The latest available data on hazardous materials shipments by mode in the U.S. were collected as part of the 1997 Commodity Flow Survey (CFS). Data from the 2002 CFS, conducted in partnership by BTS and the U.S. Census Bureau, will be released in late 2004.
U.S. Department of Transportation defines hazardous materials as belonging to one of nine hazard classes:
Class 1 - Explosives
Class 2 - Gases
Class 3 - Flammable liquids
Class 4 - Flammable solids
Class 5 - Oxidizers and Organic Peroxides
Class 6 - Toxic Materials and Infectious Substances
Class 7 - Radioactive Materials
Class 8 - Corrosive Materials
Class 9 - Miscellaneous Dangerous Goods
Respondents to the 1997 Commodity Flow Survey (CFS) provided a four-digit United Nations (UN) or North American (NA) identification number to help identify the shipment as hazardous material, and allow BTS to assign the shipment to one of the nine hazardous materials classes and their divisions and make summary tabulations.
Please note that because of the industry coverage and shipment definitions of the CFS, certain hazardous materials such as infectious substances or radioactive wastes were not well represented in the CFS data.
