Köln Hauptbahnhof is notoriously congested, and it is on the wrong side of the river for ICE services from Düsseldorf to Frankfurt. They must either reverse, or use Köln-Deutz instead, at the other end of the Hohenzollern Bridge. A new link line across the Rhine, north of Leverkusen, would solve that problem. However, it would not add capacity in Köln itself, and extra capacity is needed for the proposed high-speed rail line Nijmegen – Köln, and the associated HSL from Venlo.
Click to enlarge: the Hohenzollernbrücke is aligned exactly with the Cathedral. This symbolic plan required a sharp bend into the station, further restricting capacity. Creative Commons licence 2.0, image by dolorix.
The proposal here would link the right-bank Leverkusen line, to the left-bank Bonn line, via a new 6-km tunnel under the city centre. Existing lines through Köln Hauptbahnhof do that already, but they are overloaded. (S-Bahn service on the existing western ring line is planned, but that will not increase capacity through the Hauptbahnhof). The alignment shown is indicative. Detailed investigation would be needed for any tunnel under the historic centre of Köln – the city archive collapsed into a Stadtbahn tunnel construction site in 2009.
Click to enlarge…
The proposed new line would carry primarily S-Bahn and regional services. It would have a maximum of four intermediate stations, connecting with the existing Stadtbahn Köln network (which has tunnel and surface sections):
- a station in eastern Deutz would connect with Stadtbahn lines 1 and 9 (at Deutz-Kalker Bad)
- a station close to the Rhine bank in Deutz, would connect with Stadtbahn line 7 (at Severinsbrücke)
- a station near Severinstrasse would connect with Stadtbahn lines 3 and 4, and with the new north-south Stadtbahn line
- a station at Eifelstrasse, where the line crosses the Boulevard ring, would connect with Stadtbahn lines 12, 15, and 16.
A minimal option, for express services only, would have only one station, at Severinstrasse.
The northern portal of the tunnel would be at the north end of the railway yards at Köln-Deutzerfeld, south of Köln-Mülheim station. It would be accessible from the lines out of Köln to the north-east, to Düsseldorf and Wuppertal. Present services through Köln-Mülheim are:
- S-Bahn S6 to Essen via Düsseldorf, and S11 to Bergisch Gladbach
- Regional-Express RE1 to Hamm via Essen, RE5 to Emmerich via Duisburg, RE7 to Dortmund via Wuppertal
- Regionalbahn RB48 to Wuppertal.
The southern portal would be at the Köln-Eifeltor rail yard, on the line from Bonn. It would be south of the junction with the western ring line, between the planned S-Bahn stations Köln-Klettenberg and Köln-Weisshausstrasse. Via Hürth on the Bonn line, the tunnel would also be accessible from the Trier line, which will be electrified for the planned S14 to Jünkerath. Present services through Köln-Eifeltor are:
- Regional-Express RE5 to Koblenz, RE12 to Trier, RE22 to Gerolstein
- Regionalbahn RB26 to Koblenz, RB48 to Bonn-Mehlem, RB24 to Gerolstein.
Both portals are at 50-55 m elevation. Under the Rhine, the tunnel must drop to 15-20 m – river level at Köln varies from 35 m to 45m elevation. The north-south Stadtbahn line is 20 m under the surface at Severinstrasse, i.e. at about 30 m elevation. A descending gradient of 2,5% from the southern portal should be sufficient to clear the Stadtbahn tunnel and the Rhine: the northern portal is less of a problem in that respect.
Click to enlarge: existing route highlighted in blue, proposed line in red.
The major disadvantage of this tunnel, is that is has no interchange, with the south-east to north-west lines through Köln Hauptbahnhof. It therefore requires retention of some existing parallel services, through Köln-Mülheim, Hürth-Kalscheuren, and the planned S-Bahn station Köln-Klettenberg. Its great advantage is a shorter direct route from north-east to south-west (existing route in blue). It also needs no complex junction with the south-east to north-west line, and construction will not disrupt services on the most overloaded lines in Köln.