ABSTRACT
At the beginning of the 21st century most cities and nations find themselves moving more freight than ever before, a good deal of it over long distances and across national borders. On an average day in 1997
some 41 million tons of freight, valued at over $23 billion, was transported within the United States. This represented an average daily freight flow of 310 lb, moving an average distance of 40 mi, for each U.S. resident. In total, this represented some 14.8 billion tons and $8.6 trillion dollars of merchandise, requiring almost 3.9 billion ton-miles of freight activity (BTS, 2001). Much of this freight is a direct result of the growth in population and economic activity, while technological developments have also contributed to a greater reliance on transportation in the production process. The world is also engaging in more trade than ever before. Worldwide merchandise trade (exports) is estimated to have grown from $58 billion in 1948 to $6168 billion in 2000. Between 1960 and 2000, while the worldwide production of merchandised goods grew more than threefold, the volume of international trade increased by a factor of almost 10 (WTO, 2002). Recent projections call for increases in both U.S. and worldwide trade and associated freight volumes well into the current century. Significantly, these growth rates are well in excess of the historical growth rates in freight handling infrastructures and vehicle fleets. With many of these infrastructures already under stress, and suffering from costly traffic congestion, freight planners have an important role to play in the future of the world’s transportation and economic systems.
