The Rhine-Ruhr S-Bahn () is a polycentric and electrically driven S-bahn network covering the Rhine-Ruhr Metropolitan Region in the German federated state of North Rhine-Westphalia. This includes most of the Ruhr (and cities such as Dortmund, Duisburg and Essen), the Berg cities of Wuppertal and Solingen and parts of the Rhineland (with cities such as Cologne and Düsseldorf). The easternmost city within the S-Bahn Rhine-Ruhr network is Unna, the westernmost city served is Mönchengladbach.
The S-Bahn operates in the areas of the Verkehrsverbund Rhein-Ruhr and Verkehrsverbund Rhein-Sieg tariff associations, touching areas of the Aachener Verkehrsverbund (AVV) at Düren and Westfalentarif at Unna. The network was established in 1967 with a line connecting Ratingen Ost to Düsseldorf-Garath.
The system consists of 16 lines. With a system length of , it is the second-largest S-Bahn network in Germany, behind only the S-Bahn Mitteldeutschland. Most of them are operated by DB Regio NRW, while line S28 is operated by Regiobahn and S7 by Vias. The S19 will run 24/7 between Düren and Hennef for 17 stations and not only between Cologne Hbf and Cologne/Bonn Airport.
Rolling stock history
Age of steam
The predecessor of the S-Bahn was the so-called Bezirksschnellverkehr between the cities of Düsseldorf and Essen, which consisted of steam-powered push-pull trains, mainly hauled by Class 78, since 1951 also Class 65 engines.
Early electric years
The first S-Bahn lines were operated using Silberling cars and Class 141 locomotives. However these were not suited for operations on a rapid transit network and were soon replaced by Class 420 electric multiple units.
Originally designed for the Munich S-Bahn, the Class 420 was judged in the mid-1970s to be unsuitable for the network, mainly due to being uncomfortable and lacking on-board toilets and not being walk-through, since one could travel rather long distances on the Rhine-Ruhr network.
The x-Wagen era
Constructing an improved version of the 420 with the tentative designation Class 422 was discussed, but in 1978 the Deutsche Bundesbahn commissioned a batch of coaches from Duewag and MBB. These lightweight and modern coaches were designated as x-Wagen ("x-car") after their classification code Bx. Among the design elements inherited from the recent LHB prototype carriages were the bogies with disc brakes and rubber airbag shock absorbers that also included automated level control, ensuring level boarding from S-Bahn platforms with a standard height of 96 cm regardless of varying passenger loading.
In late 1978, the first prototypes of 2nd class type Bx 794.0 cars and Bxf 796.0 control cars were handed over to DB, followed by split first/second class cars type ABx 791.0 in early 1979. The prototypes were successful, so from 1981 to 1994 several series were commissioned, with some going to the Nuremberg S-Bahn system.
The x-Wagen were mechanically coupled to form fixed sets of typically one ABx car, one or two Bx cars and one Bxf control car. This way a train offered seating for a total of 222 to 302 passengers and standing room for another 429 to 539 passengers. A few five-car sets ran on peak time services. All cars were of a walk-through design with mechanical doors at each end. Initially the ABx car ran on the loco end to keep passengers looking for a seat from disturbing first-class passengers. The orientation of trains was not predictable in practice however, so the ABx car was instead put in the middle of the train. In later years, when insufficient numbers of Bx cars were ready for service, some trains ran with two ABx cars.
Traction was provided by the Class 111 locomotives produced locally by Krupp in Essen. They had been designed for long-haul Intercity and limited-stop commuter train services with a maximum speed of and were not an ideal fit for rapid transit duty. After the German reunification, even before the old Deutsche Bundesbahn was merged with the Deutsche Reichsbahn of East Germany to form the new Deutsche Bahn AG, the Class 143 Reichsbahn engines replaced the Class 111 on the S-Bahn network, limiting the top speed on the network to but with better acceleration and noticeably less jolting.
Rolling stock today
The Cologne S-Bahn section went into full operation in 2002 in conjunction with the opening of the Cologne-Frankfurt high speed line. It runs with Class 423 EMUs on lines S11, S12 and S13/S19. Due to recent service improvements, there are insufficient numbers of Class 423 EMUs available, so Class 420 electric multiple units can be found on line S12.