Its principal business was the operation of a metre-gauge railway serving Mannheim, Heidelberg and Weinheim. Until December , the OEG also operated municipal buses in Weinheim, some bus routes in the southeast of Mannheim and several other bus routes in the vicinity of Schriesheim and Ladenburg. In order to focus on electric trams, a few railways were spun off the SEG and transferred to newly established companies. In order to carry out the electrification of the line and to allow the expansion of its tram network, the city of Mannheim in cooperation with the SEG, which had acquired the Mannheim-Weinheim-Heidelberg-Mannheim railway, founded the Oberrheinische Eisenbahn-Gesellschaft AG OEG in In order to prevent domination by the RWE, the city of Mannheim held a majority of the shares of the company.
The rest was accounted for by three other shareholders. The OEG took over the operation of the lines on 1 April To mitigate financial problems after the First World War, the city of Mannheim took over the railways from the OEG, while the company with retained power plants and electric distribution remained in the hands of Stinnes and was renamed Kraftwerke Rheinau. The city of Mannheim contributed the railway of the former OEG to the new company.
At the time of the line's construction, Rheinau was not yet incorporated in Mannheim and was therefore in the jurisdiction of the OEG according to the existing cooperation agreements.
This changed with its incorporation in Mannheim in , so the line was then used by the city's tramway and it passed into its possession in In , the first section of the MannheimโFeudenheimโ Ilvesheim โLadenburgโSchriesheim line was opened to Feudenheim for temporary freight traffic. In addition, the line was operated for two months by the city's tram services, prior to the commencement of OEG operations.
Land on the adjacent section had been purchased and works had commenced including on bridges on the remaining route, but work had to be abandoned because of the First World War. Since the construction could not be completed even after the war for economic reasons, the OEG began operating its first bus line on the route in It was intended to be temporary, awaiting the finishing of the line, but it has continued to this day.
