Assessment of the Topology and Efficiency of a Railway Network: The Case of Deutsche Bahn

Under the light of recent studies, it seems that not only the structure and topology of networks but also their growth follows some laws of nature. It appears that this statement is also true for transport and logistics networks. Moreover, specific attributes of a given network like small-world and scale-free properties have additional influences on the efficiency of a network. The principal concern of this study is to assess the topology and structure of the different types of weighted and unweighted networks of “Deutsche Bahn (DB)” or German Railway and to evaluate their local and global efficiencies. Additionally, the different types of efficiencies of a network are used to develop an algorithm that will further help in optimising the network in the case of some planned addition or alteration of edges to the underlying or basic topology of the network. The assessment processes are divided into two parts and carried out on three different networks (both weighted and unweighted) namely, the core infrastructure network of DB and the two service networks, i.e. the long-distance InterCity (IC) service network and the high-speed InterCity Express (ICE) service network. These networks are evaluated under the lens of six different indicators; the average shortest path Length (L), clustering Coefficient (C), network Density (d), power law Coefficient (γ), local Efficiency (E_Loc) and global Efficiency (E_Glob). Finally, the results from the analyses are compared to the results available from the other studies on different railway networks of different sizes (as the transportation and logistics networks show similar properties irrespective of their sizes). The study reveals that the service networks are more efficient than the infrastructure network. Additionally, the ICE service network turns out to be more efficient than the IC service network. Further, during the development process of the algorithm, this study finds certain deficiencies in the existing quantification of the efficiency of a network and tries to form a basis to address these deficiencies.