Annual highway vehicle-miles of travel (vmt) amounted to 2.9 trillion in 2003, rising by 26 percent since 1993 , an annual 2.3 percent rate of change. Vmt per capita rose by 13 percent during the same period.
In recent years, the makeup and use of the highway vehicle fleet in the United States has changed, altering the share of vmt by vehicle type (figure 1-21). With the increasing popularity of sport utility vehicles and other light trucks, this class of vehicles registered the fastest passenger vmt growth (34 percent) between 1993 and 2003. During the same period, freight vehicle vmt for single-unit and combination trucks grew 35 percent, outpacing total passenger vehicle vmt growth (25 percent). Nevertheless, in 2003, passenger vehicles accounted for more than 90 percent of highway vmt.1
Vehicle travel has also generally increased in other modes of transportation including freight and passenger rail, air, and transit rail.2 Vehicle-miles by rail (measured in train-miles and excluding transit rail) grew 26 percent between 1993 and 2003. Freight train-miles made up over 90 percent of all rail vehicle travel in 2003. This share increased slightly between 1993 and 2003 as freight rail vehicle movements outpaced those of passenger rail over the period (figure 1-22).
Domestic service air carrier aircraft vmt increased by 46 percent between 1993 and 2003. Air carrier aircraft vmt reached 5.7 million in 2000, falling back to 5.5 million in 2001, mainly because of the terrorist attacks that year. Aircraft vmt has grown since then, reaching 6.1 million in 2003 .
The biggest change in transit rail between 1993 and 2003 was a doubling of light rail vmt as existing systems were expanded and new systems were built (e.g., in Baltimore, Dallas, Denver, St. Louis, and Salt Lake City). Commuter rail vehicle-miles were up 28 percent over this period and heavy rail vehicle-miles, 21 percent (figure 1-23).
1. U.S. Department of Transportation, Federal Highway Administration, Highway Statistics 2003 (Washington, DC: 2004), table VM-1.
2. U.S. Department of Transportation, Research and Innovative Technology Administration, Bureau of Transportation Statistics, Air Carrier Traffic Statistics (Washington, DC: Annual December issues).
1 Here, passenger vehicles includes passenger car, light truck, bus, and motorcycle vmt. Passenger cars alone accounted for 57 percent of highway vmt. See table 1-21b for detailed data.
2 A vehicle-mile of travel (1 vehicle traveling 1 mile) is a concept that is more easily applied to highway vehicles than to other modes of transportation. For instance, rail can be measured in car-miles (1 car, 1 mile) or in train-miles, which include any number of cars but may be more comparable to highway vmt. For air transportation, vmt is synonymous with an aircraft-mile of travel (1 aircraft, 1 mile).