On Multimodal Freight Databases for Scalable Global-Local Transport Research and Applications

Freight transportation modeling is the key to informed infrastructure planning, economic growth, and policy-making around the world, but the available data is still highly fragmented, differing widely in classification schemes, spatial granularity, temporal coverage, and documentation standards. The paper will discuss these challenges in a systematic way by creating an integrated and structured catalog of freight data in the United States, European Union, and China, arranged in a four-step freight-modeling structure, namely: Trip Generation, Trip Distribution, Mode Choice, and Route Assignment. Nine core data classes (socioeconomic-demographic, commodity/goods, multimodal networks, ports, trade, flow databases, geographical references, regulation/code and transportation means) were thoroughly listed, normalized and described in a single metadata spreadsheet. Methodological advances are elaborate criteria of dataset evaluation (spatial and temporal coverage, completeness, accuracy, accessibility, licensing and metadata quality), standardized commodity classification crosswalks and spatial and temporal harmonization workflows that can be reproduced. Among the barriers to data access and reuse, the paper mentions inconsistent documentation, the lack of appropriate metadata standards, inconsistent frequencies of update, and schema incompatibility. The paper suggests feasible solutions that may be used to improve the interoperability of datasets such as standard documentation, open-access portals, consistent version control, and stable APIs. Filling in the identified data gaps, especially at sub-national granularity, time resolution, commodity and mode specificity, and regulatory standardization will go a long way to increasing the accuracy and applicability of freight models. This data-driven systematic framework assists researchers and policymakers to develop more transparent, reproducible and internationally comparable freight-flow models that can be used to make informed infrastructure decisions and effective freight transportation policies.