sustainability Article Study of the Structural and Robustness Characteristics of Madrid Metro Network Elisa Frutos Bernal 1,*,† and Angel Martín del Rey 2,† 1 Department of Statistics, University of Salamanca, 37008 Salamanca, Spain 2 Department of Applied Mathematics, Institute of Fundamental Physics and Mathematics, University of Salamanca, 37008 Salamanca, Spain;
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[email protected] † These authors contributed equally to this work. Received: 8 May 2019; Accepted: 19 June 2019; Published: 25 June 2019 Abstract: A transportation service must be sustainable, respectful of the environment, and socially and economically responsible. These requirements make metro networks the ideal candidate as the most efficient mean of transport in our society. Now, a correct management of this type of infrastructures entails the analysis of the structure and robustness of these networks. This allows us to detect malfunctions and, above all, to design in the most appropriate way the expansion of subway networks. This is one of the major challenges facing the study of transport networks in sustainable smart cities. In this sense, the complex network analysis provides us with the necessary scientific tools to perform both quantitative and qualitative analysis of metro networks. This work deals with Madrid metro network, which is the largest in Spain. The main structural and topological characteristics, and robustness features of Madrid metro network were studied. The results obtained were analyzed and some conclusions were derived. Keywords: complex network analysis; subway networks; centrality measures; robustness; Madrid metro network 1. Introduction One of the central pillars on which sustainability is based is the design and implementation of procedures that allow us to manage in an efficient way the public resources, services and infrastructures.