The Regionalbahn (abbreviated RB) is a type of local passenger train (stopping train) in Germany.
Regionalbahn trains usually call at all stations on a given line, with the exception of RB trains within S-Bahn networks, these may only call at selected stations. Thus, they rank below the Regional-Express train, which regularly stops only at selected stations on its route.
RB trains are subject to franchising by the federal states of Germany; whilst many RB trains are still operated by DB Regio, the local traffic division of the former monopolist Deutsche Bahn, franchises often go to other companies, like Veolia Verkehr, eurobahn or Abellio Rail.
There is no obligation to use the term Regionalbahn for basic local services; some private rail operators therefore use their own names to denote their trains.
RB services make use of vastly different types of rolling stock; on electrified lines, double-deck cars or EMUs may be used, on non-electrified lines one will often find Class 218 locomotives with Silberling cars or newer DMUs like the Bombardier Talent.
The Hagen–Dieringhausen railway (also called the Volmetalbahn: Volme Valley Railway) is a mostly single-track (continuously double track as far as Brügge) and non-electrified railway line from Hagen Hauptbahnhof via Brügge, Meinerzhagen and Gummersbach to Dieringhausen in the German state of North Rhine-Westphalia.
The Volmetalbahn is also the name of the trains running on this line as Regionalbahn service RB 52, from Lüdenscheid via Hagen to Dortmund. The Brügge–Marienheide section is not used for passenger services, but the RB 25 (Oberbergische Bahn) service runs from Marienheide to Cologne on the line.
The railway and the Regionalbahn service is named after the Volme river, which it largely follows.
The route was studied in the 1840s as an alternative to the route of the Ruhr–Sieg railway. In May 1870, the Bergisch-Märkische Railway Company (Bergisch-Märkischen Eisenbahn-Gesellschaft, BME) began construction of the Volme Valley Railway. The route was opened from Hagen to Oberhagen on 16 October 1871 and the line was extended to Dahl for freight traffic on 15 March 1874. On 6 September 1874 this section was released for passenger services. After the nationalisation of the BME, the Volme Valley Railway was extended to Brügge via Meinerzhagen towards Marienheide and Gummersbach in 1891/92. The entire route was completed to Dieringhausen in 1893. Construction of an extension via Krummenerl for connection to the Finnentrop–Freudenberg railway (Bigge Valley Railway) and on to Kreuztal was started several times, but not completed. Construction stopped at Krummenerl in 1927.