(Based on 1997 method and 1997 procedure)
|Air||Rail; transit and ground passen-ger trans-portation||Water||Truck||Ware-housing||Pipeline; freight forward-ers; and other trans-portation servicesa||Truckb||Air, rail, and water|
|1992 procedure; 1992 classification||1.9583||1.9023||1.9422||2.0110||NA||1.7326||1.4994||NA|
|1997 procedure; 1997 classification||1.9764||1.9107||2.0313||1.9444||1.8071||1.8932||1.6081||NA|
|1997 procedure; 1997 classification||2.1416||1.8675||2.3115||1.9932||1.5738||1.8945||2.1548||2.2190|
a Includes arrangement of passenger transportation.
b In-house truck in 1992 also includes in-house bus operations as these two operations were estimated together in the 1992 TSAs.
SOURCE: U.S. Department of Transportation, Research and Innovative Technology Administration, Bureau of Transportation Statistics.