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Quadrillion Btu
30
25
20
15
TRANSPORTATION ENERGY USE
10
1978 1984 1990
SOURCE: See chapter 4, figure 4-9.
Energy use had 1972
conditions continued
Actual
energy use
the efficiency gains derive from improvements
in energy use per vehicle-mile for passenger
cars, light trucks, and aircraft, with a cumulative
reduction over 20 years of 4.8 quads.
Changes in modal composition affect energy
use, depending on the energy intensities and
load factors of the modes. In highway travel,
declining vehicle occupancy rates have worked
against efficiency gains, although these have
been partially offset by smaller and more fuelefficient
vehicles. Improved load factors have
been key to enormous efficiency gains of rail
freight and commercial air passenger traffic.
The net effect of modal structure changes has
been to increase energy use, cumulatively over
the past two decades, by a little less than 1 quad.
In the case of passenger air travel, without the
efficiency gains due to technological improvements,
larger aircraft, and improving load factors,
energy use would have been more than two
times higher than it was in 1993 (4.7 quads
instead of 2.3 quads), almost as much as all
freight modes combined.
In recent years, highway vehicle energy efficiency
improvements (based on energy use per
passenger- and ton-mile) have tapered off. Gains
from the corporate average fuel economy standards
and initiatives have nearly reached their full
effects. Also, the collapse of oil prices in 1986
negatively affected efficiency improvements:
lower prices and stable supplies greatly weakened
the market incentives for energy efficiency.
Government energy efficiency regulations, technological
change, and transportation capital stock
turnover drove efficiency for several years after
the fall in oil prices until the early 1990s when
energy efficiency improvements slowed.
Concerns about the transportation sector’s dependence
on oil imports and the environmental
impacts of fossil fuel combustion spurred interest
in alternative fuels and vehicles. The Alternative
Motor Fuels Act of 1989, the Clean Air
Act Amendments of 1990, and the Energy Policy
Act of 1992 established programs and incentives
to encourage the use of alternative fuels
and vehicles. If successfully implemented, these
programs could result in a significant increase in
the number of alternative vehicles on the road
and supplies and availability of alternative fuels.
Whether these programs will be sufficient to initiate
a self-sustaining market for these fuels and
vehicles is not known.
The State of Transportation Statistics
A great deal is known about the physical
components of the transportation system and
their location. Much less is known about the
condition and performance of the system, how
the system is used, and how use of the system
affects the economy and society. In some cases,
data gaps impede understanding. In other cases,
basic measurement concepts need to be more
fully developed. Examples include how to fully
measure the economic importance of transportation,
and how to measure the full social costs
and benefits of transportation.
To further the state of knowledge, BTS’s research
program is building on its base of expertise
and working with other agencies to collect
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