far as Frankfurt Süd, while the S3 and S4 were extended to Darmstadt and Langen. The section of the S3 between Höchst and Bad Soden im Taunus also ceased to be served by S-Bahn trains. In 1999, the S8 was effectively divided into two lines, the S8 and S9, both of which travel between Hanau and Wiesbaden via Bischofsheim. The S8 continues to travel through the centre of Mainz, while the S9 travels via Mainz-Kastel. This arrangement means that it is possible to travel between Wiesbaden, the capital of the state of Hesse, and Frankfurt, the state's largest city, by three different routes. In the same year, a new station on lines S3-S6 was opened in the Frankfurt fairground (Frankfurt Messe station). In 2002, a new S-Bahn line, the S7, between Frankfurt Hauptbahnhof (main arrivals hall) and Riedstadt-Goddelau was added to the system (replacing the regional train line on the northern part of the Mannheim–Frankfurt railway). Due to a shortage of capacity in the Citytunnel, these trains are not currently able to reach Frankfurt's inner city. At present, these trains do not operate on a 30-minute schedule because of several ICE lines that operate on the same tracks. In 2003 the Rodgaubahn, a commuter rail system serving Offenbach and its environs, was incorporated into the Rhine-Main S-Bahn system. This resulted in the S1 being extended from Offenbach Ost to Rödermark-Ober Roden, while the S2 was also rerouted from Frankfurt Süd to serve Offenbach Ost and all stations to its new terminus in Dietzenbach. The current system has an almost 5-minute frequency for services between Frankfurt and Offenbach Ost and an actual 5-minute frequency for services between Frankfurt Hauptbahnhof and Frankfurt Süd. The group of lines S1, S2, S8 and S9 all share 10 stations, as do the group of lines S3, S4, S5 and S6. All the lines, with the exception of the S7, share 5 stations. Initially this arrangement gave rise to some considerable delays caused by poorly functioning signalling. To some extent this has been allayed by routing every second westbound S2 train in peak times to Offenbach am Main (Hauptbahnhof) and every second eastbound S2 train in peak times to the main arrivals hall of the Frankfurt Hauptbahnhof, rather than running these services through the Citytunnel. Reconstruction of the signalling technology in the Citytunnel enabled all westbound S2 trains to travel all the way to Niedernhausen at