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Major Technical Breakthrough Proposed Design |
Safety Considerations |
SUMMARY
A concept is introduced for a new mode
of freight transportation in which commodity cargoes are "pumped"
through underground or underwater pipelines. The concept itself is not new, but
a recent technical breakthrough has transformed the technology to a point where
moving freight through underground pipelines becomes a cost-effective
alternative to shipment by long-haul truck. The technology is based on an
extensive body of knowledge pertaining to existing pneumatic capsule pipeline
systems which move products, like ore or coal.
TubeXpress, or TubeX, as the new system is known, has the potential to displace a majority of long-haul trucks from the nation's roads and highways. When compared to long-haul trucks, tube freight is more economical, safer, more energy efficient and environmentally friendlier. The TubeXpress system will operate automatically under computer control, so delivery times are precisely predictable, unaffected by surface traffic, accidents or weather. Preliminary studies confirm that TubeXpress is technically and economically feasible. The technology involved is state-of-the-art and nothing new needs to be invented. The major obstacle to TubeXpress implementation is that the concept is little known, much less understood, by the transportation community. Reluctance by members of Congress to support further studies of this new technology stems from their fear that opposition from the Teamsters Union and the American Trucking Association may cost them financial support.
HISTORICAL DEVELOPMENT OF TUBE FREIGHT
The concept of moving solid objects through ducts is two centuries old. (For a history of the subject, see "Tube Transportation" by the Volpe National Transportation Systems Center (2).), sponsored by the Federal Highway Administration of the Federal Department of Transportation. The study covers the state of the art for tube freight transportation as of 1994 and it should be noted that references to SUBTRANS and TubeXpress are different names for the same system. Significant refinements in the development of pneumatic capsule pipeline (PCP) systems, (a forerunner technology to TubeXpress), began in the late 1960s. These PCP systems operated with multiple capsules in a continuous stream. Development of PCP technology was pursued independently by Dr. M. Robert Carstens in the United States (M.R. Carstens, TubeXpress Systems, Inc., unpublished data) and Dr. A.M. Alexandrov in the USSR (3). The work of both Alexandrov and Carstens was aimed at transporting bulk granular cargoes, such as ore or coal, over limited distances.
All PCP systems built to date have been powered by pumping or blowing air and using the force of the air to move the cargo-carrying capsules. Starting in 1968, a 10-year research and development program, under the direction of Dr. M.R.Carstens, developed algorithms and computer simulations of the dynamic behavior of a pneumatic capsule pipeline system (Carstens, proprietary TubeXpress data). Because a heavily loaded PCP system involves many capsules rolling through a pipeline and controlled only by pressure in the air pockets between them, design of a PCP system must be based on a simulated operation of the system. A reasonable simulation must account for the injection of discreet masses (capsules) into the air stream, acceleration of these masses after injection, acceleration of these masses as the capsules traverse grades in the pipeline, and separation of the capsules from the air stream at the downstream terminal. Simulation is of particular importance because pneumatic capsule systems tend toward dynamic instability in a resonant mode because their behavior is typical of a lightly damped spring-mass system in which the capsules act as masses and the intervening air pockets as springs. The control problem is complex because, once the capsules leave the pump station, direct control of capsule spacing and velocity is lost.
A
major drawback of all air-pumped systems is the throughput capacity limitation
imposed by the valves and airlocks needed to enable the capsules to bypass the
air pumps. The airlocks required that the capsule(s) be brought to a momentary
stop, thereby severely limiting the throughput of the system and this
limitation has been the main reason why all pneumatic capsule pipeline systems
built to date never achieved commercial success.
A MAJOR TECHNICAL BREAKTHROUGH
In 1980, William Vandersteel of Alpine, New Jersey, President of TubeXpress Systems, Inc. and its parent, Ampower Corporation, invented and patented (U.S. Patent No. 4,458,602, 1984) the embodiment of an entirely new concept for motivating a capsule pipeline system. Rather than pumping air to propel the capsules, as had been the practice with every system built up to that time, Vandersteel proposed to impart thrust to the capsules directly, recognizing that the closely fitting capsules act like pistons in a long cylinder, and, by imparting thrust to the capsules directly, they will act like pistons pumping air, thereby motivating other capsules in the line. The Patent broadly covers any stationary means of imparting thrust to the capsules, except motivating the capsules by pumping the fluid medium (air).
Though various means of inducing thrust to
the capsules could be considered, Vandersteel proposed the use of linear
induction and/or linear synchronous propulsion, whereby an electromagnetic
thrust is induced in each capsule as it passes over magnetic induction coils
embedded in the base. Propelling the capsules directly avoids the restriction
imposed by the airlocks and valves with the necessity of stopping the capsules
in the airlocks, allowing the system to operate continuously without
interruptions or distance limitation. Propelling the capsules directly, rather
than by pumping the air, is a fundamental advance, which brings about at least
a ten-fold increase in throughput capacity of a 2-meter ID capsule
pipeline system. It also explains why, to date, air pumped capsule pipeline
systems have never achieved commercial success. For the first time, it is now
practical to consider capsule pipelines for the automated transportation of
general commodity freight, in direct competition with surface transport.
The first demonstration of this new
technology was developed by Magplane Technology, Inc. of Bedford, MA (www.magplane.com) It consists of a
700 ft, 24 inch diameter fiberglass pipeline, including a 200 ft long
accelerator/decelerator section and a load/unloading station. The capsules are
designed to each carry 600 lbs of phosphate rock and they can move back and
forth through the 700 ft test section at up to 40 mph. Capsules are fitted with an array of
neodymium-iron boron permanent magnets, which interact with the linear
synchronous motor mounted external to the tube to provide propulsion and
braking forces. This is a proto-type for a 30-mile system to haul several
million tons per year of phosphate rock from Florida mines to marine terminals
for ocean shipment.
TUNNEL CONFIGURATION
Two basic approaches are possible. Either you start with tunnels wherein the vehicles (capsules) have a close fit with minimal clearance in the tunnel, or you start with a cross-section with large clearance to accommodate aerodynamic constraints. The system with closely fitting capsules is generally called a pneumatic capsule pipeline system, generically referred to as “tube freight”. The system operation is similar to a conveyer as it operates continuously, providing a constant maximum capacity. Actual the utilization depends on the cargo volume to be transported.
Tthe use of pallets and forklifts will most likely survive the tube freight revolution and, therefore, the palletized load dictates the minimum cross-section of the tunnel. The TubeXpress system uses 2-meter ID reinforced concrete pressure pipe and 2-meter ID is the smallest diameter to clear capsules carrying palletized cargoes. The choice of a circular cross-section is dictated by various considerations. Circular concrete pipe is a standard product of the concrete pipe industry with nation-wide delivery capability. Round holes lend themselves to underground boring machines. Round pipe is best suited to withstand underground forces to which it is subjected. Watertight connections are easy to achieve and maintain with round pipe.
The bottom quadrant segment is filled with concrete in which the rails and magnetic induction coils are flush embedded. Also, provision is made for pipes containing power and communication and control cabling, along with pipes for natural gas to feed the power modules. The use of concrete pressure pipe follows the current state of the art for underground conduit operating at or near near ambient pressures, but it is logical to assume that more cost effective solutions will be developed, specifically configured for TubeXpress.
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PROPOSED DESIGN PARAMETERS FOR THE TUBEXPRESS SYSTEM
The TubeXpress system, as currently envisaged, is designed to transport general commodity freight of the kind now hauled by long-haul trucks. The proposed tube system uses 2-m (6.5-ft) inside diameter reinforced concrete pressure pipes, similar to those used for sewage, drainage and aqua ducts. A concrete bed is poured in the lower quadrant segment to form a base in which the rails and propulsion components are flush embedded. Also embedded are tubes for power and control cabling, along with conduits for natural gas and fiber optic communication lines.
Continuously circulating through the main tubes (one tube for each direction) is a constant number of capsules fitted with wheels, running on steel rails. When a capsule reaches its assigned destination it is sidetracked at speed onto a parallel track where it is brought to a halt and processed. As currently proposed, each capsule has a cargo volume of 11.33 m3 (400 ft3) and will support a maximum load of 8 metric tons. The capsules' internal dimensions are 11.33 x 11.33 x 7.62 m (4 x 4 x 25 ft) to accommodate palletized freight. Each capsule is fitted with seals at the capsule ends, which clear the pipe wall by about 2.5 cm (1 in.), resulting in a drag coefficient of about 1000. The intervening air pockets, trapped between adjacent capsules, act as buffers to prevent collisions while they provide pneumatic linkage for the capsule stream. The linkage insures energy regeneration as the stream of capsules traverse up and down grades.
A characteristic of capsule pipeline systems is that, for any given cross-sectional area of the conduit, there is an optimum operating condition in which energy consumption is at a minimum. This is because a given throughput can be achieved with a few capsules operating at high speed or a larger number of capsules operating at a lower speed. Aerodynamic losses rise with increasing capsule speed, while the rolling resistance goes down with a lesser number of capsules, assuming a constant load per capsule. Conversely, as the capsule speed is reduced, aerodynamic losses decrease but the number of capsules increase, causing a rise in total rolling friction. Somewhere between these extremes, the system will operate with minimum energy consumption.
If a TubeXpress system operates at a throughput of 1000 tons per hour (TPH) in each direction, operating at a 73% load factor, with a capsule speed of 10 meters/sec (32.8 ft/sec or 22.4 mph), the capsule spacing will be 210 m (688 ft) (center-to-center) operating with a headway of 21 seconds. This interval allows sufficient time for side-tracking and re-inserting capsules as they arrive at, and depart from, the terminals. When operating at 10 meters/sec, power consumption is at a minimum but the system can operate at 25 meters/sec (56 mph) with reasonable energy cost. Even higher speeds are possible, though at increased energy cost.
Capsules are supported on four flangeless steel wheels, rolling on flush-embedded flat steel rails. Rubber-tired guide wheels are fitted at the four end corners, along the horizontal centerline of the capsule, ensuring that the support wheels track the rails and the seals clear the pipe wall. Rolling resistance of steel wheels on rails is low. Because there are no "headwinds", aerodynamic losses are confined to the friction between the moving air columns and the pipe wall, along with some eddy current losses at the seal perimeters. Flangeless wheels reduce the wear and friction characteristic off flanged railroad wheels on rails. The rolling resistance of the rubber-tired guide wheels is low because they operate with very light side loads most of the time.
The capsule stream is kept in motion by linear induction and/or linear synchronous propulsion. Magnetic coil stators, flush embedded in the concrete base, induce magnetic thrust in each capsule in much the same way as the stator of an electric motor induces a rotational thrust in the rotor. The central computer control system monitors the speed of each capsule, while preventing resonant longitudinal speed oscillations and ensuring that capsule spacing remains uniform. The induced magnetic thrust must be greater when capsules run upgrade and less or negative when running downgrade. With capsules operating at an average speed of 10 m/sec (22.4 mph), energy consumption is at a minimum and coast-to-coast transit is under 5 days. The system can operate at greater speeds up to 25 m/sec (56 mph) with reasonable expenditure of extra energy.
A central computer controls the entire system, monitors the location and speed of all capsules, maintains a record of cargo content, and assigns the origin and destination for each capsule. Concurrently, toll charges for each shipment are recorded and billed to the shipper.
Conceptually, any rotary motor has a linear counterpart. Although all electric motors operate on principles of electromagnetic interactions, there are different kinds of motors. In general, linear synchronous motors can achieve better energy conversion levels than linear induction motors, but at the price of a higher cost per motor. Linear synchronous motors are better suited for precise control of capsule spacing, while such control is more difficult to achieve with linear induction motors. For linear synchronous propulsion, the secondary, mounted on the capsule, is in the form of permanent magnets, eliminating the need to energize electromagnets. Because the maintenance of capsule spacing is critical, TubeXpress will use linear synchronous propulsion in the main lines while linear induction propulsion may be used in the terminals. The propulsion technology is under development by Magplane Technology, Inc. and the first demonstration of a capsule pipeline system, propelled by linear synchronous motors, is under test at a Florida phosphate mine where it is intended to transport 3 million tons per year of phosphate over a 30 mile distance.
ECONOMIC CONSIDERATIONS FOR TUBEXPRESS
Economic analysis of tube freight made to date suggests that a TubeXpress system can compete with trucks, even with the cost of the TubeXpress infrastructure included, provided the system is installed in corridors with sufficient freight traffic. The economic analysis takes into account all installation and operating costs, with system infrastructure amortized over 30 years, and with freight charges competitive with current rates charged by trucking companies. A competitive shipping rate for interstate trucking is assumed at 8 cents per metric ton per mile. The chart below shows that installation of a TubeXpress system in high-traffic corridors will cut the cost of freight shipment to rates about 7 cents per metric ton per mile when hauling 1000 tons per hour at 45 mph. As the traffic volume rises, cost will continue to decrease.
Assumptions:
Pipe installed for $300/ft per single
pipeline
Motor and control systems are $1,000,000/mi per pipeline
Terminal cost is $250,000/mi per pipeline
Capsules are $7000 each
All above costs financed at 7% for 30 yr
Energy cost at $0.06/KWH
Maintenance, personnel, and overhead costs are $40,000/mi/yr
per pipeline
Notes for Economic Considerations
Consumer
cost is based on breakeven cost for first year of operation. Breakeven costs
for future years will depend on the inflation of variable costs vs. inflation
of revenue. Estimates for pipeline
installation are based on current costs for boring tunnels or using cut and
cover. As the technology for
underground boring is based on current practice, it is reasonable to assume
that these costs will lower substantially once there is a need to bore
thousands of miles of tunnels.
Not
generally recognized is the substantial logistical cost attributable to the
large volume of a truck or container, dictated primarily by the cost of the
truck driver and the cost of the tractor unit. To spread these costs over many
tons of freight, trucks are much larger than the optimum size for minimizing
handling and inventory carrying costs. By reducing the module size to that of a
TubeXpress
capsule, the materials handling, warehousing and inventory costs are reduced.
To this should be added the substantial savings that are derived from the
logistical ability to meet just-in-time (JIT) delivery requirements. The
capsule, a low-cost vehicle with low demurrage cost, can serve the function of
a storage bin or pallet, thereby further reducing materials handling costs.
The
question is often raised: why not size a tube freight system to accommodate
standard ISO containers and trailers? The tube diameter increase would raise
the infrastructure cost exponentially and the system throughput capacity would
be far greater than could conceivably be needed. In addition, and of more
importance, the logistical benefit of the smaller module size of capsules,
compared to trucks, would be lost. Not generally recognized is the substantial
cost associated with consolidating cargoes to fill a truck and distributing the
contents during deliveries. The much smaller content of a capsule alleviates
this problem.
Although
the infrastructure cost of a nation-wide TubeXpress system is substantial, it is less than the cost of
expanding the existing infrastructure to accommodate future growth in truck
traffic. Additionally, since trailer-trucks cause vastly more damage to
highways than cars, shifting freight transport from trucks to underground tubes
will yield a significant increase in the life expectancy of highways and substantially
lower maintenance costs.
In
considering the cost of underground reinforced concrete pressure pipe, it is
useful to keep in mind that, in the United States today, about 1.3 million km
(over 800,000 miles) of concrete pipe has been installed. This is 20 times the
length of the Interstate Highway system. These concrete pipes move sewage,
water and drainage; yet the cost seldom precludes such investment. Virtually
all of these pipes are installed in urban areas, whereas TubeXpress lines will generally run in rural areas, with
lower easement and installation costs.
In
comparing the economics of truck versus TubeXpress, account must be taken of the fact that trucks have
nearly free use of the highways with their cost subsidized by the gasoline tax
paid mostly by motorists. For example, the Texas Department of Transportation
estimates that truck licensing in Texas, only provides about 50% of the
direct costs for maintenance of the roads and highways. These costs do not
include the substantial cost effect large truck loadings have on the original
design of road and highway projects. The TubeXpress infrastructure, on the other hand, should depend on
private financing, though Federal and State government support could likely
develop in the form of underground easement grants, tax exempt revenue bonds or direct subsidies.
The main reason TubeXpress can
compete is because trucking costs remain high.
ENERGY CONSIDERATIONS FOR TUBEXPRESS
A fully implemented, nation-wide TubeXpress system could displace most of the semi-trailer trucks that now haul interstate commodity freight. In 1998, long-haul trailer trucks accounted for 10.3% of the total oil consumption for all forms of transportation. To the extent that trucks are displaced, a fully implemented TubeXpress system will bring about a proportionate drop in total U.S. oil consumption. TubeXpress uses electric energy; hence the TubeXpress freight transportation system would no longer be at risk of becoming hostage to a foreign-imposed oil crisis. TubeXpress is the only transportation system, except for conveyers, in which the vehicle (capsule) is passive and freewheeling, fitted with neither a fuel supply, power, brakes, nor steering. The stream of capsules is kept in motion by stationary power sources. Because of this, the live-to-dead load ratio of cargo to capsules is much higher than for other cargo-carrying vehicles which must haul their own motive power and fuel. Capsules will ride on steel wheels on flat steel rails and the capsules will be aligned with the rails and center in the duct by four rubber-tired guide wheels, mounted at the four corners on the horizontal centerline of the capsule. All this results in low rolling friction, less than one quarterssssssss of that for trucks. Because the rubber-tired guide wheels are lightly loaded, they contribute little to rolling friction.
Eliminating the dissipation of energy that occurs when trucks brake and accelerate is a major source for energy saving. Unlike trucks, which start and stop as they operate in traffic, the capsule stream moves continuously. Only individual capsules, as they are side-tracked at speed when they reach their destinations, are electrically and/or pneumatically braked to a stop, but even this energy can be partially recovered to accelerate another capsule at the same location as it is phased back into the capsule stream. Because the capsule stream moves continuously, electric power consumption is steady, almost entirely in the form of base load energy.
Pneumatic linkage between the capsules provides energy regeneration whenever the capsule stream traverses mountainous terrain. And as stated previously, there are no headwinds to overcome because the capsules move along with the air columns trapped between them. As the capsule stream moves up and down grades, energy regeneration takes place as the down hill running capsules generate energy used by uphill running capsules.
Aerodynamic losses are confined to the friction between the moving air columns and the pipe wall, along with some eddy current losses around the capsule seals. The total energy required for TubeXpress is less than one-third of the energy used by trucks to move the same tonnage the same distance. Additionally, energy used by TubeXpress is in the form of electric energy, whereas trucks use diesel fuel.
As the total energy requirement to operate a nation-wide TubeXpress system substantially exceeds the installed capacity of the utility industry, the system will need to generate its own power. This can best be accomplished by automated natural gas turbine generating stations situated along the pipeline routing and spaced at intervals as dictated by power requirements. By the time the TubeXpress system in being built, fuel cell technology may well have supplanted gas turbines.
SAFETY CONSIDERATIONS FOR TUBEXPRESS
The TubeXpress system is inherently safe because it operates automatically and almost entirely underground or underwater, protecting the system from the public and the public from the system. To the extent that TubeXpress displaces trucks, highway safety is improved and traffic congestion alleviated. In 1997, medium and heavy-duty trucks were involved in more than 200,000 police-reported accidents, resulting in nearly 6000 fatalities. Nearly all of these fatalities were occupants of vehicles other than the trucks. This does not include the untold number of injuries and property damage caused by truck accidents. Traffic delays, many of them caused by trucks, add billions of dollars to the cost of hauling freight. Eliminating exhaust pollution is an added benefit of TubeXpress.
With TubeXpress, the only areas of concern from a safety standpoint will be at the terminals, where personnel is involved in transferring the cargo to door-to-door delivery trucks or other means of local distribution. Because the system is protected from the public, there will be no public exposure that could lead to safety problems. TubeXpress cargo damage is minimized because the system operates at ambient pressures and temperatures in a benign environment, not subject to shock, vibration, or adverse climatic conditions.
TubeXpress is well suited for the transport of hazardous cargoes. A loaded gasoline delivery truck, moving through a crowded city is a disaster waiting to happen. A gasoline-filled capsule traveling through an underground tube is virtually explosion and fireproof because the small supply of oxygen between adjacent capsules will quickly snuff out fires. Even this hazard may be academic because it is difficult to visualize an event that could lead to an underground accident. An earthquake or similar large movement of earth is virtually the only possible cause for trouble or accidents, and proper system design can mitigate the effects where such problems are expected.
MAINTENANCE CONSIDERATIONS FOR TUBEXPRESS
One main concern is minimizing maintenance problems within the pipelines. Buried reinforced concrete pipes have a service life of 50 to 100 years. The flat rails supporting the capsules are subject to minimum wear and expected to have a comparable life. Railroad rails suffer flange wear, particularly on curves, and the tracks wear because of accelerating and braking forces when trains start, stop, climb grades, slow down, or brake downgrade. None of these problems apply to TubeXpress because the capsules are freewheeling. Accordingly, it is estimated that the rail replacement period for TubeXpress (with respect to wear) will be much longer than that for railroad rails.
The linear or synchronous induction propulsion system uses magnetic coils embedded in the concrete base and these have a service life comparable to that of concrete pipes. If a single coil failure occurs, the system will continue to function without interruption. Nevertheless, manholes will be spaced at intervals, accessible from the surface, for use by maintenance personnel. The capsules, the only moving parts of the system, will require periodic maintenance, usually for replacement of the anti-friction wheel bearings. Incipient-failure analysis will provide timely warning, so a defective capsule can be sidetracked off-line to the nearest maintenance station(s) for replacement with a repaired capsule.
TubeXpress
should be developed privately, for the same reason that railroads, airlines,
trucking companies and pipelines are privately owned and operated. Capital finance can be provided in the private market through
the issuance of long term (100 year) revenue bonds, in the same manner that the
early railroad industry was financed.
Some indirect forms of government assistance will likely become
available in the form of tax free revenue bonds and no cost easements for
underground use of Federal lands.
Direct government subsidies should e avoided.
FUTURE DEVELOPMENT
Preliminary studies confirm the technical feasibility of installing TubeXpress systems for shallow water crossings, such as rivers or lakes. The technology is similar to vehicular tunnels used to cross rivers or bays. For this purpose, tunnels are constructed as steel fabricated pipe sections encased in concrete of sufficient weight to allow the pipeline to rest on the river bottom or in dredged ditches where the pipelines may be a hazard to surface shipping.
For deep water crossings, the use of suspended submerged tunnels is indicated. Unlike for shallow water crossings, the tunnels are designed to have a controlled buoyancy and they are kept submerged by steel cables, spaced at intervals, to concrete weights resting on the lake, sea or ocean bed. To allow safe passage for surface shipping and submarines, the tunnels would positioned at a depth of 100 to 125 meters.
Tunnels would be constructed in shipyard graving docks as dual pipe sections, welded together in a steel structure and encased in concrete.. Each section length is limited by the graving dock, which usually runs from 800 to 1000 feet. On completion of each section, both end openings are capped off and the structure is designed to achieve slightly more than neutral buoyancy, controlled by water ballasting. Once each section is completed, it is “launched” by filling the dock and an ocean tugboat will tow the floating structure out to sea.
Once the tow arrives at the tunnel construction site, a specially fitted vessel will “dry dock” the coupling between adjacent sections, remove the capped ends and bolt and seal both sections together. By adding ballast, the section still suspended from the surface vessel, will be lowered to working depth and anchored to cables attached to the concrete weights resting on the ocean bottom. The tunnel structure must have sufficient buoyancy to keep the anchoring cables in tension even when both tunnels are loaded to capacity.
Though much development work remains, the technical feasibility is not in question and, eventually, trans-ocean TubeXpress will become a major alternative to container ships.
TubeXpress competes primarily with long-haul trailer trucks and eventually will displace most of them. Neither trailer trucks nor TubeXpress is suited to make door-to-door deliveries as both move between terminals where cargoes are transferred to smaller trucks for distribution and final delivery to each addressee. TubeXpress terminals can serve multiple locations along the pipeline routing, as the loading/unloading functions are divorced from the main traffic flow. Final delivery will use door-to-door trucks.
In the future, the door-to-door or final delivery function will take place through a smaller diameter TubeXpress system, probably 24’ to 36’ diameter. Robots for all goods that fit within the smaller diameter system will handle the intermodal transfer at the TubeXpress terminals. Outsize goods will use conventional truck delivery.
Eventually, these smaller systems will link virtually every establishment, including private residences, to the TubeXpress main lines. A typical home would order most, if not all, of its purchases for food, household goods, dry cleaning, etc. by Internet and the delivery by TubeXpress would end up inside the house, like the kitchen. At the same time, household refuse and recyclables would ship out via TubeXpress to destinations encrypted on the capsule or specified by the shipper.
CONCLUSION
Most modem industries have adopted a substantial amount of automation. As a result, the productivity of these industries has risen dramatically, in many cases by several orders of magnitude. Trucks, on the other hand, have undergone little change for nearly a century, when the first Exide electric truck could manage to move 10 tons at 10 mph. Though there has been improvement in the logistical management of trucks, little progress has been made in automating trucks. Due to traffic, weather, and loading delays, one man, on average, still only moves 10 tons at about 10 mph, and productivity levels remain constrained by some highly labor-intensive practices.
The idea of moving freight through pipelines
is two centuries old and numerous attempts were made in various countries to
achieve commercial feasibility without success. But these were all air-pumped systems with the throughput
severely restricted by the need to provide airlocks and valves and this doomed
every attempt to failure. By “pumping”
the capsules directly, as introduced by TubeXpress in 1980, a ten-fold increase in throughput capacity is
achieved and, this, for the first time, allows the system to be competitive
with surface freight.
If TubeXpress transport is as economical as claimed, why is it not in use? The answer is partly political (lack of Congressional support for an economic and technical evaluation) and partly due to the fact that the capacity of existing means of surface freight transport are ample, decreasing the pressure to introduce a wholly new means of freight transport. For this reason, TubeXpress will likely first be introduced in China or one of the Asian tigers where the road infrastructure is deficient or non-existing. Just like these countries have leapfrogged us by going directly to wireless phones, obviating the need for installing a hard-wired system, they may adopt TubeXpress, reducing the need to build highways.
TubeXpress, arguably, is destined to become the greatest advance in our transportation infrastructure since the railroad displaced the stagecoach.
I . Transportation in America. ENO Transportation Foundation, 1994, pp. 9, 40.
2. Vance, L. L., and P. Matson. Tube Transportation. Report RSPA/VNTCSSS- HW495-01. Volpe National Transportation Systems Center, U.S. Department of Transportation, Cambridge, Mass., Feb. 1994.
3. Alexandrov, A. M. Theoretical Analysis of Motion Processes in Pneumatic Capsule Pipeline Systems. TRANSPROGRESS Research Station, Moscow, Russia,USSR,'79
4. Zhao, Y., and T. S. Lundgren. Dynamics and Stability of Capsules in Pipeline Transportation. Report 97-17. Aerospace Engineering and Mechanics Department, University of Minnesota, Minneapolis.
5. Hammitt, A. G. Aerodynamic Analysis of Tube Vehicle Systems. AIAA Journal, Vol. 10, No. 3, March 1972, pp. 282-290.
6. Laithwaite, E. R. A History of Linear Electric Motors. Macmillan, 1987.
7. 1995 Annual Report. American Concrete Pipe Association, 1995, Vienna, Va.
8. Transportation Statistics Annual Report 1996. Bureau of Transportation Statistics, U.S. Department of Transportation, 1996, p. 88
9. FHWA Transporter, Federal Highway Administration, US Dept. Transportation, July, '94