Freight modeling is a crucial tool in transportation planning, providing a systematic way to understand and forecast the movement of goods and vehicles. Freight models use data and quantitative methods to represent the transport of goods between origins and destinations. These models help predict routes and freight volumes throughout transportation networks, considering factors like economic activity, modal networks, infrastructure capacity, shipping costs, and commodity flows. Freight modeling enables society to plan for efficient, reliable, and sustainable freight transportation systems that serve the needs of shippers, receivers, and carriers now and in the future. A few typical planning applications of freight models are described here:
Example Planning Applications of Freight Models
This primer explains freight models from the perspectives of decision-makers, planners, policy analysts, and modelers. It describes what freight models are and how each group uses them. Briefly, decision-makers use model results to help them make policy, funding, or other choices. Planners and policy analysts are usually tasked with summarizing model results and interpreting them in a way that helps inform decision-makers about various scenarios. Modelers typically apply (or “run”) the model, which involves developing models, customizing model inputs to represent scenarios of interest, and executing the software code to produce model estimates.
For example, a decision-maker at a State DOT might need to select which projects to fund that meet state goals for urban truck traffic reduction. One option may be for the state to implement a freight rail subsidy program to shift more freight from road to rail. Freight modeling is used to evaluate the potential impact of the subsidy on freight mode choices and volumes by truck in urban areas. This information helps decision-makers understand the potential benefits of this option, which they can then compare to the program cost and to impacts of other possible projects that could alleviate urban truck traffic. The following page has more details on how decision-makers can use freight models:
A Primer for Decision-Makers: How to Use Freight Models
The rest of this primer discusses how models connect to questions that often arise in freight planning or policy exercises. Our primer aims to provide each type of freight model user with information that is commensurate with their use cases. For instance, decision-makers usually don’t need to know very detailed information about freight models, although their awareness of key assumptions or limitations may be necessary for using the model outputs to inform decisions. In contrast, planners and policy makers often benefit from more knowledge of the model, including its capabilities, how to run the model, and basic understanding of its inputs and processes. For the example above, the planner could be tasked with summarizing model results for the proposed project and presenting the results alongside other project details, such as its potential equity impacts, in a way that helps the decision-maker understand the full context. The following page has more information on how planners and policy analysts can use freight models:
Freight Model Essentials For Planners and Policy Analysts
Modelers need the most information about freight modeling, since they are typically responsible for developing the model, running it, or both. As such, this primer also offers freight modelers both information on the essentials of freight models as well as a more nuanced view of certain features and how they relate to policy questions. The following page has more information on how planners and policy analysts can use freight models:
Freight Modeling: Advanced Materials for Modelers
The scope of this primer is freight models that are widely deployed in transportation demand forecasting applications (in the US, these are mainly limited to state and regional models).