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^{[citation needed]}, mainly due to being uncomfortable and lacking on-board toilets^{[citation needed]} and not being walk-through, since one could travel rather long distances on the Rhine-Ruhr network.^{[original research?]}

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 160 km/h (99 mph) 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 120 km/h (75 mph) 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.

Starting in 2008, 84 units of Class 422 were introduced in the Ruhr area section and around Düsseldorf, replacing the x-Wagen loco-hauled trains.

These newer classes of EMUs once again increased the maximum speed on the network to 140 km/h (87 mph) where permitted, which together with the better acceleration of the EMUs did reduce delays that had become entrenched in the latter years of x-Wagen operations.

The S28 is not operated by DB Regio NRW, but by Regiobahn, which uses Bombardier TALENT DMUs. The S7 uses Alstom Coradia LINT DMUs and is operated by Abellio Rail NRW.

New electric rolling stock for the S5 and S8 lines was introduced in December 2014 after having been tested on S68 since October 2014. These Alstom Coradia trains are operated by DB Regio NRW and offer on-board toilet facilities.

All trains of Rhine-Ruhr S-Bahn ran with the red DB livery except for the S7 and S28 trainsets which are painted in the colours of their respective operators.

Rolling stock after 2019

Starting in December 2019, there will be major changes in the Ruhr area section of the network: The standard service pattern will be altered from a 20-minute to a 30-minute or 15-minute headway. Services around Düsseldorf and Cologne will not be affected and remain on their 20-minute schedule.

Several services will no longer be operated by DB Regio NRW, but by Abellio Rail NRW.^[3] Simultaneously, the livery of all trains will change to green and white to uphold a uniform appearance regardless of operator.^[4]

Lines S2, S3 and S9 as well as several Regionalbahn lines that will complement or supplant S-Bahn services will use Stadler FLIRT 3 XL units. Upon eventual electrification, those are also going to run on line S28, sporting Regiobahn's red and white livery.

Lines before December 2019

Kursbuchstrecken 450.x (x is equivalent to the number of the line), as of 13 December 2009.

Lines after December 2019