The Rhein-Main agglomeration has 2-5 million inhabitants, depending on its definition. Its core is the region between Mainz, Wiesbaden and Frankfurt. The present rail lines between Wiesbaden and Frankfurt follow the river Main. A new and shorter northern route is possible, generally along Autobahn 66 (Rhein-Main Schnellweg). The new line could carry an express service from city centre to city centre, or a new S-Bahn line, connecting to line S2 of the Rhein-Main network.
There was no historical railway on this alignment, but in 2002 a new link line was built from Wiesbaden to the Köln – Frankfurt high-speed line (HSL). The 13-km Wiesbaden – Breckenheim link never attracted much traffic, and is severely underused (a few trains per day). With no intermediate stations, it is suitable for fast regional services: it could be extended toward Frankfurt. It was not, however, designed for an S-Bahn service.
Route and services
There are three options for a new line. The first is an inter-urban express service via Frankfurt Airport, with one stop there.
From Wiesbaden, trains would use the Breckenheim link line. The first 3 km follow an older alignment (the single-track Ländchesbahn). At the edge of Wiesbaden, the new link dives under the Autobahn 66. It then runs alongside it on the south side, to Junction 8 (Wallau). There it turns north, to join the Köln – Frankfurt HSL toward Köln.
A new 3-km curve could connect the Breckenheim link to the HSL, in the direction of Frankfurt. This option, the Wallauer Spange, has local political support, but there is no immediate prospect of construction.
The HSL crosses the Main, and turns east into the airport station (S-Bahn and regional trains have their own station). Frankfurt am Main Flughafen Fernbahnhof has 210 trains per day, so it has spare capacity – at present. With more frequent ICE and Intercity trains, there would be capacity problems on the HSL between Breckenheim, the airport, and Frankfurt Hauptbahnhof. Extra tracks can be added relatively easily: the station has enough platform capacity.
Via this route, the airport would be 26 km from Wiesbaden, and the route to Frankfurt Hauptbahnhof 38 km long. Even with a stop at the airport, a journey time of under 20 minutes should be possible. The service could also run Wiesbaden – Airport- Darmstadt. This option has some local support, primarily as compensation for loss of ICE services to Darmstadt.
The second option is a non-stop express service, from Wiesbaden to Frankfurt, via the shortest possible route. (That is approximately the function of Autobahn 66). The new line would be 34 km long, saving 6-7 km compared to the existing 41-km Taunus line, on the north bank of the Main. It would also create extra capacity.
For this option, the Breckenheim link line can simply be extended alongside the A66, on the southern side, to the Autobahn junction at Kriftel. There, the new line would leave the Autobahn, and join the existing Main-Lahn railway, about 1 km west of Zeilsheim station. The only problem on this alignment is the area of gravel pits beside the A66 at Weilbach, combined with a sharp bend. The Autobahn can be shifted to the north, allowing a rail curve for high speeds.
The line through Zeilsheim carries S-Bahn line S2, and would need separate tracks for an express service. At Höchst, it joins the Taunus line, and from there the S-Bahn has separate tracks into Frankfurt Hauptbahnhof.
Click to enlarge: A66 alignment…
This line is intended to link the city centres. Adding an additional stop at Höchst would improve interchange with S-Bahn lines, and another stop at Höchst Farbwerke would serve over 20 000 employees at the Industriepark Höchst. However, if extra stops are added, then this would not be an express line anymore.
That leads to the third option: a new direct S-Bahn line Wiesbaden – Frankfurt.
An optimal route would be mainly on the north side of the A66, for better station locations. However, it would share the Breckenheim link line as far as Erbenheim. There is no conflict with the few ICE services – they might be withdrawn entirely. However it is not possible to run S-Bahn trains on the Köln – Frankfurt HSL itself (via the Wallauer Spange), as some local opinion prefers.
Click to enlarge: S-Bahn via Wallau…
At Erbenheim, there would be a new station on the south side of the Autobahn, at the Rennbahn underpass. There is insufficient space on the north side, and this option avoids a new tunnel under junction 6.
The S-Bahn would then cross back to the north side, on a new separate alignment. That allows a better station location at Nordenstadt (behind the Real-Markt), but it must be in tunnel, because the line would cross junction 7. There would be a similar station location at Wallau, behind the IKEA.
Click to enlarge: S-Bahn to Wallau IKEA…
The new line would now cross the Breckenheim link, the Wiesbadener Kreuz, and the HSL Köln – Frankfurt. After passing junction 10, the line would turn away from the Autobahn. It would run along the edge of the built-up area, past Hofheim-Diedenbergen and Hofheim-Marxheim, with stations at Weilbacher Strasse and Königsberger Weg. The line would then turn toward the existing S-Bahn line S2, east of Kriftel station. This section would be in tunnel.
Click to enlarge: S-Bahn Wallau – Kriftel…
From Kriftel, it is 15 km over the existing line. to Frankfurt Hauptbahnhof. The existing S2 continues under the city centre: the new line from Wiesbaden could terminate at Hauptbahnhof, or use the planned tunnel to Frankfurt-Ost station. Its eastern terminus is not considered further here.
The S-Bahn line would also be 34 km long, Hauptbahnhof to Hauptbahnhof, with about 12 km of completely new alignment, and 5 new stations. With 10 intermediate stations, the average station spacing would be 3 km, which is normal for an S-Bahn line. Compared to the existing S1 line along the river, it has a shorter route, and serves areas which have no S-Bahn stations at present.
The three lines have different functions, and are not directly comparable. The first two options could however be combined: that is simply a question of adding more infrastructure. Even with a 15-minute service interval, the Breckenheim link has enough capacity for two express services.