Berlin outer ring

The Berlin outer ring (BAR; German: Berliner Außenring) is a 125 km (78 mi) long double track electrified railway located in Berlin and Brandenburg, Germany. Its route forms a ring around the former West Berlin, and includes parts of some older lines such as the Outer Freight Ring, Jüterbog–Nauen railway, and Michendorf–Großbeeren railway. The BAR was originally built by the German Democratic Republic (East Germany) between 1950 and 1961 to bypass West Berlin for political, economic, and military reasons. It allowed East Germany to seal off West Berlin without disrupting its transport links, in preparation for the building of the Berlin Wall during the division of Germany, by encircling West Berlin through East Berlin and the suburbs in Bezirk Potsdam. The BAR was integrated into the Deutsche Bahn railway system in the 1990s after German reunification. The term Outer ring is used to distinguish the line from the Ringbahn of inner Berlin.