Activity Modeling of Freight Flows in Washington State: Case Studies of the Resilience of Potato and Diesel Distribution Systems

This paper describes the development and use of a network model using publicly available industry data to analyze the resilience of two important Washington state industries. Modeling of freight activity in support of the potato and diesel industry in Washington state demonstrates how individual industries utilize the road network and how they are affected by a transportation disruption. We estimate the potato industry, which relies entirely on trucks for intra-state deliveries, generates about 50 cross-Cascade truck trips per day. Roughly 90 percent of the trucks deliver potatoes from processing facilities on the east side of the state to markets on the west side, while 10 percent carry fresh potatoes from the west to the east for processing. The coupled origins and destinations do not vary unless there is a disruption to the network. The diesel distribution system in Washington state also relies heavily on trucks, but only for the final segment of the logistics chain because both barge transport and pipelines are more cost effective modes. By necessity, trucks deliver from terminals to racks, but there is an established flexibility in these distribution operations as routes and travel distances regularly change because of variations in commodity price at each terminal and the presence of multiple terminals. As a consequence, we demonstrate that the diesel distribution system is much more resilient to roadway disruptions, especially those which occur along the cross-Cascades routes. These examples demonstrate the necessity of understanding industry practice as it relates to analyzing needed infrastructure and operational improvements to reduce economic impacts resulting from transportation disruptions.