Historically, there were three routes from Vienna (Wien) to Bratislava (formerly Pressburg / Pozsony). One was south of the Danube, via Bruck an der Leitha and the Wien-Raaber Bahn. It was a main route from Vienna to Budapest, the two capitals of Austria-Hungary. (The river Leitha formed the boundary, between the two halves of the empire). At Parndorf, 49 km from Vienna, the Pressburg line branched off. This route is still in use to Petržalka, today a southern suburb of Bratislava (73 km, in just under one hour). The former single-track link over the Danube to the city centre, has been abandoned, but a circuitous route through the western suburbs connects Petržalka to the main station Bratislava Hlavná Stanica.
The second main route is north of the Danube: the Marchfeld line via Marchegg and Devínska Nová Ves. From Bratislava, this line continued to Budapest. Near the station, it also connects to the line to Žilina via Trnava. Journey time (Wien Südbahnhof to Bratislava Hlavná Stanica) is also just under one hour. A third Vienna – Bratislava route followed the south bank of the Danube. It was a single-track local railway, more like an interlocal tram: the Pressburger Bahn. It is still in use as line 7 of the Vienna S-Bahn, as far as Wolfsthal. It has been substantially upgraded between the city centre and Schwechat airport .
The proposal here is a new line, from just east of the airport, to just south of Petržalka station. It would create a shorter main route to Bratislava – perhaps the shortest realistic route. From Petržalka, it would connect to a future north-south tunnel, across the Danube through Bratislava. The line (shown in blue) would fit into this future pattern of long-distance services through Bratislava (using a north-south tunnel):
The proposed line is an alternative for Vienna – Bratislava services via the planned Spange Götzendorf. That project would connect the airport station to the Wien-Raaber Bahn: trains from Budapest can then run via the airport into Vienna. However, routing Vienna – Bratislava trains via Götzendorf does not make much sense, if a shorter route is available. The section between Götzendorf and Parndorf would probably be overloaded – requiring additional construction anyway. Preparation for the Spange Götzendorf does include additional capacity between the city centre and the airport, which would benefit the alternative route proposed here. However, the alignment through Schwechat village is very restricted: it could be replaced by a bypass tunnel, from Kledering to Mannswörth station. An indicative alignment is shown below:
The new line would run in a relatively straight line, from the airport boundary to south of Kittsee, and then turn north to pass Kittsee and join the line to Petržalka. It would be under 40 km long, if it passes Kittsee on the western side. For about half its length, it would parallel the Pressburger Bahn. East of Petronell, it runs south of the hills at the Danube bend (Hainburger Berge). The line would be built for 200 – 250 km/h – it is a relatively short route.
The existing line goes through the village of Fischamend, after it emerges from the eastern airport tunnel. To avoid the S-curve in the tunnel, and the passage of the village, a second tunnel further south would be preferable. The variant shown (in blue) avoids the built-up area. From Fischamend, the line would run almost due east, to join the alignment of Bundesstrasse 9, east of Neu-Haslau.
At Regelsbrunn, the new line would turn away from the B9, passing south of Petronell. From there it would pass between Prellenkirchen and the Spitzer Berg, toward Kittsee. The variant shown red-white avoids the higher ground west of Kittsee, and the built-up area there.
A shorter route option west of Kittsee, over higher ground, would run close to the Batthyány castle: it would probably need an S-curve to connect with the line into Petržalka.
The line from Kittsee to Petržalka would be upgraded and 4-tracked. A reconstructed Petržalka station would be the interchange point with other services, including an urban-regional metro in Bratislava. All options would include at least one new tunnel under the Danube, to connect to the city centre and/or Bratislava Hlavná Stanica.
The shortest total length of the new route Vienna – central Bratislava would be about 65 km, starting from the future Wien Hauptbahnhof, and assuming a Schwechat bypass, a route west of Kittsee, and a Danube tunnel in Bratislava. Even with two intermediate stops (Vienna airport and Petržalka), journey time should be under 30 minutes.