 The S12, S13 and S19 services provide a service every 15 minutes on the central section between Köln-Ehrenfeld and Köln-Trimbornstraße.The route runs on the Cologne–Aachen line (opened by the Rhenish Railway Company between Cologne and Düren in three stages between 1839 and 1841), the East Rhine Railway (opened to Troisdorf by the Rhenish Railway in 1870, with an extension to Cologne opened in 1874) and the Cologne Airport loop (opened in 2004) The western section of the S 13 service from Düren to Köln Messe/Deutz was opened on 15 December 2002.It was extended to Troisdorf on 13 June 2004.