S-Bahn ( , ; ) is a type of hybrid commuter rail and rapid transit service, originating in German-speaking countries. In general, S-Bahn systems link suburbs with the city centre at moderate speeds, while continuing across the urban core over a central high-frequency corridor where multiple lines converge, where they provide a rapid means of travel across the city. The name S-Bahn derives from the German terms (), (), and (; not to be confused with the modern Stadtbahn).

The first such network, the Berlin S-Bahn, began operation in December 1930 and inspired similar systems across Europe. The term "S-Bahn" has since become a generic term for hybrid suburban–urban rail networks, with counterparts such as the Stog in Denmark, STrein/TrainS in Belgium, Esko/Slines in the Czech Republic, LineeS in Italy, and SKM in Poland. The S-Bahn is also recognized as a train category in several European countries. The concept also influenced systems outside the German-speaking world, including the Réseau Express Régional (RER) in Paris and its counterparts in other cities.

S-Bahn network design principles are also present in several regional rail and commuter rail systems in the English speaking world primarily in Australia and New Zealand. The commuter rail systems of Auckland and of Australia's three largest state capitals (Sydney, Melbourne, and Brisbane) all have city centre viaducts or tunnels which enable through-running service for electrified suburban trains. In the US, SEPTA Regional Rail in Philadelphia is similar to an S-Bahn, using a city centre tunnel to enable extensive through-running. The San Francisco Bay Area's BART also uses a similar trunk-and-branches design with the Transbay Tube forming part of an interlined high-frequency trunk between West Oakland and Daly City.

Sydney and Philadelphia have also adopted a similar route naming system to European S-Bahn systems by using a letter (“T” in Sydney and “R” in Philadelphia) and a number to represent each line. Philadelphia dropped this naming system in 2010 in favour of giving each line the name of its terminal station.

Characteristics

There is no single, universally accepted definition of an S-Bahn system. In general, in the outer parts of a city, S-Bahn trains operate in a manner similar to conventional commuter rail, linking outlying towns with the city centre at moderate speeds. Unlike most commuter railways, however, S-Bahn services typically continue beyond the city’s main railway station, crossing the urban core on a high-frequency corridor where multiple routes converge. Stations along these central sections are spaced farther apart than on a typical rapid transit system (U-Bahn), enabling higher average speeds and providing a rapid means of travel across the city, even for passengers not travelling to or from the suburbs.

The Copenhagen S-tog, for example, operates at speeds of up to , while the Rhine-Main S-Bahn operates at up to . In densely populated areas, S-Bahn lines can link multiple urban centres rather than serving a single core city, as with the Rhine-Ruhr S-Bahn, which interconnects the cities and suburbs of the Ruhr region.

Many large S-Bahn systems have a dedicated underground or elevated trunk line through the central city, that individual suburban branches feed into, creating a high frequency corridor. In many cases, this is a grade-separated line in the city centre with close stop spacing and a high frequency, similar to metro systems. A good example of this is Berliner Stadtbahn, the main east–west axis of Berlin’s S-Bahn, which is regarded as a tourist attraction.

Outside city centres, S-Bahn services often run on existing local or regional railway infrastructure, sometimes parallel to long-distance tracks. In some cases, new infrastructure has been purpose-built, such as the Køgebugt (Køge Bay) line in Copenhagen, constructed between 1971 and 1983, or the S-Bahn tunnel between Hamburg Central Station and Altona, completed in 1979.

S-Bahn systems typically use electric trains supplied by overhead lines or a third rail; in Hamburg, both systems are used depending on the line.

Station spacing and service frequency vary widely. In suburban sections, stations may be more than apart and headways may extend to 30 or 60 minutes during off-peak hours. In contrast, central trunk lines in larger systems can operate at intervals as short as two minutes.

Rolling stock reflects this hybrid function: interiors are designed with standing room for those making short trip, but usually offer more seating comfort than metro trains.

S-Bahn systems are typically integrated into a city’s wider public transport network, with unified ticketing and convenient interchanges. In cities with both S-Bahn and metro systems, tickets are often valid across both, and interchange stations are common. Examples include the S-Bahn Mitteldeutschland, which serves Leipzig and Halle, and the Rostock S-Bahn, a smaller regional system

Etymology Germany, Austria and Switzerland The name S-Bahn is an abbreviation of the German Stadtschnellbahn ("city rapid railway") and was introduced in December 1930 in Berlin. The name was introduced at the time of the reconstruction of the suburban commuter train tracks— the first section to be electrified was a section of the Berlin–Stettin railway from Berlin Nordbahnhof to Bernau bei Berlin station in 1924, leading to the formation of the Berlin S-Bahn.

The main line Berliner Stadtbahn ("Berlin city railway") was electrified with a 750 volt third rail in 1928 (some steam trains ran until 1929) and the circle line Berliner Ringbahn was electrified in 1929. The electrification continued on the radial suburban railway tracks along with the timetable moving to a rapid transit model with no more than a 20-minute headway per line where a number of lines overlapped on the main line. The system peaked during the 1936 Summer Olympics in Berlin with trains scheduled at least every 2 minutes.

The idea of heavy rail rapid transit was not unique to Berlin. Hamburg had an electric railway between the central station (Hauptbahnhof) and Altona which opened in 1906, and in 1934 the system adopted the S-Bahn label from Berlin. In the same year in Denmark, Copenhagen's S-tog opened its first line. In Austria, Vienna had its Stadtbahn main line electrified in 1908 and also introduced the term Schnellbahn ("rapid railway") in 1954 for its planned commuter railway network, which started operations in 1962. The S-Bahn label was sometimes used as well, but the name was only switched to S-Bahn Wien in 2005.

As for Munich, in 1938 the Nazi government broke ground for an S-Bahn-like rapid transport system in Lindwurmstraße near what is now Goetheplatz station on line U6. The system was supposed to run through tunnels in the city centre. The planning process mainly consisted of the bundling and interconnecting of existing suburban and local railways, plus the construction of a few new lines. Plans and construction work - including the building shell of Goetheplatz station - came to a very early halt during World War II and were not pursued in its aftermath. Very extensive nowadays, Munich's existing S-Bahn system, together with the first two U-Bahn lines, only began to operate prior to the 1972 Summer Olympics.

The term S-Bahn was a registered wordmark of Deutsche Bahn until 14 March 2012, when, at the request of a transportation association, the Federal Patent Court of Germany ordered its removal from the records of the German Patent and Trade Mark Office.Beschluss Bundespatentgericht vom 14. März 2012. Juris.bundespatentgericht.de, Retrieved 14 April 2013. Prior to this Deutsche Bahn collected a royalty of 0.4 cents per train kilometer for the use of the term.

China China has a history of suburban railways (Chinese: 市郊铁路, which starts with an S in pinyin, Shìjiāo tiělù). In the early People's Republic of China, these trains were slow, stopping trains between a city and its suburbs, with only scarce frequency and limited capacity, not quite in the same sense as a German S-Bahn. They were gradually abolished over time as the railway improved.

However, a modern form in the sense of a rapid urban-suburban railway has since returned in 2011, when the Beijing Suburban Railway started to use S-prefixed numbers and was integrated into the urban transport system. Since then, the concept has spread to various metropolitan cities in China (see suburban and regional rail in China).

Denmark

The "S" stood for "station". Just before the opening of the first line in the Copenhagen S-train network, the newspaper Politiken on 17 February 1934 held a competition about the name, which in Danish became known as Den elektriske enquete or "The electrical survey" (as the Copenhagen S-trains would become the first electrical railways in Denmark). But since an "S" already was put up at all the stations, weeks before the survey, the result became S-tog which means "S-train".John Poulsen: S-bane 1934-2009 side 47 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 .

Poland These systems are called SKM, short for Szybka Kolej Miejska, meaning Rapid Urban Railway. It corresponds to the German term Stadtschnellbahn which means City Rapid Railway, although in Poland, the S means fast instead of city.

The first system in Poland was in Tricity, created in 1952, followed by Warsaw where the current form began in 2005.

History The history of the S-Bahn in present-day Germany begins in the 19th century in Prussia.

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 fare for the newly founded Berliner Stadt-, Ring- und Vorortbahn (Berlin City, Circular and Suburban Rail) was introduced on 1 October 1891. This fare and the increased frequency 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.See picture of Berliner Stadtbahn by Hackescher Markt S-Bahn station, the third rail is clearly seen between the two S-Bahn tracks. Original name of that station was "Börse", or "the Stock Market" (which now is located in Frankfurt am Main)

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.