Global heterogeneity in urban bus networks: A multi-scale analysis of topology, resilience, and functional alignment

Efficient bus networks are pivotal for sustainable urbanism, yet existing research often lacks a unified framework to compare their structural and functional heterogeneity globally. This study addresses this gap by establishing a multi-dimensional framework that integrates macro-topology, network resilience, micro-accessibility, and functional alignment. Through a comparative analysis of 12 major metropolises, we demonstrate that the trade-off between efficiency and resilience is structurally determined. Reticular networks, exemplified by London and Paris, exhibit a structural separation of hub and bridge roles that ensures gradual degradation under targeted attacks. In contrast, monocentric systems like Birmingham and Delhi rely on aligned centrality roles, creating critical vulnerabilities where single-node failure triggers system collapse. At the micro-scale, we find that spatial compactness can compensate for topological deficiencies, enabling peripheral communities to maintain high walkability despite weak network integration. Functionally, the study identifies a morphological lag in developing cities where functionally important centers are topologically isolated from transport backbones. These insights validate our framework as a robust diagnostic tool and highlight that planning strategies must be context-specific. Specifically, monocentric systems require enhanced core redundancy to mitigate fragility, while peripheral areas benefit most from spatial consolidation and micro-connectivity improvements.