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A Decade of Growth in Domestic Freight - Rail and Truck Ton-Miles Continue to Rise

A Decade of Growth in Domestic Freight - Rail and Truck Ton-Miles Continue to Rise

by Scott M. Dennis, Ph.D.

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Domestic freight traffic carried by air, truck, rail, water, and pipeline
totaled more than 4.5 trillion
ton-miles in 2005—an increase of more
than 350
billion over the 1996 total. This 8.7 percent growth in
ton-miles, the primary physical measure of
freight transportation output, reflects a 0.9 percent compound annual growth rate between 1996 and 2005, the
latest year for which complete data
are available. However, the overall
growth masks some notable differences among modes, with ton-miles in
three modes (rail, truck, and air)
increasing while ton-miles in the other two
modes (pipeline and water) declined over the 10-year
span. Figure 1 illustrates the growth of domestic freight
ton-miles during this time period.1 While there was mostly
year-to-year growth in overall ton-miles
during the decade, it is estimated that
total domestic ton-miles declined from 4.542 trillion in 2004 to 4.538 trillion
in 2005, a decline of 0.1 percent.
This preliminary estimate is essentially unchanged for 2005 relative to the
previous year.

Modal Trends

What is a ton-mile?

A ton-mile is defined as one ton of
freight shipped one mile and, therefore,
reflects both the volume shipped
(tons) and the distance shipped (miles).
Ton-miles provide a key measure of the
overall demand for freight transportation
services, which in turn reflects
the overall level of industrial activity
in the economy. In addition, ton-miles
are used to calculate other measures
of transportation system performance,
such as energy efficiency and accident,
injury, and fatality rates.

The two largest modes in
terms of ton-miles, rail and truck, grew the fastest between 1996 and 2005—25.9 percent for rail (a compound
annual growth rate of 2.6 percent) and
21.8 percent for trucks (a compound
annual growth rate of 2.2 percent). The growth of these two modes reflects the continued growth of the goods sector of the economy generally. Air
freight ton-miles, while a small fraction of railroad and truck ton-miles, also
grew faster than domestic freight
ton-miles as a whole—14.3 percent over
the period (a compound annual growth rate of 1.5 percent). The growth
pattern of air freight ton-miles over the
period reflects a dramatic decline in
air traffic after September 11, 2001 and its subsequent recovery. Figure 2 presents change for each mode relative to
its 1996 value.

Pipeline traffic declined by 5.5 percent from 1996 to 2005 (a compound annual growth rate of -0.6 percent). The decline in pipeline ton-miles
largely reflects the
decline in domestic petroleum
production. Waterborne ton-miles declined by 22.7 percent over the
period (a compound annual growth rate of -2.8
percent). The decline in waterborne ton-miles is primarily due to
declining coastwise shipments of Alaskan petroleum.

Market Share

Figure 3 illustrates the
market shares as measured by ton-miles for each of the modes in 1996
and 2005. Although the rank order for each mode
did not change, nevertheless there were shifts in market
shares among the five modes. While the market shares in
this figure illustrate the
primary physical measure of freight
transportation output, they do not reflect the revenues earned or value of commodities transported by various modes.

The railroad mode includes
large Class I railroads (2005 operating revenue in excess of
$319.3 million) as well as smaller local and regional
railroads. Railroads carry the largest share of ton-miles, with a
market share of 38.2 percent in 2005, up from 33.0
percent in 1996. Trucking, which includes both local and intracity truck transportation, carries the next largest share at
28.5 percent–a more than 3-percentage
point increase from 1996. Pipelines, which include crude petroleum, petroleum
products, and natural gas pipelines, account for
19.9 percent of domestic freight ton-miles—a 3.0 percent decline in
market share over the 10-year span. Waterborne traffic, which includes coastal, Great Lakes, inland
waterway, and local port traffic, accounts for 13.0 percent of domestic freight ton-miles—compared to 18.3 percent in 1996.
Air freight, which includes freight carried
by passenger operators as well as all-cargo operators,
accounts for 0.3 percent of domestic freight ton-miles.

Table 1: U.S. Domestic Freight Ton-Miles by Mode (ton-miles, billions)

Estimation of Ton-Miles

Several different national
estimates of ton-miles have been developed by various organizations
over the years. These estimates have differed in coverage
and reliability. The Bureau of Transportation
Statistics (BTS) is working to improve basic measures of
transportation activity, including ton-miles. In this report BTS
estimates for air, truck, rail, water, and pipelines were
developed using a more comprehensive approach than was used in prior
estimates. Fuller coverage is achieved
by combining reported data from established sources,
estimates from surveys, and calculations based on certain
assumptions. For more information on the improved approach,
including discussion of data sources and methods used,
visit the BTS web site at www.bts.gov, and use the
search engine to find improved estimates of ton-miles.

BTS has used the improved
methodology to estimate ton-miles from 1980 onwards. The figures on the next page show the change in ton-miles
for this period. Data points for each year from 1980 to
2005 are found in National Transportation Statistics, an online publication also on the BTS
website, at table 1-46(b).

About the report

This article was prepared by Scott M. Dennis, Economist, of the Bureau
of Transportation Statistics (BTS). BTS is a component of DOT’s
Research and Innovative Technology Administration (RITA).

The estimates in this report were developed from a variety of data
sources. The principal data sources for each mode are:

Air: USDOT, RITA, BTS, Air Carrier Traffic Statistics Monthly

Truck: USDOT, RITA, BTS, 2002 Commodity Flow Survey

Rail: Surface Transportation Board, Carload Waybill Sample

Water: U. S. Army Corps of Engineers, Waterborne Commerce of
the United States


Pipeline: Association of Oil Pipelines, Shifts in Petroleum Transportation; U. S. Department of Energy, Energy Information Administration, Annual Energy Review

For related data and reports visit www.bts.gov

For questions about this or other BTS reports, call
1-800-853-1351, email answers@bts.gov, or visit
www.bts.gov.

Data —

  • Commodity Flow Survey—survey reporting value, weight, and
    ton-miles by commodity, mode, origin, and destination.
  • National Transportation Statistics—ton-mile data from 1980
    to present.

Publications —

  • Journal of Transportation Statistics, Vol. 8, No. 1, Improved
    Estimates of Ton-Miles
  • Freight in America, A New National Picture 2006

1 Ton-miles do not reflect revenues earned
or the value of commodities transported.

Updated: Sunday, May 21, 2017