Sieg Railway
From Cologne, the Rhine-Sieg Express follows the Sieg Railway along the Sieg to Siegen. In Siegen there is a regular connection with the Main-Sieg-Express (RE 99) towards Gießen and Frankfurt. In addition connections exist to the Rothaar Railway (RB 93) to Bad Berleburg and to the Ruhr-Sieg-Express (RE 16) to Essen.