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S4 (Rhine-Main S-Bahn)

S4
Frankfurt S4.svg
Frankfurt-Westbahnhof Gleis 1.jpg
S4 at Frankfurt West station, bound for Kronberg
Overview
Type Rapid transit, Commuter rail
System S-Bahn Rhein-Main
Status Operational
Locale Frankfurt Rhine-Main
Termini Kronberg
Darmstadt Hauptbahnhof
Stations 22
Services Kronberg Railway, Homburg Railway, Citytunnel Frankfurt, Main-Neckar Railway
Line number 4
Operation
Opened 28 May 1978 (1978-05-28)
Owner Rhein-Main-Verkehrsverbund
Operator(s) DB Regio
Depot(s) Frankfurt Hbf
Rolling stock DBAG Class 423
Technical
Line length 33.5 km (20.8 mi)
Track gauge 1,435 mm (4 ft 8 12 in) standard gauge
Electrification Overhead line
Route number 645.4

The S4 service of the S-Bahn Rhein-Main system bearing the KBS (German scheduled railway route) number 645.4

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). In a short section between Mühlberg and Offenbach-Kaiserlei the South Main railway is used.

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 (Konstablerwache) and 1990 (Ostendstraße and Lokalbahnhof) so that the Südbahnhof (South station) became the service's eastern terminal.


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