Passenger-Miles of Travel
Box
Data on Passenger-Miles of Travel
Two national estimates of passenger-miles of travel (pmt) are available; they differ in coverage, methodology, and other
factors. The 2000 pmt data presented in Section 2 come from the Bureau of Transportation Statistics (BTS) publication, National
Transportation Statistics 2002 (NTS). BTS compiles these data for NTS annually, primarily using mode-by-mode data
derived in various ways by BTS and others. For instance, pmt for large air carriers and intercity trains are estimated from ticket sales and trip
lengths; for transit, the data are reported by transit authorities. Each method used to estimate these pmt has differing strengths and weaknesses,
as discussed in the Accuracy Profiles for table 1-34 in NTS 2002, available at http://www.bts.gov/.
Section 5, Variables Influencing Traveling Behavior, presents 2001 pmt data from the 2001 National
Household Travel Survey, jointly conducted by BTS and the Federal Highway Administration. As survey data, they are
collected using a single methodology. This provides a coherence and comparability not available with the NTS data. However, these data are not
collected annually, making them unsuitable for year-to-year trend analyses. Another difference between the NTS and NHTS data is the extent of
their coverage among modes. It can be expected, then, that because of methodological and coverage issues the NTS and NHTS data will differ.
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