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Introduction
International trade plays a substantial role in the economy of the United States. More than 1.6 billion tons of international merchandise was conveyed using the U.S. transportation system in 2001, representing 10 percent of the nearly 16 billion tons of freight (Bureau of Transportation Statistics, 2004). The need to transport this merchandise raises concerns about the quality of the transportation system and its ability to support this component of freight movement. To that end, Congress directed the Bureau of Transportation Statistics (BTS) to carry out a study under Section 5115 of P.L. 105-178, the Transportation Equity Act for the 21st Century (hereafter referred to as TEA-21). The legislation states (U.S. Department of Transportation, 2003):
The Director shall carry out a study (1) to measure the ton-miles and value-miles of international trade traffic carried by highway for each state; (2) to evaluate the accuracy and reliability of such measures for use in the formula for highway apportionments…; (3) to evaluate the accuracy and reliability of the use of diesel fuel data as a measure of international trade traffic by state; and (4) to identify needed improvements in long-term data collection programs to provide accurate and reliable measures of international trade traffic for use in the formula for highway apportionments.
Basis for Evaluation—The study shall evaluate the quality and reliability of measures for use as formula factors based on statistical quality standards
developed by the Bureau in consultation with the Committee on National Statistics of the National Academy of Sciences.
Report—Not later than three years after the date of enactment of this Act, the Director shall submit to the Committee on Environment and Public Works of the Senate and the Committee on Transportation and Infrastructure of the House of Representatives a report on the results of the study carried out under paragraph (1) including recommendations for changes in law necessary to implement the identified needs for improvements in long-term data collection programs.
Under these provisions of Section 5115, the BTS requested the Committee on National Statistics to convene a panel to evaluate the accuracy and reliability of measures of ton-miles and value-miles of international trade traffic carried by highway for each state for use as formula factors for highway apportionments. The specific goals of the study were to review the findings and recommendations of a BTS staff report (Bureau of Transportation Statistics, 2003) prepared in response to Section 5115 and to explore additional data sources and methods for providing improved estimates for use in apportionment formulas.
Since its formation in August 2003, the panel has held two open meetings and two meetings in executive session and commissioned two independent studies. At an initial fact-finding meeting in September 2003, the panel heard presentations from BTS staff and experts who had contributed to the development of BTS’s 5115 report (see the agenda, Appendix A). Subsequently, the panel held a workshop in November 2003, at which outside experts and government officials discussed specific aspects of the report (see the agenda, Appendix B). In total, 15 presentations were provided to the panel in open session. The experts provided advice on the validity and quality of data used in developing the report, on alternative and emerging means of developing data on international trade traffic, and on matters of access to public and proprietary data sources (see list of presenters and their topics, Appendix C).
The Panel on BTS International Trade Traffic Study submitted a letter report to BTS in February 2004 that addressed the various conclusions of the BTS report, and several key aspects of the findings (National Research Council, 2004). The letter report assessed the validity of the findings and recommendations in the report prepared in response to Section 5115 of
TEA-21, offered interpretations of its conclusions, and provided suggestions for areas of investigation and analysis.
This final report of the panel represents an expansion of the panel’s letter report, going into more depth in several areas, in particular, more fully assessing the validity of the findings and recommendations in the BTS report. This final report draws on workshop presentations and studies commissioned by the committee to address the utility of current data sources, to examine alternative and emerging means for new data collection or increased data access, and to assess the BTS estimation methodology. In addition, this final report of the panel provides suggestions for areas of further investigation and analysis that would improve the analysis contained in the BTS report.
