Table 3 Comparison of NHTS Trip Estimates to Other Travel Data

Table 3 Comparison of NHTS Trip Estimates to Other Travel Data

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  Monthly average pre-9/11 period (Mar. 2001-Sept. 11 2001) Monthly average post-9/11 period (Sept. 12, 2001 - May 2002) Percent change
Vehicle Miles Traveled      
Actual 242.3 225.1 -7.1
Forecast in absence of 9/11 242.3 225 -7.2
NHTS Personal Vehicle Trips (millions.)      
Estimated 201.8 181.2 -10.2
Air RPM (millions.)      
Actual 63.1 46.4 -26.4
Forecast in absence of 9/11 63.1 58.1 -7.8
NHTS Air Trips (millions)      
Estimated 18 14.1 -21.7
Rail RPM (millions.)      
Actual 508.3 439.1 -13.6
Forecast in absence of 9/11 508.3 436.4 -14.1
NHTS Train Trips (millions.)      
Estimated 1.7 1.6 -5.5
NHTS Bus Trips (millions.)      
Estimated 5.1 4.5 -12.1

SOURCE: U.S. Department of Transportation, Research and Innovative Technology Administration, Bureau of Transportation Statistics.

NOTE: Shaded difference not significant at a 0.05 level. Pre- and Post-9/11 monthly estimates of VMT are prorated for the NHTS survey overlap months of March, April, and May 2001 and 2002, using NHTS pre-and post-9/11 datasets. The weights for the overlap months are calculated using the proportion of trips taken in those months from the pre-and post-9/11 datasets. September 2001 is prorated using 0.33 for the pre-9/11 weight, and 0.67 for the post-9/11 weight.