Vehicle miles of travel (VMT) are key data for highway planning and management, and a common measure of roadway use. Along with other data, VMT are often used in estimating congestion, air quality, and potential gas-tax revenues, and can provide a general measure of the level of the nation's economic activity.
Previous statistical analysis revealed an unexpected drop in the VMT data between August 2000 and October 2000. This drop proved to be significant, but temporary. VMT levels for latter months of the trend, as can be seen in the graph, rise slowly to return to their previous level of growth.
|Vehicle Miles Traveled||Apr-01||Apr-02|
|Millions of highway miles||231,086||233,517|
|Vehicle miles percent change from same month previous year||1.33||1.05|
NOTE: The current value is compared to the value from the same period in the previous year to account for seasonality.
A trendline has been provided for vehicle miles traveled. The trend has been calculated through a statistical procedure called Structural Modeling, in which the time series under study is decomposed into seasonal, trend and irregular components. For further information on this statistical procedure, see: S.J. Koopman, et al., Structural Time Series Analyser Modeller and Predictor (STAMP), London: Timberlake Consultants Ltd., 2000
SOURCE: U.S. Department of Transportation, Federal Highway Administration, Office of Highway Policy Information, available at http://www.fhwa.dot.gov/ohim/tvtw/tvtpage.htm.