The Warburg–Sarnau railway is a 100.9 kilometre-long, single-track, partially disused secondary railway line in North Rhine-Westphalia and North Hesse. The middle section, Korbach–Frankenberg, is called the Untere Edertalbahn or the Nationalparkbahn and the southern section, Frankenberg–Sarnau(–Marburg), is called the Burgwaldbahn.

The Kreuztal–Cölbe railway is a 88-kilometre-long main line in Hesse and North Rhine-Westphalia, Germany. It branches off the Ruhr–Sieg railway at Kreuztal and runs via Erndtebrück, Bad Laasphe and Biedenkopf to Cölbe. Operationally, the line is now divided into two parts. The Kreuztal–Erndtebrück section is operated together with the Erndtebrück–Bad Berleburg railway as the Rothaar-Bahn and the subsequent section to Cölbe, now operated by the Kurhessenbahn, is called the Obere Lahntalbahn. Trains at the eastern end of the line run to/from Marburg (Lahn).