The Frankfurt U-Bahn is a Stadtbahn (premetro) system serving Frankfurt, Germany. Together with the Rhine-Main S-Bahn and the tram network, it forms the backbone of the public transport system in Frankfurt. Its name derives from the German term for underground railway, Untergrundbahn. Since 1996, the U-Bahn has been owned and operated by (VGF), the public transport company of Frankfurt, and is part of the Rhein-Main-Verkehrsverbund (RMV) transport association. The licence contract is up to 31 December 2031 and is renewable. The contracting authority of VGF is the municipal transport company .
The U-Bahn opened in 1968, and has been expanded several times. It consists of three inner-city tunnels and above-ground lines in the suburbs. About 59% of the track length is underground. The network operates on a variety of right of ways typical of a light rail system, with core sections running underground in the inner city and some above-ground sections operating on street.
Like all public transport lines in Frankfurt, the system has been integrated in the Rhein-Main Verkehrsverbund (RMV) since 1995. From 1974 until the founding of the RMV, the Stadtwerke were shareholders in the predecessor group, the Frankfurter Verkehrsverbund (FVV; Frankfurt Transport Association).
The network consists of 84 stations on nine lines, with a total length of . Eight of the nine lines travel through the city center (line U9 being the exception). In 2023, the U-Bahn carried 123.6 million passengers, an average of approximately 338,600 passengers per day. The most recent expansion of the network was on 12 December 2010 when two new lines were added, the U8 and the U9 (both part of the long-planned but only partially completed fourth route), which opened up the university campus area and the new development area at Riedberg.
History
At the beginning of the 1950s, the first plans were made to relieve the then already overburdened tram. More than 100,000 motor vehicles were registered in Frankfurt in 1958, and more than 180,000 commuters used the transport infrastructure on a daily basis. Various alternatives to the construction of a modern high-speed traffic system and the separation of above-ground traffic flows were discussed. On 5 April 1960, the SPD faction requested that the city council might commit to a two-line straddle-beam monorail system designed by Alweg. Lord Mayor Werner Bockelmann, however, advocated from the outset the construction of a U-Bahn, which was however considered the most expensive option. On 7 July 1960, the city council therefore commissioned a city planner with the preparation of a general planning overview in order to compare the costs of the three systems: Alweg straddle-beam monorail, U-Bahn and Stadtbahn (premetro). Responsible for the planning was in October 1961 designated to the head of the Traffic Department Walter Möller. The decision was finally made in late 1961 in favour of a U-Bahn system, which was to be built in several sections initially using existing tram infrastructure. In the first construction phase, the tunnels of the inner city were to be built for the time being, which were to be connected via provisional ramps to the adjacent tram routes. It was not until the second construction phase that the tunnels were to be extended beyond the inner city and connected to suitable upgraded above-ground routes in the suburbs. In the third construction phase, the change from Stadtbahn to U-Bahn would have been completed, which was to operate completely independently of traffic in tunnels, cuts and dams.
On 28 June 1963 the first pile of rubble for the construction of the -long tunnel under the Eschersheimer Landstraße. For the first stage of development until 1975 - approximately corresponding to today's main lines A and B - construction costs of 565 million DM were expected. The new Lord Mayor Willi Brundert compared the "boldly begun subway construction" in 1964 in its dimensions with the medieval cathedral building.
After just one year, the ambitious mammoth project threatened to fail due to financing problems. Falling tax revenues and a tax policy geared towards federal and state governments drove the municipalities close to ruin in the mid-1960s. Frankfurt was 1.4 billion DM in debt in 1964, the most heavily indebted city in Germany, with a regular budget of 733 million DM. Under pressure to stabilize the budget deficit, the 1964–65 municipal assembly reduced long-term investment planning from 2.7 billion DM to 1.7 billion DM and even hinted that for some time that Eschersheimer Landstraße would be "impassable desert" after completion of the tunnelling work.
The U-Bahn opened on 4 October 1968, with the first route running from Hauptwache to Nordweststadt (now line U1). This first section ended up costing 344 million DM to construct, of which the federal government contributed 56 million DM and the state of Hesse contributed 129 million DM.
Current lines
The route network consists of the four routes "A", "B", "C" and "D" used by a total of nine different services, U1 to U9. The total operating length of is . The first three routes ("A", "B" and "C") each have a separate tunnelled section under the city centre. The fourth, D, route is still only partially completed. Central sections of the routes, shared by multiple services, are called "basic route" or "trunk route"; these branch out into several "connecting lines", which are usually used by only one service and are sometimes referred to as "upgraded lines". The terms "basic section" and "connecting section" and their designations are based on the names of the construction sections. Sections of the legs were designated by the letter of the route and a Roman numerical suffix - sections of the connecting lines with an Arabic numeral. The designation of the connecting lines "A1", "A2", "A3" and "B1" was also used to designate the lines until 1978.
Like all light rail vehicles, trams and subways in Germany, the Frankfurt U-Bahn is subject to the BOStrab tram regulations. The tunnels and the above-ground section between Römerstadt and Ginnheim are completely separate from other traffic. Most of the other above-ground sections run on reserved track but have numerous level crossings for road traffic and pedestrians. The section of the U5 between Friedberger Anlage and Marbachweg operates in the largely on street.
Tunnels exist at - A Line: South of Dornbusch, into the city centre, Nordwestzentrum (small section) B Line: Scheffeleck and Seckbacher Landstraße to Bockenheimer Warte. C Line: Kirchplatz to Johanna-Tesch-Platz and Ostbahnhof
Route Line Path Stations A(and D) Ginnheim - Römerstadt - Nordwestzentrum - Hauptwache - Willy-Brandt-Platz - Südbahnhof 20 A Bad Homburg-Gonzenheim - Ober-Eschbach - Nieder-Eschbach - Bonames - Hauptwache - Willy-Brandt-Platz - Südbahnhof 21 A Oberursel-Hohemark - Oberursel - Niederursel - Hauptwache - Willy-Brandt-Platz - Südbahnhof 28 B(and C+D) Enkheim - Schäfflestraße - Seckbacher Landstraße - Bornheim - Konstablerwache - Willy-Brandt-Platz - Hauptbahnhof - Festhalle/Messe - Bockenheimer Warte 15 B Preungesheim - Eckenheim - Hauptfriedhof - Konstablerwache - Willy-Brandt-Platz - Hauptbahnhof 16 C Hausen - Bockenheimer Warte - Hauptwache - Konstablerwache - Ostbahnhof 12 C Heerstraße - Bockenheimer Warte - Hauptwache - Konstablerwache - Eissporthalle - Hessen-Center - Enkheim 20 A(and D) Riedberg - Niederursel - Hauptwache - Willy-Brandt-Platz - Südbahnhof 19 D(and A) Nieder-Eschbach - Riedberg - Niederursel - Nordwestzentrum - Römerstadt - Ginnheim 12
Routings These are individual routings. Stretch Line Routing Opening Stations Frequency A1 Ginnheim ↔ HeddernheimHochbahn: Ginnheim – Römerstadt – Tunnel: Nordwestzentrum – Heddernh. Landstr. – Eisenbahn: Zeilweg – Heddernheim 1968–1978 ½ A2 Bad Homburg-Gonzenheim ↔ HeddernheimEisenbahn: Gonzenheim – Ndr.-Eschb. – Bonames – Mertonviertel – Heddernheim 1971 ½ A3 Oberursel-Hohemark ↔ HeddernheimEisenbahn: Hohemark – Oberursel – Weißkirchen – Niederursel – Heddernheim 1978 ½ B1 Preungesheim ↔ KonstablerwacheStadtbahn: Preungesheim – Gießener Straße – Eckenheim – Marbachweg – Straßenbahn: Hauptfriedhof – Eckenh. Landstr. – Nordend – Tunnel: Scheffeleck – Konstablerwache 1974–1978 ½ –20 B2 Bornheim Seckbacher Landstr. ↔ KonstablerwacheTunnel: Bornheim – Berger Straße – Nordend – KonstablerwacheStadtbahn: Bornheim Seckbacher Landstr. – Schäfflestraße – (Enkheim mit U7) 1980 ½ –20 C1The connecting line C1 between the stations Schäfflestraße and Enkheim is additionally driven by individual trains of the line U4. The data in the table refers only to line U7. Zoo ↔ EnkheimTunnel: Zoo – Ostend – Eissporthalle (U7 only) – Stadtbahn: Riederwald – Borsigallee – Enkheim (U4 und U7) 1992 ½ C4The construction section C IV is actually a part of the basic section C. Since the section corresponds operatively to a connecting section, it is listed in this table. Zoo ↔ OstbahnhofTunnel: Zoo – Ostbahnhof 1999 ½ Hausen Hausen ↔ IndustriehofStadtbahn: Hausen – Industriehof 1986 ½ Heerstr. Praunheim Heerstraße ↔ IndustriehofStadtbahn: Praunheim – Ludwig-Landmann-Str. – Hausen – Industriehof 1986 ½ D4 (formerly known as A2) Niederursel ↔ Abzweig KalbachStadtbahn: – Niederursel – Riedberg – Bonames → Nieder-Eschbach 2010
Future plans extensions of the system in planning or under construction include: U5 Extension to the Europaviertel Closure of the Ginnheim–Bockenheimer Warte gap (currently served only by the ground-level tram system)
Depots
There are two depots for U-Bahn trains: Heddernheim Depot () is located to the north of Heddernheim station, next to the A Line, and is used by trains from services on the A Line and the northern section of the D Line (U1, U2, U3, U8 and U9). It opened in 1910 as a tram depot and became the first U-Bahn depot in 1968 when the network opened. The East Depot () in Riederwald opened in 2003, and since then has been the home for trains on the B and C Lines (U4-U7) as well as some trams. It is located on the connecting track from the B Line station at Seckbacher Landstraße to the C Line between Johanna-Tesch-Platz and Schäfflestraße.
Rolling stock
U6/U1 Class
The U1 Class consists of two six-axle, two-section prototype vehicles built by Duewag in 1965, derived from the manufacturer's previous tramcars. The original designation was U6 (U-Bahn vehicle with 6 axles), but this was changed to U1 when the U2 Class were delivered. The first prototype was delivered in cream livery but both were painted red and white from 1968. The U1 Class were removed from service in 1976 because they were incompatible with newer vehicle types. One non-operational U1 Class is now in the collection of the Frankfurt Transport Museum.
P/Pt/Ptb Tram/LRV Hybrid
A total of 100 P/Pt/Ptb Class vehicles were built by Duewag in three batches from 1972-1978 and used until 2016 on the U-Bahn network. While the first batch of 30 vehicles were fitted with folding steps, to facilitate access from street level in tram service or high platforms at U-Bahn stations, the second and third batches had fixed steps and thus was initially incompatible with the platforms on the U-Bahn lines. To differentiate the two subclasses, the batch with folding steps was designated Pt (t for , operable in tunnels). Between 1984 and 1986 the third batch was rebuilt with folding steps in order to be operated on the C Line, and the second batch were also rebuilt as Pt Class in 1992 when the U7 was extended to Enkheim.