Following the suit of other German cities such as Berlin, Cologne and Hanover, on 1 March 2008 a Low Emission Zone (LEZ) came into effect in Stuttgart with the aim of improving air quality. This affects all vehicles entering the Stuttgart 'Environmental zone' (Umweltzone), including vehicles from abroad.
Stuttgart has a light rail system known as the Stuttgart Stadtbahn. In the city centre and densely built-up areas, the Stadtbahn runs underground. Stations are signposted with a 'U' symbol, which stands for Unabh�ngig (independent). Until 2007, Stuttgart also operated regular trams. Stuttgart also has a large bus network. Stadtbahn lines and buses are operated by the Stuttgarter Stra�enbahnen AG (SSB). The outlying suburbs of Stuttgart and nearby towns are served by a suburban railway system called the Stuttgart S-Bahn, using tracks supplied by the national Deutsche Bahn AG (DBAG).
A peculiarity of Stuttgart is the Zahnradbahn, a rack railway that is powered by electricity and operates between Marienplatz in the southern inner-city district of the city and the district of Degerloch. It is the only urban rack railway in Germany. Stuttgart also has a Standseilbahn, a funicular railway that operates in the Heslach area and the forest cemetery (Waldfriedhof). In Killesberg Park, on a prominent hill overlooking the city, there is the miniature railway run by diesel (and on weekends with steam).
Stuttgart is a hub in the InterCityExpress and InterCity networks of Deutsche Bahn AG (DBAG), with through services to most other major German cities. It also operates international services to Strasbourg, Vienna, Zurich and Paris (four times a day, journey time 3 hours 40 minutes).
Long distance trains stop at Stuttgart Hauptbahnhof, the city's main line terminus which is also used by regional DBAG RegionalExpress and RegionalBahn for services to stations in the Stuttgart metropolitan area. The local rail networks (see above) operate underneath the
