A model to analyze the export grain transportation system

Typescript (photocopy).Agricultural exports have shown a substantial increase during the 1970s and are expected to continue to grow during the 1980s. Because grain is a low-valued, bulky commodity, international grain flows are very sensitive to changes in the domestic and international transportation systems. The principal objective of this study is to develop a research tool to analyze the effect of modifications or shocks to the export grain transportation system. In addition, the developed model is used to analyze the effect of multiple car shipments on the efficiency of export grain transportation. A multicommodity, multiperiod, cost-minimizing spatial model was developed. The model links U.S. surplus grain and soybean producing regions to domestic demand and foreign demand locations. The model includes all grain handling, storage and transportation costs associated with marketing and distribution. The least-cost network flow model includes corn, soybeans, wheat (hard, soft and durum) and sorghum and represents four quarters or one crop year. The model selects the grain distribution pattern that minimizes total costs and satisfies predetermined domestic and foreign demands. To gain insight into the realism of the model-generated flows, model-derived flow patterns were compared with results of a recent national grain flow study. In general, the generated flow patterns closely correspond to historical flows. The developed model was used to evaluate the effect of unit trains on efficiency of export grain movements in the U.S. Many midwest corn and soybean producing states currently have unit train service. The estimated annual marketing system savings associated with unit train movement was $7.0 million for corn and $9.8 million for soybeans. Wheat and grain sorghum production regions have historically had only single car movements available. Results indicated an annual cost savings with unit trains of $8.5 million for sorghum and $116.8 million for wheat could be realized