The city tunnel is an underground, pure S-Bahn route used by almost all services (except for the S7 service which terminates at the central station).
History
Year
Stations
Route
1974 (R6)
13
Friedberg – Frankfurt Hbf
1978
16 (+3)
Friedberg – Hauptwache
1983
17 (+1)
Friedberg – Konstablerwache
1990
21 (+4)
Friedberg – Stresemannallee
1997
20 (-1)
Friedberg – Frankfurt Süd
1999
21 (+1)
Friedberg – Frankfurt Süd
The S6 was one of the first six services of the Rhine-Main S-Bahn system. In a prior test operation it ran between Kronberg and Frankfurt Central Station. The service was then called R6 where the letter "R" stands for regional. After the opening of the Frankfurt Citytunnel the service was renamed to S6 and extended to the new Hauptwache underground station. Further extensions of the tunnel followed in 1983 (Konstablerwache) and 1990 (Ostendstraße and Lokalbahnhof) so that Stresemannallee became the service's eastern terminal.
