In 1951 the track was extended to 4.4 kilometres (2.7 mi) running from Zoo via Carolasee and Palaisteich back to Zoo. Later in the same year the station Karcherallee was opened and the line reached its current length of 5.6 kilometres (3.5 mi). In 1968 an additional track was added between Zoo and Fučíkplatz.[1]