Freight Fluidity

“Defining Freight Fluidity: A Framework for Implementation in Maryland and Beyond”

Related TRB paper16-1897. Implementing Freight Fluidity in the State of Maryland. William Eisele, Reuben Juster, Kaveh Farokhi Sadabadi

 The transportation system is complex. It includes travelers and carriers using a variety of modes to satisfy a multitude of trips. There is increased interest in the transport of goods and supply chain activities, particularly in light of the Moving Ahead for Progress in the 21st Century Act (MAP-21), and the associated performance management expectations. Understanding freight movement with an eye toward performance management requires multi-modal data and supply chain information for informed decision-making on the freight network.

What is Freight Fluidity?
The concept of a “fluidity indicator” has been popularized by Transport Canada to evaluate the performance of trade corridors and multi-modal supply chains. For Transport Canada’s applications, the fluidity indicator measures total transit time and travel time reliability of goods along defined supply chains. There is increasing interest by the Federal Highway Administration (FHWA) to adapt “freight fluidity” in the United States, though a specific documented definition and application of what “freight fluidity” means for the U.S. – and what it might look like – is elusive.

What is clear is that any concept of freight fluidity requires multi-modal data across the entire freight network, including information on origins and destinations of freight movements by mode (i.e., supply chains). It includes an understanding of how “fluid” the supply chains are – in terms of mobility, reliability, and resiliency. There is also a need for information on the quantity of goods moved (e.g., volume, weight, value – and by commodity type) throughout the network to understand flows and to weight performance measures across the supply chain. The resiliency of the freight network is critical to shippers and carriers and is included as another element within freight fluidity performance. With this information as context and background, TTI proposes this definition of “freight fluidity.”

“Freight fluidity” is a broad term referring to the characteristics of a multi-modal freight network in a geographic area of interest, where any number of specific modal data elements and performance measures are used to describe the network performance (including costs and resiliency) and quantity of freight moved (including commodity value) to inform decision-making.”

Just how “fluid” the freight network is can be captured by quantifying performance (including resiliency) and quantity of freight moved. These elements are described in Table 1. The “geographic area” over which these elements are monitored could be a specific route (e.g., roadway, rail-line, drayage line), supply chain (combination of routes and transload “nodes”), urban area(s), statewide, regional, or global.

The Components of Freight Fluidity (Mind Your Freight Network “Ps and Qs”)


1These are selected measures and considerations. These measures are ideally obtained by mode and by commodity for complete freight network evaluation.

2Costs in the “performance” component and value in the “quantity” component capture the economic impact of freight fluidity.

3Resiliency is an element of the “performance” component because current system resiliency is captured in measures of mobility, reliability and associated costs. Note that the “4 Rs” (robustness, rapidity, redundancy, resourcefulness) of resiliency can typically be expressed in time, and hence, delay and associated cost measures. Resiliency is included in the freight fluidity framework here because it is critical for efficient goods movement during system disruptions. Evaluating and improving transportation system resiliency during disruptions serves to better understand and improve performance during challenging times of goods movement.

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