Assessing the Robustness of European and Chinese Air and High Speed Rail Network Accessibility

Abstract Aviation and High-speed rail (HSR) are primary modes for continental long-distance travel. While their integration can significantly enhance systemic robustness, network topologies and governance models differ drastically between Air and HSR networks across regions. We conduct a quantitative, comparative robustness analysis of the aviation-only network against the integrated aviation-HSR network for both Europe and China. Using a multi-layer network representation of scheduled services, topological metrics and a schedule-based routing algorithm, the networks are subjected to simulated random airport failures, adaptive targeted hub attacks, and operational airline shutdowns. The results reveal that under random failures, both unimodal aviation networks exhibit similar topological decay. However, under targeted attacks, China's reliance on a highly concentrated hub-and-spoke system leads to an earlier topological collapse compared to Europe's decentralized, point-to-point network. Crucially, integrating the HSR layer fundamentally shifts this dynamic. China's unified HSR mega-grid acts as a safeguard that nearly halves topological vulnerability and preserves substantial service availability during major aviation disruptions. Conversely, Europe's fragmented HSR ''patchwork" provides only marginal redundancy during aviation crises. While China can strategically leverage its HSR grid to mitigate disruptions in the aviation network, Europe must prioritize cross-border rail services to create a viable multimodal safety net for long-distance travel.