A Personal Rapid Transit (PRT) is an automated vehicle system based on the use of modest sized electric powered ‘cab’ vehicles running on any of a variety of types of ‘track’ structure and driven entirely automatically, using either simple distributed electromechanical control devices in cab and track or by a distributed network of computers and sensors. Most provide simple surface transit but some can combine vertical and elevator-like horizontal transit. PRT vehicles are summoned on-demand like elevators to access terminals located in strategic destinations points and can potentially provide door-to-door transportation. They are also capable of higher transit speeds and traffic density than automobiles using track and control systems that preclude the possibility of cabs separating from the track. And the general elimination of human control greatly increases safety while the electric power use makes these systems quiet, clean, and pollution-free.
PRT technology first emerged in the mid 20th century, long promising to become the ultimate replacement for the primitive automobile, at least in urban areas. But despite the seemingly endless list of virtues for this transportation technology, the development and demonstration of many sophisticated systems, and many grand project proposals to the present day, none have ever been implemented on a scale larger than a college campus. There are many reasons for this but the chief one is that, by the middle of the 20th century, combustion powered automobiles had established an intractable hegemony in transit by physically altering the structure of so much of the built habitat.
As has been discussed in other articles, our civilization’s choices in energy technology are ultimately reflected in the physical structure of our habitat. Once a technology has been adopted sufficiently widely, it has so altered our built habitat that adapting to other technologies becomes difficult because of the difficulty our civilization has in structurally evolving its habitat. This is what has made Global Warming and the comprehensive implementation of renewable energy such difficult problems to deal with. The only way to address them adequately is to physically change our habitat accordingly, which in turn alters our patterns of energy and resource utilization. Fossil fuels have the characteristic of being highly portable, which in turn means that little infrastructure is needed to support transportation that can rely on carrying its own energy reserves, which in turn has resulted in a human habitat more dispersed than it has ever been in human history.
By the middle of the 20th century the automobile had so radically altered the habitat, so greatly dispersing the civilization’s footprint and compelling so many100-year municipal investments in automobile-specific infrastructures, that the comprehensive implementation of PRTs, no matter how superior they might be in efficiency and simple convenience, became impossible. PRT designers in the late 20th century responded to this by devising systems that could co-exist in parallel with the existing roadway system, abandoning some of the PRT systems’ potential conveniences and specializing its transportation roles. This tactic has not helped make this technology any more popular and today only a very tiny portion of the public has ever even heard the term ‘personal rapid transit’ or knows what it means. What PRT designers have consistently failed to understand is that they cannot consider the design and implementation of their technology independently of the rest of the built habitat. Just as the automobile cultivated a habitat of a particular structure around its characteristics –amplifying its virtues, working around or concealing its detriments– so too must the PRT encourage a similar restructuring of the habitat around its characteristics. In other words, a PRT system cannot be competitive with the automobile independent of a community engineered around its virtues. Or to put it another way, the competition between the auto and the PRT is really a real-estate value competition between communities designed around their individual virtues –a competition between models for standard of living. The same is true of renewable energy, which likewise, needs to be considered in the context of the physical structure of its habitat.
The marine colony presents an ideal situation for the implementation of PRT systems because the conventional automobile simply doesn’t work in its habitat. As a kind of arcology, a marine colony is dense and volumetrically organized and so its transportation must be deeply integrated with its structure in a volumetric way. Automobiles simply cannot do this, but this sort of integration is a key virtue of the PRT. Initially, marine settlements will have little need of any mechanized transportation because of their small size and high density. Virtually everything will be within casual walking distance. But by the time it reaches a late intermediate stage or becomes a full equatorial colony, the Aquarius marine colony structure would be sufficiently large, high, and dispersed and involved in industrial activities of such scale that mechanized transportation would become increasingly necessary to maintain the same level of convenience in moving around one had when it was small. At this point a PRT system may become critical to the further development of the colony.
Marshal Savage did not suggest anything like a PRT in the original TMP because he saw the static Aquarius design he envisioned as the maximum likely colony scale and considered that small enough to preclude the need of mechanized transit. But he did recognize that there was a need for elevators in the conventional sense and for moving material around the colony and so he proposed what is known as a Personal Packet Transit system in the form of a modernized version of the old-fashioned pneumatic tube transport system once common in office buildings around the world. We will be discussing the concept of PPTs and how they would integrate with PRT use in the next article in this subsection. But for now, we understand today that a colony’s internal transit needs are likely to far exceed the scale of a pneumatic tube system, that one needs to quickly move around more than just people and small packets, and that the colony in general may easily become much larger in scale than Savage anticipated –may need to be larger in scale just to reach the Equator because of the economy of scale of the long distance transit it needs to access the rest of the world. Thus we arrive at the notion of deploying a sophisticated multi-purpose PRT into the structure of the Aquarius colony, providing door-to-door transit throughout its structure for goods, people, and machinery.
Because the Aquarius colony is a volumetric structure and because its likely architecture produces vast volumes of internal space, implementation of a PRT would be relatively simple, easily adaptable, and have fairly low demands on its performance. There’s no need for a system that can travel 150mph. It’s sufficiently convenient to insure that all points in the colony are a few minutes away from each other. This, in turn, reduces the complexity and robustness of the necessary systems. They would all operate mostly indoors and be relatively light. Indeed, aside from its large scale, the Aquarian PRT would probably not be inconsistent in sophistication and robustness from the transport systems used in a lot of modern theme park attractions. Many types of PRT system have been devised to the present day. Though all electric, they vary mostly in the design of cabs, the type of track system, and the type of drive.
The Aquarius PRT is likely to be a supported system –which means its supported from underneath– that uses the existing concrete deck structure of the colony and a retrofit guide-way system. Cabs would be carried on a simple flat and modular four-or-more wheel bogey structure with polyurethane rollers. Its ‘wheels’ could be conventional small wheels or balls that allow for many directions of in-line motion. It may employ a linear motor drive as part of its retrofit guide-way or simple in-wheel motors powered by an inductive power pick-up in the guide-way or supercapacitors charged at terminal points. It would be a hybrid system in that it is intended to integrate with elevators –at least for some of its cabs, and may possibly integrate with overhead monorails in some situations.
The basic cab design would be a simple box about the size of a mini-van or Asian ‘kai’ van with two sliding side doors, bench seating, upper box perimeter lighting, and touch-screen controls. There may be two windows in the doors with an option for ones front and back, possibly integrating the touch displays to save space. Bench seats could fold up to make for more cargo space or to accommodate wheelchairs or mobile equipment with recessed tie-down loops in the floor at strategic points. Highly integrated into the colony Internet, the cabs would support in-transit entertainment and personal communications through its flat panel displays as well as audio-visual cues for its transit status.
Aside from the basic cab, there would be a vast menagerie of more specialized vehicles based on the same modular components –and this is something key to PRT design that is very often overlooked by contemporary designers. The plain bogey unit alone would contain all the basic systems a vehicle needs. Used alone (with a plug-in touch-control panel) or with plug-in bins or containers, it would serve as a pallet transport unit carrying unattended cargo around the colony. This could form the basis of sophisticated just-in-time productions spread widely around the colony’s industrial areas and possibly even linking to resident’s homes. Combined with a large walk-in container or special automated materials handling modules this would become the basis of the colony PPT –as we will discuss later. With several of the basic bogeys ganged together and using swivel carrier frames, the system would be used as an automated ISO container transport system, though limited to only certain transit routes owing to their large size. Adding bucket seats and a simple roll cage, the bogey becomes an industrial transport unit suited to maintenance activities and the transport of tools. Given manual controls and on-board power, these little vehicles could detach completely from the PRT guide-way to be operated as free-roaming vehicles indoors or out. An entire robot could be built on top of the bogey to create an automated maintenance system for the colony interior. Or the bogey could be used as a pallet carrier for other self-mobile robots used in landscape and interior care. Specialized cab units –open or enclosed– could be devised for innumerable other tasks. Tool sets and mini-workshops for different jobs could be made into a self-contained unit. Likewise, fire control and emergency response units. And though no marine colony is likely to become a military power by any stretch of the imagination, should it truly prove necessary (this author doubts it…), defense systems in the form of automated and compact sensor, missile, torpedo, and gun batteries could be made into cabs for automatic deployment to pre-assigned ‘hard points’ on terrace edges in a defense emergency, turning the colony into a formidable fortress in minutes.
PRT cabs also offer the possibility of small self-portable rooms which would be particularly useful in reducing the costs of health care and the sharing of large sophisticated tools. A complete doctor’s examination room could be built into a cab to allow for door-to-door health care. Likewise an ambulance or emergency first-aid unit. Larger diagnostic equipment might also be built into a cab to allow them to be brought right to a home. In this way a colony would largely eliminate the need for a conventional hospital facility. Only critical care facilities would be needed as patients homes could be as easily accessible to doctors and nurses as the conventional hospital room and any specialized equipment could be brought right to the home with ease. Many other kinds of workers could similarly employ these mobile rooms, allowing them to take all their tools with them around the colony; dentists, maintenance workers, masseuses, etc. Similarly, special tools, exercise equipment, or workshop facilities that might only be needed temporarily –such as an unusually large fabber system or automated machine tool– could be contained in a workshop cab for transport right to a home, office, or workshop door.
Thus we see that a PRT can potentially become as complex and diverse in the services it hosts as the Internet, turning a colony –or for that matter any other arcology-like community– into a sophisticated intelligent machine offering an exceptional degree of personal convenience and a standard of living that makes contemporary life seem like the Stone Age. If only more PRT designers understood their technology in the context of lifestyle and commerce rather than the abstracts of technical performance, perhaps then this technology might not be as hard a sell as it has been.
- Solar Ferry
- Solar Wingsail Cruiser
- Relay Archipelago
- Aquarian Airship
- Aquarian Personal Packet Transit and SuperStore
- Aquarian SE Downstation
- Circum-Equatorial Transit Network