nowing the indirect or ‘embodied’ transportation needed for the manufacturing and distribution of products is helpful when considering transportation costs, impacts,

and potential supply chain vulnerabilities. Over the past decades, the movement of goods and the logistics networks supporting them have become faster, more complex, and more important in the US economy. Transportation also represents a major investment of public funds, with over $45 Billion invested in transportation infrastructure by the federal government in 2006 and a comparable amount by state and local agencies [1]. Understanding the preferred methods of transportation, magnitude of commodities shipped, and kinds of commodities shipped can provide insight into the resiliency and future infrastructure improvements necessary to create more reliable and efficient methods of transportation.

RESULTS We use an input-output based transportation model to estimate the modal freight requirements, direct and indirect ton-km, for 428 sectors of the U.S. economy. Indirect transportation is the transportation that occurs in the supply chain, while direct transportation is the allocated and normalized freight data from the 2002 Commodity Flow Survey [2]. Across all economic sectors, pipeline direct transport is only evident in one aggregate sector (petroleum), but is significant in the supply chain of the remaining 27 aggregate sectors. Domestic truck and rail are similar in magnitude for both direct and indirect transportation of goods and services. International water and air freight transport are also included in the model and approximately double the magnitude of freight transport for each sector, with only a small percentage of commodities being transported by international air.

Figure 1 shows the model results aggregated into 28 sectors. This figure shows the embodied transportation (in ton-km) related to the consumption of products and services in the US excluding imports. The sector with the largest embodied freight transportation is final petroleum products (e.g. gasoline, diesel, asphalt, etc) followed by government services, construction, food products, vehicle manufacturing and utilities.

Figure 1. Total embodied transportation (in ton-km) by mode for products in 28 aggregated sectors with error bars that show the 5th and 95th percentiles.

CONCLUSION This model estimates the ton-km required for each sector in

the US economy which is important in understanding freight movement, modal resiliency, the relative dependence on transportation and transportation choices for various products and services. Relating this estimated freight movement to energy requirements and greenhouse gas emissions may lead to more effective policies in reducing the freight transportation emissions.

REFERENCES [1] CBO, 2007. Trends in Public Spending in Transportation

and Water Infrastructure, 1956 to 2004. Congress of the United States, Congressional Budget Office.

[2] BTS, 2009. Commodity Flow Survey 2002. US Department of Commerce, Services Division, Washington, DC.

Rachael Nealer, Christopher L. Weber, Chris Hendrickson, H. Scott Matthews

Modal Freight Transport Required for US Goods and Services Production

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