The current network of the U-Bahn is composed of three lines, serving 49 stations, and comprising 38.2 kilometres (23.7 mi) of operational route, making it the shortest of the four metro systems in Germany, behind Berlin, Hamburg and Munich.

The suggestion of the Ulm professor Max-Erich Feuchtinger to move the tram between Plärrer and main station under the earth, was rejected by the Nuremberg city council on 19 March 1958.

In 1962, the city council commissioned the Stuttgart traffic scientist Professor Walther Lambert to prepare an opinion on the future of Nuremberg public transport.

This was preceded by a personal statement by Hans von Hanffstengel, head of the Nuremberg city planning office, on the opinion of Professor Lambert.

He was supported indirectly by the federal government, which offered a participation in the construction costs of 50%, and the then Bavarian Prime Minister Alfons Goppel, who assured the financial equality of the Nuremberg metro plans with those of the state capital.

Other reasons brought forth at the time were the claimed necessity to close the entire line during a conversion (from underground tram to metro) for a period of several years.

All these considerations eventually led to a large number of network proposals, of which the models P, Q, R and S most closely approximated the specifications.

The main drawbacks would be a potential overburdening of the single interchange station (compare Châtelet–Les Halles in Paris) and the difficulty of tunneling in several levels (for the various lines) near the center of the historic old town.

Positive effects are attributed to this network model for the development of the new settlement axis, negative could be the transfer links from the U3 to the city center and the supply of defective trains to the depots.

It was slightly modified and formed the basis of the "Nuremberg General Transit Plan" (GNVP) adopted on 8 September 1971 by the City Council.

One point of criticism is the insufficient consideration of the territories incorporated into the GNVP on 1 July 1972 (when several suburbs were annexed into Nuremberg in the course of a Bavaria-wide redrawing of municipal boundaries), since metro planning was only slightly adapted to the new settlements.

On 20 March 1967, German transport minister Georg Leber and Nuremberg Oberbürgermeister ("Lord Mayor") Andreas Urschlechter (both SPD) had the honour of "striking the first blow" for the new metro.

Uniquely, the metro was built "from the outside in", starting in the rather outlying area of Langwasser before reaching the historical core and the central train station.

Similar issues in the past plagued Opernhaus station on U2/U3 as birds often fly in from the side of the tracks open to the moat.

At first the trains ran by day as line U21 (not to be confused with the later U21) by way of Weißer Turm and Lorenzkirche to Aufseßplatz or Langwasser Süd.

While those shorter runs still operate, they are no longer differentiated by line number but only by the display of their final destination (e.g. a train that would have been signed "U21" prior to 2017 is now simply an U2 direction "Ziegelstein") Eberhardshof ↔ Messe U11 service ran on the U1 line between Eberhardshof and Messe most of the day, adding passenger capacity between Nuremberg main station, the car-free main shopping district and the Plärrer.

However, the city of Fürth has rejected various plans for developing the area currently filled with home supply and grocery stores.

The metro stop is projected in the Brunecker Straße industrial area, between Hasenbuck and Bauernfeindstraße stations, where the university and the new urban quarter of Lichtenreuth are planned.

Further extensions of such a branch towards Reichelsdorf have thus far failed to reach a benefit cost ratio above 1.0 and are thus unlikely to get the federal money that is widely seen as precondition for construction.

[citation needed] The southern branch (U3 Süd) diverts from the U2 tunnel south of Rothenburger Straße and runs to the west as well.

A new station called "Großreuth bei Schweinau" started service on 15 October 2020 marking the latest extension of the network.

However, in the 2020 municipal elections the office of Lord Mayor was won by CSU-candidate Marcus König who had campaigned on the promise of metro extensions.

[20] The current southern terminus of U2, Röthenbach, is by far the busiest in the network and as it is served by both a large P&R multistory carpark (shut down in 2020 and subsequently demolished[21][22][23]) and several bus lines, the question of extending the line to serve those currently using the buses and the parking garage has come up repeatedly since the opening of the station in 1986.

[29][30][31][32] The DT2 which was last used during the 50 year anniversary celebrations of the network in 2022 is to be scrapped entirely due to lack of space to store any preserved units.

German regulations mandate that all metro trains must not stop inside a tunnel after the emergency brake has been pulled or if any other hazard like a fire is detected, but instead should proceed to the next station if possible to ease rescue operations.

Installing doors between track and platform (like on Paris's Météor Line) would have been the superior solution, but since 6 stations which were already in full operation (the section Rathenauplatz to Rothenburger Straße) needed to be converted, fitting doors to the platform edges would have led to severe service disruptions and station closures.

After tests with laser light barriers (from the station ceiling to the platform edge) at Plärrer, a combination of CCTV cameras overlooking the track bed and radio frequency barriers between from under the platform edge to the opposing wall were chosen and installed at all stations served by U3.

In such a case the ATC will stop any approaching trains on that track immediately and alert the control centre, from where an operator can visually inspect the trackbed at the platform over CCTV and then take the appropriate action.

Initially it was thought by Siemens and VAG that development, testing and certification of the ATC components could be conducted during those 3 years in parallel to the construction of the line, at first in simulations and, after the first DT3 units had been delivered, on a test track at the Langwasser Depot, and that the new line could enter service immediately after the tunnels and stations were built.

Full ATC operation of the U2 begun in January 2010 and on the shared section of track between Rathenauplatz and Rothenburger Straße the interval between trains on that tunnel segment reduced to 100 seconds.