The secondary research process involved comprehensive analysis of trade databases, regulatory filings, transport statistics repositories, and authoritative logistics publications. Key sources included the US Department of Transportation (USDOT), Federal Motor Carrier Safety Administration (FMCSA), Federal Maritime Commission (FMC), Bureau of Transportation Statistics (BTS), European Commission Directorate-General for Mobility and Transport (DG MOVE), Eurostat Transport Database, International Transport Forum (ITF), World Trade Organization (WTO) Trade Statistics, UNCTAD Review of Maritime Transport, International Air Transport Association (IATA) Cargo Intelligence, International Maritime Organization (IMO) shipping statistics, World Bank Logistics Performance Index (LPI), and national customs authorities from key markets. These sources were used to collect freight volume data (ton-kilometers and TEU), modal split statistics, carrier fleet capacities, infrastructure investment figures, customs clearance metrics, and regulatory compliance frameworks across road freight, air cargo, maritime shipping, and rail logistics segments.
Additional industry sources included the Council of Supply Chain Management Professionals (CSCMP) State of Logistics Report, International Association of Logistics and Supply Chain Management (IALSCM) trade data, Warehousing Education and Research Council (WERC) benchmarking studies, American Trucking Associations (ATA) freight tonnage reports, Association of American Railroads (AAR) commodity statistics, and International Federation of Freight Forwarders Associations (FIATA) market intelligence. Peer-reviewed sources included the International Journal of Logistics Management, Journal of Business Logistics, Transportation Research Part E: Logistics and Transportation Review, and Supply Chain Management: An International Journal to gather insights on supply chain optimization, last-mile delivery innovations, cold chain logistics, and intermodal transportation trends.