An efficient and effective transportation is considered as one of the central goals of a sustainable spatial development. Therefore, transport plays a multi-dimensional role, and its ambivalence is explicitly pronounced in urban areas, where more than the half of the word population is concentrated. After decades of focusing on the promotion of individual motor car traffic, an expansion of public transport services has been strongly demanded in the last thirty years, whereas the tramway, being an environmentally sustainable and customer-friendly means of transport, plays an important role in the realization of this goal. The uptrend in the development of light rail systems, which has been observed since the 1980s, is often called the rebirth of the light rail. In some regions, the construction of rail routes was not just limited to the urban cores, but networks were also expanded in the sub- and peri-urban areas or were even joined with existing heavy rail tracks. This allows for the establishment of direct connections in a region by the use of a tram-train or light rail technology.

As opposed to the earlier dominating conceptualization of transport issues as problems which are to be solved technically, the rebirth of the light rail systems is understood within this research project as a complex socio-technical phenomenon, which is shaped by urban and social demands and developments. Given a generally unchanged propulsion technology of light rail over the years, its large technical system and its perception have undergone a substantial transformation in the framework of the institutional and fiscal set-up, the land use planning and regulation, as well as the overall travel patterns. Hence, the goal will be to conduct an integrated analysis of the rebirth of the light rail systems, which goes beyond the general transport planning, operational and technical aspects.

In the research, the transformation of local public transport will be placed in an appropriate conceptual framework and will be examined with respect to the multidimensional interrelations between technology, transport markets, policy, culture and society. For this purpose, debates about innovation in large technical systems and socio-technical regimes, infrastructure research and transportation planning paradigms and models will serve as useful theoretical platforms. The spatial perspective will be explicitly treated, whereas space is considered not only in physical, but also in relational terms and as an institutional network. In the scope of case studies in four European cities, a context-sensitive analysis should thus reveal the overlaying relationship structures and networks in a particular place.