The city of Karlsruhe (about 300,000 inhabitants) has a tram network with a system length of approx. 70 kilometres. Already in 1958, the tram was extended to the surrounding communities for the first time. The metre-gauged Alb Valley Railway reconstructed with standard-gauge tracks, electrified with 750 Volt and converted to operation by tram vehicles. The success encouraged the construction of further interurban tram lines, partly using former railway tracks (today's S1, S11 and S2). In 1992, a new tram-train with dual system vehicles was inaugurated for the first time in the world, which switched between the regular railway network and the city's local tram network near Durlach. This idea was so successful that it has been copied as the "Karlsruhe model" in several regions in Germany and abroad. The tram-train network has grown up to a length of almost 600 kilometers by now, has numerous connections between railway and tram and has also extended to the wider area of Heilbronn.
The trams in Karlsruhe are operated by VBK (Verkehrsbetriebe Karlsruhe), the interurban trams and tram-trains by AVG (Albtal-Verkehrsgesellschaft). Both work together in the → KVV (Karlsruher Verkehrsverbund)