Table 3 Comparison of NHTS Trip Estimates to Other Travel Data
|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|
|Forecast in absence of 9/11||242.3||225||-7.2|
|NHTS Personal Vehicle Trips (millions.)|
|Air RPM (millions.)|
|Forecast in absence of 9/11||63.1||58.1||-7.8|
|NHTS Air Trips (millions)|
|Rail RPM (millions.)|
|Forecast in absence of 9/11||508.3||436.4||-14.1|
|NHTS Train Trips (millions.)|
|NHTS Bus Trips (millions.)|
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.