Transport infrastructure determines accessibility and thus the spatially unequally distributed potential of interaction. Accessibility is an important prerequisite for knowledge exchange and production, which, against the background of the transformation to the knowledge economy, has an increasing influence on urban and regional development. As a result of the expansion of high-speed rail (HSR) in many countries in recent decades - including Germany - HSR stations are now among the central access points for national passenger transport. By means of their accessibility effects, they not only influence the probability of interaction between resident companies and households, but they also have the potential to catalytically influence locational decisions and thus the spatial structure itself, in the medium to long term. These catalytic effects make HSR a potential instrument of regional planning and policy. This is of high societal and political relevance, particularly against the background of past and future large public investment sums in HSR infrastructure. Scientifically, the question of highest interest is whether such mediumand long-term effects of HSR stations - dependent on further influencing factors - can be observed. The recent academic discussion is far from unequivocal on the assessment of these effects and emphasizes the need for further research. It also focuses on the fast-growing transport systems in China, Spain and France, which are, however, only to a limited extent comparable with those in Germany. In addition, most studies consider the effects of accessibility improvement through aggregated inputs and outputs, while lacking spatially differentiated analyses and local drivers as well as qualitative bottom-up methods. The aim of this project is to systematically estimate the functional and spatial effects of HSR stations in Germany on decision-relevant scale levels. A particular focus is placed on the connection between the accessibility increase in the local and regional environment of HSR stations and the location decisions of knowledge economy firms. Our approach is based on a contrasting comparison of case studies and the principle of methodical triangulation: quantitative and qualitative approaches complement each other both in terms of the fine-grained nature of the data used and the combination of spatial-scientific analysis methods. In this way, we contribute to understanding the mutual reinforcing, catalytic effects of HSR infrastructure in Germany.