The amount of freight carried by railroads between 1993 and 2003 increased 29 percent (in tons) and 33 percent (by carload) on railcars (figure 13-6). However, on average, the weight per loaded railcar remained fairly constant, ranging from 62 to 67 tons during the same period (figure 13-7).
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 2003, was 111 tons, up from 101 tons in 1993 (figure 13-8). Farm products, food and kindred products, nonmetallic minerals, and chemicals and allied products, which together represented 30 percent of tonnage in 2003, were also shipped in heavier average carloads in 2003 than in 1993 [1, 2].
Miscellaneous mixed shipments and transportation equipment were the only categories of goods that resulted in lighter average carloads in 2003 than 1993. For instance, miscellaneous mixed shipments increased by 53 percent in terms of tonnage and by 77 percent in numbers of carloads between 1993 and 2003, resulting in tons per carload that were 13 percent lighter in 2003 [1, 2]. Miscellaneous mixed shipments are primarily intermodal freight composed of shipping containers on flatbed railcars. The containers, which are mostly 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.
1. Association of American Railroads, Railroad Facts 2004 (Washington, DC: 2004).
2. U.S. Department of Transportation, Research and Innovative Technology Administration, Bureau of Transportation Statistics, calculations based on Association of American Railroads, Railroad Ten-Year Trends, 1990-1999 (Washington, DC: 2000).