Compares subway and metro networks across multiple cities, computing topology, frequency, centrality, walk-shed population coverage, and station criticality. Follows Derrible & Kennedy (2009) and extends it with modern efficiency, community-detection (Blondel et al.), edge-level centrality (Girvan & Newman), and station-criticality measures (Latora & Marchiori). Built from public GTFS feeds and visualized on an interactive MapLibre map; the compare tab lets you benchmark cities on each metric.