line to be built between Heimeranplatz and Olympiakreuz. The close proximity of Nymphenburg Palace and the west–east lines at Donnersbergerbrücke station would require the construction of tunnels between south of Heimeranplatz and Olympiakreuz. Most of the Ringbahn would use the existing railway lines with seven S-Bahn stations (Heimeranplatz, Donnersbergerbrücke, Johanneskirchen, Englschalking, Daglfing, Leuchtenbergring, and Ostbahnhof) currently in use. Five new surface stations (BMW Forschungszentrum, Ingolstädter Straße, Aumeister, Kolumbusplatz, and Poccisstraße) and three new underground stations (Nymphenburg, Neuhausen, and Olympiakreuz) would have to be built. One additional advantage of this Ringbahn concept is an airport express train service from Hauptbahnhof via Olympiakreuz, following the proposed tracking for the finally abandoned Munich Airport Transrapid. That could potentially shorten the travel time from the Hauptbahnhof on the west side, bypassing the current S2 with numerous stops along the line. Southern Ring The alternative to the Circular Ring is the Southern Ring between Ostbahnhof and Heimeranplatz, with stations at Heimeranplatz, Poccistraße and Kolumbusplatz, which is the express variant. Northern Tunnels along the Airport In 2009, a Nordtunnel was proposed by Vieregg-Rössler as a further extension, which connects the main railway station with the Kunstareal (with the three Pinakotheken) Nordring, football stadium, Garching, airport). In the inner city area, the planned route is roughly equal to that of the planned U9. In addition to the S-Bahn, the route would also include regional and long-distance transport, in this way the central orientation of the Munich local transport system should be replaced by the city center. The Nordtunnel was not followed, among other things due to higher costs with at the same time lower profitability. S-Bahn Vision 2050 On 31 March 2017, MVV announced the Vision 2050 expansion proposal. The vision for the year 2050 includes double-decked wagons, 24-hour operations, new stations, and extensions further beyond the city limit. The possible extensions are: S1 North from Freising to Landshut S2 North from Altomünster to Aichach and from Petershausen to Pfaffenhofen S2 East from Markt Schwaben to Dorfen S3 West from Mammendorf to Augsburg S3 South from Holzkirchen to Schaftlach which splits to Lenggries and Tegernsee S4/S6 East from Ebersberg to Wasserburg and from Grafing Bahnhof to Rosenheim S4/S6 West from Geltendorf to Kaufering and beyond S7 South to Geretsried (Geretsried Süd railway station) via Gelting and Geretsried Mitte. The environmental impact study is planned for 2017. Work started in 2022, and the projected completion date is 2027