For financial reasons, however, only the southern tunnel section was built and the track north of the Miquelallee led over a ramp to the surface.

Despite the above-ground routing, the stations were built very complex and had spacious underground distribution bullets, isolated was also the ground-level access by traffic lights possible.

It had five underground stations in the city center (Hauptwache, Eschenheimer Tor, Grüneburgweg, Holzhausenstraße and Miquel / Adickesallee) and the subterranean terminus Nordweststadt in the same large housing estate.

The mixed operation with underground tram cars was abandoned, the tunnel ramp in the Great Gallus road shut down, the reinforcement service A4 accounted for.

Apart from the merger of two stops and the establishment of a new one in Oberursel as well as the construction of the high station Niddapark to the Federal Horticultural Show 1989 there was no increase here.

The next subway station Schweizer Platz is located below the block of houses bordered by Swiss, Schneckenhof, Cranach and Gartenstraße.

North of it, the subway runs under three blocks, the German Museum of Architecture on Museumsufer and then, just west of the Untermain Bridge, the Main, whose underpass was also associated with very particular difficulties (see Tunneling).

The subway passes, coming from the Main, the Nice and the Jewish Museum, in order to reach the level of the urban stages, the New Mainzer Straße.

This North-Main continuation of the Swiss road is the main axis of the Frankfurt financial district, a worth seeing street canyon.

When building the U-Bahn station Eschenheimer Tor, it was not only intended to banish public transport but also pedestrians underground to create maximum space on the surface for motor vehicle traffic: the historic square, as early as the early 20th century a large intersection, was to be crossed by passers-by only after the planning of the 1960s by the distribution floor of the station.

The districts Dornbusch and Eschersheim are in fact cut in two halves, the guidance of the subway on the road led to numerous serious accidents with motor vehicles and pedestrians.

However, the urban planning and operationally very unsatisfactory situation can not be remedied for the foreseeable future, as an extension of the tunnel is currently considered unfeasible.

North of the station Dornbusch branches off to the east from a largely single-track, street-level operating route, which connects the A-line with the U-tram line served by the U5 and the Wagenhalle corner home.

In Eschersheim, the line north of the station Steiner Stein first crosses the terrain cut, in which the Main-Weser-Bahn (S-Bahn service S6) runs, and then on the Maybach bridge on the Nidda to Heddernheimer shore sink.

For this purpose, a correspondingly deep excavation pit was dug and secured with the aid of numerous steel girders and screed walls driven into the ground (Berliner Verbau).

While the other names, with the exception of the buttons of the subsequently installed elevators, have disappeared, the term "B-level" has remained in common usage until today.

The U2 to Bad Homburg wore from 1910 to 1971 as the overland tram of the Frankfurt local train route number 25, then she operated until 1978 as the subway service "A2".

While the other names, with the exception of the buttons of the subsequently installed elevators, have disappeared, the term "B-level" has remained in common usage until today.

It was part of the first Frankfurt subway line, which led from 1968 from the Hauptwache in the early 1960s built large housing estate northwest city.

South of the station, the tunnel swings back to the axis of Rosa-Luxemburg-Straße and ends after about 600 meters on the median strip of the city highway.

Due to the low passenger usage in the evenings and lack of social control, the station, afflicted by countless vandals, today offers a sad image.

The local railway used in Frankfurt and Homburg along the street-level tracks of urban trams, the intermediate part was traced in the manner of a railroad independent of the road network.

After the railroad crossing Homburger Landstraße immediately after the station Bonames Mitte lies on the right hand side the Friedrich-Fauldrath-Anlage, which is a relic of the former tram turning loop.

Then the route follows for a short stretch of Steinernen Straße, a historic main street from Mainz into the Wetterau, and then turns towards Nieder-Eschbach, the last district before the city limits.

The new route is to begin about 200 meters before today's final stop with a ramp to which a 350-meter long single-track tunnel between the portals Erlenweg and Gotenstraße connects.

A subsidy under the municipal transport financing law is very unlikely because of the expected negative cost-benefit factor, since the forecast zero case, on the other hand, a new tunnel would be assessed, would reflect the present state, ie an already operated ground-level route, and the economic Benefits, above all, take into account the travel time profit, which could not outweigh the expected high construction costs.

The plans for the underground extension of the A-line from the Südbahnhof to the Sachsenhäuser Warte (with an intermediate station Milan Street) were already well advanced in the late 1990s, when the federal government withdrew its funding commitment.

After elimination of the parallel operation, the stations were rebuilt to 87 cm platform height or equalized by lowering the ballast bed and the steps of the subway cars are removed.

This provisional remained initially even after the elimination of the tram operation required because with regard to the gauge of the freight wagon, the platforms between Heddernheim and Oberursel had been kept only 32 cm above rail level.

Therefore, from 1999 onwards, all stations were gradually brought to a uniform height of 80 cm above the rail level in extensive construction work, which allows stepless entry into the trains of the U4 series.