| Basic data | |
|---|---|
| Opening | 1974 |
| Client body | RMV |
| Operational data | |
| Operator | Stadtwerke Frankfurt |
| Vehicle type | Siemens–Duewag U2, U3-Triebwagen |
| Route and performance data | |
| Route length | 11.3 km |
| Stations | 15 |
| Journey time | 24 Minutes |
| Speed | 28.3 km/h (avg.) |
| Station distance | 753 m (avg.) |
| Frequency (RH/MD/N) | 5 / 7/8 / 15 Minutes |
| Hours | 04:08 am – 01:08 am |
The U4 is a line on the Frankfurt U-Bahn. At the time of the line's inauguration in 1980, it ran from the central railway station to the Konstablerwache and then continued along the Berger Straße all the way up to Seckbacher Landstraße in Bornheim, making it the first line to run entirely underground over its total length. In 2001, the U4 was extended from the central railway station to Bockenheimer Warte, with an additional stop at the Frankfurt Trade Fair along the way. In 2008, some of the trains started continuing past Seckbacher Landstraße to Schäfflestraße and then overground to Enkheim together with the U7.