The Rhine-Erft-Express runs from Mönchengladbach via the Cologne–Mönchengladbach line to Cologne, where it stops, despite its classification as a Regional-Express, at all stations.
Near Grevenbroich it crosses the Erft river.
In Cologne, it crosses the Rhine on the Hohenzollern Bridge and runs on the eastern bank via Porz (Rhein) to Troisdorf, where it runs on to the Right Rhine line.
Between Menden (Rheinl) and Unkel it stops at all stations.
Trains cross the Urmitz Railway Bridge over the Rhine via Koblenz Stadtmitte to Koblenz Hauptbahnhof.

In contrast, the RB 27 Rhein-Erft-Bahn takes a longer way via the airport loop with stop at Cologne/Bonn Airport to Troisdorf, also on to the Right Rhine line.
From Neuwied, the line RB 27 runs via Koblenz-Ehrenbreitstein and cross the Horchheim Railway Bridge over the Rhine to Koblenz Hauptbahnhof.
The Rhine-Erft-Express runs from Mönchengladbach via the Cologne–Mönchengladbach line to Cologne, where it stops, despite its classification as a Regional-Express, at all stations. Near Grevenbroich it crosses the Erft river. In Cologne, it crosses the Rhine on the Hohenzollern Bridge and runs on the eastern bank via Porz (Rhein) to Troisdorf, where it runs on to the Right Rhine line. Between Menden (Rheinl) and Unkel it stops at all stations. Trains cross the Urmitz Railway Bridge over the Rhine via Koblenz Stadtmitte to Koblenz Hauptbahnhof.
In contrast, the RB 27 Rhein-Erft-Bahn takes a longer way via the airport loop with stop at Cologne/Bonn Airport to Troisdorf, also on to the Right Rhine line. From Neuwied, the line RB 27 runs via Koblenz-Ehrenbreitstein and cross the Horchheim Railway Bridge over the Rhine to Koblenz Hauptbahnhof.
Rhein-Erft-Express