Searching for the Optimum Dual-mode System


J. Richard Guadagno, Cimarron Technology, Ltd

July 15, 2000

I was pleased to find so many truly perceptive observations in the recent Reynolds' contribution with the above title. InTranSys doesn’t technically qualify as dual-mode, since from the beginning it has treated three modes of transportation with equal facility: private automobiles, public transit vehicles, and freight containers. However, so many of Reynolds' statements are pertinent to InTranSys that they deserve further comment. I believe this can best be accomplished by tracing the manner in which InTranSys has evolved into its present form.

1. Suspension system.

During the 1970s, before the effort to develop the system really began in earnest, only two suspension systems were considered for InTranSys: magnetic levitation and air suspension. It was about this time, however, that early high-speed trains in Europe and Japan demonstrated that steel wheels running on steel rails could provide stable, efficient, and long-lasting support at speeds in the 150-200 mph range. At about the same time, research by the Ontario Department of Transportation revealed that properly designed rail systems – even conventional ones – could be made to operate with almost complete silence. Thus when fuel consumption became a primary consideration after the first energy [read "petroleum"] crisis of 1973, this energy-saving method was also brought under study by Cimarron as a third alternative.

Maglev requires the constant application of an upward force (and therefore the constant expenditure of a great deal of energy) just to keep the vehicles suspended above the roadway, without contributing to the movement of said vehicles from one place to another. By comparison, the energy consumed by merely supporting vehicles on a well-designed rail system is negligible. Air suspension is even less efficient, and inevitably leads to objectionable noise levels as well. Therefore it was dropped quite early in the process. Maglev was deemed to be worthy of further consideration only if higher speeds, in the 300-500 mph range exceeding the practical limits of rails, proved to be necessary. At the time, we saw no need for such high speeds (a decision which was to be reconsidered years later) and consequently set out to design the finest steel-on-steel rail system possible.

What we came up with is a far cry from the "big heavy flanged wheels" which you cited and which are traditional in conventional railroading. Railroad cars, and especially locomotives, are by far the largest and heaviest items ever used for ground transportation purposes, exceeding even the largest trucks, trailers, and military tanks by a wide margin (giant shovels for strip mining may be bigger, but they are not really designed for transportation). Railroad cars are both supported and pushed around by these big heavy wheels; therefore they need them – and big, heavy rails as well. But it was noticed early on in the design of InTranSys that very few of the freight and passenger loads now being transported by railroads, trucks, and other surface vehicles are incapable of being subdivided into a larger number of smaller loads. InTranSys was designed to do exactly this, to assure that the maximum load applied to each wheel of the high-speed carriers used could be kept to a small fraction of that for which railroad wheels must be designed. The few large, inseparable loads were not neglected, however; multiple carriers can be used for them, with the same per-wheel loading effect.

But there is another factor regarding wheel size and life which is even more important. Both railroad wheels and rails wear out rather quickly, and must therefore be replaced quite often, because of the three purposes for which these wheels have been traditionally used in addition to that of simply supporting the load: traction (from the locomotives), steering around curves, and braking. Each of these uses involves a great deal of sliding friction between wheels and rails, and this kind of friction causes nearly all of the wear observed. By contrast, the simple rolling friction occasioned by vehicle support is almost negligible.

By employing linear synchronous motors (SCRs) for the propulsion system, InTranSys has succeeded in virtually eliminating all three of these sources of wheel and rail wear. The constant speed of travel allows the banking of all curves in the track for precisely this speed, reducing the need for steering immensely. A concave running surface on the rails improves this advantage even more, allowing the wheels to seek a middle course and eliminating all contact between the wheel flanges and the rails except under conditions of strong crosswinds. Normal braking is also accomplished by the LSMs, resulting in the automatic regeneration of electrical power to save even more energy. Even in the case of emergency braking, the wheels won’t be involved. The rails will, but only on exceedingly rare occasions. As a result of all these differences, nearly all of the wheel friction generated is of the trivial rolling type. Thus both wheels and rails on InTranSys can be expected to last many times longer than those on conventional railroads, with the life expectancy of the average wheel possibly running into millions of miles.

In fact, it is not the wheels which must be periodically checked for wear, but rather the wheel bearings. And a different method of greatly increasing the lifetime of these parts is now available: coating both the bearing balls (or rollers) and the bearing races with a thin layer of microcrystalline diamond. Diamond is an incredibly unique material which is ideally suited for this purpose. Not only is it the hardest, strongest, and stiffest material known (thus leading to exceedingly low wear rates), but it also possesses extremely high thermal conductivity, thus reducing potentially damaging heat buildup in the adjacent steel as well. These coatings can be applied by a very simple and surprisingly inexpensive process involving the sublimation and condensation of high-purity carbon in vacuo. Recent revelations by the synthetic diamond industry show that their present production capacity greatly exceeds the demand for their products (they have mistakenly concentrated more on gem stones than on industrial applications) and they are desperately looking for more work. There is a possibility that in the future even the wheel and rail running surfaces could be diamond-coated as well.

2. Platforms (pallets).

The first design for InTranSys included connectors located on the roof of each vehicle which joined with mating connectors on the overhead vehicle carriers – much like your suggested vehicle-based pallets. But this would have required reinforcing the roofs of all vehicles to support the load – a major modification to existing designs. It would also have precluded the use of such things as rooftop luggage carriers, loaded ski or boat racks, or similar projections mounted on the cars while they were using InTranSys. This also constitutes a major restriction and significantly limits one of the most important virtues of the private automobile: its versatility. In addition, any integral pallet adds some weight to each vehicle, which does add to energy consumption whenever that vehicle is either riding on rubber tires or being carried on a Maglev system. And so, with much reluctance at first, this design was dropped in favor of system-owned platforms (or pallets) suspended directly from the carriers. These can easily be designed to fit a wide variety of private vehicle types and sizes.

This turned out to be a surprisingly beneficial substitution. First of all, the use of steel-on-steel suspension greatly reduces the energy penalty of carrying additional weight, especially when compared to rubber tires or Maglev loads. Secondly, the selected platform design consists of nothing more than a flat bottom plate, four vertical columns, a small upper array of horizontal connecting bars, and clamps for the vehicle wheels. Not only can the total frontal area be kept to a tiny fraction of that of the loads carried, but each of these items can also be designed to conform to an airfoil shape along the direction of motion. These factors thus minimize air drag and the energy required to move platforms around. At the same time, they allow users to retain virtually all of today’s vast variety of vehicle shapes and sizes, each tailored to the needs and desires of its owner – providing care is taken to tie down all exterior loads to withstand the higher speeds of 150 mph. And it leaves each user with only a minimal modification to be made to his own vehicle: a simple electrical connection and nothing more.

At one time the possibility of reducing the frontal area of the platforms even more was studied. Both telescoping and folding (pantographs) of the vertical struts were considered. But both methods would have required the installation of additional components to the structures, as well as more material. As a result, the benefits in both cases would have been minimal, while the greater complexity would have entailed major increases in costs while reducing reliability significantly. But the main argument against them came when the issue of storage of the platforms was addressed. The final solution to this potential problem revealed that such measures were not necessary at all.

It was decided that these system-owned platforms would be stored precisely where they are needed, with each of them – more or less permanently connected to its own vehicle carrier – being located at one of the millions of loading stalls located at the many stations on the system. Since the system capacity can not exceed the number of stalls, this feature alone provides more than enough storage space. The only times a platform would be detached from the carriers is when it is lowered to the floor of the station to allow the next vehicle to drive onto it.

Today’s annual mileage figures show that the average car is actually moving only about 3% of the total time. It has been estimated that carriers (with platforms) could be used far more frequently, perhaps as much as 60% of the time instead. Thus the total number of carriers would only have to be about 1/20th as great as the number of vehicles using them. The cost of providing 10 to 12 million simple platforms would undoubtedly be much lower than that of refitting 200 million vehicles with extensive modifications. And the platforms, with their carriers, could always be found exactly where they are needed, stored in the stations where every user of the system must begin and end each journey. Travelers never need to make any separate arrangements to assure their availability. It is this combination of maintaining the freedom of each driver to own a vehicle of his own choosing, while still allowing that driver to follow the much easier, cheaper, and faster process of having that vehicle carried on an automated system whenever he chooses, which has propelled InTranSys so far ahead of all other dual-mode or tri-modal systems.

Unlike "the inherent ugliness of integral pallets", the platforms of InTranSys would expose to the public below the tracks nothing more than neat, uniform, smooth rectangles carrying automobiles – most of which are far uglier themselves, especially if seen from below. While the tops of the platforms might have to be cleaned occasionally after a motorist drives directly from a muddy dirt road into a station, the bottom surfaces should always remain free of any disfiguring materials. In fact, the greatest visual problem may turn out to be resisting any temptation to rent these spaces out to commercial advertisers, who will undoubtedly wish to extend the veritable plague of garish ugliness which now covers so many facets of our lives, ranging from athletes’ uniforms to race cars to arena walls to Interstate roadsides to overhead blimps.

3. Maglev compatibility.

When energy efficiency became the prime design requisite for InTranSys back in 1975, and it became known that its leave-anytime feature could provide faster door-to-door travel than either airlines or 500-mph Maglev for distances up to at least 750 miles, any further consideration of the latter means of suspension was discontinued. After all, air drag even at 300 mph is four times as high as at 150, and we felt that no valid arguments could be found to justify such an energy waste.

But we were wrong. All of the world’s current transportation methods will be severely affected by the impending exhaustion of petroleum (and it is very heartening to see that someone else recognizes this fact). But all ground transportation can readily be converted to electric power, whether it is automated rail guideways of any type, electric cars for short-range travel, mass transit lines, or conventional railroads. In fact, the power for all of these can eventually be provided by the only truly sustainable source we have available to us: solar energy. But there are two important types of transport which cannot readily avail themselves of this virtually limitless energy source: airplanes and ocean-going ships.

In the not-too-distant future, we can expect that all of the latter vessels will be nuclear-powered, whether our gut reaction favors this or not. Actually, the dangers of nuclear vessels are far less than those associated with Diesel-powered ships. Oil spills and shipboard fires and explosions occur so frequently that we have long since come to accept them, whereas even the slightest radiation leak makes worldwide news. But the small nuclear reactors needed for ships can easily be designed so that they are mechanically isolated from the rest of the craft and can remain so even in the event of a sinking caused by unrelated matters. If such events should take place in shallow water, retrieval methods developed for sunken submarines can get them out safely. If a sinking should take place in deep water, then the reactor has already been disposed of in the safest spot we can think of.

But no such simple solution can be found for airplanes. There will always be some demand for rapid long-distance travel, especially across the oceans. And it also appears that airplanes will always be dependent on high-energy chemical fuels, even when those fuels will have to be produced artificially by means of expensive, energy-consuming processes. Unless we continue the asinine policy of heavily subsiding air travel as we now do with SSTs, the cost of such travel will inevitably rise to unheard-of figures, and the medium will be available solely to the very wealthy and the military. Thus it behooves us to find a substitute – different from InTranSys – which can out-compete tomorrow’s air travel. The only solution is Maglev, whose high energy consumption compared with InTranSys becomes relatively low energy consumption when compared to that of future airplanes.

But to accomplish this, we will have to design Maglev systems which are far different from the few extravagant demonstration projects now in existence. The first change we must make is to abandon the cattle-car mentality which has long been employed for mass transit systems. It works like this: cattle breeders learned centuries ago that it is far cheaper to employ just a few cowboys to drive a large herd of cattle than to transport the same cows one at a time. Therefore they round up all the cattle they can and put them temporarily into holding pens until a sufficient number are present to make the drive of a large herd economical. In the same way, passenger trains, airliners, and large public transit vehicles follow the same practice. But in this case they don’t even have to round the cattle up. Their customers voluntarily migrate on their own to the holding pens (also known as stations or airports) and wait with many others until a large enough number of them are present to justify the use of the large cattle cars they must ride in. Then they are herded aboard, transported all at once to their destination, and dispersed. Passengers who can’t make that flight or train must then wait – often for hours or even days – before the next cattle car becomes available.

Modern jet liners, luxury trains, and large subsidized public transit vehicles may be highly sophisticated cattle cars, but they are cattle cars nevertheless. Most proposed Maglev systems are the same. This is why it is so easy for a system like InTranSys, with its leave-anytime capability, to offer much faster door-to-door travel while moving at slower (and cheaper) speeds. But there is no reason why future Maglev systems cannot do the same. Large, 100-passenger vehicles should be forgotten and replaced by much smaller ones leaving at much higher frequencies, just as the public transit vehicles on InTranSys will do. This would have many other advantages in addition to offering the customers a chance to leave when they want. Large vehicles beget large concentrations of weight, and thus require much more bulky track structures to support them. Thus construction costs could be reduced by well over half if smaller vehicles were used instead. Since Maglev vehicles, like InTranSys ones, cannot leave the track and, if employing the same linear synchronous motors as InTranSys, are always in complete control, they need no drivers; this would eliminate what now constitutes the largest single cost for taxicabs, city buses, and most cargo trucks.

The greater frequency of travel offered and the reduced costs would induce a far greater number of people to travel via Maglev. It would also provide a 300-mph Maglev system with faster door-to-door service than airlines up to about 2000 miles. This would eventually leave airlines with nothing to do except transport passengers coast-to-coast and overseas. Interior travel via air would probably drop to near nothing, with the saving of vast amounts of expensive synthetic chemical fuels. Airports could be turned into housing developments or, even better, farmland. Private flying would become nothing more than a millionaire’s hobby or a tourist attraction, since it would be needed for transportation purposes only for a few isolated islands. And the inevitable exhaustion of world petroleum resources would eventually become nothing more than an unpleasant memory.

But Maglev could do far better than this, both economically and in terms of service provided, if it were to be combined with InTranSys into a super-integrated system with standardized features. With this combination, a more limited and much less expensive Maglev network would be able to serve the entire continent. For the United States, for example, no more than 3 or 4 east-west Maglev lines would be needed, crossed by 5 to 7 north-south ones. At each Maglev station along this network, a station of the far more extensive InTranSys network would be installed, linking the two systems.

Let’s look at an example to see how this would work. Suppose that I had a need to travel from my rural home in western Colorado to our nation’s capitol, and I am in too much of a hurry to use InTranSys all the way. At any time I pleased, I would make the ten-minute drive to the nearest InTranSys station and express my desire electronically to travel via Maglev to Washington, D. C. In one hour I would cover the 150 miles to the nearest Maglev station in Denver. At this point, I would drive my car off of the InTranSys platform and directly into an enclosed, streamlined capsule of the right size for the remainder of the journey, since the simple InTranSys platforms need not be suitable for 300-mph travel. The platform I had used would then become available for use by an incoming Denver Maglev traveler to use to continue his own journey. Meanwhile I would begin the 5-hour, 1500-mile journey to Washington, arriving there hours earlier (and far richer) than I could have if I had used a typical avian jet cattle car. Moreover, I would have my own car immediately available for travel around Washington, with no reason to fool with rentals. When I had finished my business, I would merely follow the same procedure in reverse back to my home, perhaps taking the "redeye" and sleeping in my folded-back seat all the way home (except for my brief transfer in Denver).

Maglev pallets used for the use of private autos would be streamlined enclosures designed to minimize air drag at the faster 300-mph speed. Enclosures of this type could also be used for a variety of other loads as well, and would come in a variety of sizes. Public passenger vehicles and large freight containers designed for use on both systems could use streamlined front and rear attachments instead. In the case of both private cars and other loads, this procedure would approximately double the length of the overall package. But if linear synchronous motors were used for the Maglev system as well (and it would be foolish to use anything else), the extremely high rural traffic capacity of InTranSys (36,000 vehicles per hour) could still be maintained at the 300-mph speed.

This combination system would provide a means of rapid long-distance travel which the airlines could never be able to match. Not only would it be faster door-to-door, but it would also be much cheaper and safer. It would be totally invulnerable to adverse weather conditions, and would require neither the use of scarce natural energy resources nor prohibitively expensive synthetic substitutes. This would be, at long last, a truly sustainable transportation system which would be affordable for all citizens for as long as we can foresee.

Thus, when we consider the ease with which InTranSys can also be combined with personal rapid transit (PRT) systems, as has already been described elsewhere, we may already have ended our Search for the Optimum Dual-mode (let’s make that Tri-modal instead) System. Why should we bother with anything less?


Last modified: July 15, 2000