The system belongs to the Rhein-Main-Verkehrsverbund (RMV) and is operated by DB Regio, a subsidiary of Deutsche Bahn.

During the construction phase, some rearrangements were carried out to the commuter network in the area around Frankfurt, including creation of a link line between Bad Soden am Taunus and Niederhöchstadt.

In 1978 the first section of the "Citytunnel" of the Rhine-Main S-Bahn was opened, with all lines sharing the tunnel between Hauptbahnhof and Hauptwache.

The initial system, which lay entirely to the north of the river Main, comprised the following lines: In 1980, two further lines were added to the network, made possible by construction of a new rail bridge over the river Main: Completion in 1983 of a 600m long easterly extension of the Citytunnel, as far as Konstablerwache, improved the opportunities for train turnaround in the tunnel.

The section of the S3 between Höchst and Bad Soden im Taunus also ceased to be served by S-Bahn trains.

Initially this arrangement gave rise to some considerable delays caused by poorly functioning signalling.

Reconstruction of the signalling technology in the Citytunnel enabled all westbound S2 trains to travel all the way to Niedernhausen at a frequency of 15 minutes in 2010.

From July 31 to August 18, 2006, the mainline tunnel between the main station and Konstablerwache was completely closed to exchange 30 switches.

Opening: 1995 Plans for the system include a line to Hanau via Maintal, largely running north of the river Main.

Later, the plan was changed to build the S6 for their entire run until Friedberg own two tracks for a scheduled operation independent of long-distance, regional and freight traffic.

After 24 years of planning and resolution of legal challenges, construction of the first phase between Frankfurt-West and Bad Vilbel started in December 2017.

Furthermore, such a fast connection between Darmstadt and Rüsselsheim would have been created, which would have brought a significant time savings for the many commuters.

The biggest problem experienced on the Rhine-Main S-Bahn is frequent unpunctuality, one reason for which is the shortage of capacity in the Citytunnel.

Longer distance passenger trains take priority over the S-Bahn, which frequently has to stand for up to 10 minutes to allow the other service to overtake.

This is part of the contract that RMV signed with Deutsche Bahn in November 2011 following the tendering of transport services.

In the early years trains of the second and third series of electric locomotive class 420 in the color pure orange / Kieselgrau (contrary to original plans, the proposed paint carmine / kieselgrau was not used) were used in Frankfurt, although occasionally lent to 1990 due to lack of vehicles also from Munich blue white 420s were used, for example, the opening of the trunk line extension to Frankfurt South.

As of 2004, Frankfurt ET 420 no longer received any main examinations; this was only in 2007 with 420 271 started when it became clear that the delivery of the last railcar due to registration problems would have to be postponed indefinitely.

All Frankfurt vehicles were also from 2007 to 2008 for three million euros, a modernization in the interior, which included light gray instead of striped partitions and new upholstery in the current design.

At the same time, the already quite advanced phasing-out was severely curtailed and henceforth focused on the railcars of the third construction series in order to be able to take at least the oldest vehicles out of service.

The rapid-transit railway Rhine Main had the first completely traffic-red vehicle park of the German course AG.

This status was maintained until the end of 2003, when the S-Bahn Stuttgart handed over the orange-white and orange-pebble-gray units to Frankfurt.

In 2009, when the use of the class 420 at the S-Bahn Rhein-Ruhr was completed, the Essen depot delivered several ET 420 of the fifth and sixth series to Frankfurt.

Although the Frankfurt plant made great efforts to align the railcars to the Frankfurt units (for example, most railcars were still redesigned in 2007), they were in such poor condition by the end of years of poor maintenance in North Rhine-Westphalia that From then on, they were usually taken out of service directly at the end of the investigation period.

After the main inspection, three of them were initially deployed from mid-June, primarily on the S7 and the airport short-commuter (S8 / S9), later normal in mixed operation with older units on all ET 420 rides.

After an early deployment was already foreseeable at that time, no great efforts were made to adapt the car to the Frankfurt railcar - some of them were in the interior until the withdrawal with Stuttgarter advertising stickers.

Since the conversion of the S7 and some of the S1 (which had previously been performed by 420s since the autumn of 2013) to the new 430 series in May 2014 made numerous 420s redundant, the phasing out progressed sharply.

However, a private association of railway friends in Gießen was able to take over the unit 420 298 on a permanent loan and undertake regular special services in the Frankfurt area with this railcar, which they also work up (initially in their last operational condition).

This includes: The last point brought the modernized railcar and the RMV as the initiator of the modernization in the early days of severe criticism, as many passengers and train employees the new door signals (which also include a signal when the doors are open) as annoying, even annoying.

On 5 May 2014 took place on the S1 (Wiesbaden - Rödermark-Ober-Roden) and the amplifier courses of the S8 between Frankfurt Hbf and Kelsterbach the first passenger service of the class 430 in the Rhine-Main area.

With the transition to RMV, the marking of these routes as S-Bahn was omitted, which had become largely obsolete because of the network extensions.