Sunday, December 13, 2009
There has previously been, in my mind at least, some question about whether ULTra is really PRT. After all, the 40 km (25mph) speed is hardly “rapid”. And the distances that passengers will be willing to travel at those speeds are somewhat limited as well, although I suppose they are far enough to be legitimately called “transit”.
I started writing this post with a number of negative suppositions. I have previously criticized the ULTra design for being little more than a golf cart, and wondered aloud what the advantage of automating such a vehicle really was. Actually I was about to call for ATS (The company that makes ULTra) to consider a purchase of company like Taxi 2000, or PRT International, as a way forward out of the constraints of it’s present design limitations. I am forced, however, to reconsider.
I have been selling the ULTra designers short, I now believe, and this is why. Many of the aspects I don’t like about ULTra are truly intermediary. They will not stop ULTra from becoming much better (and more versatile) in future iterations. It seems that the designers over at ITS have a motto of extreme simplicity and conservatism. Anything else is kept “close to the vest”. Here is one example. The traditional steering, (as opposed to track constrained steering) at first glance, would seem to have all of the negatives of cars. It would skid on ice, for example. Safety issues would seem to prohibit any kind of speed with an automated guidance system. The idea of a track would seem SO much better than trying to center the vehicle with lasers and sensors. So why didn’t they do it? Well for one thing, tracks are less versatile, because they prohibit the vehicle from being able to move freely on any paved surface. But it is mostly, I believe, because they didn’t need to. Tracks would offer the potential of much higher speed but they don’t need speed. It’s only an airport “people-mover”. But the fact is that a track or guide rail is still perfectly compatible with ULTra. They just chose not to use one, for now. Lasers can be turned off, but you can’t easily pull up the tracks. Therefore lasers win. If and when speed becomes an issue a simple rail that sticks up under the center of the vehicle could be added, with minimal modifications to the vehicle.
One interesting aspect of ULTra is that it could presumably be driven away by a human operator, using a plug-in video game style controller. This would seem like a natural way for mechanics to move vehicles around a maintenance facility, for example. That raises intriguing questions about dual-mode, doesn’t it?
Don’t be too put off by the weight. They are using the old, heavy, lead-acid batteries. But once again, the only trade-off has been to design-in some extra space. They can upgrade to Lithium-Ion or even third rail at any time. It was explained to me that track electrification was deemed too costly, but I can’t help but wonder about partial electrification, so that the batteries could get some on-route charging. The possibility of easily swappable batteries also comes to mind.
I also hate the track, especially as seen from below. That would seem to be a hard sell for city streets. This, also, is not really an issue that can’t be much improved. There is nothing that says that the track must be massive concrete, for example, although noise could become an issue of the track was pure steel. There is a gradation between rails and roads. If redundant road area (anything not in line with being directly under the wheels) is removed you are left with a pair of very narrow beams – seems pretty much like a pair of rails to me. ULTra can theoretically drive on such “rails”.
I guess the lesson here is to beware of false choices. This does not just apply to Ultra. I was bemoaning the huge turning radius of the Anderson designs and a similar thought occurred to me. There is nothing inherent in the concept that prohibits tight turns. It I just that it necessitates a more complex bogie than is called for in the current business plan.
It is easy to look at a system from afar and the hard choices that have been made and to rap them up as defining that system, rather than see them as a collection of business decisions. ULTra is not a clunky, slow, heavy vehicle on an ugly, massive roadway. ULTra, like other systems, is an architecture first, and the rest of it is a means to salable iteration of that vision. This architecture, I am finding, is surprisingly tweekable.