Resilience-oriented pathways for the China–Europe multimodal transport network under policy shocks and price competition

The sustainability–resilience nexus of the China–Europe rail–sea corridor is increasingly shaped by environmental and conventional policy shocks under capacity constraints, yet their joint equilibrium effects on modal prices and chain flows remain insufficiently quantified. A static variational inequality (VI) equilibrium framework is developed for coupled rail–sea chains under price competition with binding capacity. Tariffs, subsidies, and fuel surcharges are represented as chain-specific wedges in generalized costs, and sustainability is captured by flow-weighted carbon exposure (USD/TEU). Existence and uniqueness are ensured under standard monotonicity and Lipschitz regularity, and equilibria are computed via a projection Euler method. Scenario sweeps show that conventional tariffs mostly shift interior equilibria, whereas Carbon Border Adjustment Mechanism (CBAM) compress feasibility and precipitate earlier boundary solutions with sharper corridor contraction. Subsidy escalation produces switching bands and can concentrate flows in one mode when capacity binds. Conventional BAF-like surcharges largely rescale rankings, while low-sulfur compliance adders induce discontinuities and chain deactivation. Policy pathways are operationalized as threshold-staged tariff escalation under capacity signals, guardrail subsidies, and feasibility-triggered surcharge playbooks with booking controls, rail backstops, and rerouting bundles.