Siegstrecke
From 1998 the train service ran on the route from Krefeld via Neuss, Cologne, Siegburg and Siegen to Gießen. The service used old rolling stock, consisting of class 111 locomotives hauling five double-deck carriages. At the introduction of the next stage of the integrated timetable (ITF2) in December 2002, the line was the most vulnerable to delay in North Rhine-Westphalia. The causes of these delays were the single track sections of the Sieg Railway, work in connection with the completion of the Cologne–Frankfurt high-speed line and the upgrading of the Sieg Railway for S-Bahn operations, speed restrictions between Cologne and Krefeld and a very short turnaround time in Krefeld of 12 minutes.