and the time spent in auto travel by each person (now about 50 min/day) is not likely to increase greatly. Data from the United States and other affluent countries indicate that there is a saturation effect in auto ownership at high income levels. Auto ownership in the United States is approaching one vehicle per licensed driver, although it is believed that a firmer upper limit in auto ownership is one vehicle per person of driving age (about 71 percent of the population in the United States).

  • Light-duty trucks and vans: The assumptions for this mode are essentially similar to those for automobiles, except for a slightly higher gasoline tax per vehicle-mile.

  • Air travel: The percentage of passenger transportation dollars spent on air travel will increase with rising incomes and saturation of expenditures on auto travel. The load factor will increase linearly until 2000 and remain constant thereafter. The energy intensity (Btu per passenger-mile) will decrease linearly until 2000 and remain constant thereafter.

  • Mass transportation15 and other passenger modes: All nonfuel operating costs (in 1975 dollars) will remain constant to 2010. For mass transportation, load factors rise in each scenario except B′, as shown below.

Average load factors in 2010 by scenario for mass transportation


(17.9 passengers per vehicle)

A*, A

31.0 passengers per vehicle


27.0 passengers per vehicle


22.0 passengers per vehicle


17.9 passengers per vehicle

The energy intensity of the vehicles used remains unchanged over the period.

  • All freight modes: The growth in all modes of freight transport per capita will be proportional to the growth in real GNP per capita. Where load factors and efficiencies change, they change linearly during the 1975–2010 period.

Industry16 The analysis of energy consumption in the industrial sector concentrated on 14 industries that account for 80 percent of the energy consumed by industry: 9 energy-consuming industries (agriculture, aluminum, cement, chemicals, construction, food, glass, iron and steel, and paper) and 5 energy-producing industries (oil and gas extraction, oil and gas refining, coal mining, synthetic fuels, and electrical generation). The energy these industries are likely to require in the future was estimated by multiplying the projected level of production for each industry in 2010 by its expected energy intensity. The projected growth

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