Upper Rhine Railway Company

After the death of Hermann Bachstein in 1908, the Rhenish industrialist Hugo Stinnes took over the majority of SEG in 1909 with the aim of taking control of the electric tramways of the Ruhr and other major cities as part of the RWE (Rheinisch-Westfälisches Elektrizitätswerk AG) power company so that they could be connected to the electric grid of western Germany. 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 1911. In order to prevent domination by the RWE, the city of Mannheim held a majority of the shares of the company. The Schwetzingen–Ketsch Tramway (Straßenbahn Schwetzingen–Ketsch) and two power plants in Ladenburg and Rheinau were acquired by the OEG. 51% of the share capital was held by the city of Mannheim and 26% by the SEG. The rest was accounted for by three other shareholders. The OEG took over the operation of the lines on 1 April 1911.

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 now independent company of Oberrheinische Eisenbahngesellschaft was established by the cities of Mannheim, Heidelberg, Weinheim, Viernheim and the Rhein-Haardtbahn GmbH (Rhine-Haardt Railway, builder of the Bad Dürkheim–Ludwigshafen-Oggersheim railway). The city of Mannheim contributed the railway of the former OEG to the new company.

The OEG tram line from Neckarau to Rheinau (then called Rhenaniastraße) was opened in 1913. 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 1913, so the line was then used by the city's tramway and it passed into its possession in 1921.

In 1914, the first section of the Mannheim–Feudenheim–Ilvesheim–Ladenburg–Schriesheim 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 1925. It was intended to be temporary, awaiting the finishing of the line, but it has continued to this day. The freight traffic to Freudenheim was abandoned along with the line in the late 1920s.

Like most transport companies in Germany, the OEG had a huge increase in ridership after the war to cope with, especially in 1945 when only half of its fleet was available. In 1947 patronage reached a peak of 25.6 million passengers. One of the reasons for the increase was the phenomenon of so-called "foraging trips", when cheap fares encouraged people to barter for food with farmers. Ridership returned to normal after the currency reform of 1948.

After overcoming the post-war difficulties, the OEG had to deal with incipient mass motorisation. Its goal was to become faster and more convenient in order to hang on to patronage. A first step was the purchase of four open coaches, together with trailer carriages from Waggonfabrik Fuchs.

With the founding of the RNV, it was faced with the problem that there were up to three vehicles designated with the same company number. So as not to have to fundamentally change all documents and vehicle files, the former operating numbers were simply preceded by a fourth digit. This number usually represents the old company. Initially, the new numbering system was used internally for the automatic vehicle location system and then it was installed on the outside of almost all vehicles during 2009 and 2010.

The rail vehicles of the OEG were given the initial designation of 4. So former car 98 is now called 4098 and car 123 is now 4123.

The buses of the OEG were given the initial designation of 9. However, due to the suspension of OEG bus operations in December 2009, the extended numbers were never attached to the outsides of the buses.