The Munich S-Bahn () is an electric rail transit system in Munich, Germany. "S-Bahn" is the German abbreviation for Stadtschnellbahn (literally, "urban rapid rail"), and the Munich S-Bahn exhibits characteristics of both rapid transit and commuter rail systems. The Munich S-Bahn network is operated by S-Bahn München, a subsidiary of DB Regio Bayern, which is itself a subsidiary of the German national railway company, Deutsche Bahn. It is integrated into the Munich Transport and Tariff Association (Münchner Verkehrs- und Tarifverbund, MVV) and interconnected throughout the city with the locally owned Munich U-Bahn. Today, the S-Bahn covers most of the populated area of the Munich metropolitan area of about 2.7 million inhabitants. The Munich S-Bahn was established on 28 May 1972. It was intended as part of the scheme to provide an adequate transport system during the 1972 Summer Olympics held in Munich by connecting the pre-existing suburban rail services in the west and east of the city via a new tunnel section from Hauptbahnhof to Ostbahnhof. Lines System The system has seven branches in the west, which were originally numbered from north to south from the S 1 (to Freising) to the S 7 (Wolfratshausen). These are coupled with the five eastern branches. Operational requirements have changed several times, particularly due to line extensions, resulting in random numbering in the east. Two lines end at Munich East station (Ostbahnhof), these are currently S 1 and S 6. The first change was made in June 1991 when the branch to Ebersberg changed from S 4 to S 5 as a requirement to shorten the travel time to and from Herrsching. The line to Wolfratshausen was first called the S 10, but when it was connected to run over the trunk line it was changed to the S 7. The S-Bahn branch in the east via Ismaning to the airport was designated as the S 8. Later this was combined with the original line S 3, which shared part the route of the S 8, and the new route is called the S 8. This eliminated route S 3. The old route S 5 was later largely replaced by the current S 3, so there is currently no line S 5. In addition, there is line S 20, which runs from Pasing to Höllriegelskreuth. These two lines do not run through the trunk line tunnel. The numbers beginning with 2 comes from