A tram-train is a light-rail public transport tram vehicle which runs through from an urban tramway network to main-line railway lines which are shared with conventional trains. This combines the tram's flexibility and accessibility with a train's greater speed, and bridges the distance between main railway stations and a city centre. The tram-train concept was pioneered with the Karlsruhe model in Germany, and has since been adopted in Mulhouse in France and in Kassel and Saarbrücken in Germany.