What is a freight pipeline?
Freight pipelines is a generic term used for describing a variety of pipeline systems aimed at transporting solids or bottled liquid and gas to long, medium or short distances. There are three general categories of freight pipelines: pneumatic pipelines (also called "pneumatic conveying" or "pneumotransport") slurry pipelines, and capsule pipelines. Depending on whether water or air is used as the medium, capsule pipelines can be further divided into pneumatic capsule pipelines (PCP) and hydraulic capsule pipeline (HCP).

Most types of freight pipelines have a long history of successful commercial application. They have been used to transport grain, coal, rocks, sand, minerals, mine tailings, mail, library books, and a myriad of other products. Generally, freight pipelines are used only in situations where pipelines provide the most economical and most reliable way of transportation. However, since freight pipelines are normally underground, noiseless, pollution-free, and very safe, great environmental and social benefits can also be gained by using freight pipelines instead of trucks or trains to transport freight.