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FIGURE 5 Railroad Ton-MilesTon-miles (billions)1,7001,600Improved BTS1,5001,4001,300EnoNTS1,2001,1001,0001990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002p2003Key: p = preliminary.while Eno’s ton-mile estimates for non-Class I railroadsare based on financial survey data, theimproved BTS estimates are based on actual tonmiledata and should be considered more reliable.Finally, railroad ton-mile data may not includeshipments originating in Mexico and terminating inCanada. Based on data from Transport Canada, itappears that these shipments account for less thanone tenth of one percent of all U.S. railroad traffic.WaterDomestic waterborne ton-mile estimates are presentedin figure 6 (also see appendix table A6). Thecurrent NTS estimates of annual water transportationton-miles were taken from Waterborne Commerceof the United States (U.S. Army Corps ofEngineers 2003). Data in this source are developedfrom lock data and individual trip reports that mustbe filed with the U.S. Coast Guard. Therefore, thissource represents the entire population of all domesticwater traffic, including inland waterways, coastwise,Great Lakes, and intraport traffic, along withtraffic to and from Alaska, Hawaii, and PuertoRico. The NTS and Eno estimates differ substantially,because NTS includes coastwise (domesticocean) traffic and Eno does not. Thus, the currentNTS data, which are proposed for use here, aremore comprehensive than Eno’s estimates.PipelineFigure 7 shows pipeline ton-miles (also see appendixtables A7(a) and A7(b)). Annual oil and oilproducts pipeline ton-miles were obtained fromShifts in Petroleum Transportation (Association ofOil Pipelines 2003). These data represent the entirepopulation of crude petroleum and petroleumproducts carried in domestic transportation byboth federally regulated and nonfederally regulatedpipelines. Both NTS and Eno currently use thesedata, which we also propose for use here.FIGURE 6 Waterborne Ton-Miles900800700600500400300Ton-miles (billions)19901992EnoKey: p = preliminary.19941996Improved BTS,NTS19982000p2002200328 JOURNAL OF TRANSPORTATION AND STATISTICS V8, N1 2005
FIGURE 7 Pipeline Ton-MilesTon-miles (billions)700Improved BTS, NTS,and Eno oil pipeline60050040030020019901992Key: p = preliminary.1994Improved BTSnatural gas199619982000Natural gas pipeline ton-miles are also presentedin figure 7. These new estimates are based on naturalgas deliveries reported in the Annual EnergyReview (USDOE 2003a). BTS first converted thegas deliveries, measured in cubic feet, to metric tonsand then to tons using a standard conversion factorof 48,700 cubic feet per metric ton as reported inthe International Energy Annual (USDOE 2001).There are no data available on the length of haulfor natural gas shipments, because natural gas isdrawn from a common pipeline rather than shippedto a specific consignee. Origination and terminationdata indicate that natural gas has a distribution patternsimilar to oil and oil products (USDOE 2003band 2003c). The oil and natural gas pipeline networksare also very similar. Therefore, the length ofhaul for oil and oil products was applied to the tonnageof natural gas to estimate natural gas ton-milesin transmission lines. 3Natural gas ton-miles in distribution lines (i.e.,local utilities) were estimated using 5% of transmissionlength of haul, which is approximately half thediameter of a major metropolitan area. Natural gaston-miles in gathering lines (i.e., from well to processingplant) were estimated using the same lengthof haul as in distribution lines. The ton-miles forgathering, transmission, and distribution lines were3 The 2000 to 2003 oil pipeline length of haul data aresomewhat suspect; thus, the average length of haul from1990 to 1999 was used in place of these data.p20022003then summed to provide an estimate of total naturalgas ton-miles. Natural gas ton-miles, which havenot to our knowledge been previously estimated,represent nearly as much traffic as that carried onthe inland waterway system. These new estimatesfill a substantial gap in the existing ton-mile data.The natural gas pipeline data do not include gasused to repressurize gas fields or power the pipelineitself, because these uses do not represent gascarried in revenue transportation. The pipelinedata also exclude coal slurry, ammonia, and othertypes of pipelines. There are only a few such pipelines,which tend to have either short haul or lowvolume, and appear to account for well under 1%of all pipeline ton-miles. BTS will investigate therecent decline in the oil pipeline ton-mile data andthe resulting reduction in the estimate of naturalgas ton-miles in order to improve the most recentestimates.CONCLUSIONThe improved ton-mile estimates for the air, truck,rail, water, and pipeline modes described in thispaper are both more comprehensive and more reliablethan well-known existing estimates. Theimprovements are most noticeable with respect totrucking and natural gas pipelines. Additional workwill allow BTS to further improve these basic estimatesof transportation activity.BTS has already incorporated these improvedestimates of domestic freight ton-miles into theTransportation Statistics Annual Report (USDOTBTS 2004, p. 213). 4 BTS plans to extend theimproved estimates back to 1980 in the fall 2005update to National Transportation Statistics. 5Future research will be conducted to further extendthe improved estimates back to 1960 where data areavailable.REFERENCESAssociation of Oil Pipelines. 2003. Shifts in Petroleum Transportation.Washington, DC. Table 1.Eno Transportation Foundation. 2002. Transportation inAmerica. Washington, DC.4 Estimates presented in this paper reflect subsequent revisionsin the source data.5 Available on the BTS website at www.bts.dot.gov.DENNIS 29
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Page 13 and 14: FIGURE 2 Aircraft Degradation and R
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Page 46 and 47: account for premature investments i
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Page 66 and 67: INTRODUCTIONThe Intermodal Surface
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FIGURE 1 Map of the M4 MotorwayA40A
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TABLE 2 Variables in the Fuzzy Logi
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FIGURE 9 Result of the ANN ModelMod
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TABLE 3 Modeling Results for the MG
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REFERENCESAbdalla, M. 2003. Modelin
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BOOK REVIEWSEconomic Impacts of Int
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