Policy insights from empty trip reduction in Colombia’s road freight transport: Evidence from national freight data

The Colombian road freight transport sector is a major contributor to greenhouse gas (GHG) emissions and plays a critical role in achieving the country’s net-zero target by 2050. While technological solutions such as vehicle electrification and alternative fuels are essential, substantial mitigation potential also lies in improving operational efficiency. A persistent source of inefficiency is the prevalence of empty trips, cargo-free freight movements that increase logistics costs, reduce fleet utilisation, and generate avoidable emissions. This study addresses empty trips from a national, system-level planning perspective by introducing a spatio-temporal synchronisation model that identifies opportunities to coordinate independent freight movements travelling in opposite directions based on temporal and spatial compatibility. By relying on aggregated information rather than firm-level routing optimisation, the model enables scalable coordination across the freight network without requiring centralised control. Two algorithms were developed to estimate current empty-trip rates from observed trip sequences and the minimum achievable rate under ideal synchronisation. Applied to more than 7.99 million trips from Colombia’s National Freight Registry, the results indicate that synchronisation could reduce empty kilometres by up to 39.34% for light and medium-duty vehicles and 37.37% for heavy-duty vehicles, corresponding to an estimated annual reduction of 130,470 tons of C O 2 e . The study also introduces the concept of structural residual empty trip revenue (SRETR) to assess the economic potential of empty trips that remain unavoidable under optimal coordination. These insights support policymakers in prioritising interventions, addressing regional freight imbalances, and integrating operational efficiency measures into national decarbonisation strategies.