The U3 is an underground line in Nuremberg. The line was opened on 14 June 2008. It is about long, making it the shortest in the system. The number of stations is 14. The termini are Nordwestring and Großreuth. U 3 trains are run driverless and have been since the opening of the line. U3 shares part of its route (from Rathenauplatz to Rothenburger Straße) with the older U2. History While the original plans of the U-Bahn network to be all called for at least three main trunk lines on their entire dedicated corridors, financial constraints and the decision not to abandon the Tramway network as had been planned at the time the U-Bahn began construction, made it clear after the construction of U2 that a third trunk line would be economical only if the Tram network was abandoned after all. A political consensus emerged to keep the Tram network, but still expand the U-Bahn system, if a bit slower and more moderately. Therefore, it was decided to use parts of existing tunnels for the U3 instead of building an entire dedicated tunnel. However, as it was deemed impossible to reduce the frequency and the existing signalling system was at its limits along the line U2, the decision was taken to automate the existing line to allow for higher throughput. The new U3 thus opened as the first fully automated U-Bahn in Germany and has been fully driverless from its first day of commercial operations. The U2 was automated in the following two years whereas U1, the oldest and longest line in the system and the only one to operate outside the municipal boundaries of Nuremberg is still fully driver operated. U3 which forms a rough C-shape with both branches lying to the West of downtown has been extended twice on its northern branch, first in 2011 with the two new stations Kaublachplatz and Friedrich Ebert Platz and then in 2017 with the two new stations Klinikum Nord and Nordwestring. The 2011 extension of the northern branch of the U3 led to the - to date - last major permanent shutdown of service on part of the Nuremberg tramway network, as service thru Pirckheimer Straße was shut down (while the rails and overhead wiring remained as a backup in case of closures on other routes) due to the potential of one line "cannibalizing" the ridership of the other. An extension