All PRT is not created equal. That fact benefits some
systems (and proposed systems) and penalizes others. The system that has been
evolving in this blog sufferers from this effect more than most because it
offers a host of subtle benefits that other systems don’t. But it is also, in
all fairness, probably the most expensive in terms of vehicle costs. I did not
reject these extra expenses for three reasons. First, highly optimized designs
can be scaled back to be more affordable, but designs in which affordability is
“baked in” cannot generally be so easily supercharged after the fact. Second,
manufactured items get cheaper with more volume and over time and a vehicle is such
a manufactured item. Third, it is important to understand how system
performance is compromised by various tradeoffs. How do you know if dumbing
down a system was worth it unless you know what you would have gotten and what it
would have cost if you hadn’t?
I could spend the rest of this post extolling the virtues of
a multi-axis system but since that is not what this post is about, I will leave
it at this: A faster system that can
perform tight radius and 3D maneuvers is a system that can be adapted to any
city’s landscape much more easily. It provides the absolute minimal amount of track
per covered area, maximum flexibility in station design and routing, and the
fastest trip time for the passengers. (maximum throughput and highest revenue
per vehicle/hour.) Thus what is difficult and expensive from a system development
point of view translates into unprecedented advantages from a deployment point
of view. It puts the customer, (local city and transit entities) the affected
third parties (along the routes) and the passengers first.
I have previously written about the desirability of having
standards for PRT. Proprietary track, in particular, seems worrisome because it
would permanently lock cities into a relationship with a particular PRT
company. I can also see why many people
would be very wary of standards, since they are frequently used to gain a
competitive advantage (Blu-ray vs. HD DVD) or result in locked-in
incompatibilities. (electrical plugs that don’t fit in the sockets in a
different country) Isn’t it WAY too
early to start thinking about standards? Yes and no. It really depends on what
you mean by “standards.”
When a standard becomes legally codified by an organization,
given an ISO number etc., that is the last step of a long process. First, there
must be some kind of common language – some kind of definition. Whether it is a
description of a physical thing or a process, long before it can be defined
legally it must be developed into something that can, at least, be discussed
coherently.
This point was brought home by a recent discussion on the
PRT innovators site. The subject was a project underway using the Vectus
system, which is, by any measure, “standard” PRT. But it was revealed that the
track configuration was a simple loop, and so it was questioned whether this is
a PRT project at all, since “standard” PRT utilizes a network of off-line
stations. Is a PRT vehicle, running on PRT track but only in a loop really PRT?
Does an offline maintenance building count? Or is it, perhaps, simply
unfinished, since PRT is inherently expandable? Another example is ULTra, where
the traditionally assumed PRT model of a vehicle on a guiding track has been
replaced by a robocar that could presumably free-roam on any paved surface. Is it
PRT just because other vehicles and pedestrians are kept off the guideway? PRT as a definable concept is becoming more and
more vague. If I say “PRT” and I am thinking of one thing, and you are hearing
me and picturing something completely different, we have a problem. Once upon a
time, PRT only meant one thing to everybody but the formal definition has
become increasingly irrelevant as additional contrasting PRT-like offshoots are
added to the picture. At a certain point
the discussion needs to shift from the more inclusive “PRT” to those subsets,
which themselves need to be better defined. Let’s use the analogy of dogs. Once
upon a time, there was only a single general type of dog in a given region of
the world and so the word “dog” was sufficient. Over time though, the addition
of different breeds added increasing imprecision to the word. Toy Poodles and St.
Bernards may both be dogs but making blanket statements about dogs with either
as your example is confusing at best. At some point you need to call the breed
by name or you are not speaking with clarity. Such informal “standardization”
always precedes any type of legally binding definition.
Recently it was suggested that, since PRT has not gotten
very far in decades, it is human nature to interpret this as proof that the PRT
concept is somehow inherently flawed, so perhaps the name should be abandoned
in favor of something new. The term “ATN” (Automated Transit Network) was
suggested. Whereas I think the term has merit, I have to point out that it is
just as imprecise as “PRT.” It is unfortunate that “PRT,” “Podcar,” “PAT,”“ATN”
or even “APM” (Automated People Mover) are such obscure terms. When talking to a layman, first one needs to
explain the genus, then one needs to explain the species.
A while back, (post 61) I suggested a shorthand system for
classifying PRT. With such a system one could better weigh the pros and cons of
the various systems generically. Of course there is no governing body to adopt
such a system, and it would only be good for academic discussions between
people who had already learned it. But there is a problem, it seems to me, when
there is confusion between what is an inherent quality of some whole branch of PRT
and what is decided upon by the designers of a specific system. Many people
around Heathrow Airport, for example, no doubt believe that PRT is a system of battery
powered vehicles. More troublesome is the growing army of people who now
believe that PRT systems require winter snow removal. Maybe a downloadable branching -tree type
diagram would be a more useful way to start.
The “breed” I personally advocate is a high-speed Suspended,
Multi-axis, Automated Rail Transport network. We can shorten that to a SMART
network. (or “HS SMART” network?) This clearly is a very specific subgroup of
PRT, and establishing definitions and standards for such specific systems is
much easier. Hey, I’m doing my part…it has a generic name! Now, how steep (in
degrees) do we need to go to be considered “multi-axis?” Some particularly
alert readers are already wondering, “Would systems like MISTER or FlyWay considered
“SMART?” Whereas Mister could probably be adapted for completely 3D movement,
Flyway has another take, which is a scissoring lift. This means the track
doesn’t have to follow 3D routing for the actual passenger compartment to do
so. The plot thickens!
Unfortunately, “SMART” only goes so far… It does not, for
example, describe the power source, switching, or other important
considerations. Can this “standardization”
make the leap from simple classification to defining certain interfaces, such
as between the track and the vehicle, so that they may be described in precise enough
language that vehicle makers and track makers don’t need to negotiate each and
every detail before they can get on with their respective jobs? With all of the
options that have been explored in this blog I am gaining confidence that there
is some foundation for developing such standardized interfaces, not as SMART
per se, but as some version-numbered subspecies. The trick is not to stifle
creativity, innovation, or profitability in third party implementations while
also ensuring that the project can’t be easily coopted into a fully proprietary
system monopolized by a single company. There is considerable precedent for
such “open source” standards in the software field.
As for PRT generally, though, I fear ever more confusion as
spin-off and hybrid systems continue to blur the lines. Making the case for PRT
has always required a patient audience because it is a synergetic combination
of ideas that, if taken separately, are not particularly revolutionary.
Unfortunately, limited startup capital forces equally limited implementations
of PRT, redefining the technology downward in a quest for affordability. In a perverse reversal of the “divide and
conquer” strategy, we divide PRT into so many flavors that it is no longer
distinguishable, even to ourselves. Alas, here we stand, like the confused
architects of Babel, wondering how to advance, when we cannot understand each
other, let alone pass along our vision. Classification, definition, and yes,
standardization. It’s all about communication. And so is persuasion. We really
need to sit down and assess, in this day and age, what it will take to put our
collective best foot forward.
I wish I had the answers. Not only does the quest for
affordability put practical PRT designs into a race to the bottom,
capability-wise, but the PRT community is very forgiving. After all, this is a
needed technology that must be encouraged, right? The problem with this
approach is that it doesn’t separate conceptual pipe dreams or inherently handicapped
designs from those that are more capable, practical or whose engineering is
farther along.
Maybe it’s like politics. Lesser candidates can’t get too
deep into specifics or their flawed platform will be revealed, while the better
platform, if revealed in too much detail, will only confuse the voters and invite
FUD. (Intentionally spread Fear, Uncertainty, Doubt) Better, perhaps, that we do what politicians
do, which is hone a simple, more thematic message. We can describe the results,
rather than the means, at least when explaining PRT to a newbie. Keep it
“back-of-a-business-card” simple. But meanwhile we need to have real answers on
the tips of our tongues for those who want detail. We need to be able to recite
the generic pros and cons of suspended vs. supported, track based vs.
free-roaming, etc. Without some standardized definitions, the weak will
continue to pull down the strong, and policy makers will continue to throw up
their hands in confusion.
