existing tram infrastructure as well as railway lines and stations, enabling a single service to operate across both networks. A tram-train combines the urban accessibility of a tram or light rail with a mainline train's greater speed in the suburbs.

The modern tram-train concept was pioneered by the German city of Karlsruhe in the late 1980s, resulting in the creation of the Karlsruhe Stadtbahn. This concept is often referred to as the Karlsruhe model,