Abstract Manager

Commodity flow models are used to understand the movement of goods across the intricate network of regional and global supply chains. The movement of commodities from their origin to destination often involves multiple modes such as truck, rail, or maritime, with the need for multiple intermodal transfers between these modes. Moreover, the commodities need to pass through various regional or national borders, each governed by its own set of tariffs and cross-border policies.

There are several commodity flow modes that are used to simulate the behavior of goods, across the different permutations of routes and modes than can be selected between an origin and destination. However, these traditional commodity flow models are often complex and require substantial amount of data for their development, validation, and calibration. Consequently, this complexity contributes to increased project costs and extended timelines.

This study presents a simplified approach towards modeling commodity flows across a multimodal transportation system. The model considers travel times, intermodal transfer times, border crossing times, and the corresponding tariffs associated with movement of each commodity. These costs and times are categorized by commodity type and are represented as a link- or node-based generalized cost. The generalized cost function build-up also accounts for bottlenecks, inefficiencies, congestion, border crossing issues, and delays, etc.

The feature of the model is that it uses a combined mode choice and route assignment approach to effectively capture the multimodal nature of the commodity flows. The methodology uses a path enumeration algorithm at first to find the best possible multimodal routes between a given origin and destination for a given commodity type. The generalized transportation costs are calculated for each alternate route identified by the model. A nested logit model is used to find the probabilities based on the generalized cost. Finally, a simple traffic assignment model assigns the commodity flows to the multimodal transport network.

The model has been applied in the Middle East to understand the regional freight flows and to test the commodity flow shift to a potential rail connection. The proposed methodology will help transportation agencies, consultants, and researchers to quickly develop a baseline of freight flows within a given geography, as well as assess the trade implications of new multimodal trade corridors. The model can be easily adapted and expanded to different scenarios and regions.