and solid wastes. Speed of transportation is not a crucial factor in
transporting these commodities. In contrast, PCP is more suitable
for transporting higher valued products that must be delivered
speedily, such as mail and parcels, fruits and vegetables,
and many other commercial products. Details about HCP and
PCP and their expected applications can be found in a 1998 publication
of the Task Committee on Freight Pipelines, American
Society of Civil Engineers (1).
The advantages of using PCP to transport freight are not difficult
to see. When PCP is used to transport a significant portion of
freight in the future, it will reduce the number of trucks on highways
and streets, resulting in reduced traffic jams, accidents, air
and noise pollution, and damage to pavement and bridges, that
would otherwise be caused by trucks. Consequently, PCP can
make a significant contribution to the U.S. highway system in
the future.
The purpose of this paper is to discuss the basic concept, practical
considerations, and current research on PCP, especially with
respect to its potential future use as a means of underground
freight transport between major cities.