT WITH THE VEHICLE AHEAD. WHEN ATTEMPTING TO MOVE THE VEHICLE TO THE SIDE OF THE ROAD, THE ELECTRONIC TRANSMISSION REPEATEDLY JUMPED INTO PARK FROM DRIVE, REQUIRING ME TO TURN OFF THE IGNITION AND RESTART THE VEHICLE BEFORE I COULD SAFELY MOVE IT TO THE SIDE OF THE ROAD.