Berlin outer ring

Grunau Cross in 1980

On 8 July 1951, the section between Genshagener Heide and Schönefeld was opened along with the connecting curves between Genshagener Heide east and Ludwigsfelde and between Glasower Damm east and Blankenfelde. This was followed by the opening of the Schönefeld–Grünau Cross section on 12 August 1951 and its extension to Wendenheide on 2 December of that year. On 22 November 1952 the opening of the section from the Outer freight ring at today’s Karow cross and Bergfelde and the connecting curve from Bergfelde junction to Birkenwerder. The next steps were the opening of the connecting curve from Karow West junction to Blankenburg (1953), the Wuhlheide marshalling yard (1 October 1953) and, simultaneously, the section from Bergfelde to Falkenhagen and Brieselang, initially as a single track. This was followed between 1953 and 1955 with the opening of a connection curve between Karow west junction and Karow north junction, the doubling of the former Brandenburg Ring line between Saarmund and Genshagener Heide, and the opening of several connecting curves: between Hennigsdorf west junction and Hennigsdorf, Hennigsdorf east and Hennigsdorf, between Hohen Neuendorf west and Birkenwerder and between Falkenhagen and Finkenkrug and Brieselang. On 2 October 1955, the section between Falkenhagen junction and Wustermark was opened along with the connection curves to Wustermark freight yard and Wustermark. On 11 December 1955 the line from Wustermark Junction to Elstal Junction was opened, completing the connection with the Brandenburg Ring line between Golm and Elstal.

The last section of the line was the difficult section between Saarmund and Golm across the Templiner See. On 30 September 1956, the connecting curve between Potsdam south and Werder was opened to traffic, completing the ring. This was followed by several connecting curves: Nesselgrund east to Wilhelmshorst and Golm to Wildpark (28 September 1957), Genshagener Heide to Birkengrund (north-west curve, 1 June 1958), Werder to Golm (6 February 1959) and finally Glasower Damm - Blankenfelde (south-west curve, 25 May 1961).

In 1958, passenger trains began running on the outer ring as part of the Berlin S-Bahn fare scheme. As this followed the launch of the first Soviet satellite, these trains, which ran partly on a circular orbit around West Berlin, were commonly called "Sputniks”.

On 13 August 1961, the Berlin Wall was built closing East Germany’s border with West Berlin. This made necessary the construction of an S-Bahn connection between Berlin-Blankenburg and Hohen Neuendorf towards Oranienburg. In 1962 separate S-Bahn tracks between Schönfließ and Bergfelde were put into operation (on the rest of the section S-Bahn and mainline trains shared tracks) and the connection between Bergfelde/Bergfelde East and Birkenwerder were built. Also in 1962 an S-Bahn line from Adlershof station to Berlin-Schoenefeld Airport was opened and this line also made available for long-distance trains. Previously, it had served only as a station for border checkpoint purposes.

In the same year track was completed on the connection between Hasselberg and Brieselang, and the Hennigsdorf–Wustermark section were electrified experimentally with the 25 kV/50 Hz system. Class E 251 locomotives built in the Lokomotivbau Elektrotechnische Werke in Hennigsdorf (now owned by Bombardier) were used on the line. In 1973, the catenary was removed, although some masts were preserved and reused for the 15 kV electrification in 1983.

In 1982, the Saarmund–Glasower Damm section and the connection to Blankenfelde was electrified, including the Saarmund–Michendorf connecting line and the Genshagen Heath/Genshagen Heath east–Ludwigsfelde curves as well as the Priort–Saarmund section. In 1983 this was followed by the electrification of several sections: Wustermark/Wustermark marshalling yard–Priort, Berlin-Schönefeld Airport–Grünau Cross, Birkenwerder junction (near Hohen Neuendorf West)–Wustermark South junction as well as the connecting curves at Golm/Wildpark west junction–Werder, Wustermark north junction–Wustermark marshalling yard/Wustermark and Falkenhagener cross.

On 17 May 1983, the third track—and on 26 September 1986 the fourth track—was opened between Glasower Damm junction and Berlin-Schönefeld Airport. Between Karow Cross and Schönfließ two separate tracks were brought into operation on 2 September 1984 as part of the planned electrification of long-distance tracks.

As a result of the decline in freight traffic after German reunification, the Wuhlheide marshalling yard was decommissioned on 10 June 1994 and later abandoned completely.

With the opening of the North-South mainline on 28 May 2006, its southern connection to the Anhalt Railway was re-opened, but not to the Dresden line. Since then, trains to Dresden have run on the outer ring between Genshagener Cross and Glasower Damm. These trains use a connecting curve from the direction of Teltow and Berlin and use a newly built curve.

As part of the western rail link being built to Berlin-Brandenburg International Airport, in early 2008, the two main lines connecting from the Berlin-Dresden line between Glasower Damm east junction and Berlin-Schönefeld Airport station were taken out of service and the tracks have mostly been removed. The main line to the airport will be constructed from the new grade-separated Selchow junction (between junction Glasower Damm east and Waßmannsdorf) and run south of the Outer ring from the west on a somewhat S-shaped route to the new airport railway station. A total of 15 kilometres of line is being rebuilt for mainline and regional services and eight kilometres is being rebuilt for S-Bahn services. While both routes were expected to open to the airport in early November 2011,[2] continued delays with construction of the new airport[3] have meant that service to Berlin-Schönefeld Flughafen will continue to operate until at least 2020. Airport shuttle services will operate from Berlin Hauptbahnhof via the Anhalt line rather than the shorter Dresden line, because a connecting curve has not been built to connect with the North-South mainline.[4]