Can a bottleneck capacity enhancement policy postpone infrastructure network collapse?

In the operational processes of infrastructure networks, the occurrence of supply-demand imbalances can precipitate component overloads, and the rupture of critical bottlenecks may culminate in the collapse of the entire network. Consequently, it is important to comprehend the characteristics of these critical bottlenecks under diverse circumstances. This paper examines directed transportation infrastructure networks as a case study and, drawing upon percolation theory, precisely identifies the network's critical bottlenecks. It also considers the various perturbations or enhancement scenarios these bottlenecks might encounter in reality. A comprehensive analysis is conducted on the propagation characteristics of both strong and weak bottlenecks under different scenarios, as well as changes in the network's performance. Additionally, this study categorizes the modes of bottleneck propagation within the network into five distinct types: continuous, dispersed, coalescing, jumping, and spanning propagation. Our findings reveal that applying disturbances to the network's strong and weak bottlenecks can precipitate the premature collapse of the network. However, enhancing the capacity of these bottlenecks leads to uncertain outcomes—sometimes delaying and other times hastening the network collapse. The conclusions derived from this research not only offer guidance for the routine maintenance of infrastructure networks but also provide theoretical support for the improvement of such networks, thereby ensuring their high-performance and normal operation.