Energy and Environment
As people travel and freight is transported, damage can occur to the human and natural environment. Transportation also impacts the environment when transportation equipment and fuels are produced and infrastructure is built, during repair and maintenance of equipment and infrastructure, and when equipment and infrastructure are no longer usable and are discarded and dismantled. The extent of damage throughout these life cycles of transportation fuel, equipment, and infrastructure can vary by mode. In all cases, actual impacts on the human and natural environment are dependent on ambient levels or concentrations of pollutants and rates of exposure. Many of the environmental consequences of transportation arise from widespread use of petroleum, such as, air quality impacts from burning fossil fuels and water quality impacts from spills while transporting petroleum.
Consequences of transportation for the human and natural environment
- The transportation sector used 17 percent more energy in 2005 (28.0 quadrillion British thermal units—Btu) than it did in 1995 (24.0 quadrillion Btu). (Table K-1 in Chapter 2)
- Transportation consumed 67% of U.S. petroleum usage in 2005. (Table K-3)
- Highway vehicles emitted 82% of all transportation carbon dioxide emissions in 2004. (Table K-4)
- Transportation emitted 58% of the nation’s pollution from carbon monoxide, 45% of nitrogen oxides, 36% of volatile organic compounds, and 3% of sulfur dioxide in 2002. All of these emissions have generally declined in the last decade despite a rise in vehicle-miles of travel. (Table K-5)
- Travel in passenger cars was 6.5% more energy efficient in 2004 than in 1994. (Table K-6)