The proposed high-speed rail line Nijmegen – Köln would create a new route into Krefeld from the Netherlands. A new line from Krefeld to Düsseldorf is a logical extension of that route. The high-speed line (HSL) would bypass Krefeld itself, but would have a short link to the existing line from Kempen. With a new line across the Rhine, trains from Nijmegen could leave the HSL, serve Krefeld, and then continue to Düsseldorf. The new line would also give the existing regional line from Kleve (Linksniederrheinische Strecke), a more direct route into Düsseldorf.
The proposed HSL Venlo – Neuss would also create a new route into Krefeld. It would connect to the Viersen – Krefeld line at Anrath. In that case, however, it is more logical that trains from Venlo continue toward Duisburg over existing lines.
Existing routes Krefeld – Düsseldorf
There is no direct rail connection from Krefeld to Düsseldorf, at least no mainline railway. The Stadtbahn Düsseldorf has two lines to Krefeld, U70 and U76. Despite the U prefix, only the central Düsseldorf section is in tunnel. With 25 intermediate stations on the 23-km route, this line is not intended for fast travel between city centres. Built in 1898 as an interurban tram line, it is unsuitable for any other type of service.
Otherwise, travel from Krefeld to Düsseldorf requires a detour. The shortest route is south to Neuss, and then across the Rhine into Düsseldorf. It is also possible to go northeast to Duisburg, and then south to Düsseldorf. That route passes Düsseldorf Airport, the third largest in Germany. However, Bahnhof Düsseldorf Flughafen has a peripheral location, with a people-mover connection to the terminals.
There were plans for a new S-Bahn line S22, from the airport terminal across the Rhine, to Meerbusch on the Neuss – Krefeld line. That would have connected Krefeld to Düsseldorf, but again via an indirect route: the plans have been abandoned anyway.
The ideal route would be from Düsseldorf, via the airport, to Krefeld. That would require a new station under the terminal and under the existing S-Bahn station, aligned roughly northwest to southeast, with a tunnel under the runways. That seems impossible to build under a functioning airport. There is no point in building a second peripheral station, so the best option is to use the existing line past the airport, and the existing Düsseldorf Flughafen station. Trains would therefore use the main Düsseldorf – Duisburg line for 8 km, to that station. It has sufficient capacity: two platforms for the S-Bahn Rhein-Ruhr, and four tracks for the main line.
A new alignment to Krefeld would diverge from the main line at the airport perimeter, and turn west to cross the Rhine. It would join the line into Krefeld at the Oppum rail junction, about 3 km from Krefeld Hauptbahnhof. The exact alignment would be determined by the built-up areas, and possibly by the local geology. Certainly the Rhine would be crossed in tunnel, somewhere between Wittlaer and Kaiserswerth. To pass under the built-up area here, the entire alignment on the east bank could be in tunnel.
On the west bank, the line would probably pass under Nierst: it would still be in deep tunnel here, so close to the river. After that, the line would pass between Gellep-Stratum and Lank, toward Oppum. This is an agricultural area, so the line could be on surface.
Close to Oppum the line must cross a new commercial zone. Some demolition will be inevitable here, but that can be minimised by following the Heinrich-Malina Strasse. This section would be in cut-and-cover tunnel, ending at a grade-separated junction with the line from Duisburg. It would be logical to reconstruct the entire three-way junction at Oppum. If there is insufficient space, then the new line might continue in tunnel alongside Krefeld-Oppum station, joining the existing four-track section west of the station.
The new alignment would be about 13 km long. Krefeld would then be 17 km from Düsseldorf Flughafen station, and 25 km from Düsseldorf Hauptbahnhof. The route would have two intermediate stations: Düsseldorf Flughafen and Oppum (if the junction design allows access to the platforms).
The constraints on the alignment will limit high speeds, but the journey time should be under 12 minutes. For the HSL, the new line would create two routes from Nijmegen to Köln: one via Neuss, and one via Krefeld and Düsseldorf. Some high-speed trains might stop at Düsseldorf Flughafen station. All regional services from the Linksniederrheinische Strecke would certainly stop at the airport.