S1 (Rhine-Ruhr S-Bahn) Services ran via Düsseldorf Airport Terminal station from 24 May 1998 to 28 May 2000. Services were extended from Düsseldorf to Solingen on 13 December 2009, replacing part of the former line S 7 service. S1 (Rhine-Ruhr S-Bahn) Line S1 is a S-Bahn line on the Rhine-Ruhr network. It is operated by DB Regio. It runs from Dortmund west over Essen to Duisburg. From there it travels south to Düsseldorf and Hilden before continuing to Solingen. It is operated at 20 minute intervals, using coupled sets of class 422 four-car electrical multiple units. Line S 1 runs over lines built
S-train tunnel under the central station and the city centre. The high number of large cities in the Ruhr area promotes a polycentric network connecting all cities and suburbs. The "S-Bahn Rhein-Ruhr", as it is called, features few tunnels, and its routes are longer than those of other networks. The Ruhr S-Bahn is the only S-Bahn network to be run by more than one corporation in Germany, and the Salzburg S-Bahn holds a similar distinction in Austria. Most Swiss S-Bahn systems are multi-corporation networks, however. Most German S-Bahn networks have a unique ticket system, separated from the "Deutsche Bahn" rates, instead