I WAS DRIVING FORWARD AT ABOUT 15 MPH ON A SNOW COVERED ROAD (RESIDENTIAL CITY STREET). I CAME UPON AN UNCONTROLLED INTERSECTION WHEN I NOTICED A CAR COMING FROM MY RIGHT SIDE, I THEN ATTEMPTED TO SLOW DOWN AND STOP. WHILE TRYING TO SLOW DOWN MY BRAKE PEDAL LOST ALL PRESSURE AND WENT TO THE FLOOR, CAUSING AN INABILITY TO SLOW DOWN PROPERLY. RESULTING IN MY CAR HITTING THE REAR DRIVER SIDE OF THE OTHER CAR IN THE MIDDLE OF THE INTERSECTION. MY BRAKE PEDAL HAS LOST PRESSURE 3 TIMES PREVIOUSLY ALL IN THE SAME WINTER CONDITIONS (SNOW AND ICY ROAD) AND WHILE TRYING TO SLOW DOWN. I TOOK MY CAR TO 2 DIFFERENT MECHANICS, WITH NO ISSUES FOUND WITH THE BRAKE SYSTEM. 1 OF THE PREVIOUS TIMES I HAD TO USE MY EMERGENCY BRAKE FOR THE CAR TO STOP COMPLETELY THE OTHER 2 TIMES TOOK AN EXTENDED AMOUNT OF TIME FOR THE CAR TO STOP. WHEN MY BRAKE PEDAL LOSES PRESSURE I IMMEDIATELY PARK MY CAR, THE PRESSURE ON THE BRAKE PEDAL WITH GO BACK TO NORMAL AFTER LETTING THE CAR SIT FOR AT LEAST 5 HOURS IF NOT LONGER.