A tram-train is a railway public transport vehicle that meets a national mainline standard, but which simultaneously meets the standards of a designated light rail system (usually an urban tramway). This allows services that can utilise both mainline railway networks & stations and existing urban light rail systems, and thus also allows a combination of the tram system's or light rail system's flexibility & urban accessibility with a mainline train's greater speed. 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.