Inaccessibility in Public Transit Networks
The study of networks derived from infrastructure systems has received considerable attention, yet the accessibility of such systems, particularly within public transit networks, remains comparatively underexplored. Accessibility encompasses a broad range of considerations, from infrastructure-based features such as elevators and step-free access to spatial factors such as the geographic distribution of accessible stations. In this work, we investigate infrastructure-based accessibility in two major transit systems: the London Underground and the New York City Subway. We construct network models in which nodes represent accessible stations and edges represent adjacency along transit lines. Using tools from network analysis, we examine the structural properties of these accessibility networks, including clustering patterns and the spatial distribution of accessible nodes. We further employ centrality measures to identify stations that serve as major accessible hubs. Finally, we analyze socioeconomic and tourism-related variables to assess the influence of neighborhood wealth and popularity on the prevalence of accessible stations. Our findings highlight significant disparities in accessibility across both systems and demonstrate the utility of mathematical and network-theoretic methods in understanding and improving modern transit infrastructure.