U2 (Nuremberg U-Bahn)
The U2 is an underground line in Nuremberg, opened on 28 January 1984 and the last station along the line to open was Flughafen (Airport) in 1999. The line is about 13.1 km long and has 16 stations; the termini are Röthenbach and Flughafen. Since 2010 all trains in regular operations are run driverless. Overview. The route begins in the southwest of Nuremberg at Röthenbach station, at the western end of a three-track parking and turning system, and continues east along the Schweinauer main street under the Main-Danube Canal and the "Südwesttangente" highway (southwest  tangent) to the station Hohe Marter. This station is the longest in the Nuremberg subway network with 268 m and replaces the two abandoned tram stops Friesenstraße and Schweinau, which were formerly located at the two present-day subway exits. The route continues under Schweinauer Hauptstraße to Schweinau train station and St. Leonhard train station, which, due to its location in the middle of Schweinauer Straße, is completely elastic so as not to give off the vibrations caused by driving to the surrounding houses. Next is the Rothenburger Straße station under the Frankenschnellweg (A73). The last part of the route  runs in a curve under the Obere Kanalstraße and then leads in a right arc to the station Plärrer, where the U2 meets the U1. After the station Plärrer the route runs under the Frauentorgraben to the station Opernhaus. This station is open to the moat, which was uncovered in the course of subway construction and designed as a pedestrian area. The route continues to the main train station, where the U2 meets the U1 for the second time, and then heads north to the Wöhrder Wiese station. Due to its location in the Pegnitzgrund, the station had to be  lowered and the northern branch of the Pegnitz had to be incorporated into the station building, which can be seen in the lower ceiling, which extends across the entire station. The following route runs under the Laufertorgraben and steeply climbs towards the station Rathenauplatz, which can be observed in the station itself, as the ceiling from the southern to the northern platform has a significant difference in height. After the Rathenauplatz station, the route initially runs under the Bayreuther Straße, turns right to the Rennweg station under the same-named street and continues under Schoppershofstraße to the Schoppershof train station . Between this and the following station Nordostbahnhof under the Leipziger Platz the two tracks run together in the same single bore tunnel. This is opposed to most of the rest of the line where the two tracks run in separate tunnels. In the further course under the Bessemerstraße is located in a tube together with the city-side track a parking and turning system and at the junction with the Äußere Bayreuther Straße the station Herrnhütte. Then the route leads in a narrow counter arc under housing development to the station Ziegelstein under the Fritz Munkert Platz, at whose northern  end is another parking and turning system. The two railway tracks are then merged and run as a single-track tunnel in a westerly direction to the terminus airport. Due to the long single track section between Ziegelstein and Airport, only one train every ten minutes continues to the airport with most trains during the day terminating at Ziegelstein. This was formerly indicated by short terminating trains being indicated as "U21". Operations. During the rush hour peak trains leave every 3 1/3 minutes (200 seconds) overlapping with U3 to a 100 second headway between Rothenburger Straße and Rathenauplatz. As the  section of track between Airport and Ziegelstein is single track, only one train every ten minutes serves the airport with most other trains terminating early at Ziegelstein. Planned extensions. Southern end. As early as the first U-Bahn plans which formed the basis for the decision to build an U-Bahn, an extension towards Stein was proposed. However, the problem with such an extension is the municipal border involved and local politicians in Stein have been reluctant to assume the financial burden of construction and especially the long term burden of maintenance and operation. Another problem is the "" (municipal traffic  financing law or GVFG) which regulates which construction projects get federal and state funding and mandates a so-called "Benefit-Cost Quotient" above 1.0 (i.e. "benefits" exceeding "costs") and an extension to Stein is unlikely to meet that as only the newly built stretch would be taken under consideration. Northern end. Another extension variously suggested since the extension of tram line 4 northwards to "am Wegfeld", a point due West of the current endpoint of U2 at the airport, was politically decided, is towards the tram/bus interchange point "am Wegfeld" in the . While various studies have failed to reach  the required benefit cost ratio above 1, the current bus service between the airport and "am Wegfeld" (line 33 with onward service to Fürth Hauptbahnhof and line 30 with onward service to Erlangen) overlaps to a 10 minute headway, the same as U2 service between the airport and Ziegelstein station. In addition to linking the airport to the interchange point and relieving the residential areas of bus traffic, such an extension would also offer an interchange between tram line 4 (which is planned to be extended towards Erlangen in the course of the "Stadt-Umland Bahn“ project) and U2 (otherwise  only possible at Plärrer station) and relieve the airport of the role as a bus/subway interchange point, that it only gained in the course of the reorganization of bus traffic in the north of Nuremberg in the course of the opening of the tram extension to "am Wegfeld" in 2016. Branches or infill stations. There are also various plans for branches and an additional infill station on the last stretch towards the airport. Including a proposed "Marienberg" station which was already indicated as a possibility in promotional material released during the opening of the extension towards the airport. Rolling  stock. Prior to the introduction of automatic operation in the course of the opening of U3 (2008) and the conversion of U2 to all automatic operation (2010), the line was served by the same VAG Class DT1, VAG Class DT2 and even MVG Class A vehicles as U1. However, with the conversion of U2 to automatic operation, those vehicles were withdrawn from service or switched to exclusively operating on U1, the last remaining all manual line. Some older units of Class DT1 still contain displays in their interior that can be switched between "U1", "U2" and the obsolete "U11" and  U21 (since abandoned designations for truncated runs on the U1 or U2 corridor), but they haven't served any purpose since the permanent switch of those vehicles to U1 service and the subsequent abandonment of the "U11" designation. As of 2022 only VAG Class DT3 (both with and without a driver's cabin) serve on U2, just as they do on U3. The VAG Class G1 is capable of both automatic and manual operation and could in the future be used on U2 as well.