Purpose of the TSAs

To provide a more comprehensive measure of transportation services and their contribution to the national economy, the U.S. Department of Transportation's Bureau of Transportation Statistics (BTS) and the U.S. Department of Commerce's Bureau of Economic Analysis (BEA) jointly developed the Transportation Satellite Accounts (TSAs) as a supplement to the U.S. Input-Output (I-O) accounts.6 The TSAs, unlike other national economic data, explicitly estimate the value of transportation services undertaken to support the activities of a business in a not-for-hire transportation industry (termed as in-house transportation) and include the value in the national measure of transportation services. Most other measures count only the value of for-hire transportation and thus miss the contribution of in-house transportation services to the U.S. economy.

In providing a comprehensive measure of transportation services, the TSAs provide the framework for conducting studies related to the role of transportation in the economy. The TSAs provide a way to answer questions such as:

  • How much do transportation services (both for-hire and in-house) contribute to U.S. gross domestic output and gross domestic product?
  • What industries rely heavily on transportation services, and what modes do these industries depend more heavily on?
  • What transportation costs do industries incur during production?
  • What is transportation's share in the total cost of commodities purchased by consumers and other end-users?
  • How much must transportation services increase to meet an increase in the final demand of particular goods and services?
  • What is the effect of a change in the amount of transportation services produced on the economy?

Before demonstrating how the TSAs can be used to answer such questions, the following first discusses how the TSAs improve other measures of transportation activities. This is followed by an overview of the data inputs and method used to develop the TSAs, which concludes with a presentation of results from the 1997 TSAs and a discussion on future work.

Measures of Transportation Activities

The TSAs facilitate analyses, such as industrial and modal evaluation of the impact of transportation consumption and expenditure on industries and the economy, because they provide data not available from other sources. Other data sources primarily provide transportation statistics on:

  • What is transported: Statistics on the conveyance of goods (freight transportation) and the conveyance of people (passenger transportation).
  • Transportation modes: Statistics about the means of transportation, such as air, highway, pipeline, rail, urban transit, and water.
  • Industry providers of transportation: Statistics on businesses or establishments that sell transportation services in the market-place as a primary commodity. Establishments selling the same primary transportation commodity, for example, air, rail, truck, or water transportation, typically are referred to as an industry.

While useful for many analyses, statistics in the above categories have weaknesses. For instance, statistics on what is transported and on transportation modes preclude direct comparison when expressed in physical units, such as ton-miles, passenger miles, or vehicle-miles instead of dollars or other statistical units. As such, these statistics often cannot be combined across modes to form a single measure of the transportation system. Furthermore, these statistics often lack the industry detail needed to analyze the relationship between transportation modes (as well as the transportation system) and specific industries.

Statistics on industry providers of transportation provide a means for measuring the relationship between transportation and industries; however, they often do not capture transportation activities for which there are no corresponding market transactions, as in the U.S. input-output (I-O) accounts. The U.S. I-O accounts provide information only for for-hire transportation services7, for example, air transportation purchased or provided by an industry. These transactions mainly are derived from data collected by the Census Bureau8 at the establishment level of detail and are classified (as of 1997) according to the North American Industry Classification System (NAICS). NAICS groups establishments according to the similarities among the production process for establishments' primary source of revenue (primary product).9 As such, only establishments using a similar production process to produce primarily transportation services are recognized as providing transportation services. Transportation services, however, may be conducted as a support activity by establishments within nontransportation enterprises. These activities are referred to as in-house transportation.

In-house transportation is not separately measured under the NAICS. Under the NAICS, a portion of in-house transportation is captured under for-hire transportation when it is provided by an establishment, owned and operated by a nontransportation enterprise, that is large enough to be identified as a separate establishment producing primarily transportation services. For example, fleet truck transportation owned by a grocery store chain to move food stuffs from distribution centers to local stores may be classified as for-hire when it is large enough to be counted in the Economic Census. Transportation provided by smaller scale establishments within nontransportation enterprises and transportation incidental to a business establishment (e.g., delivery service provided by a local furniture store) are not separately measured in the NAICS and, hence, not measured as transportation in the standard I-O accounts (the I-O accounts would capture the value added by these types of in-house transportation under the industry to which the establishment provides the services).10 In the supplementary I-O accounts, the BEA reassigns some of the secondary products to industries in which the products are primary.11 This reassignment, however, does not provide a complete or separate measure of in-house transportation services. As such, the most prominent data sources on industry providers of transportation services do not fully capture all transportation activities.

The TSAs are a relatively new source for transportation statistics that provide not only detailed industry use of transportation services but also measure in-house transportation activities. The TSAs follow from the recommendation set forth in the 1993 manual of the System of National Accounts (SNA)12 to, when necessary for analysis, measure economic ancillary activity through satellite accounts. The SNA defines ancillary activity as services rendered for immediate consumption within the same enterprise. The United Nations handbook of I-O accounts likewise recommends measuring these in-house activities, specifically in-house transportation, through satellite accounts.13 Satellite accounts measuring inhouse transportation have been developed in other countries, such as France14 and Belgium15, and have been scoped in others, such as Australia. Development and standardization of transportation satellite accounts have become an international topic, most recently considered by the International Transport Forum during the Joint Transport Research Committee Conference in Paris, France, Mar. 23-24, 2010.

Conceptual Overview of the TSAs

As satellite accounts to the 1997 benchmark I-O accounts, the TSAs primarily provide a systematic and consistent framework and dataset for conducting analytical studies on the role of transportation in the economy, both on an industry and commodity basis (see box B for information on satellite accounts). The TSAs cover all activities related to the use of vehicles (e.g., aircraft, railcars, trucks, and water vessels) and related structures (e.g., airports, railroad stations, highways, and port facilities). The contribution of these activities is measured for both inhouse and for-hire transportation services. In-house transportation consists of the services provided by nontransportation industries for their own use. It includes that from privately owned and operated vehicles of all body types, used primarily on public rights of way, and the supportive services to store, maintain, and operate those vehicles. For-hire transportation consists of the services provided by transportation firms to industries and the public on a fee-basis. The TSAs include the seven for-hire transportation industries reported in the U.S. I-O accounts (see table 5). For both in-house and for-hire transportation services, the TSAs present detailed industry use.

I-O Account Approach to the TSAs

To measure in-house transportation services, the TSAs rearrange the I-O data. The I-O accounts provide detailed estimates of intermediate purchases by industries such as for-hire transportation industries. The I-O accounts also provide an analytical framework with detailed linkages among and between industries and final demand.

In rearranging the I-O data, the TSAs maintain the following I-O accounts approach:

  • Classification of industries and commodities using the I-O industry and commodity classification system and the special definitions and conventions in the I-O accounts, with the only exception made to form in-house transportation as a new industry and a new commodity.
  • The reassignmentor using I-O terminology, the "redefinition"of secondary products to industries in which they are the primary products. Reassignment in the TSAs involves moving all intermediate and value-added inputs of inhouse transportation from the industry in which production is secondary to the newly defined in-house transportation industry.
  • Valuation of transactions in producers' prices.

The TSAs additionally maintain the following measures made in the I-O accounts:

  • The total value-added (or GDP) by all industries.
  • The valuations of purchases for final use, transportation costs (the costs to move commodities from producers to intermediate or final users), and trade margins.

The TSAs only differ from the I-O accounts in that they separately measure in-house transportation. In the TSAs, in-house transportation is treated as a separate industry where the only output is in-house transportation service. This service covers the storage, maintenance, and operation of an industry's own aircraft, railcars, trucks, and/or water vessels to move the industry's intermediate inputs or output. This coverage differs from for-hire transportation coverage in the I-O accounts. In the I-O accounts, the use of for-hire transportation by an industry includes only transportation expenses associated with moving intermediate inputs to the industry plus the expenses for certain direct transportation services. For example, if a for-hire truck carries wheat from a farm to a mill, the I-O use table credits this activity to the mill, even though the farm may have purchased the transportation service. However, if an in-house truck of the mill transports the wheat from the farm, the TSAs use table shows the mill as providing the services and credits the activity to the farm only when an in-house truck of the farm transports the wheat to the mill.

6 For a description of the U.S. input-output (I-O) accounts, see: Ann M. Lawson et al., "Benchmark Input-Output Accounts of the United States, 1997," Survey of Current Business, 2002, 82(12) p.19, available at as of Mar. 15, 2011.

7 Transportation industries in the I-O accounts include the following: air transportation, rail transportation, truck transportation, water transportation, transit and passenger ground transportation, pipeline transportation, sightseeing transportation and transportation supportive services, courier and messenger services, and warehousing and storage.

8 The Census Bureau collects information, such as revenues, payroll, employment, and other data, for all for-hire transportation industries, except air and rail transportation, as part of the Economic Census. Air data in the I-O accounts are derived from the U.S. Department of Transportation, Air Carrier Financial Statistics Quarterly and rail data from U.S. Department of Transportation, Surface Transportation Board Association of American Railroads, 1998 Railroad Facts. For more information, see Ann M. Lawson et al., "Benchmark Input-Output Accounts of the United States, 1997," Survey of Current Business, 2002, 82(12) pp.19-109, available at as of Mar. 15, 2011.

9 The NAICS differs from the Standard Industrial Classification System (SIC) in that it groups industries according to similarities among their production process rather than their products. As such, NAICS, unlike SIC, does not distinguish between operating establishments (those that primarily produce goods or services for personal or household use or for use by other enterprises) and auxiliary establishments (those that primarily perform management or provide supportive services to an industry) but rather, classifies establishments based on what they do rather than whom they serve.

10 For information on how the treatment of transportation in NAICS differs from that in the Standard Industrial Classification System (SIC), see the section "Changes in Method in the 1997 TSAs and Comparability" in this report.

11 For information on the treatment of secondary products in the 1997 U.S. I-O accounts, see: Ann M. Lawson et al., "Benchmark Input-Output Accounts of the United States, 1997," Survey of Current Business, 2002, 82(12) p. 27, available at as of Mar. 15, 2011.

12 Commission of European Communities, International Monetary Fund, Organization for Economic Cooperation and Development, United Nations, World Bank, System of National Accounts 1993, p. 490, available at as of Mar. 15, 2011.

13 United Nations, Statistics Division, Handbook of National Account Input-Output Table Compilation and Analysis, November 1997, pp. 149-50, available at as of Mar. 15, 2011.

14 France's Ministry of Transportation and Tourism developed, for 1992, a national Transportation Satellite Account, which provides estimates of transportation expenditures by transportation modes. See Commission of National Accounts, Ministry of Transportation and Tourism, Transportation Satellite Accounts 1992, March 1996.

15 For information and data, see Belgium Transport Satellite Accounts, Federal Planning Bureau,