About the research
To facilitate a region’s freight transportation systems planning and operations and minimize the risk associated with increasing multimodal freight movements, this study presents a modeling framework for evaluating and optimizing freight flows on a multimodal transportation network under disruption. Unexpected events such as earthquakes, floods, and other manmade or natural disasters would cause significant economic losses. When parts of the transportation network are closed or operated at a reduced capacity, the delay of commodity movements would further increase such losses. Shifting to an alternative route or mode might help to mitigate the negative impacts. In this study, a multimodal freight transportation network was developed to simulate commodity movements, evaluate the impacts of disruptions, and develop effective emergencyoperation plans. A fluid-based dynamic queuing approximation was used to estimate the delays at classification yards and locks caused by disruption. Using the Federal Highway Administration’s (FHWA) Freight Analysis Framework version 3 (FAF3) database, a case study was constructed to model the transportation of cereal grains from Iowa to other states. Three hypothetical disruption scenarios were tested: a reduced service level at locks along the Mississippi River, a bridge outage on I-80 at the Missouri River, and severe weather in central Iowa closing the Union Pacific tracks in the area. The impacts of these disruptions were quantified and analyzed using the presented freight network model.