Air is one of a number of fluids that can be used to propel the capsule along the pipeline. The development of alternative propulsion has been far slower than for PCPs, only becoming significant after the 1950s.

Water

The use of water based capsule pipelines, instead of air, was first suggested as early as 1860 [1]. There is no evidence that R. Crawford even tested his invention (which was only granted provisional patent protection). He describes it as "hydraulic despatch apparatus for written communications, letters [and] parcels ... . The desired parts of a building ... are connected by a ... pipe fitted with movable duplex pistons or diaphragms, the spaces between which form holders for the articles. Pressure water is admitted to the main pipe from branches ... and propels the holder to its destination, where it is stopped by suitable catches working into the main pipe and operated from without. At each station a movable water-tight segmental piece is hinged to the main tube, and on opening doors in the segmental piece the holder may be removed therefrom. Means are also provided for enabling the operator on the arrival of the carriage to release the pressure at the back thereof either by suitable valve apparatus or by letting the water escape through branch pipes."

Geoffrey Pkye

In September 1943 Lord Mountbatten, head of wartime Joint Command in London, requested Geoffrey Pyke to consider one of the most critical problems in the Pacific war theatre. Allied ships had to unload under the very worst conditions, in small, makeshift ports [2]. New roads had to be constructed through jungle swamps and over mountains to battle areas, with mules used to transport cargoes. Pyke proposed 'power-driven rivers', summed up by colleague Professor Bernal as, 'essentially for the use of pipelines to carry military and other stores in cylindrical containers travelling along with the oil or other liquid in the pipe.' Pkye suggested 4 or 6 inch pipes for smaller items, 2 foot pipes for larger items. Pipes would be extended as military forces advanced. Pyke pointed out that the idea of sending objects through a pipeline was not new, and that 'go-devil' cleaning brushes had been forced by liquid pressure through petrol pipelines in the United States as early at least as 1930. Pyke added, 'The intellectually abnormal elementary nature of the solution should not ... be allowed to obscure its importance that it is, as it were, the discovery of a discovery that is bound to be made before long, and which constitutes a new method of transport which in both war and peace for a fairly wide range of commodities may supplant railways, roads and even ships...' Pyke seems however to have been the first person to propose HCP as a means of transporting goods.

In a further June 1944 memorandum, Pyke comments, 'Owing to its - superficial - appearance of novelty and imagination, I abstained ... from all mention of the possibility of using them [power-driven rivers] for the transport of troops.' Pyke was aware that the ridicule that such a project might attract could itself undermine support for it, but commented, 'the idea of transporting human beings inside the pipe has a slightly imaginative and speculative quality about it.' Pipelines were considered as an effective means of moving over terrain (or even sea) where other transport was difficult. The provision of oxygen to troops in transit, claustrophobia or cramp in the human cargo, and the high pressures that would be needed in any such system gave Pyke cause for concern. Lampe considers ([2]) that power-driven rivers were never developed since in areas such as Burma, pipelines would have needed to have been laid on some sort of road. Strategists also pointed out the vulnerability of pipelines militarily.

Alberta Research Council

Around 1958 [3], the Canadian Alberta Research Council examined the flow of immiscible liquids in pipes to evaluate the potential of pipeline methods of transporting heavy oil [4]. In one experiment researchers observed 'large, discrete cylindrical or spherical bubbles flowing concentrically in the pipe at velocities significantly higher than that of the combined flow'. They hypothesised that it would be possible to transport solids in this manner. A series of experiments were conducted over a 20 year period. These experiments were aimed at firstly establishing the technical feasibility of HCP, then developing it into a theoretical, and then economic, transport system. Funding was provided by the Council itself (which had a mandate to assist to assist industry in Alberta), regional government in Alberta, the Canadian government, and various industrial members of the Solids Pipeline Research and Development Association.

Initial experiments were wholly laboratory based, on a small scale [4]. They provided an assessment of system behaviour. Two fields tests were carried out with industry participation in 1965 and 1967 respectively. The 1965 test involved a 123km 'gathering' pipeline, of 200mm diameter. The 1967 test used a 500mm diameter, 168km long 'trunk' line. In 1967 a test loop, 1188m long and using a pipe of diameter 100mm, was constructed. Between 1971 and 1974 further experiments were conducted using a 122m long, 524mm diameter, 'shuttle' pipeline.

The Alberta work not only formed the basis of current HCP technology, it also developed new approaches to the 'capsule'. In order to be efficient, HCP required the item being transported to be contained within some form of capsule, either within a hollow shell, or as an ingot of the solid being transported. The later option was developed as the option most likely to be economically viable, since it would not require the return transport of empty shells (capsules). Ingots were developed. These were either cast from molten material or formed from a paste of ground material agglomerated with a binding agent. Ingots were shaped into cylinders and transported through the pipeline using a carrier liquid. Coal, potash and sulphur were considered, although only coal (pasted with water and transported in oil) was tested. These ingots represent the first recorded appearance of 'containerless' capsules.

The Alberta Research Council's experiments ceased in the mid 1970s due to a reduction in industrial interest and government support. Small scale HCP experiments continued, notably in Japan, Australia, India, South Africa, USA and the Netherlands (Twente University of Technology Mechanical Engineering Department) [4]. Work at Twente University included preliminary investigation of vertical HCP, as applied to the transport of manganese nodules from the ocean floor to the water surface [5]. Currently this is done using a form of water slurry pipeline.

Missouri

Image: Capsule Pipeline Research Centre test system.
Henry Liu standing next to the Capsule Pipeline Research Centre test system at the University of Missouri (Source: Endicott/Maneater).

Henry Liu and Thomas Marrero, professors working at the University of Missouri in the USA, begun to develop HCP further during the 1980s. Liu had conducted initial work into he use of HCP to transport coal for the US Government in 1979 [6]. HCP was considered for the transport of grain in the North West of the USA, specifically those areas poorly served by barge transport [7]. Liu and Marrero developed and patented Coal Log Pipeline (CLP) technology, and formed the Capsule Pipeline Research Centre at the University of Missouri in 1991. The centre's research was focused solely on CLP until 1997 [8]. CLP technology is now almost ready for commercial application. HCP research is now focusing on the transport of solid waste and biomass. Initial examinations of the feasibility of using HCP to transport solid waste had first been conducted in the 1970s by the Alberta Research Council and the Stanford Research Institute [9].

Linear induction as a means of propulsion was first considered by Victorians for small bore systems. For example, in 1862, H. Cook [10], proposes an electromagnetic device for transmitting small articles and letters. The tube would be surrounded by a series of metal frames, wound at intervals. These would act as an energised coil. An iron carriage containing a battery would then be attached through the tube, the carriages momentum carrying it between windings.

From 1976 the team at the University of Missouri developed a tubular linear induction motor [17]. "One of the two [desktop] models was an HCP using water and linear induction motors, and the other was a PCP model using air and a set of Direct Current (DC) solenoids. Both systems were able to convey capsules of metallic walls [18]." The pump consisted of a special winding (coil) around a short segment of the pipe through which capsules move [11]. The outside winding constitutes the stator motor, while the metallic walled capsules moving through the pipe constitute the rotor.

Electro-Magnetic

The German Institute of Materials Handling and Conveying, at the University of Karlsruhe, constructed a test 'tube railway' utilising 'hydro-electric' propulsion [12]. This system was named GERZ-Bahn. It used gear motors or linear short rotor motors. The primary parts of these motors, the asynchronous travelling field motors, were located at certain intervals along pipeline. Aluminium skids were mounted on the capsules, which represented the second part of the motor. A 250m test circuit was constructed, with a single capsule train. A maximum speed of 10 m/s was achieved. An 'Integral Bahn' was proposed, a single pipeline system which would be capable of carrying not only different types of freight, but also passengers. The future use of linear motors or magnetic elevation within a vacuum tube, to achieve speeds comparable to that of an aircraft was suggested, with a possible first location for such a system being between Rotterdam and the Rhur.

Image: Magplane demonstration system.
Magplane demonstration system, constructed for the IMC-Agrico Company, in Lakeland, Florida, USA. The capsule has been rotated 180 degrees to show the magnet assembly (Source: Magplane).

William Vandersteel is sometimes attributed with the invention of capsule pipeline systems in which thrust is imparted to capsules directly using linear induction and / or linear synchronous propulsion in 1980. Both Missouri and Vandersteel successfully patented very similar technology at around the same time, however the Missouri patent pre-dated Vandersteel's by a few months [A]. Mr. Vandersteel was probably the first person to appreciate the full potential application of this technology to PCPs.

Mr Vandersteel and Tubefreight LLC are currently marketing the proposals as 'Tubexpress'. Applications have been proposed for use both on land and undersea. Tubexpress is has been proposed primarily for inter-urban commodity freight transport, with capsules conveying palletised goods. 20 years on, in spite of the existence of some detailed economic work, and several attempts to lobby the US Congress, no comprehensive research has been conducted, nor prototypes constructed [13].

Magplane have developed a capsule pipeline system using the linear synchronous motor technology developed for their original Magplane system (an elevated intracity passenger transportation system). Electromagnetic drives are designed to replace the pneumatic propulsion in PCP systems [14]. These 'can greatly improve on the constraints which limit throughput in pneumatic systems, and can result in cost effective systems able to compete with truck and rail transport'. A prototype system was developed at the bequest of the Florida Phosphate Industry, which was seeking to reduce the environmental impact of transporting large quantities of phosphate.

A 700 foot demonstration system was constructed for IMC-Agrico Company in Lakeland, Florida; using a 24 inch diameter pipeline. The test capsule is six foot in length, the capsule running on two sets of 6-wheel clusters. It has a capacity of 600 pounds, and operates at up to 40 miles per hour. The capsule 'carries an array of neodymium-iron boron permanent magnets which interact with the linear motor mounted on the outside of the tube to provide propulsion, and with external coils to provide an electromagnetic switch function' [14].

Underground Automatic Guided Vehicles

The Japanese government and Tokyo University continue to develop new ideas for the transport of freight in cities using underground pipelines. Proposals in the early 1990s for a capsule pipeline based system developed into a system using 'DMTs' - Dual Mode Trucks: part conventional truck, part automatic guided vehicle. More recently, proposals have emerged for a Smart Tube System. This would involve maglev/linear induction propulsion of a capsule travelling in semi-vacuum pipeline.

Various other schemes are in development which use automatic guided vehicles running in underground tunnels, for example, a scheme at Amsterdam's Schipol Airport primarily for the transport of fresh flowers [15], a scheme for conversion of London's Post Office Railway for general freight distribution [16], and a system in Bochum, Germany [19]. Schemes of this type are not classified as capsule pipelines using this author's definition, and hence have not been reviewed within this section.

Notes

  1. From Henry Liu [18]: "At the Washington D.C. conference and in subsequent Freight Pipeline Symposia organized by Professor Zandi, Mr. Vandersteel heard my presentations on electromagnetic pumps. At that time I was focusing on the use of such pumps for hydraulic capsule pipeline (HCP), though one of the two desk models is for PCP. So, Mr. Vandersteel can be credited for having applied the same concept that I and my colleagues developed at Missouri mainly for HCP, to be used for PCP. Later, without telling each other, he and my Missouri team separately applied for a U.S. patent, with the Missouri patent being focused on HCP, and his on PCP. Surprisingly, both patents were granted within a few months, with the Missouri patent being granted a few months prior to Vandersteel's patent. Apparently, the patent examiner of either patent did not know there was another similar patent application being processed by another examiner. After Mr.Vandersteel saw our patent preceeded his, he offered a concession. He visited our University and obtained a license from the University to use electromagnetic capsule pumps for his PCP, and his company paid the University for a one-time licensing fee which was used by me to conduct further research on the Linear Induction Motor (LIM) capsule pump. He conceded that we beat him on the patent granting date, and that if challenged his patent would be voided. On my recommendation, the University did not challenge Mr. Vandersteel's patent."
  1. UK Patent 1860, no. 2278, Crawford, R., Sept 19.
  2. Lampe, D., (1959), Pyke - the unknown genius, Evans Brothers, London, chapter 10.
  3. Round, G., (1992), Pneumatic Capsule Pipeline Systems - A short history and state-of-the-art, Bulk Solids Handling, Vol 12, no. 1, February, p67-72.
  4. Brown, R., (1987), Capsule pipeline research at the Alberta Research Council, Journal of Pipelines 6, p75-82.
  5. Polderman, H., (1982), 'Design rules for hydraulic capsule transport systems', Joural of Pipelines, 3, 123-136.
  6. Liu, H., Assadollahbaik, M., Yang, J. C., (1979) Transportation of coal by hydraulic container pipeline (HCP) - a feasibility study, US Dept of Energy Report no COO-4935-2, May.
  7. Liu, H., Wu, J., (1989), Economic Feasibility of Using Hydraulic Capsule Pipeline to Transport Grain in the Midwest of the United States, in Freight Pipelines - proceedings of the 6th International Symposium on Freight Pipelines, eds Liu, Round. (Koo, W., (1989), Can a capsule pipeline system compete with truck, rail and barge in shipping agricultural products, in Freight Pipelines - proceedings of the 6th International Symposium on Freight Pipelines, eds Liu, Round, also covers similar material, although reaches an entirely different set of conclusions).
  8. Marrero, T., (undated), Capsule Pipeline Research Center, http://www.missouri.edu/~cprc/, [cached text].
  9. Liu, H., (1981), Hydraulic Capsule Pipeline, Journal of Pipelines, 1, 11-32.
  10. UK Patent 1862, no. 58, Cook H., [Bonelli G], Jan 8.
  11. Assadollahbaik, M., Liu, H., (1986), 'Optimum design of electromagnetic pump for capsule pipelines', Journal of Pipelines, 5, 157-169.
  12. Bahke, E., (1982), Pipelines were only the beginning - modern structural design for freight pipelines, Journal of Pipelines, 2, 133-147.
  13. Vandersteel, W., (1993), 'The Future of Our Transportation Infrastructure', Ampower Corporation.
  14. Magplane Technologies, (undated), Magplane Pipeline Transport, http://www.magplane.com/, [cached text].
  15. Various publications from Delft University of Technology.
  16. CCLT, (1995), 'Metro-Freight', Unpublished, Cranfield Centre for Logistics and Transport, England.
  17. Liu, H., Rathke, J., (1976), Electromagnetic Capsule Pumps, from The International Symposium on Freight Pipelines, Washington D.C.
  18. Liu, H., (2002), Correspondence with author.
  19. Stein, D., Schößer, B., (undated), CargoCap, http://www.cargocap.com/, [cached text].