S13 (Rhine-Ruhr S-Bahn)

It was operated by DB Regio with class 423 electric multiple units.

At peak times, the S13 services began or end at Düren and run via Cologne to Troisdorf.

It ran with line S12 for most of its route, splitting from it only to run through Cologne/Bonn Airport.

The western section of the S 13 service from Düren to Köln Messe/Deutz was opened on 15 December 2002.

However, the S13 will be reintroduced after constructing the extension of the railway between Troisdorf and Bonn-Beuel (– Bonn Oberkassel) which is likely going to happen in 2025.