Measuring Urban Transport Sustainability with Indicators: Trends, Gaps, and a Vision Forward

This study conducts one of the most extensive analyses of sustainability indicators in urban transportation to date, covering 346 peer-reviewed papers and identifying over 4,300 unique indicators—making it the largest compilation both by the number of studies analyzed and the indicators identified. For the first time in the literature, it conducts a comparative analysis of proposed and applied studies, uncovering gaps between theoretical contributions and practical needs. We examine the differing treatment of passenger and freight transportation, highlighting the contrasting perspectives of public necessity versus business-centric priorities. To help tackle the persisting standardization issues, this study introduces a novel multi-layered hierarchical classification framework. Central to this framework is the concept of sustainability cores, which unify semantically similar indicators into a single core phenomenon they refer to. Extending this framework, we draw on country-level data from real-world reporting initiatives to quantify the extent to which each core provides insight into others and to facilitate optimal indicator selection.