S9 (Berlin)

S9 is a line on the Berlin S-Bahn. It operates from Flughafen BER to Spandau through Berlin Hauptbahnhof (Berlin Central Station) over:
 * a very short section of the Outer ring, opened in 1951 and electrified in 1983,
 * a short section of the former Outer freight ring opened in the early 1940s and electrified in 1983,
 * the Görlitz line, opened in 1866 and electrified in 1929,
 * the Ring line, completed in 1877 and electrified in 1926 and, via a connecting curve,
 * the Berlin–Wrocław railway, which at Berlin Ostbahnhof becomes
 * the Berlin Stadtbahn to Charlottenburg,
 * the Spandau Suburban Line.

Service history
The S9 was created on 2 June 1991, replacing the Blue route of the S3 between Charlottenburg and Flughafen Berlin Schönefeld (now Schönefeld (bei Berlin) station), with the western terminus extended by one stop to Westkreuz.