Logistics Formulation

Freight Mode and Shipment Size Choice Model

After obtaining information on the freight shipment characteristics, such as the annual shipment demands, the involved suppliers and shippers, delivery distance, commodity attributes, other questions of interest are what type of modes should be used, and how large is the shipment size. The two decisions directly influence the freight movements in the transportation network as well as the impacts on economics and emissions. The choices of freight mode and shipment size in POLARIS determine the applied mode to ship goods and the weight of a shipment, respectively. They are modeled simultaneously as a joint decision-making problem by a closed form copula-based joint multinomial logit-multinomial logit model (MNL-MNL), which can capture the effects of common observed and unobserved factors on both choices and the interrelationship between them (Pourabdollahi et al., 2013). Both mode choice and shipment size choice are modeled by the MNL model, and a copula function is then applied to decide the interrelationship between them. There are four modes to be chosen at this stage, truck, rail, air and courier (e.g. U.S. Postal Service, United Parcel Service), and five groups of shipment size referring to the observation from a large-scale shipment survey data. The available features of shipments used in the joint model include commodity type (e.g. agricultural, chemical), commodity attributes (e.g. fragile, perishable), commodity value, shipping cost, delivery distance, and decision maker characteristics.

Important

Please refer to the the following paper for more detail:

Pourabdollahi, Z., Karimi, B., & Mohammadian, A. (2013). Joint model of freight mode and shipment size choice. Transportation Research Record, 2378(1), 84-91.