How much inventory does chokepoint risk require? Regime-switching lead times and AIS-informed base-stock policies, 2019–2026
Kritik geçit riski ne kadar stok gerektirir? Rejim değiştiren tedarik süreleri ve AIS bilgili baz stok politikaları, 2019–2026
This paper is under review at a peer-reviewed journal. The journal name and full text will be added after acceptance.
Abstract
Disruptions at maritime chokepoints change the lead times of global supply chains for months or years. This study measures these regimes with vessel tracking data and evaluates how inventory policies should respond. Weekly transits at six chokepoints from January 2019 to November 2026 are analysed with Bayesian online change-point detection and hidden Markov models. Route-specific lead times for three trade lanes are derived from sea-route distances and used in a base-stock model with stochastic lead times, simulated over the observed regime path. The diversion of container shipping from the Suez Canal to the Cape of Good Hope was detected within one to two weeks and formed a regime with an expected duration of 137 weeks; disruptions at the Panama Canal, the Strait of Hormuz and the Bosporus followed. The diversion raised the required base stock by 15% on the Asia–North Europe lane and by 36% on the Asia–Mediterranean lane, and a policy calibrated on pre-crisis lead times lowered fill rates to 94% and 86%. Because the base-stock level is concave in the share of diverted ships, partial diversion required most of the inventory of full diversion. Updating the policy with the route mix observed in tracking data reduced costs at the onset by 5% and 33% relative to learning from realised lead times, and filtering the data through regime probabilities avoided overreaction in normal times. Chokepoint disruptions should be managed as persistent changes in lead-time regimes.
Keywords
Supply chain disruption; Stochastic lead time; Base-stock policy; Hidden Markov model; Change-point detection; Maritime chokepoints; AIS
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