means "S-train". This was also just a few years after the S-trains had opened in Berlin and Hamburg. Today the Copenhagen S-trains uses six lines and serves 86 stations, 32 of them are located inside the (quite tiny) municipality borders. Each line uses 6 t.p.h (trains per hour) in each direction, with exception of the (yellow) F-line. The F-line has departures in each direction every five minutes, or 12 t.p.h. service . History Germany Early steam services In 1882, the growing number of steam-powered trains around Berlin prompted the Prussian State Railway to construct separate rail tracks for suburban traffic. The Berliner Stadtbahn connected Berlin's eight intercity rail stations which were spread throughout the city (all but the Stettiner Bahnhof which today is a pure S-Bahn station known as Berlin Nordbahnhof; as the city Stettin today is Polish city Szczecin). A lower rate for the newly founded Berliner Stadt-, Ring- und Vorortbahn (Berlin City, Circular and Suburban Rail) was introduced on 1 October 1891. This rate and the growing succession of trains made the short-distance service stand out from other railways. The second suburban railway was the Hamburg-Altonaer Stadt- und Vorortbahn connecting Hamburg with Altona and Blankenese. The Altona office of the Prussian State Railway established the electric powered railway in 1906. Electricity The beginning of the 20th century saw the first electric trains, which in Germany operated at 15,000 V on overhead lines. The Berliner Stadt-, Ring- und Vorortbahn instead implemented direct current multiple units running on 750 V from a third rail. In 1924, the first electrified route went into service. The third rail was chosen because it made both the modifications of the rail tracks (especially in tunnels and under bridges) and the side-by-side use of electric and steam trains easier. To set it apart from the subterranean U-Bahn, the term S-Bahn replaced Stadt-, Ring- und Vorortbahn in 1930. The Hamburg service had established an alternating current line in 1907 with the use of multiple units with slam doors. In 1940 a new system with 1200 V DC third rail and modern electric multiple units with sliding doors was integrated on this line (on the same tracks). The old system with overhead wire remained up to 1955. The other lines of the network still used steam and later Diesel power. In 1934, the Hamburg-Altonaer Stadt- und Vorortbahn was renamed as S-Bahn. Comparable systems Austria The oldest and