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Acknowledgments US Department of Transportation - BTS

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agencies. Reliability may vary because some transit agencies cannot obtain accurate information or may misinterpretcertain data definitions.TABLE 1-10. U.S. Oil and Gas Pipeline MileageOil PipelineThe data are from <strong>Transportation</strong> in America, published by the Eno <strong>Transportation</strong> Foundation, Inc. (Eno). Thenumbers reprinted here for 1960, 1965, 1970, and 1975 are Eno estimates from the U.S. <strong>Department</strong> <strong>of</strong> Energy'sEnergy Data Report issues labeled "Crude-oil and Refined Products Mileage in the United States." Eno estimated the1980 number based on the assumption that refinement <strong>of</strong> old, less pr<strong>of</strong>itable, and smaller lines exceeded in mileagethe construction <strong>of</strong> new, larger, and more-pr<strong>of</strong>itable lines. Figures from 1985 and later years are calculated from abase figure that Eno obtained from the 1982 U.S. <strong>Department</strong> <strong>of</strong> <strong>Transportation</strong> study Liquid Pipeline Director andthen incorporated that figure with data from the Association <strong>of</strong> Oil Pipe Lines and the Oil Pipeline Research Institute.Lack <strong>of</strong> additional information raises definitional and methodological uncertainties for the data's reliability. Moreover,the three different information sources introduce data discontinuities making time comparisons less reliable.Gas PipelineThese statistics originate from annual editions <strong>of</strong> Gas Facts published by the American Gas Association (AGA). Thedata reported by AGA are based on gas utilities participation and reporting to the Uniform Statistical Report. Utilitiesreporting in 1991 represented 98 percent <strong>of</strong> total gas utility industry sales while the remaining 2 percent wasestimated for the nonreporting companies based on recent historical experience. Varying percentages <strong>of</strong>nonreporters from year to year introduce minor reliability problems for time-series comparisons.TABLE 1-11. Number <strong>of</strong> U.S. Aircraft, Vehicles, Vessels, and Other ConveyancesTABLE 1-12. Sales or Deliveries <strong>of</strong> New Aircraft, Vehicles, Vessels, and Other ConveyancesCivilian AircraftThe Aerospace Industries Association (AIA) provided this data in their annual issues Aerospace Facts and Figures,"Civil Aircraft Shipments." AIA collects their data from aircraft company reports, the General Aviation ManufacturersAssociation (GAMA), and the U.S. <strong>Department</strong> <strong>of</strong> Commerce's (DOC) International Trade Administration. DOC dataprovide total number <strong>of</strong> shipments and exports, and the difference computed by AIA equals domestic shipments.DOC collects shipments data separately for individual factories or establishments and not at the company level. Apotential limitation <strong>of</strong> this approach is when a factory producing aircraft for shipment also makes aircraft parts. If theestablishment has 80 percent <strong>of</strong> its production in aircraft and 20 percent in parts, all <strong>of</strong> the output is attributed toaircraft shipments.TransportThe Aerospace Industries Association (AIA) is the source <strong>of</strong> these data. AIA obtains quarterly data from BoeingCorp., now the sole U.S. manufacturer <strong>of</strong> transport aircraft, and publicly available financial disclosure information filedwith the U.S. Securities and Exchange Commission (SEC) via Form 10-k. SEC requires a publicly traded company t<strong>of</strong>ile an annual report 90 days after the end <strong>of</strong> the company's fiscal year to provide an overview <strong>of</strong> that business.HelicoptersAIA surveyed and received data from all 10 major helicopter manufacturers on their sales and deliveries.General AviationThe general aviation figures are taken from the General Aviation Statistical Databook published by the GAMA.General aviation refers usually to the small aircraft industry in the United States. GAMA collects quarterly data fromthe 10 to 14 manufacturers who nearly equal a census <strong>of</strong> the general aviation sector.

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