The overall concept involved a mixed system of trams (operated by the SSB) and heavy rail (operated by the KBE). However, the KBE went into financial decline at the end of the decade and survived only with the support of the North Rhine-Westphalia government; in this environment expansion was impossible. Instead, the railway lines of the KBE would be used to provide a link between Bonn and the Cologne tram network.
The overall concept involved a combined system of trams (operated by SSB) and heavy rail (operated by KBE). However, the KBE's financial struggles at decade's end made it reliant on government support; in this context, expansion was not possible. Instead, KBE's railway lines would be used to connect Bonn with Cologne's tram network.