Maritime Connectivity Vulnerability Index: Construction, Patterns, and Validation Across 185 Economies, 2006-2025

TL;DR

This paper introduces the Maritime Connectivity Vulnerability Index (MCVI), a new measure assessing structural fragility in maritime networks across 185 economies, validated through multiple statistical methods and correlated with trade and logistics indicators.

Contribution

The paper develops and validates the MCVI, a novel index quantifying maritime network vulnerability from a supply-side perspective, incorporating multiple data sources and robustness checks.

Findings

SIDS have higher vulnerability scores than non-SIDS, with the gap increasing over time.

Port concentration is a major vulnerability factor for nearly 40% of economies.

MCVI is strongly correlated with logistics performance and freight rates, and predicts trade impacts during shocks.

Abstract

Recent disruptions at major maritime chokepoints have exposed the structural fragility of liner shipping networks. Existing indicators measure connectivity, but none quantify its structural vulnerability from a supply-side perspective. We propose the Maritime Connectivity Vulnerability Index (MCVI), capturing three dimensions mapped to distinct UNCTAD sources: low overall connectivity (LSCI), weak bilateral integration (LSBCI), and port infrastructure concentration (PLSCI). The index covers 185 economies over 2006-2025 using pooled fractional rank normalization and equal-weight aggregation from publicly available data. SIDS exhibit a mean vulnerability 0.234 points above non-SIDS economies, with the gap widening from 0.232 to 0.249 over two decades. A modest global decline of 4.2% is observed. Port concentration dominates for nearly 40% of economies (72 of 185), establishing infrastructure diversification as a distinct policy priority. Rankings are highly stable across alternative weighting schemes, normalization methods (Spearman rho = 0.97-0.999), and PCA-derived weights; Monte Carlo simulation (1,000 replications) confirms rho > 0.95 in every realization. External validation shows strong negative correlation with the World Bank Logistics Performance Index (rho = -0.61 across seven waves) and positive correlation with ad valorem maritime freight rates (rho = +0.32). Panel regressions reveal a vulnerability paradox whereby small trade-dependent economies are simultaneously the most trade-open and the most vulnerable. Pre-crisis MCVI predicts trade losses during the COVID-19 supply shock (rho = -0.25, p < 0.005), while the contrasting positive correlation during the 2008-2009 demand shock (rho = +0.23, p = 0.01) validates the supply-side specificity of the index.