S-Bahn services commenced between old Lütgendortmund station and Unna station on 3 June 1984. The section from Germania to old Lütgendortmund station was closed on 31 August 1987 and operations on the new line to Lütgendortmund commenced on 23 May 1993.[2]
Extension of the S 4 line from its current western end in the tunnel at Dortmund-Lütgendortmund was formerly planned to be implemented with a target of opening it in 2015. This would have included an extension of the single-track tunnel to the immediate south of Dortmund-Bövinghausen station. The S 4 would run from there to Herne on the Duisburg-Ruhrort–Dortmund railway (the Emscher Valley Railway of the Cologne-Minden Railway Company) and there take over the Herne–Essen branch of the current S 2 line. The Emschertal-Bahn (RB 43) Regionalbahn service would only operate between Herne and Dorsten. The eastern section of the Emscher Valley Railway between Dortmund-Bövinghausen and Dortmund Hauptbahnhof would be used by a new line of the Dortmund Stadtbahn. For a long time funds have been available for the construction of the line to Bövinghausen, however, the financing for the operation of the line is not guaranteed. The Emschertal-Bahn runs between Dortmund-Bövinghausen and Herne every hour, but the S2 would run between Herne and Essen every twenty minute as an S-Bahn service, so the Verkehrsverbund Rhein-Ruhr would have to fund the increased services through savings in other areas. Upon taking office, the transport minister Oliver Wittke called for all such proposals to be re-evaluated. The line extension has been removed from the integrated transportation plan for North Rhine-Westphalia; a resubmission is possible from 2015.
References
^Eisenbahnatlas Deutschland (German railway atlas). Schweers + Wall. 2009. p. 139. ISBN978-3-89494-139-0.
