The amount of freight carried by railroads between 1992 and 2002 increased 26 percent (in tons) and 32 percent (by carload) on railcars (figure 4-5). However, on average, the weight of each railcar remained fairly constant. The average weight of a loaded railcar ranged from 62 to 67 tons during the same period (figure 4-6).
The relatively steady average weight of a loaded railcar masks countervailing trends among selected freight commodities. The average weight of a carload of coal, which represented 44 percent of rail freight tonnage in 2002, was 111 tons, up from 99 tons in 1992 (figure 4-7). Farm products, food and kindred products, nonmetallic minerals, and chemicals and allied products, which together represented 30 percent of tonnage in 2002, were also shipped in heavier average carloads in 2002 than in 1992 [1, 2].
Miscellaneous mixed shipments is the only category of goods that was transported in lighter average carloads. Miscellaneous mixed shipments are primarily intermodal freight composed of shipping containers on flatbed railcars. The containers, which are primarily used to move manufactured goods that tend to be lighter and more valuable than raw materials, may be partly transported by waterborne vessel and truck, as well. Miscellaneous mixed shipments increased by 55 percent in terms of tonnage and by 79 percent in terms of carloads between 1992 and 2002, resulting in carloads that were 14 percent lighter in 2002 [1, 2].
1. Association of American Railroads, Railroad Facts 2003 (Washington, DC: 2003).
2. U.S. Department of Transportation, Bureau of Transportation Statistics, calculations based on Association of American Railroads, Railroad Ten-Year Trends, 1990–1999 (Washington, DC: 2000).