Line S2 is a S-Bahn line in the Rhein-Ruhr network. It starts in Dortmund Hauptbahnhof and runs westerly. During weekdays one service per hour runs each to Duisburg Hauptbahnhof, Essen Hauptbahnhof and Recklinghausen Hauptbahnhof using class 422 electric multiple units. In the evenings and on weekends, only services to Duisburg and Essen are offered.
Line S2 runs over lines built by various railway companies:
from Dortmund Hauptbahnhof to Dortmund-Mengede over a line opened by Deutsche Bundesbahn on 2 June 1991, largely using part of the track bed of the Welver–Sterkrade railway, built by the Royal Westphalian Railway Company on 1 September 1878.
from Dortmund-Mengede to Duisburg via Herne station and Gelsenkirchen Hauptbahnhof over the Duisburg–Dortmund Railway opened by the Cologne-Minden Railway Company in 1847,
from Gelsenkirchen to Essen over the Essen–Gelsenkirchen railway, opened from Gelsenkirchen to Essen-Kray Nord by the Rhenish Railway Company in 1872 and from Essen-Kray Nord to Essen by the Prussian state railways in 1905,
from Herne to Recklinghausen over tracks competed in October 1901 by Deutsche Reichsbahn and the Wanne-Eickel–Hamburg railway opened by the Cologne-Minden Railway Company in 1870.
S-Bahn services commenced between Dortmund and Duisburg on 2 June 1991. Services commenced between Dortmund and Essen on 29 September 1991. Services commenced between Dortmund and Recklinghausen on 24 May 1998.
