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Line S12 is a S-Bahn

S-Bahn

S-Bahn refers to an often combined city center and suburban railway system metro in Austria, Germany, Switzerland and Denmark...

 line of the Rhine-Ruhr network in Germany

Germany

Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

. It is operated by DB Regio

DB Regio

DB Regio AG is a subsidiary of Deutsche Bahn which operates short and medium distance passenger train services in Germany, and operates light and heavy rail infrastructure in the United Kingdom.-Germany:...

. The S12 runs from Düren

Düren station

Düren station is located to the north of the centre of Düren and is the largest station in the city and the district of Düren. It is located at the intersection of the Cologne–Aachen high-speed line with the lines to Linnich, Heimbach and Euskirchen. Until 1992 it was also connected to the Erft...

 via Cologne

Köln Hauptbahnhof

Köln Hauptbahnhof is the central railway station in Cologne, Germany.The station is an important local, national and international hub, with many ICE, Thalys and Intercity trains calling there, as well as regional RegionalExpress, RegionalBahn and local S-Bahn trains...

 to Au (Sieg)

Au (Sieg) station

Au station is a railway junction in the town of Au in the German state of North Rhine-Westphalia on the Sieg Railway to Siegen, where the Engers–Au railway branches off to Altenkirchen, where it connects with the Upper Westerwald Railway ....

. It shares this route for most of its run with the line S 13. With over 105 kilometres (65.2 mi), it is the second longest line in the Rhine-Ruhr network, after S9. Services operate every 20 minutes on working days and every 30 minutes on Saturdays, Sundays and public holidays as far as Hennef (Sieg)

Hennef (Sieg) station

Hennef station is located on the Sieg Railway in the town of Hennef in the German state of North Rhine-Westphalia. It was opened in 1859 for passenger and freight traffic by the Cologne-Minden Railway Company along with the Sieg Railway....

 using class 423

DBAG Class 423

The Class 423 EMU is a light-weight articulated electric railcar for S-Bahn commuter networks in Germany. The train has similar dimensions to its predecessor, the Class 420 EMU, but is significantly lighter and has one large passenger compartment, while that of the 420 is divided into three parts...

 electric multiple units. It operates hourly between Hennef and Au.

The route runs on the Cologne–Aachen line (opened by the Rhenish Railway Company

Rhenish Railway Company

The Rhenish Railway Company was along with the Cologne-Minden Railway Company and the Bergisch-Märkische Railway Company one of the railway companies that in the mid-19th century built the first railways in the Ruhr and large parts of today's North Rhine-Westphalia.-Foundation :The...

 between Cologne and Düren in three stages between 1839 and 1841), the East Rhine Railway (opened to Troisdorf by the Rhenish Railway in 1870, with an extension to Cologne opened in 1874) and the Sieg Railway (opened by the Cologne-Minden Railway Company

Cologne-Minden Railway Company

The Cologne-Minden Railway Company was along with the Bergisch-Märkische Railway Company and the Rhenish Railway Company one of the railway companies that in the mid-19th century built the first railways in the Ruhr and large parts of today's North Rhine-Westphalia.-Founding :The founding of the...

 between 1859 and 1862). The eastern section of the S 12 service from Au (Sieg) to Köln-Nippes was opened on 2 June 1991. It was extended to Düren on 13 June 2004, dropping Köln-Nippes.