Normative Frameworks of Transport Justice and the Measurement of Accessibility Inequalities

Transport justice research has converged on accessibility as the currency of distributive justice, yet the empirical measurement of accessibility inequality rarely derives from an explicit normative principle. This narrative review synthesizes the normative foundations of transport justice and the approaches used to measure accessibility inequalities, and examines the alignment between commitments and measurement. The synthesis shows that egalitarian, sufficientarian, prioritarian and capabilities frameworks coexist but do not dictate the choice of indicator; distributional indices such as the Gini coefficient and Lorenz curve dominate empirical practice, joined by vertical and horizontal equity ratios and needs-gap thresholds. Measurement choices regarding the accessibility metric, time threshold and spatial unit materially alter inequality estimates. A persistent gap separates the philosophical and measurement literatures, although recent translation efforts that combine equality, priority and sufficiency indicators signal a path toward normatively explicit measurement. The review concludes with implications for appraisal and planning and a research agenda for conceptually coherent equity metrics.