Control Software for PRT/Dualmode Systems is a Critical Need

by William Turnbull

Control of individual vehicles is the very essence of PRT/DM, it is not just a detail. I happily concede that a brilliant new design for a guideway, for instance, can have a far greater beneficial impact on the economic viability of PRT/DM than even the most clever and imaginative control system. But absent a safe and effective means of control, even the most brilliant new guideway design remains just that - a brilliant new guideway design.

Yet judging by the quantity of discussion of this subject, one might conclude that it is of no consequence, or at best is a trivial problem. Most of what little discussion there is consists of something like " if we can go to the moon, or invent an atomic bomb, we can surely solve this problem." Or if not that, perhaps "we have a staff of talented, dedicated professionals that are fully capable of solving it."

Both may be true; to one degree or another. But you can be sure of one thing - neither contributes one whit to a solution. Control of PRT/DM is a massive problem. Moreover, it is not going to be solved by inspired amateurs, or even a small group of professionals, no matter their dedication.

Consider the air traffic control system as an analogy to illustrate the magnitude of the problem. Assume that we remove all the pilots from their cockpits, all the controllers from their towers and the air route control centers; and then require that air transportation system continues operate without a hitch. All analogies are imperfect and almost always lead to oversimplification; and this is one is no exception. Nevertheless, I think it illustrates the magnitude of the problem reasonably well.

It will be solved only by an inter-disciplinary group whose members include experts on control theory, massively distributed computer systems, secure data transmission, complexity theory, safety, quality assurance and reliability, and transportation systems. The last item on this list is last by design; to emphasize that we really are dealing with a new paradigm in transportation.

Please do not misunderstand. I am not suggesting that the problem is beyond solving. The advantage of PRT/DM is far too important for it not to be. But it will require some massive brainpower, and it needs to be applied immediately

Serious consideration of PRT/DM will not occur until politicians, regulators, and the general public can be assured that the system is safe. And as with any new approach, this assurance will have to be overwhelming. As it is, so called "experts", dedicated to the status quo, merely have to state that it is unproven, and anyway it won’t work; and the issue is dead. What is needed is a serious, comprehensive report, or better yet reports, from institution(s) of unimpeachable reputation with no commercial ties to the industry; to say, yes, it can be made to work, and, yes, it can be made safe.

I would submit that a number of universities, and possibly some think-tanks, can fill that role admirably. These possess both the many skills and dedication to rigor, and the reputation that are required. I can expect the champions of "everyman" to rise up and say that those "eggheads" can never accomplish anything practical. I would remind them that atomic energy, the computer (no it was not invented at IBM), and the transistor (the basis for the integrated circuit), to name but three, were invented at universities. Admittedly, the latter was invented at Bell Labs - a small difference.

We can still debate whether PRT is better than dualmode, whether this guideway is superior to all others, and the like; but I think it serves everybody to unite behind an effort to get underway a serious study of the control of these systems. In the first instance, I would not anticipate any serious differences between the control of PRT and DM; thus the study can be essentially generic, independent, for the most part, of specific hardware. I would not expect this to go much beyond a theoretical study, with only limited experimental work to settle basic or controversial issues. The results would be distributed to all who were interested for additional testing and incorporation, to whatever degree, into their design.

I firmly believe that unless something like this is done, we will still be discussing the advantages of PRT/DM twenty years from now. Nothing else of value will have been accomplished. I think it is essential that we collectively use whatever political or other influence we have to insure that funding is made available for such a study, at whatever level: federal, state or local. It is sometimes difficult to get funding for "unpopular" studies. That is why it is essential to coordinate our efforts and make the unpopular at least partially popular. A few million dollars would go a long, long way.

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Last modified: September 28, 2003