Freight Transport by Underground Pipelines: Past, Present and Future

Henry Liu, Capsule Pipeline Research Center, University of Missouri-Columbia, U.S.A.

In 1988, the American Society of Civil Engineers (ASCE) published a Task Committee Report on Freight Pipeline, discussing in detail the current status and anticipated future use of freight pipelines (i.e., pipelines that transport solids including finished products and boxes or crates). The writer was the chairman who led the preparation of the ASCE report. This paper draws information not only from the ASCE report but also from most recent developments such as information included in the proceedings of the 1st and 2nd ISUFT.

Freight pipelines include three general types: slurry pipeline, pneumatic pipeline and capsule pipelines. Each general type contains some subtypes. For instance, slurry pipeline can be either fine slurry pipeline or coarse slurry pipeline; pneumatic pipeline can be either dilute-phase or dense-phase transport, and capsule pipeline includes pneumatic capsule pipeline, hydraulic capsule pipeline and coal log pipeline. They all have different history, different characteristics, different applications, different current status, and different future. They will be individually described and discussed in this paper.

Slurry pipelines have been used extensively for over 100 years in mining including long-distance transport of coal and other minerals. Future increased use of slurry pipelines is expected for transporting sludges from water and sewage treatment plants, and other hazardous wastes. Pneumatic pipelines also have over 100 years of history for transporting hundreds of different types of cargoes over short distances. It is now used increasingly for transporting municipal solid wastes. Hydraulic capsule pipeline (HCP) has a shorter history and has not yet been used commercially. However, recent advancement in HCP technology has made it close to commercial use. Its most promising future applications appears to be for coarse minerals, construction materials and agricultural products, especially grain. Pneumatic capsule pipeline (PCP) of relatively small diameter and short length have been used widely and successfully for transporting mail and parcels, bank documents, medicine supplies, etc. Larger and longer lines of PCP have found use in Japan and the Republic of Georgia. At present, researchers in the United States are studying the use of an advanced system of PCP powered by electromagnetic capsule pumps, such as linear-induction or linear-synchronous motors. Being able to transport large amounts of cargoes of any type, such advanced PCP systems driven by electromagnetic pumps have strong potential for intercity freight transport, competing with trucks, and to a lesser degree, with trains.