A quantitative framework for the assessment of transport vulnerability in container liner service networks

Access to the global container liner service network is vital to international trade. Disruptions to this network have major and immediate implications for consumers, industries, markets and national economies. The measurement and understanding of the existing liner service network performance susceptibility to disruptions (transport vulnerability) is therefore of critical importance to public and private stakeholders responsible for ensuring its operability and accessibility. Methodologies that assess transport vulnerability in liner service networks face two key modelling challenges: (i) A lack of historical disruption data on network components (such as ports, canals, and liner services) and (ii) the typical size of realistic liner service networks. The first challenge limits the implementation of methodologies that require prior knowledge of disruption probabilities to quantify the vulnerability of the network. The second challenge creates the need for models capable of capturing key industry practices such as transhipment, empty repositioning, and the ability of vessels to skip disrupted ports while still allowing implementations at realistic global scales. This study addresses the above-mentioned challenges by developing a quantitative framework capable of identifying critical components in large-scale networks with limited or unavailable historical disruption data. The proposed framework consists of a game-theoretic attacker-defender model (ADM) and a cost-based container assignment model (CBCAM) adapted for the analysis of networks under disruptions. The ADM consists of a two-player, zero-sum game between a malevolent agent (attacker) that seeks to maximise disruption costs and an ocean carrier (defender) that aims to minimise routing costs. The CBCAM is used to generate the payoff matrix of the game computing routing costs for the ocean carrier and disruption costs for the attacker on each of their available strategies. Linear program formulations of the joint AD-CBCAM allow for implementations on large-scale realistic liner service networks. This scalability is tested using CPLEX to solve network instances of up to 88 distinct liner services, 230 ports, and 2,648 OD pairs. Results allow establishing performance baselines and test the effectiveness of iterative interventions aimed at increasing the resilience of the system.