S4 (Rhine-Main S-Bahn)
The S4 service of the S-Bahn Rhein-Main system bearing the KBS number 645.4
Routes
City tunnel
The city tunnel is an underground, pure S-Bahn route used by almost all services. In a short section between Mühlberg and Offenbach-Kaiserlei the South Main railway is used.History
The S4 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 R4 where the letter "R" stands for regional. After the opening of the Frankfurt Citytunnel the service was renamed to S4 and extended to the new Hauptwache underground station. Further extensions of the tunnel followed in 1983 and 1990 so that the Südbahnhof became the service's souther terminal.From 1997 until 2024 the S4 rode from Kronberg to Langen.
Operation
- Kronberg – Frankfurt Süd