Connectivity, Redundancy, and Resilience in Freight Transport Networks under Disruptive Shocks

Freight transport networks are vulnerable not only because links or nodes may be physically disconnected, but also because residual capacity may become insufficient even when origins and destinations remain topologically connected. This paper develops an analytically tractable framework for freight network resilience that treats connectivity and redundancy as explicit structural economic variables. We represent a multimodal freight system as an attributed spatial graph whose links and nodes may differ by mode, capacity, generalized cost, and transfer function. Connectivity is defined in two complementary ways: topological connectivity through edge-disjoint paths and capacity-mediated connectivity through max-flow/min-cut capacity and cut slack. Disruptive shocks are modeled as link or node removal, capacity degradation, and cost jumps, capturing freight-specific disruptions such as port closures, bridge and rail-corridor failures, border delays, canal blockages, and intermodal terminal disruptions. The analysis derives cut-based vulnerability conditions, regime boundaries between smooth degradation, capacity infeasibility, and disconnection, and spatial incidence results governed by binding cuts and corridor shadow prices. A computational experiment on a synthetic bottleneck-corridor freight network illustrates the operability of the proposed measures and shows that binary connectivity can substantially overstate resilience when residual capacity is depleted. The framework bridges network theory and spatial economics by clarifying when redundancy yields systemic resilience benefits rather than marginal capacity improvements.