Talk:Personal rapid transit/Archive 2

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Archive 1 | Archive 2 | Archive 3

Archived on the date 10:04, 18 April 2006 (UTC)

Massive Rewrite Needed

Excerpt from archive
He's not far wrong, though, the article is 50% blatant promotion and 50% hyperbole. And I speak as a massive fan of alternative transportation. Surely we can make this article better than it is now? Just zis Guy you know? 17:12, 23 March 2006 (UTC)
I agree that it is a very messy article, and could use substantial revision. However, this is virtually impossible to focus on while fending off a barrage of vandalism, which is what 99% of Avidor's edits were. As for your charge that the article is "blatant promotion" and "hyperbole" -- I'm sorry, but I believe that you're wrong. Reporting the claims of PRT proponents -- provided they're portrayed as "the claims of PRT proponents" and not "facts" -- is neither promotion nor hyperbole: it is, in fact, good NPOV reporting. If you can find anywhere where such claims are misrepresented as facts, however, I would absolutely welcome any fixes that you would care to make. Of course, there are also such things as actual non-subjective facts about PRT, as established by various current and historical attempts to implement it, and I believe the article does a reasonably good job of sourcing those facts. Again, if you find anywhere where a factual claim is either innaccurate or un-sourced, please fix it. Really, I mean it. I would be desperately happy if a hitherto-uninvolved party went over this article with a critical, rational, fine-toothed comb. Unfortunately, simply labeling the whole thing as "promotion" and "hyperbole" doesn't accomplish anything at all, as it is both untrue and un-actionable. Skybum 18:20, 23 March 2006 (UTC)
Skybum: I agree completely. We really want to make this better, but it's tough not knowing specific, actionable items to work on.
To "Just zis Guy": Read this talk page. When he's raised valid, specific concerns, we've addressed them immediately. The problem is he seems to be intentionally vague so the article remains under dispute. He seems to want the article to remain in dispute.
If you see specific issues, maybe you can help us to make it better. Can you give examples of hyperbole or promotion? I should point out that Louis Demery (a vocal anti-PRT transit professional) has made a significant contribution (in the "Cons" section) that has not been touched by anyone here -- because it's accurate and fairly presented. A Transportation Enthusiast 18:29, 23 March 2006 (UTC)
Neutrality is not achieved by merely placing the opposing views adjacent to each other, though, is it? Anyway, I will be more specific, I will try to go through it line by line this evening. Incidentally, if Avidar does edit-war I will stop him. Just zis Guy you know? 18:36, 23 March 2006 (UTC)
Thank you; I appreciate it! Skybum 18:42, 23 March 2006 (UTC)
I agree wholeheartedly with the statement that "neutrality is not achieved by merely placing the opposing views adjacent to each other". But this approach was taken at the suggestion of the cabal mediator! I was of the opinion that arguments should be interspersed, but with Avidor around it turned into a turf war (i.e. "You can't edit my Cons section!") and the mediator seemed to encourage that.
BTW, I also appreciate you examining this article with a neutral eye. If the article can be improved I'm all for it. A Transportation Enthusiast 19:00, 23 March 2006 (UTC)
End excerpt

Okay, it seems that all sides (to wit: pro-PRT, anti-PRT, PRT-neutral, sane, and "other") agree that the PRT page is a mess, and needs substantial revision. I agree. Most problematic, it seems to me, is the article's overall structure. For example, many of the technical aspects of PRT -- braking, speed, et cetera -- are filed under the heading of "Capacity Utilization". While all these things certainly do affect capacity utilization, they affect many other aspects of PRT system design as well. This kind of hierarchy seems rather arbitrary, and leads to a lot of redundancy in the article.

Therefore, I would like to propose that the article be fundamentally restructured into the following sections:

  1. Overview (basic description &comparison with other transit modes)
  2. History (needs attention, but is already roughly appropriate, category-wise)
  3. PRT system design (technical aspects, noting disuputes & variances between different systems where appropriate)
    1. Vehicle characteristics (size, features, propulsion, safety features, et cetera)
    2. Guideway characteristics (supported vs. suspended, rubber-on-concrete vs. steel-on-steel vs. linear induction levitation, et cetera)
    3. Operational characteristcs (speed, headway distances, control algorithms, passenger security, et cetera)
    4. Cost characteristics (historical & estimated)
    5. Urban Integration characteristics (public acceptance, aesthetics, sociological & urban planning impacts, compatibility and/or competition with other transit modes, et cetera)
  4. The PRT Debate (aspects of the PRT debate which are NOT about the technical minutiae detailed above; ie the politics of PRT support and opposition.)

Organized, the article would probably be much less redundant (and hence a lot shorter) than it presently is. Currently, the "pro" and the "con" aspects are in monolithic and essentially non-interacting blocks of text. Shown this way, it is difficult for one to get a sense of how those arguments actually relate to the particular details that they are addressing. By bringing the pro-and-con aspects down to the level of those details, their arguments will be much more contextualized and comprehensible. What do you folks think? Skybum 03:50, 24 March 2006 (UTC)

Okay, it's been a couple of minutes now, and nobody has responded yet. That, and I've got actual work that I ought to be doing, and am thus desperately seeking a way to procrastinate. Therefore, I shall "be bold". I have reorganized the article -- everything except for the "pro" and "con" section -- roughly into the hierarchy described above. I haven't attempt to synthesize the text at all; it was just a rough cut-and-paste hatchet job. So, it's a total jumble now, but honestly, it was a total jumble before. Now at least it's in piles which make some kind of sense, and can hopefully be organized into something better. I hope that you all approve. Skybum 04:31, 24 March 2006 (UTC)
Hey, Skybum, I like what you're doing so far. The tentative outline above looks good. And I've just done a quick scan of your recent overhaul, and I think it's an improvement. Maybe if I get time this weekend I'll scan it more thoroughly and see if I can make some improvements. But I think you've done a great job getting this started. That's a tough task, reorganizing an existing article without starting from scratch -- you seem to have gotten the effort off to a flying start.
BTW, I disagree with you that the article was a "mess". Sure, some parts of it were not organized very well, but I thought the individual points in the article were solid and well presented. It just needed someone bold enough to take on the reorg task. :-) A Transportation Enthusiast 05:52, 24 March 2006 (UTC)
Thank you! I do think there was a lot of good information there; it just wasn't structured well. This made it very difficult to improve, I think -- it was never obvious exactly where any improvements would fit in. But hopefully my edits have begun to clear that up. I'll keep going later this evening; for the time being, I think that most of what I'll be doing is consolidation and compaction. Skybum 17:14, 24 March 2006 (UTC)

25 March 2006

I have removed a fair bit of what seemed to be redundant text, some of which was advocacy on one side or the other. The "pro and con" section at the bottom is the next thing to address: it should be redundant anyway, since the substantive issues should be addressed under other heads. Advocacy is in any case likely to be unnecessary; a 'short section on criticism is possibly valid, where that criticism is based on principles rather than factual issues with individual claims. I suspect that all comments on visual impact should be moved here, as it is unquantifiable. Anyone who feels like migrating the rest of the references to {cite web} is welcome. The external links section is large but it's hard to see which should go (probably the advocacy ones on both sides, leaving the links to existing schemes). If Avidor agrees we could comfortably illustrate the criticisms simply by uploading his RKB cartoon - it states the opposition quote nicely without giving it undue weight, and would actually be an elegant solution to the problem of how to cover opposition concisely. What do others think? Just zis Guy you know? 12:34, 25 March 2006 (UTC)

Wikipedia is welcome to upload that comic or quote from my website. I would actually prefer to see this article fact-checked. It does seem to be going in that direction. One suggestion, please verify the status of the Dubai PRT project mentioned in the introduction. According to Jeral Poskey Chairman of ATRA (formerly of Taxi 2000), "PRT is no longer the high profile amenity that it once was. " [1].

Thanks. Avidor 13:37, 25 March 2006 (UTC)

Ken, it would be better if you uploaded it because you can then sign the image as being released into the public domain under GFDL (if that's what you are prepared to do). Re Dubai, if you have a proposal for a neutrally stated revision please make it here. Thanks.
Skybum, I have moved that last comment to the archive. Please understand: I care less than zip what went on in the past. I care about making this a good article. This is not to support one editor or another, actually I think there is both right and wrong on both sides, but you (all) may not make Wikipedia a battleground, you (all) may not bring your external conflicts here. OK? Just zis Guy you know? 17:07, 25 March 2006 (UTC)
Now I'm getting angry. This is not an "external conflict" -- I, too, think there is right and wrong on both sides of the PRT debate, and in the real world I have engaged in that debate (from both sides) in a civil fashion. What is going on here is an interal conflict that is based entirely upon a single editor's wanton misbehaviour. I am going leave my documentation of that misbehaviour in the archive, but I encourage anybody who is interested to have a look.
Meanwhile, I also wrote was a specific response to your proposal on this page, and it should not have been removed. I will post it again here:
"Even setting my feelings about Mr. Avidor aside, I think there ought to be a better way to handle criticism. As I noted in my comments which were quickly archived, although PRT has worked in theory and in the laboratory, there is an enormous gulf between the laboratory and reality, and PRT has not not successfully bridged that gulf. The negative experiences with CVS, Morgantown, Aramis, Raytheon PRT, et cetera all provide ample material for very some serious, substantial, and specific criticisms of PRT, and I believe we should include those criticisms, presented in the context of a rational, on-going dialog. Mr. Avidor's work fails to do this: it is mere gut-level propaganda; the few "facts" it implies are either unprovable or demonstrably false; and it cannot be considered to be part of a rational dialog, because it is irrational, and no rational response is possible. Wikipedia should be able to do much better than this. Skybum 17:01, 25 March 2006 (UTC)"
Because this is pertinent to the current proposal, and not predicated upon what has happened here in the past, I respectfully request that you not remove this text again. And please note that I am not acting as a PRT partisan here: I am requesting that the criticism of PRT be more specific, detailed, and comprehensive than what you are proposing. I sincerely believe that this would make for a better article. Skybum 17:27, 25 March 2006 (UTC)
(A little while later...) Actually, it looks like you're now putting together the nucleus of exactly the kind of criticims section that I would to see. Excellent, and thank you. Skybum 18:13, 25 March 2006 (UTC)

JzG: I like the work you've done so far. It's an improvement, although I think now that the "Pros" section has been removed we should include references to the rebuttals to OKI, Vuchic, etc. in the cons section. And I don't agree with including Avidor's cartoon in the article. A reference to it is more than sufficient; embedding it in the actual article gives it undue weight, as it is essentially a hostile political cartoon that parodies PRT. A Transportation Enthusiast 19:00, 25 March 2006 (UTC)

Okey-dokey, I have now finished a first cut at toning down the article. The old criticism and advocacy section is at Talk:Personal rapid transit/Pro and con. I suspect that not much form there needs to come back, since a lot of it does appear to be covered adequately elsewhere, but let's not throw it away just yet.
I believe that the overall tone is now about right: I believe it presents this a technology which has some interesting possibilities, but is largely unporoven, which is still being actively pursued (in a way that monorails, for example, probably are not) but which faces some serious technical and regulatory challenges if it is ever to rise above the level of small-scale localised installations. Now, may I suggest that we start from this point and sharpen the text up, removing any unfounded comments, weasel words and so on. Also, convert the refs to standard citation format.
I will work on the external links later as well, since these are in need of a severe pruning.
Specifically in respect of the above, the ""pros" section is gone because it does little other than rehash what went before. We are not here to sell it, we are here to describe it for a general audience. The table at the top is, I think, sufficient to give a lfavour of the claimed advantages.
All constructive criticism is welcome. Please, please do not personalise any issues. Just zis Guy you know? 19:07, 25 March 2006 (UTC)
I think it should be pointed out in the article that Vuchic is a light rail advocate, and PRT is a potential competitor to LRT. I also think that the entire Vuchic debate should be explicitly referenced (IIRC, there was an article by Vuchic, a set of rebuttals, a response to the rebuttals by Vuchic, and another rebuttal to that response) A Transportation Enthusiast 19:34, 25 March 2006 (UTC)

I'll repeat my concern voiced earlier: I disagree with the inclusion of the RKB cartoon on the page. It's filled with blatant propaganda and is basically a campaign poster for Avidor's anti-PRT political campaign. It deserves to be referenced as a criticism, but including it in the page is not appropriate because of its POV. I think we should have a discussion on it before it is included. Perhaps a better place to include it would be the Gadgetbahn article, which documents the anti-PRT (as well as other forms of what they perceive to be "gadget transit") movement. A Transportation Enthusiast 17:02, 26 March 2006 (UTC)
May I weigh in on the cartoon? This particular cartoon is notable because, first, it may be Avidor's earliest PRT cartoon, and second, it is demonstrably wrong--and therefore an ideal example of Avidor's anti-PRT efforts. The truth is that good PRT designs make it impossible for the public to initiate riderless trips, by requiring a person push a Go button after the doors close. I have personally called Avidor's attention to this fact, yet he has never modified it.
Therefore if the cartoon is to be included as an example of anti-PRT information, it should be presented as an example of propaganda, insofar as it attempts to instill fear without acknowledging that designers anticipated the potential for misuse and preemptively engineered a solution. Mr Grant 10:56 PST 26 March 2006
It is clearly labelled as a light-earted take on someof the objections raised. Both the objections and the solutions are theoretical until such time as a real scheme is built and running. Of course it's a poster for Avidor's campaign, just as the text from Jerry Schneider and the PRT wiki is a poster for the pro campaign. I'm not making this a point of principle, but it does get the message across without simply rehashing all the arguments again. The reader should be trusted here, I think. Just zis Guy you know? 19:12, 26 March 2006 (UTC)
I strongly disagree. It's not light-hearted. It's a political cartoon intended to belittle the technology. Furthermore, the Schneider and PRT wiki sites are primarily document archives, not political pages, so the comparison to those sites does not apply. Think of it this way: if a pro-highway advocate published a cartoon showing terrorists setting off bombs in train tunnels, would you say it should be displayed in the light rail article? A Transportation Enthusiast 20:38, 26 March 2006 (UTC)

First cut done

I've gone through the text and now the links as well. I have tried to get down to one link per site, where the page linked is not the root, if there is a better page, feel free to suggest it. I have tried to classify the schemes correctly, and where possible link to the "official" (i.e. manufacturer's or scheme sponsor's) website. This section is harder to work with so feel free to make suggestions.

I belive the article is now a more concise and encyclopaedic treatment of the subject, the next step is to polish the text and ensure that the tone is consistent and the subject developed in a logical manner through the article.

Since I have now finished the initial hacking it should be safe for others to edit directly, with due regard to past problems! Just zis Guy you know? 19:12, 26 March 2006 (UTC)

JzG: I really like most of your changes, however, there are two things I disagree with: (1) the inclusion of a political cartoon with a very strong POV (discussion above) and (2) removal of the Light Rail Now rebuttal links. There are serious questions about the POV of that report (it's posted anonymously on a pro-light-rail web site). It is perhaps the most controversial PRT document in existence, the subject of at least 4 public rebuttals, and yet none of that controversy is reflected in the latest article. I think that (a) the word "controversial" should be added -- this is not a commentary, since it's been one of the most hotly contested documents in the PRT debate; (b) it should be explicitly noted that it is written by a light rail advocate; and (c) the rebuttal links should be included. In my view, (c) is the most critical point, as those rebuttals correct several critical mistakes in the original article. Those rebuttals should be listed if the Light Rail Now report is listed. A Transportation Enthusiast 21:05, 26 March 2006 (UTC)
Well now, I think the cartoon is amusing and not excessively harsh - it is a lighthearted look at some of the arguments. But I'm not saying it has to stay, I just think it illustrates the opposition in an accessible way. As to the rebuttal to light rail now, why? We link to the root of the site which carries the rebuttal, we link to several sites which are uncritically favourable, and we link to the light rail article in a section and with a summary which make any misunderstanding about neutrality of that source unlikely. Part of the problem of the article in recent times has been a tendency to develop the argument rather than simply present the opposing sides of the debate. There are a lot of uncritically pro sources in this article, and the tone is broadly accepting of the premise, at least as a concept. Just zis Guy you know? 22:13, 26 March 2006 (UTC)
On the two points of contention:
  1. How can a cartoon depicting a terrorist attack be considered lighthearted? In this age, depicting a terrorist attack is the antithesis of lighthearted. This is a blatantly unfair scare tactic meant to terrify people away from PRT, and, as such, it expresses a very extreme POV that does not belong in the article.
  2. With regards to the Light Rail Now article, this should not be about balancing viewpoints. The rebuttals are out there, they should be linked explicitly. They shouldn't be suppressed just because there happen to be other favorable PRT links. If the author of the Light Rail Now report decides to write his/her own response to the rebuttals, then that can be linked too. But at this point, it seems incredibly unbalanced to link to an article as controversial as that one, without linking to its rebuttals. I believe this is a very glaring omission, for the following reason: the Light Rail Now report presents arguments that seem very compelling and convincing, until you realize that many of them are wrong -- i.e. the technical arguments presented are fundamentally flawed. In some cases, the flawed arguments reflect a basic misunderstanding of PRT designs, in other cases, they're just basic physics errors. But once you are made aware of the errors, the Light Rail Now arguments are much less compelling. There is still some relevance to the LRN article (a few valid points are raised) and hence it should be linked. But the rebuttals should be linked too. A Transportation Enthusiast 00:26, 27 March 2006 (UTC)
No response to these two concerns. I'll give it another day or so and if there are no objections, I'm going to make these two changes. A Transportation Enthusiast 00:38, 28 March 2006 (UTC)
I vote to keep it as it is... the comic is a visual balance to the Taxi 2000 promotional graphic. I think we can trust readers to make up their own minds about the comic and the LRN article. Avidor 01:51, 28 March 2006 (UTC)
The Taxi 2000 picture is just a photo of an actual vehicle, even though it is a promotional photo. As such, it doesn't express a POV. If it were more explicit in its promotion of Taxi 2000, I might agree, but there's very little there except the vehicle and some people to give it some dimension. Not even a logo, as far as I can tell, about as non-POV as you can get in a promotional photo. A Transportation Enthusiast 03:24, 28 March 2006 (UTC)
Delete the cartoon. It's nothing but POV mudslinging. pstudier 02:37, 28 March 2006 (UTC)
Do you prefer this one?[2]Avidor 03:02, 28 March 2006 (UTC)
That doesn't even mention PRT. A Transportation Enthusiast 03:26, 28 March 2006 (UTC)

28 March 2006

Keep the Road Kill Bill Cartoon and the Light Rail Now article. Eva Young

Hey what happened to all the opposition references to the Denver Airport luggage handler (PRT for suitcases)a huge failure of PRT tech that cost hundreds of millions to the public, and why get rid of a cartoon? It is certainly as real as any fake "pod" pix. The "con" section seems to be getting pretty small for the number of PRT failures, cost overruns, and PRT scams out there. - Joe Sixpack

I think it's also fair to keep the cartoon in. I think it's clear from the present treatment that it's a subjective and is just as controversial as PRT itself. - Randall Ghent

It's like this: I think the cartoon is a lighthearted take on the whole thing. Some others - pro and con - seem to take it altogether too seriously. So I am now reconsidering. I still think it's good, as an example of "anti" spin in the same way the fake pod picture at the top is an example of "pro" spin, but I need to think about it a bit more.
The Light Rail Now article stays in, definitely, as it is a well written critique. I am not going to start getting into the rebuttals, because (a) they are linked from at least one of the cited sources and (b) that way lies the same he-said-she-said nonsense which led to the original mess. So either all the pro and con links go, or they stay very much as they are, less a couple if I can decide which of the pro ones are least good, since the article is still a bit weighted towards pro, and the consensus seems to be not proven (to quote one of the best bits of Scottish law). Just zis Guy you know? 18:50, 28 March 2006 (UTC)
It seems that the picture of the pod is a point of contention. I don't agree with the assertion that the pod is "fake" (it's an actual photo of a prototype vehicle), but others disagree, so I've removed it. I don't think it adds too much to the article anyway, and if it raises concerns then maybe it should be gone.
Regarding the Light Rail Now article, I propose the following: in the spirit of "one link per site", how about the following:
Monorail, PRT, AGT, and "Gadget Transit" Analyses - Several Light Rail Now articles skeptical of PRT
This is a more general link that actually provides access to a wider set of critical articles and doesn't give undue weight to the Cyberspace Dream article. I think it balances nicely with the links to PRT document collections in the Advocacy section. What do you all think? A Transportation Enthusiast 20:30, 28 March 2006 (UTC)
(in response to JzG's latest changes) JzG: How can you remove all responses to criticism? This is a debate, and you are turning it into a "he said" with the "she said" removed! I absolutely disagree with this and I will go to formal arbitration if I have to. I've seen other examples of Wikipedia articles that showed both sides of the debate in the critical analysis section. This is reasoned debate that is being suppressed and it's inappropriate for Wikipedia. I strongly oppose. A Transportation Enthusiast 20:57, 28 March 2006 (UTC)
Easily: 90% of the article is responses to criticism, and the criticism section is criticism; if it was supposed to rehash the argument we'd call it "rehashing the argument". We are not supposed to play he-said-she-said or get into special pleading. It's sufficient to state the criticisms which have been made, and let the reader judge. All the rebuttals are in other cited sources. Just zis Guy you know? 22:13, 28 March 2006 (UTC)
No, 90% of article is presentation of fact -- presented in an NPOV way. The other 10% is criticism. How can you present only half the debate, criticism without response? Other controversial articles intersperse responses to criticism in with the criticism itself. Or, sometimes there is a separate section for each side of the debate. Either is acceptable. Presenting one without the other is not. A third option: intersperse the "pro" arguments back into the 90% where they've been removed. I hate this, but it's better than the current one-sided critical presentation. A Transportation Enthusiast 22:27, 28 March 2006 (UTC)
You are missing the point that by stating the facts about this subject we are already supporting the statement that it is a real technology rather than an unproven and contentious technology. We include several links advocating the technology, including ones which have reubttals. We are not here to rehash the argument. Just zis Guy you know? 22:56, 28 March 2006 (UTC)
No, you are missing the point. There is no debate as to whether this is a real technology. There is 40 years of scientific analysis, design, engineering, and prototypes to support it. PRT has a history -- nothing "pro" about that; nothing "pro" about listing the design elements either. There is no disputing any of the information presented in the history and system design sections. It doesn't advocate a position, it only states facts.
The debate is not whether designs exist, this is unassailable fact. The debate is whether these designs are practical, whether they are applicable to typical city environments, whether they would be accepted by the community. These are the positions for which there would be "pro" and "con" arguments, and as of now, the "pro" side of this debate is completely unrepresented. A Transportation Enthusiast 23:41, 28 March 2006 (UTC)
Designs exist for spaceships propelled by detonation of nuclear devices (a patent has even been found). We don't have an article on these. I see no pressing reason to rehash the acrimonious exchanges between proponents and opponents; the proponents' case is stated, their websites are linked, the opponents' case is stated, their websites are linked, the body of the article is stated as neutrally as I could make it (and I'm sure it has scope for improvement). Leave the balance to the reader. Just zis Guy you know? 08:54, 29 March 2006 (UTC)
"Designs exist for spaceships propelled by detonation of nuclear devices (a patent has even been found). We don't have an article on these." -- Excellent point, becuase yes, we absolutely do. Actually, Project Orion has a much more detailed article than Personal Rapid Transit currently does. There is no prohibition in Wikipedia on discussing the theoretical arguments in detail. And even if there was such a prohibition, PRT is not just theoretical. Unlike Project Orion or Fusion Power, for example, fully-functional PRT prototypes have been demonstrated. And there is certainly no prohibition on discussing non-theoretical arguments in detail. Skybum 04:30, 31 March 2006 (UTC)
So we're intentionally suppressing this factual information on a relevant debate, and the reason given is that there's no article on nuclear-detonated spacecraft? How arbitrary is this? Go back and look at what I had added to the criticism section. Tell me what was "acrimonoious" about it. It was a neutral presentation of rational, civil debate between two professionals (Vuchic and Anderson). The Skyloop response I added was a one-sentence summary of why they objected, with a reference. What exactly is the problem with this? Why are we intentionally suppressing factual information here? A Transportation Enthusiast 14:28, 29 March 2006 (UTC)
Perhaps it would help to instead discuss the difference between facts and claims that can be shown to be false. The former deserve to be presented in a neutral fashion. The latter may be presented, but in the interest of Truth they need to be identified as being misconceptions, and how they arose. Merely presenting (known) erroneous claims at face value helps them attain mythic status--perceived to be true or having a kernel of truth, when there is none.
I agree with the gist of this, but in the case of the Vuchic argument, it's basically just an expert opinion that is very difficult to prove or disprove. He doesn't present any mathematical proof of his claims, so the bast you can do is present a reasoned rebuttal -- which has been done. This is why I feel that the Vuchic and Anderson positions in this debate needed to be presented as equals: they obviously both have strong (and compelling) opinions on this issue, so why present only one and give the impression that Vuchic's statements are factual? A Transportation Enthusiast 14:52, 30 March 2006 (UTC)
Vuchic, being a reasonable academic, was not who I had in mind. Rather, the ultimate question is what is the Wiki standard of accuracy? Is something allowed to stand as a Fact just because someone says it? Because in most people's view, a claim that is shown to be false is an opinion, not a fact. But the direction we seem to be headed in is, Avidor could state that "PRT is a quadruped that lives in the Amazon," and, by virtue of it having been stated, it could stay in the article.
I wasn't aware that we did quote Ken Avidor. We certainly don't quote him by name. Nor do we assert as fact what Vuchic states - we offer it as his interpretation, identified as such. That is not at all the same as saying that it is fact, just one informed opinion which is not otherwise represented. Just zis Guy you know? 16:03, 30 March 2006 (UTC)
I think the link should be restored to the Light Rail Now article as it was. The "Cyberspace" article was specific to PRT unlike the new link. Both would be okay, but if there needs to be a choice shouldn't we go with the specific link?Avidor 16:00, 29 March 2006 (UTC)
I have no problem with that, as long as the rebuttals are also listed specifically in the advocacy section. So I've converted the gettherefast link in the advocacy section to point to the rebuttals page. A Transportation Enthusiast 18:08, 29 March 2006 (UTC)

"Proposed cost overuns"? Aramis, Raytheon and Morgantown went way over cost estimates. It should read "cost overuns" period...and Dubai should be removed-unless somebody can prove it is still happening Avidor 21:57, 29 March 2006 (UTC)

It reads "concerns about potential cost overruns." Potential, not proposed. Keep the line as-is.
The Dubai PRT tender is still listed. Let's assume it's still going to happen until we hear otherwise, facts don't necessarily have a freshness date. It takes a long time to plan and build any transit system, PRT will be no different.

A Vuchic quote, but no Anderson quote?

Vukan Vuchic has never taken more than a cursory look at PRT. Anderson has studied it his whole life. Vuchic published one paper in which he made a very generic, high level argument against PRT. Anderson has published books detailing every aspect of PRT design in excruciating detail, and has been the leading authority on PRT for 30 years.

Does it strike anybody as incredibly unbalanced that this Wikipedia article has a full paragraph quote from Vuchic, that basically summarized the only public statement he has ever made on PRT, while Anderson is barely even mentioned in the article, let alone quoted?!

Tell me how this can be. Would an article on evolution have only a passing mention of Darwin and a full paragraph quote from Pat Robertson?

This is the kind of inequity that I feel must be dealt with before this article can be considered truly NPOV. Certainly, it's come a long way just in the last week. JzG, your changes to the factual portions of the article have improved them tremendously. Your expert guidance is exactly what was needed on those sections. But I still disagree strongly with what you are doing with the criticism section. It is absurd to have an article on PRT that gives more weight to the arguments of Vuchic than to those of Anderson.

I would like to address this by making the criticism section a full-fledged debate section, where the pro and con arguments can be presented in an NPOV way. In other words, show both sides of the debate on the feasibility and practicality of PRT. But if this is absolutely not an option (and I've seen other articles do it, so it seems that it would be, but if for some reason it can't be done on this page), then I suggest we prune the criticism down to some very brief statements with links to references to both sides of the debate. This is the only fair way to represent a two-sided debate. A Transportation Enthusiast 05:13, 30 March 2006 (UTC)

While I applaud your spirit, this may be venturing down a long and annoying path resulting in the rehash we wish to avoid. Before JZG decides on direction, I suggest zis guy review pre-existing debates and critiques. They shouldn't be too hard to Google. It might be sufficient to have a set of Debate Links at the end, instead of a full-fledged Point-Counterpoint.
Comparing Professor Vuchic to Robertson is outrageous. Especially since PRT has been promoted by the Discovery Institute[3]. Here are Professor Vuchic's qualifications [4] What are Anderson's qualifications in the transportation field?Avidor 09:48, 30 March 2006 (UTC)
Please don't revert the link to the LRN "Cyberspace" article. The PRT promoters don't like the fact that this article ranks high on a Google search for PRT. They think that removing links will lower the article's ranking.Avidor 10:07, 30 March 2006 (UTC)
The LRN link should be to the article list, it's a more useful link (links to multiple articles). Unless they have a subject specific list which includes all and only the articles on PRT?
If the LRN article is linked, at least one rebuttal should be linked, since that would frame the Point-Counterpoint, helping readers to decide for themselves. The Get There Fast rebuttal is the better one for this, since it contains side-by-side comparisons to LRN's content.
Vuchic is quoted as a reputable academic source in the Criticism section. It's a statement of the opposition view. The pro view is well represented and does not need ot be stated in the form of a personal view. Just zis Guy you know? 11:15, 30 March 2006 (UTC)
It comes back to this: should the neutral statement of facts be considered "the pro view?" You say yes, I still say no. The point I made earlier is, the Vuchuc quote is not debating the facts or the history, he's debating technical feasibility in the real world. Anderson responds to this feasibility question. By presenting only Vuchic's position, you are suppressing one side of that debate (there is no section presenting the arguments that support feasibility anywhere in the article).
But, aside from the POV question, I have a more fundamental question here: why are we suppressing factual information? The facts of this debate are indisputable. It's a reasoned debate between two experts at polar opposite positions on the issue. How can the inclusion of such a debate be against policy, especially when it introduces no POV? To me it's just suppression of information in order to achieve some artificial balance of views, and I can't believe that's the right thing to do. A Transportation Enthusiast 14:41, 30 March 2006 (UTC)
It's also available in the linked sources. Following that line was what led to the mess before - it's a bit like elections; we list what the major issues were, but we don't include the transcript of the candiates' debate.
I am neither for nor against PRT, I do have a degree in Electrical Engineering so I can understand at least some of the technical issues, and I have a friend who was on the civil engineering team of DLR (a system I have travelled on as well) so I also understand a fair bit of the potential of automated rapid transit. My specialisation at University was control systems and I have been a real-time control systems programmer, so I also understand the challenges of controlling this type of system. I am also an enthuisiast for anything which reduces the reliance of society on private motor transport. And I've spent some time reading through the links and what sources are available online. I have taken some trouble to try to understand the proposition and why it is contentious.
In describing the proposed advantages of the system, as we do in the box at the top, we imply that we think it could work. We describe the schemes as tried, in satisfactorily neutral terms. We link to articles on these where such exist. Vuchic's comment, in a section clearly identgified as opposition and controversy, is autoritative and neutrally stated. It states an objection which is not made clear elsewhere, and as such it has a valid and defensible place in the article. We acknowledge that there is debate on this issue, the debate is in the linked sources, I do not see that we need to go any further. If we tried, we would probably shed more heat than light on the subject. Just zis Guy you know? 15:46, 30 March 2006 (UTC)
The article also glosses over the overriding concern: COST. The article impies that PRT systems are not only feasible from an engineering standpoint, but that they are feasible from a cost standpoint as well. That is, PRT will reduce congestion and move people at least as well as competing public transit modes (rail, bus), but will do so in ways that are roughly cost-equivalent, if not in fact substantially cheaper. But the only hard cost figures provided are for guideway construction, while the more speculative operational and rolling-stock costs are dismissed with assumptions that they "should" be "low". Compared to what? Obviously, the implicit comparison is to rail - light rail, specifically. But why should the PRT claims be true? There is no way to evaluate or make the comparison without specifying what is being compared: heavy rail, on-street light rail, elevated or grade-separated light rail, etc.
I agree that "are feasible from a cost standpoint" should be changed. The point should be that transportation construction costs tend to be directly related to the complexity and amount of materials used per unit length. So it would be better to say that PRT ought to be cheaper than conventional rail, all things being equal. See this page at Electric-Bikes. In addition, the British project had a $10M/mile target and they say they achieved that. Unknown is whether costs of R&D and manufacturing start-up are being included. The BAA Heathrow implementation may validate all this.
As for right-of-ways, the article says that light rail requires 100-300ft rights of way - which is absurd. On-street non-separated rail requires NO dedicated right-of-way; even grade-separated rail requires little more space than a similar auto lane, perhaps 30 feet for two tracks. Rail stations may take up more space, but 300ft-wide stations would only include the parking lots and bus-lanes of a suburban commuter station (I'm thinking BART), which is not the "highest density and most expensive part" of the system. Yet PRT also needs stations, and presumably some would offer the ability to transfer to buses - why not include these in the PRT right-of-way? The article does not make clear that it is refering to rail station parking lots - it appears to be comparing the narrow right-of-way for an elevated PRT guideway to some hypotheical maximum-sized inter-modal transit center. Again, apples and oranges here. -- Transit Guest 16:23, 30 March 2006 (UTC)
The ROW width reference should be corrected, but consider that elevated and at grade LRT would occupy continuous ROW, no matter the width. The space used by PRT would be that needed for support posts spaced 60-90 ft apart, depending on the system. A PRT station would be analagous to an elevator lobby, sized according to the number of berths. An intermodal station would be larger as required by the modes sharing it with PRT.

Not to open a new can of worms here, but the "saftey statistics" are deceptive, for two reasons. First, while the Morgantown system may not have caused any accidents, is Morgantown PRT? Most experts consider it to be an Automated Guideway System, or AGT, and the US Dept. of Transportation reports that between 1992 and 2000, AGT systems (nationwide) experienced higher injury rates than any other mode of rail transportation. See:

Secondly, the idea that "transit kills more" is only true when ordinary buses are included in the definition of "transit". But most of the debate about PRT centers on comparisons to rail - including buses is a false comparison. -- Transit Guest 15:56, 30 March 2006 (UTC)

M-PRT, as it is known, should probably be considered an AGT that offers a PRT mode. It is likely too linear and lacking sufficient number of vehicles to offer PRT 24/7. Its safety record of no serious accidents or injuries therefore means it is a very safe AGT with very safe PRT operation. Question: how do you think the USDOT injury rate figures reflect on Morgantown? Does M-PRT's design say something about how all AGTs should be designed, or do you think M-PRT just hasn't had its serious accidents yet (even after 35 years)? Would one accident in 35 years make it too dangerous? What about our widely used transit modes that have accidents?
Here is some anecdotal evidence that Morgantown may not be as safe as they claim [5] " So, our PRT car goes from 40 mph to a dead stop in under 1 second. I was immediately reminded of physics class; objects in motion tend to stay in motion unless acted upon by an outside force. I was standing up at the time. Fortunately, the outside force acting upon me was the soft and squishy back of the person in front of me. The people sitting in the front had the less pleasant experience of having their faces acted upon at 40 mph by the front plexiglass window."Avidor 17:06, 30 March 2006 (UTC)
This is how anecdotal the above "evidence" is: M-PRT can't go 40, the top speed is 44 ft/sec, or THIRTY mph ( Braking deceleration is 0.062g normal / 0.45g emergency (9.9 mph/sec). 30 to Zero at 9.9 mph/sec takes 54-ish feet. Can that distance be traversed in under a second while decelerating?
The same sudden-braking-while-standing thing happened to me yesterday! The bus driver started to accelerate to enter an intersection, when the light went yellow and he slammed on his brakes. I was stopped by the "soft and squishy" in front of me. Why is this OK for a bus, but "may not be as safe" in PRT--where riders will always be seated? And belted-in, if that is desired by the operating agency.
"...political interference in the design requirements"- I read in the affidavits of the Taxi 2000 lawsuit against Ed Anderson that Taxi 2000 has no patents for PRT (except possibly a software simulation program). That would explain why Raytheon and the OKI Parsons Brinkerhoff engineers had to invent their own versions of PRT. I've heard that Parsons Brinkerhoff had no choice but to do Ed Anderson's engineering homework for him. There is no evidence, as this statement implies, that there was some conspiracy to screw up the enginneering of Raytheon's PRT project or the simaler charge that the OKI engineers schemed to make PRT look bad. The transportation engineers I've talked to privately ridicule PRT while treating PRT proponents with courtesy and respect. This claim of "political interference" in the engineering of failed PRT projects needs to be documented or removed from the text. Avidor 18:03, 30 March 2006 (UTC)
Here's the thing: that "Taxi 2000 has no patents" is true, because its patents have expired. They are now in the public domain, which means other PRT developers can benefit from Taxi's and Anderson's work. The most well-known component is the in-vehicle switch, and has often been referred to as "patented." Saying there are no patents, while failing to mention there once were patents, is disingenuous.
As for conspiracies and "simaler" charges, that is a quick and easy dismissal that does a disservice to Skyloop Committee's extremely detailed dissent to the OKI report.
The rebuttal provides context by pointing out flaws in the OKI report. This effectively transforms many of the report's conclusions about PRT from facts into claims.
By the way, I am reminded of something that might help JZG decide to restore the link to the Skyloop rebuttal. It is that the Skyloop Committee is part of Forward Quest, an OKI stakeholder. From a public policy perspective Skyloop's rebuttal has as much legitimacy as Parsons', because both reports emerged from the same process. Linking to Parsons' report but not Skyloop's is like doing half a jigsaw puzzle and calling it finished.
The Skyloop Committee; "Tappan, a developer and builder of shopping centers and warehouses, has spent the last few months drumming up support for the idea. Disbelief usually greets his sales pitch."[6].
That evidence is provided in sources that have recently been removed from this article (because they were "superfluous"). Briefly, there was well-documented political interference in the Morgantown project in the form of the required October 1972 opening date -- Nixon's administration hoped to use it to advantage in the November 1972 election. Because this left only 22 months to design & implement the system, the guideway had to be built while the vehicle design was in progress. Among numerous other SNAFU situations, the guideway contractor was told to engineer for "typical transit vehicles", which meant that the elevated guideways and stations were designed to support heavy trains rather than small, lightweight vehicles. Naturally the cost and difficulty multiplied accordingly. In the case of the Raytheon (Rosemont, IL) PRT, the contracting government agencies put in a requirement that all vehicle components had to have been previously "transit certified". Since the smallest such vehicles were busses, this meant that the tiny vehicle had to use a 30-inch wheelbase (IIRC), rather than the 10 to 12-inch wheelbase which it should have used. And yet again with the cost, et cetera.
It's Nixon's fault...Raytheon's fault...Parsons Brinckerhoff's fault...always somebody else's fault why PRT has failed for over 30 years. PRT has had every chance and plenty of financing and it has blown every chance.Avidor 14:06, 1 April 2006 (UTC)
We seem to be stuck in a rather nasty feedback loop whereby sources and supporting information are removed for being "too detailed"; then sources are demanded for any and all information that remains. Absent that, the information is deleted, and if the sourcing is actually provided, then the article becomes cluttered and the cycle starts all over again. This has got to stop. Skybum 05:10, 31 March 2006 (UTC)
Instead of commenting on patents, engineering and politics, I instead ask: I thought we weren't going to get into another he said/she said rehash. Because that's where this is going if we start talking again about Morgantown anectdotes and OKI.

Where did this article go?

Ok, the last time I was here, this article seemed decent. Now I noticed that huge HUGE portions have been cut out, including the pros and cons sections. I don't have time to look over every detailed change, but this looks very wrong to me. What gives?

Also, I noticed Avidor is back, and his edits and comments have been very productive so far. I agree with him, keep the LRN article specific. Fresheneesz 10:50, 30 March 2006 (UTC)

The article is now more like what it should be: a statement of the facts as understood. The pro and con section was merely a rehashing of the argument, much of it violating WP:NOR. This is now a much simpler article, which still (hopefully) contains enough information for a reader to make up their own mind. It is, on balance, sceptical since the concept is, on balance, unproven. Just zis Guy you know? 11:18, 30 March 2006 (UTC)
Take the evolution article as an example. By your logic above, the evolution article should be, on balance, skeptical since the concept is, on balance, unproven. Evolution is a theory with mounds of scientific evidence to support it... but still a theory. PRT is a concept with mounds of scientific evidence to support it... but still not real-world proven. If the evolution article were constructed like this one, it would contain a NPOV discussion of evolutionary theory, followed by unanswered criticism from creationists and ID proponents. A Transportation Enthusiast 22:42, 30 March 2006 (UTC)

Fresheneesz: Other than the concerns I've outlined above, I think the changes are good. If you step through them edit by edit, you can see the improvement on a point-by-point basis. I still don't agree with the criticism section (and the lack of a "pros") and that debate continues, but the rest of the changes seem to be for the better. A Transportation Enthusiast 16:53, 30 March 2006 (UTC)

I'll have to take your words for it for now. Have fun fixing it up : ) Fresheneesz 21:11, 30 March 2006 (UTC)
Weasel words are creeping back into the text. What and where are these "simulations" that prove that PRT is better than other modes? Are they peer reviewed?Avidor 22:27, 30 March 2006 (UTC)
"Simulation" is not a weasel word. It's an accepted method of analysis.
Is the OKI report peer reviewed? A Transportation Enthusiast 22:30, 30 March 2006 (UTC)
The OKI Report was a study paid for by the goverment and prepared by professional transportation engineers. It was an evaluation, not a simulation. Where are the simulations you refer to and who initiated them and paid for them? Were they prepared by professional transportation engineers?Avidor 23:23, 30 March 2006 (UTC)
The OKI report includes a ridership simulation in which PRT achieved much higher ridership than the other options, even despite conservative assumptions. That's what I was referring to. A Transportation Enthusiast 23:46, 30 March 2006 (UTC)

But you have disputed the OKI report's other findings-that's cherry picking. Either you accept findings of the entire OKI Report or you don't...and the other simulations you referred to are...?Avidor 23:59, 30 March 2006 (UTC)

Several links listed here. A Transportation Enthusiast 05:28, 31 March 2006 (UTC)


Too bad you can't use the Taxi 2000 graphic anymore. When did Jeral Poskey upload that? I think the article needs another one for balance [7] ..and it's copyright free, unlike the one that's there now. Avidor 23:36, 30 March 2006 (UTC)

If it's balance you seek, a better choice would be that animation from your web page of the wino throwing up on people. It's pretty much the mirror of any image created by a PRT company.
That new graphic is one of the silliest PRT graphics I ever saw...I hope it stays... how are those hanging pods supposed to operate on a windy day?
That would be a problem. If the pods were connected to the guideway with free-swinging hinges.
Check out the "station"... real ADA compliant. A flash animation like the wino cartoon would be good here... In light of recent news[8], perhaps this one would be better:[9]Avidor 04:46, 31 March 2006 (UTC)
again with the Inside Politics: Minnesota. Stop with the rehash.

Actually, I have some concerns about this graphic. Skytran is a less-than-representative PRT system in several respects. As opposed to the systems which have been seriously prototyped (CVS, Cabintaxi, Aramis, Taxi 2000) or present systems that have a serious degree of prototyping and/or funding (Skyweb, Skycab, Vectus, ULTra), Skytran differs in the following respects:

  • It uses much smaller vehicles than any of these systems. PRT vehicles are supposed to be small, but Skytran is the extreme rather than the norm.
  • It is suspended rather than elevated; with the exception of Cabintaxi, where half of the vehicles were suspended, all of the above-mentioned systems are elevated.
  • As Avidor points out, the Skytran designers largely dismissed accessibility concerns, whereas it is paramount in all of the above designs.

For these reasons, I would suggest trying to find another graphic. My personal preference would be something from ULTra, given that it is both more typical and less speculative. I will contact ATS ltd. to see if we may use any of their materials. Skybum 10:50, 31 March 2006 (UTC)

I definately agree with you, SkyTran is not very representative. However, rather than removing it, I would suggest adding pictures from a bunch of other PRT pages. I've took it upon myself to put up this picture because I thought the page looked blank without one. That, and I got actual permission for it.
As for other concerns, I'd like to point out that SkyTran does *not* simply dismiss accessibility concerns. SkyTran plans to have a *door-to-door* service rather than making every part of the system "accessible". I'm sure Avidor is skeptical of the economy of this, but its like having ambulances for the critically injured, rather than equiping *everyones* car with medical equipment.
Also, I'd like to point out that there are no *hinges* on SkyTran. What does it look like to you? Its connected to a track forced up by maglev or wheels. How do you think a *train* stays on the tracks on a windy day? Yes, its gravity, once again saving us from falling off this god-forsaken planet. Please now, I don't want this talk page turning into a ridiculous battle of the "wits" again. Fresheneesz 07:51, 1 April 2006 (UTC)

Different Kinds of Claims

I think that there is some confusion here regarding the nature of various different claims. When looking at a claim, it is useful to consider the following factors:

  1. Whether or not it is an empirical claim or a non-empirical claim.
  2. Whether or not it is an objective claim or a subjective claim (this is different from #1!)
  3. Last and often least: who is making the claim.

Consider the following claims, for example: "Cabintaxi built a test track with six off-line stations and dozens of vehicles. It tested this prototype system for approximately 400,000 vehicle miles, with headway distances between 1 and 3 seconds, and was approved for passenger transportation by the German government", or "The Morgantown "PRT" system has operated for 110 million passenger-miles without any fatalities or serious injuries."

Such claims are something that can be (and often are) used by PRT proponents, leading some people here to classify them as "pro-PRT" claims requiring at least a modicum of balance from "anti-PRT" crowd. Who uses the claims is immaterial, however, because the claims are verifiable, empirical, incontestable facts. Empirical facts can certainly be presented in a slanted fashion, and this should of course be avoided, but empirical facts are intrinsically not able to be "pro" or "anti"-anything. To present this information in a slant-free fashion is one thing, but to attempt "temper" or "balance" it is to do violence to the truth, nothing more or less.

Now, consider this claim: "Simulations have shown that PRT would attract much higher ridership levels than other forms of public transport". It may be empirically true that simulations have in fact been conducted, and did in fact show what this claim says they showed — but this is beside the point, because the prediction of a simulation (which is what we're interested in here) cannot be emperically true. It may be objectively true, in the sense that it can be proven or disproven, but it because it cannot be verified with one's own senses -- or indeed, without knowing and accepting the parameters of the simulation -- it cannot be emperically true. In this situation, it becomes important to look at who is making the claim. If it is coming from a pro-PRT partisan, then this would count as a pro-PRT argument, even if it is an objective one. This is because, unlike emperical reality, the parameters of a simulation could potentially be varied to produce a contrary result. In this case, it would be appropriate to provide an opposing claim, if such exists, for balance. I would also suggest that it is worthwhile looking at such claims in as much detail as possible, becuase objective claims such as this become more interesting when examined thoroughly.

For the record, I would consider any claims of installation costs, operational costs, ridership attraction, et cetera, as far as any proposed system is concerned, to be in the realm of "objective but partisan" claims, which should be well-documented from both pro- and con- perspectives.

Lastly, there are subjective claims, such as "PRT guideways would create ugly visually clutter.". Well, personally, and since beauty is in the eye of the beholder, I disagree. I think PRT guideways and vehicles would be nifty-looking, particularly in contrast to what they would replace. But there's really no point in belaboring the subject, because no amount of verbiage will resolve a difference of subjective opinion. Such claims should be made very briefly, alongside their opposing claims, and left at that.

I suspect that in an ideal world, this article would consist of about 50% emperical claims, 40% objective claims, and 10% subjective claims. Skybum 13:06, 31 March 2006 (UTC)

I'll make it simpler...When any salesman makes a claim, it should always be treated with skepticism. In the case of PRT, the salesmen's claims are all we got. Frankly, I think used car salesmen are more believable than the stuff I've heard PRT proponents say. Listen to Dean Zimmermann at the Minnesota Capitol[10]. When Zimmermann and Olson pitched PRT to the Mpls City Council, I was sitting next to a city engineer who worked on right-of-way for the city. I thought he was going to explode when Zimmermann said a PRT company could erect a block-long PRT guideway section every day. Remember, these guys have asked for and gotten taxpayers' and investors' dollars and they want more. An encyclopedia has a responsibility to report verifiable facts and only facts when so much is at stake.Avidor 14:08, 31 March 2006 (UTC)
No, "salesman's claims" are not "all we got". We also have operational prototype sytems, about which empirical statements can be made. We also have operational systems that are in one way or another analogous to PRT, about which empirical statements can be made. You can not simply ignore this reality, as you have consistently attempted to do. As stated above, I agree that when proponents make non-verifiable claims about proposed systems, those claims should be analyzed as rigourously and objectively as possible. In the case of Zimmerman's claim that you cite, it would certainly be fair to say that it was an unproven statement by a proponent. But to state that those kinds of claims are "all we got" is completely false, and you need to stop approaching the subject in this fashion. Skybum 14:22, 31 March 2006 (UTC)
Why should we give the supposed PRT vendors a different standard of proof than than other salesmen? The would-be vendors of PRT need to prove their claims before an encyclopedia can report the claims as facts. Most of the claims the PRT proponents make, such as headway, capacity, network, structural integrity could be proved or disproved with peer-reviewed computer models... to date they have not done this. Instead they spend their time and money on promotion..including this article...and along with the promotion comes a good dollop of LRT-bashing. I looked at the online Encyclopedia Britannica and it doesn't even have a page on PRT.Avidor 14:43, 31 March 2006 (UTC)
What the Britannica does or doesn't have in it is irrelevant. I am saying that we must use exactly the same standard of proof for the claims of PRT proponents as for the claims of anyone else, and I have proposed a reasonable and impartial framework for doing so. Such as: empirical claims are empirical claims, regardless of who makes them. This applies as much to you as to them. Are you completely incapable of comprehending this? Skybum 14:55, 31 March 2006 (UTC)
If I may interject: let's all take a deep breath before another war starts here. Skybum and Avidor: you disagree, leave it at that. I'll weigh in and say that, while there are always claims made by salesmen and marketers, much of what is in this article today (other than the criticism section) is based on proven fact. The underlying theory comes from the Aerospace Corporation work of the 1970s, which is certainly not marketing material. Dr. Anderson has documented much of his Taxi2000 designs and engineering, and this is certainly much more detailed (and verifiable) than the typical marketing fluff. And there are the functioning prototypes: Cabintaxi and ULTra. To say that "the salesmen's claims are all we got" is just plain wrong. A Transportation Enthusiast 15:19, 31 March 2006 (UTC)
The equivalent to the null hypothesis in this case is scepticism. We should reflect that. It's an interesting but unproven idea, there are credible criticisms of it and there are (despite over four decades passing since the invention of the concept) no actual systems in operation which prove the claims re system capacity and mode switching. We reflect that, too. I do not suggest that it is pseudoscience (wow! that is a huge category!), but it is most important that we accurately reflect the fact that this is a barrow which is being pushed up a very steep hill. Just zis Guy you know? 15:47, 31 March 2006 (UTC)
Please consider that there is also a big difference between a neutral form of skepticism, and skepticism like Avidor's that has a stated agenda. His goal is not to perform a scientific inquiry of PRT, but rather to stop it. Some might call that bias, not skepticism.
None of this is valid justification for suppressing one side of an academic debate. A Transportation Enthusiast 16:30, 31 March 2006 (UTC)
I'd also like to add: why are we making the judgement as to how it is "reflected"? Shouldn't we be listing all the relevant information in an NPOV and let readers decide? Why are we suppressing information here? Do you not think it is more dangerous to suppress information in the name of "balancing an article", than it would be to include the infomation in a neutral way even if it might tip some artificially imposed balance one way or the other? Really, I find it hard to believe that Wikipedia policy would support suppression of information for such a vague and subjective goal as "balance" A Transportation Enthusiast 16:35, 31 March 2006 (UTC)
Agreed. Wikipedia is not a scientific laboratory or a court of law. We do not "perform a scientific inquiry," we present the information that's out there. That means we give the facts, and when the facts are disputed by reputable sources, we give both sides of that dispute. Fagstein 04:43, 1 April 2006 (UTC)

Regulatory Concerns

This section needs some help. I've heard that regulatory concerns played a role in the demise of Japan's CVS system (tested during the 60s and 70s), where regulators were unwilling to accept anything less than then the standard 15-second minimum headway for rail vehicles. However I'm not presently able to dig up a good citation for this, and I think we should say more about it. Also, as far as disability access goes, there are a handful of systems (Skytran, Unimodal) that would clearly clash with the ADA. We ought to document this better. We should also make it clear that the accessibility concerns do not apply to most systems, becuase it is true (in the case of the OKI study, for example, the accessibility concerns were based on a flat-out incorrect reading of the ADA, as can be verified by anyone). In the meantime, the section where we have the most detail is:

For example, the California Public Utilities Commission states that its 
"Safety Rules and Regulations Governing Light Rail Transit" (General Order
143-B) and "Rules and Regulations Governing State Safety Oversight of Rail
Fixed Guideway Systems" (General Order 164-C) are applicable to PRT [3].
Both documents are available online [4]. The degree to which CPUC would
hold PRT to "light rail" and "rail fixed guideway" safety standards as a
condition for safety certification is not clear.

I've just looked through both those documents, and aside from clauses relating to "vehicle operators" (which the CPUC already is clearly willing to make exceptions for, where they regulate other APM systems), there is not a single item which would in any way contraindicate PRT. Most of those regulations are about keeping proper vehicle and guideway inspection logs, specifying that vehicles "shall be operated at all times within the maximum speed profiles established for the system," and so forth. As they say in California (where I've been stranded all night in an airport): like, duh. Nothing about minimum headway distances, or anything else that might conflict with PRT. Therefore, citing this as a "regulatory concern" seems to be incorrect. If nobody has any substantial objections, I'd like to remove it. Skybum 14:13, 31 March 2006 (UTC)

Skybum, your recent edits are not sufficiently neutral. We do not, for example, say that a document "has been reviewed many times since then". How many? Many by what standards? More or less than a comparable article on other technologies? Revoewed by whom? In what context? And so on. Please do not make large scale edits without discussing here first, or I will be forced to lock the article temporarily. We are not going to go into the level of detail you suggest above, because that is what got us in trouble in the first place. Less is more. Just zis Guy you know? 15:28, 31 March 2006 (UTC)
JzG, I've looked at your recent edits, and I have issue with some of them. Perhaps you should also discuss changes here before implementing. A Transportation Enthusiast 15:55, 31 March 2006 (UTC)
From the Taxi 2000 prospectus; Risk Factors: "Federal and State safety regulation of automated transit systems can make PRT systems unworkable" [11][12] As for ADA compliance..PRT won't get it. Without ADA compliance, there will be no funding from the Feds. Without funding from the Feds no city in America is going to build PRT. more regulations PRT won't ever get past--Historic Preservation Districts, zoning overlay districts, parks and recreation areas etc....good luck trying to build an elevated guideway through Greenwich Village or Central Park.Avidor 16:05, 31 March 2006 (UTC)
"As for ADA compliance..PRT won't get it." That's a tremendous leap, unsupported by any facts. PRT (other than the exceptions noted elsewhere, e.g. Unimodal) would treat all riders equally. No special lifts or ramps will be required for those with physical challenges.
JzG, details re: your latest edits:
  • "There is also opposition from advocates of other, more proven transport modes." I had removed "more proven" because it's vague. You put it back in. What modes are proven? By what standard are they proven? Autos are proven in ridership, not in safety or efficiency. Light rail has been proven safer, but lack ridership. This is an inherently subjective statement that introduces POV. The more accurate statement is "more traditional" transit modes.
  • "Stops can be along sidings, allowing thru traffic to bypass stations unimpeded." - Skybum changed "can be" to "are always", because offline stations are inherent to PRT. If stations are online, it's not PRT by every definition of PRT since the 1970s. I don't think this can be disputed. "are always" is appropriate here.
  • "Offset against this, trains have much greater seating capacity. As a result, in order to achieve equivalent capacity, most PRT models require much shorter headway distances than are permitted by rail regulators." - First, the degree to which rail regulations would apply to PRT is hazy at best. Second, which rail regulators? US? Japanese? Swedish? British? The rail regulation argument, while somewhat relevant in the criticism section, is inappropriate here where the technical aspects are discussed.
I would also like to say, I am surprised at the threat to lock the article. We have all been cooperating here since you arrived. Skybum made some edits that he thought were appropriate. You reverted them. Why the threats to lock? A Transportation Enthusiast 16:22, 31 March 2006 (UTC)

JzG's Recent Edits

(Just making this a topic unto itself, since the above thread is getting rather confused.)

JzG, please review what I actually wrote; much of your distress is based upon a mis-reading. I wrote that PRT had been reinvented numerous times, not reviewed numerous time (which I agree would have been a problem). That it has been reinvented is a well-documented fact, which is well-supported by various sources that, having recently been removed from the article, I am not inclined to dig up again. Anyhow, the fact that it has been reinvented is factual, relavent, and strictly NPOV. As are my other edits. Please do not revert them en masse, tell me to "cool it," and threaten to lock down the article. That is starting to look like a dangerously biased thing for an administrator to do, particularly when an self-admittedly biased editor like Avidor, who you have expressed admiration for, appears to be getting carte blanch.

As for any other issues that you may have had, the fact that stops are always located along sidings in PRT design has been adequately addressed above. As has the issue of political interference in the design requirements. I also changed references from the Docklands Light Railway to Automated People Movers in general, because PRT does have some similarities to APMs in general, but there is nothing in particular about the Docklands APM that makes it worthy of note. The only APMs which would be worth singling out as particularly PRT-like would be the Morgantown system and the FROG system, both of which use much smaller vehicles and quasi-direct routing, unlike the Docklands APM.

My remaining edits were mostly just tightening up the verbiage. If you have any other specific concerns about my edits, please bring them up with me here. Skybum 21:16, 31 March 2006 (UTC)

No, I read each edit in the history, including the comment "and has been reviewed many times since" against the 1960s study. History indicates that proponents of a given technology are less likely to be neutral than disinterested third party admins called in to stop edit wars. Now, please don't make me protect the article; during a mediation process changes from the prior editors should be discussed first, not argued about afterwards. I don't intend making any further edits myself unless there is ocnsensus here. Just zis Guy you know? 21:55, 31 March 2006 (UTC)
I assume you are referring to this change. The exact quote is: " The concept dates back to the mid 1960s, and has been independantly reinvented many times since then." (emphasis mine) A Transportation Enthusiast 22:50, 31 March 2006 (UTC)
So you revert all of the changes that were made, all of which were fully explained and justified here on the talk page, and you do so with no explanation as to why those changes were inappropriate in the first place. Is this the way it's supposed to work? Might I suggest, JzG, that you are allowing your own biases to taint your judgement here? A Transportation Enthusiast 22:05, 31 March 2006 (UTC)
By the way, JzG, with regard to your edit comment "History indicates that disinterested third parties are more likely to be neutral than proponents.", I'd like to point out that until a few months ago I didn't know PRT from tuna casserole. I've never been a proponent of PRT or any other transit mode. I became interested in PRT because I am an engineer and I am interested in novel approaches to common problems, especially in the areas of transportation and communication. Since then, I've read almost all the negative and some of the positive about PRT. What I've found is that much of the negative is vague and non-specific (read Vuchic's article, for example -- he deals with PRT in very general terms), while much of the positive is very detailed and backed by irrefutable scientific theory and in a few cases, fully functioning prototypes. Is it real-world proven? No! But to call it a hoax and a fraud (as Avidor has always done) or even to hint that it is pseudoscience (as you did earlier) is a severe misrepresentation. It doesn't take a proponent to see that.
So, do not mistake my interest in this technology with advocacy. All I've done is try to counter some very blatant misinformation that was being spread by Avidor, here and elsewhere (he gets around quite a bit in his political campaignings). Frankly, I resent the insinuation that just because I have taken a side in support of fact, that I am automatically labelled a "proponent". A Transportation Enthusiast 22:28, 31 March 2006 (UTC)
Keep in mind, being a proponent isn't bad or anything. If your opinion is based on all your reading, it's respectable and appropriate. There's nothing wrong with having an opinion, as long as you're still open-minded about it, and your contributions to the article are verifiable. Fagstein 04:59, 1 April 2006 (UTC)
"Proponent" is a dirty word around here. Our latest edits were verifiable and we discussed them at length here on the talk page... yet they were summarily reverted based on the presumption that, coming from supposed "proponents", they must be non-neutral. A Transportation Enthusiast 06:50, 1 April 2006 (UTC)
JzG: I have another question: on several occasions now, you've justified decisions you've made with a statement like "that's what got us into trouble in the first place". What trouble are you referring to? Who, besides Avidor, has called the article troublesome? We've had one of the most vocal anti-PRT transportaton engineers (Louis Demery) here, and other than adding some notes about regulations, he was not troubled by the article even before all the edits to reduce POV in the facts section (which have improved it). It seems like we are suppressing a lot to avoid "trouble", and in the process we have an article that has a very strong anti- POV. It doesn't make sense to me. Even after all this, I still cannot fathom why we are suppressing facts about a relevant debate in an encyclopedia article.
The trouble was the request which brought me along. The mess of he-said-she-said, claim and counter-claim. And of course the edit war, which shows little sign of slowing down. Just zis Guy you know? 21:47, 1 April 2006 (UTC)
And I thought we were supposed to draw a line and forget about that previous trouble, weren't we? What happened previously is irrelevant, right? Why are we making decisions based on previous fights? We should be making decisions based on fact and reason. We should not be suppressing the facts about a very well known debate just to appease a single user who has himself admitted his extreme bias. A Transportation Enthusiast 22:30, 1 April 2006 (UTC)

Look, I did not write "REVIEWED". You're either mis-reading this repeatedly, or just plain making it up. I wrote "RE-INVENTED". As in, invented many time over, which is TRUE. Now, I agree that saying it was "reviewed many times since," which is what you say I wrote -- implying that it has passed approval from some mysterious unstated authority -- would be completely POV and inappropriate. BUT I DID NOT WRITE ANYTHING LIKE THAT. Sorry to revert to the all-caps here, but this is just completely absurd. That isn't what I wrote, and that isn't what you're reverting away from.
If you have a problem with the article stating that it has been RE-INVENTED many times over, then I would love to hear it! To me, that statement seems factual and should be non-controversial. But please don't substitute one word for another completely different word, and then make a straw man argument against it!
Also, please explain why you keep singling out the Docklands light railway, even though it doesn't really have the slightest thing to do with PRT. There are hundreds of automated people mover systems in the world, many of which are much more analogous to PRT than the Docklands system. Skybum 22:15, 31 March 2006 (UTC)
How many fully-automated driverless transit systems are there? Just zis Guy you know? 21:47, 1 April 2006 (UTC)
  • Bombardier systems
  • Detroit People Mover
  • Jacksonville People Mover
  • current generation monorails
  • Morgantown

Furthermore, PLEASE elaborate on why you are insisting that stations "can be" along sidings, which is utterly false, rather than "are always" along sidings, which is absolutely true. You will not find a single PRT system where this is otherwise, period. The entire concept, by definition, is utterly dependant upon off-line stops! At this point, you are introducing and preserving outright misinformation, and for the life of me I can't figure out why. Skybum 22:22, 31 March 2006 (UTC)
If it's "by definition", then it should be indicated as such (who's definition?). From what I read of the article, that appears to be the case. I've switched it to "are" from "can be" to reflect this. Of course, a good explanation of why this is always the case might be useful here. In the meantime, leave the article at least consistent with itself. Fagstein 04:59, 1 April 2006 (UTC)
See the Overview, "Routing is point-to-point, with no intermediate stops or transfers." If a station were on the main line and not on a siding, vehicles stopped there would get in the way of vehicles not stopping there. Every definition of PRT I've ever seen includes stations on sidings. See for one example.
Perhaps, rather than saying "by definition", it would be clearer to say it is "fundamental to" PRT. Take away offline stations and PRT vehicles must stop at every station... which means capacity would diminish drastically... which means vehicle sizes would go up to recover that lost capacity... which means guideways must be bigger to support the added weight... at which point we have elevated light rail or monorail. In other words, PRT is not PRT unless there are offline stations. A Transportation Enthusiast 06:40, 1 April 2006 (UTC)

Quick question

This sentence in the "Cost Characteristics" section confused me:

"Smaller vehicles tend to be less efficient for a given journey than larger ones."

What is its purpose in that section? It doesn't at all fit with the paragraph its in (about fuel conversion efficiency), and it seems simply wrong to me. If this were any other article i'd simply delete it, but I thought it might have some sort of con-affiliation to it. Does anyone understand why its there?Fresheneesz 08:20, 1 April 2006 (UTC)

I'm about to retire for the evening, so I must be brief. This does have a con affilliation with it. I believe the point that it's making is one that's worth keeping, but probably not at this location. For personal vehicles, the statement is obviously wrong, otherwise an SUV would be more efficient than a scooter. That's not what this is talking about. As any vehicle grows larger (or any kind of hollow object, actually) the internal volume increases in as a third-power function while the surface area increases as a second-power function. And passenger capacity is primarily a function of internal volume, whereas weight is primarily a function of surface area. This means that, when utilized to full capacity, a large vehicle will carry a much greater mass ratio of passengers-to-vehicle than a small vehicle will. Thus it is more efficient. Coming up with numbers at random, a 1,000kg PRT vehicle may only be able to carry 300kg worth of passengers, whereas a 50,000kg LRT vehicle may be able to carry, say, 20,000kg worth of passengers. This gives the PRT a mass ratio of .3, and the LRT a mass ratio of .4; thus the latter is more efficient. Of course such theoretical ratios don't always work in real life -- my local LRT has a mass ratio that is not really any better than most PRT designs [13]. And of course the whole argument hinges on actual vehicle utilization -- an under-utilized vehicle can have a very poor mass ratio indeed. Anyhow, like I say, this argument is something raised by PRT opponents, so it probably belongs somewhere, but probably not at this location, and probably stated in a less confusing fashion. Skybum 08:50, 1 April 2006 (UTC)

Added a paragraph about it in a different spot. Fresheneesz 21:15, 2 April 2006 (UTC)

Illustration from the light rail now report

Um... why is that there? This page has *two* pictures on it, and one of them is a picture of a random monorail from LRN's report. It seems quite... inappropriate. Fresheneesz 08:45, 1 April 2006 (UTC)

The illustration shows an actual PRT guideway (Raytheon) on an actual street in Minneapolis (where Dean Zimmermann[14] and the CPRT[15] propose to build a PRT system).Avidor 12:59, 1 April 2006 (UTC)
To clarify: that is a composite photo, the Raytheon demonstration guideway Photoshopped into the street scene. That is not necessarily what a real PRT guideway would look like (see the, or sites for some examples). Furthermore, the composite has the guideway out of scale. The guideway supports are less than 36"[16], the composite makes it look larger.
It is also an example of the interference by corporate politics in the design process. The oversized pipe on which the frames are welded was selected because Raytheon ordered the PRT project to use it--because it was manufactured by a different division of Raytheon, not because it was best for the task. In contrast, Vectus has also selected a pipe to use in its guideway; it bears some resemblance to Raytheon's, but because it is correctly-sized, it is much smaller with a lower visual profile.[17]
The Raytheon guideway is not out of scale, see for yourself-[18]Avidor 06:51, 2 April 2006 (UTC)
Measuring within the image, the 6'8" doorway at left (not including transom) is .25" high. The width of the post next to it is .14". Simple cross-multiplication shows the post is being represented as about 44" wide--well over 8" too large if the horizontal pipe is 36" wide.[19]. Now then, if this composite had been created by Raytheon or a PRT group, I'd say Oh Well. But since it was created by a PRT opponent for the purpose of claiming PRT is too big, this inaccuracy--intentional or not--is a misrepresentation, and should either be corrected or the image removed. But on the other hand, the image is located in the Opposition section, so I would not oppose its inclusion so long as the inaccuracy is noted.
The first photo on the page Avidor linked[20] might be an acceptable alternative.
Ok, well I don't know where a good spot for that picture would be, but it needs to be refered to in the text. Simply having it in there as "a picture from the LRN report" or whatever, is not appropriate. Also, since it seems that picture is an *edited pic* I think its fair to say - remove it, and find a real picture of raytheon guideway to plunk in there. Fresheneesz 07:21, 2 April 2006 (UTC)
"Not appropriate"....for the skeptic section? Why not let readers make up their own minds...if the LRN picture and article is as bogus as you claim, then it should be obvious. I think the Skytran illustration is a total goof...which is why I think it ought to stay...keep 'em bothAvidor 00:55, 3 April 2006 (UTC)
You created the LRN image. I have not called it bogus, I merely looked at the original Raytheon photos, compared them to your composite, and your composite didn't look right. So I checked, and found problems with the proportions. I have suggested removing the picture, but I have also suggested correcting it as well. Do you want your claims to be accurate? Or do you just want to complain.
When people look something up in an encyclopedia, they want facts. I expect they want the same from Wikipedia. If readers find Wikipedia articles contain contested claims instead of verified facts, 'decide for yourself' warnings and unchallenged repetitive skepticism, then Wikipedia has a problem.
Are you suggesting Avidor created the LRN image? I doubt it.
The page where the image resides[21] shows "Ken Avidor" as the image's creator.
What i meant by "not appropriate" was that its not an appropriate picture to have at all. It overemphasizes an article that shouldn't be overemphasized. A link to the LRN report is enough. Also, that picture gives nothing to this article other than to point to the LRN report. I think you can agree that while it is important that such a famous (or infamous) report be listed on this page, refering to it in the text, or having pictures from it is simply overrepresenting an article that is most definately NPOV.
You can think what you want of the SkyTran illustration, its obviously fabricated. I really don't see why you think its so goofy, but this is NOT the place to discuss that. However, it is an illustration that is used by a *real* PRT organization. Remember that this is a page about PRT, not about PRT opposition. Obviously opposition has its place on this page, but it should not take the main focus. I'm going to have to remove the image. Sorry. Fresheneesz 07:13, 3 April 2006 (UTC)
Be my guest. But somebody will object that removing it as NPOV is itself NPOV.
Well I can't argue with that. BTW, could you please put some sort of signiture to identify who's talking, just so I know it isn't someone who forgot to put their signiture, or so I can see that its the same anon that wrote some previous message? Fresheneesz 07:45, 3 April 2006 (UTC)
"shows "Ken Avidor" as the image's creator."
Well I'll be. So it does. That really is interesting. Avidor is not only bias, but has affiliation with this article. I really don't want to have to deal with LRN's report anymore. I think I speak for everyone when I say it gets one link, and one link only, with *no* other reference anywhere else on this page. Except of course links to pages that specifically are in response to the LRN article. Fresheneesz 07:52, 3 April 2006 (UTC)

PRT-No Government Subsidy?

One of the claims I hear all the time from PRT promoters like Michele Bachmann [22] is that PRT may not require a public's the actual quote: "People on the right, people on the left, we have the common goal of moving people with transit, but doing it in the most cost-effective manner, in fact, in a manner that may end up costing no government subsidy, it may end up paying for itself."[23] Shouldn't this article explain this claim? Please explain how a system of this size can operate without a government subsidy.Avidor 13:20, 1 April 2006 (UTC)

Unless I've missed it, there is nothing in the article about not requiring a public subsidy. A Transportation Enthusiast 14:46, 1 April 2006 (UTC)
I quoted it. in this article Olson says he's against subsidies but he's for PRT[24]. If you can find an estimate of how much of an operating subsidy would be required for a PRT system, please share it with us.Avidor 16:12, 1 April 2006 (UTC)
"One of Olson’s priorities is a vision for transportation that doesn’t require decades of subsidy."Avidor 16:15, 1 April 2006 (UTC)
This has nothing to do with the article, and I'm not commenting further on it. A Transportation Enthusiast 16:19, 1 April 2006 (UTC)
Mark Olson introduced the PRT bills in the Minnesota Legislature last year and years before. He worked closely with Ed Anderson so Anderson was well aware of Olson's claim that PRT would not require an operating subsidy[25] Olson and other right-wingers and Libertarians said PRT was better than LRT because it wouldn't require an operating subsidy... this fact should go into the article. I really thnk it belongs in the article.Avidor 06:26, 2 April 2006 (UTC)
I found the article with the Olson quote[26]. Olson doesn't sound too extreme, except for the pro-life stuff. The article also says he didn't sign something called a No New Taxes Pledge. His reactionary party must have been really irate at him. Anyhow, why do you, Avidor, think "transportation that doesn’t require decades of subsidy" is a bad thing? If we could still have transit while subsidizing it less, we save money that could be spent on things like teachers, child care and universal health care. Or even more transit.
This is really a simple question with a simple answer. PRT proponents think that PRT is *efficient enough* that private investment can actually make money from it. Size doesn't matter, if you have one vending machine making money, a million of them making money isn't gonna somehow now cost the government money. Avidor, if you want to discuss the idea that PRT can go without subsidy, thats your call. Fresheneesz 06:55, 2 April 2006 (UTC)
Avidor, I've gone ahead and added a paragraph which addresses this. Right now the "cost characteristics" section is getting a bit unwieldy and muddy; it needs to be divided into "Installation Costs" and "Operation Costs" to clarify the differing issues. But I'm waiting for some replies from JzG before making any more substantial changes, since he's seemed a bit... erratic lately, with regards to my contributions. Anyhow, let me know if you have any issues with what I've written. Right now, the basis for both the cost claims of PRT proponents and the skepticism of its detractors is left fairly vague. Of course, since no operational systems are in existence, neither side has any genuinely empirical basis for their position, whether pro or con. While educating myself on these issues, I have seen some fairly detailed analysis from PRT developers, showing how they arrive at their cost estimates, but I have not seen any equivalent analysis from the skeptics, showing how they arrive at their skepticism -- basically just that it sounds really dubious. If you are aware of any more specific and detailed skepticism on this account, I would be happy to include it in the article, provided that we do the same for the pro- camp as well. Skybum 07:21, 2 April 2006 (UTC)
If PRT doesn't receive a subsidy, what would be the typical fare for a ride on PRT system?Avidor 07:04, 2 April 2006 (UTC)
That's not a question of cost — that's a question of price. Presumably it would be determined by the individual PRT system operator, just as the price of a LRT ticket is determined by individual LRT system operators. Since there currently aren't any PRT system operators, that question is currently unanswerable. (Personally, I believe that it would be a mistake to try to make a PRT system profitable. Even if PRT is as cheap as its proponents claim, it should still be subsidized, just as roads and public transit are subsidized. Localities derive tremendous benefit from enabling transportation for their citizens; this is why a city/country with a free (ie subsidized) roadway system is more prosperous than a hypothetical city/country which is entirely based on tollways (if so stupid a thing were ever to exist)) Skybum 07:30, 2 April 2006 (UTC)
Skybum, I'd just like to point out that the paragraph you added is misleading. It basically says that "since its as efficient as cars, or maybe a little bit more efficient, it can go without government subsidy". This is simply not the case. The reason that PRT claims to be able to be privately run is that it is cheap enough to pull a total profit, rather than be an economic drain like every other transportation system in existance. I say its misleading because while a car's private "cost per passanger mile" may be around 50 cents, that doesn't count road costs and other associated costs. I would bet that cars/roads are the most expensive per passanger mile when figuring in all the costs. Fresheneesz 07:27, 2 April 2006 (UTC)

Okay, JzG, it's like this...

Because most of your work on this page has clearly been in good faith, and I have really appreciated it, I'm going to give you the benefit of the doubt here. I believe that what transpired above was a sincere misunderstanding on your part. I think that this is what happened: you saw that I had made many edits to the page, and, looking at the very first sentence of my edits, mistakenly read "re-V-I-E-W-E-D" rather than "re-I-N-V-E-N-T-E-D". This misreading completely changed the meaning of that first sentence, making it appear highly POV, and based upon this, you incorrectly assumed that I was attempting to insert pro-PRT statements back into the article. You then reverted all of my edits, every single one of which was actually quite NPOV, and so thoroughly non-controversial that not even Avidor has attempted to contest them.

Now, why you persisted in making this mistake a second time, even after it had been explicitly pointed out to you, is a mystery to me. I'm guessing that you were tired, or in a hurry, or something else like that. I know that I have certainly made mistakes when editing Wikipedia when I'm not at my sharpest. In any case, you once again mis-read "re-I-N-V-E-N-T-E-D" as "re-V-I-E-W-E-D", and once again reverted my edits, with comments about how partisan I was and threats to lock down the article.

I re-explained the situation again, and given you time to respond. You haven't done so, so I am taking actions into my own hands. I am re-instating all of the edits that I made. If you revert them again, or lock down the article, you will be very clearly abusing your administrator privileges, and I will be calling you in for arbitration. If, on the other hand, you can let go of acting upon this one mistake, then I will welcome your continued participation in this article.

If you do have a problem with any of the edits that I make, please re-read what I've written, make sure that you've got it correct, and then spell out your objections on this page. Labelling me as "a promoter" is not an acceptable objection: first of all, it's untrue, and second of all, it's what I write that is relevant, not who I am. Skybum 16:56, 1 April 2006 (UTC)

Yes, it's like this. We can't say stops "are" off the main guideway, becaise no systems exist. Just zis Guy you know? 16:50, 1 April 2006 (UTC)

That's complete sophistry. When we're talking about the design of something -- and this is under the heading of PRT System Design -- it is legitimate to describe the design's essential features, even if it hasn't been built yet. Skybum 17:01, 1 April 2006 (UTC)

JzG: I would like to add: even if you did just misread the word "reinvented" (which I believe you did), by automatically assuming all edits were bad you have violated the WP:FAITH guideline. Based on a mis-reading of a single word, you leapt to the conclusion that (a) all of Skybum's edits were bad, and (b) that he is a proponent and was allowing his views to permeate the article. Furthermore, even when Skybum and I tried to correct you with a polite correction on the talk page (the word was clearly "reinvented", not "reviewed"), you continued to assume bad faith and again threatened to freeze the article. Now, I agree with Skybum, your initial help on this article was invaluble and much appreciated. But perhaps your affection for Avidor has gotten the better of your judgment in recent days. There is evidence that this whole misunderstanding started when Avidor requested you lock the page, because it was less than an hour later that you made that same threat here. And, clearly, throughout this whole process, your verbiage has been much more hostile to Skybum and me than to Avidor, even as Avidor has once again begun cluttering this talk page with political banter. A Transportation Enthusiast 19:39, 1 April 2006 (UTC)

Don't be silly. I have not assumed that any edits were bad. I am notorious for assuming good faith long after others have given up - look at the history of User:Jason Gastrich some time. On the other hand, as one who is neither for nor against PRT I do see some evidence of strong opinions creeping into edits. It's perfectly normal, almost unavoidable. Just zis Guy you know? 21:56, 1 April 2006 (UTC)
Well, I'll say the same thing: as one who is neither for nor against PRT, I also see some evidence of strong opinions creeping into edits. Like, for example, the allusion to rail regulations in the design section, added by you. The line "As a result, in order to achieve equivalent capacity, most PRT models require much shorter headway distances than are permitted by rail regulators" is clearly POV. First, PRT doesn't have to be rail (see ULTra). Second, rail regulations vary from place to place. Third, there is no reason to believe that PRT would be regulated the same as rail; as you well know, PRT doesn't have an existing installation so there are no regulations specific to it. Fourth, the regulatory argument is already presented in the criticism section, where it belongs. But am I not allowed to raise these concerns, because I've been labelled a "proponent"? This is the second time I've raised this point here, and there it is again, back in the article without so much as a word of explanation here on the talk page.
Also, for the record: I also see the suppression of half the feasibility debate as a strong POV issue, one that I've raised repeatedly with little or no response. A Transportation Enthusiast 22:21, 1 April 2006 (UTC)
Agreed. Althouh JzG's edits started out well, they are now exhibiting increasing and disturbing bias. It is clearly time to bring another administrator into the mix, one who doesn't have a prior affinity for any of the editors on this page. Skybum 22:33, 1 April 2006 (UTC)
JzG: if you didn't assume that my edits were bad, then why did you repeatedly delete them, giving no reason other than "History indicates that disinterested third parties are more likely ot be neutral than proponents"? And why did you repeatedly misquote me by way of demonstrating my supposed "advertorial" bias? And why haven't you responded to any of my questions or complaints about this matter? Skybum 22:59, 1 April 2006 (UTC)
Hmm, i've looked at the last couple of JzG's edits, and they seem fine to me. I disagreed with the "can be" edit, but he's since changed it to "is designed to be" which is perfect. Is there still a problem regarding his edits? Fresheneesz 07:36, 2 April 2006 (UTC)

Speculating about Design

JzG apparently doesn't approve of the article stating that stops in PRT system designs "are" along sidings, despite that there is no PRT system design in existence where this is not the case, and despite the utterly self-evident fact that PRT system design falls apart completely if stops are not along sidings. Anyhow, he's changed the verbiage to redundantly state that stops in PRT system designs "are designed to be" along sidings, since that is somehow less "speculative". If that's how he wants it, let me sarcastically suggest that we change the entire overview to be more in line with this verbiage:

  • Vehicles are designed to be small -- typically 2 to 6 passengers.
  • Vehicles are designed to be individually hired, like taxis, and only designed to be shared with the passengers of one's choosing.
  • Vehicles are designed to travel along a network of guideways, which are designed to be much like a network of streets. Routing is designed to be point-to-point, with no intermediate stops or transfers.
  • Service is designed to be be available on an on-demand, around-the-clock basis.

Et cetera, ad nauseum. Either that, or we can just accept the fact that it is perfectly valid and neutral to make positive, non-qualified statements about a design! Skybum 22:29, 1 April 2006 (UTC)

I'm happy with occasional reminders in the text that PRT systems are at the design stage. I know many fans of systems like these, though I can also envisage a future where PRT systems are introduced via an intermediate self-driving taxi system which runs on existing roads. This would run on existing infrastructure, making it vastly cheaper and more likely to happen. There is no space in London for another travel system. We already have roads, bus lanes, cycle lanes, mainline trains, underground trains and pavements for pedestrians, as well as occasional helicopter pads. A PRT system which was slower but accessible to everyone would be more useful than one which is only available on a handful of routes (where a train, coach or taxi with special lanes works comparably well). So small and individually hired are likely (IMHO) to be stepping stones to an expensive separate network. If PRT proponents split their main goal into smaller pieces, each one may be attainable in turn. Stephen B Streater 08:37, 2 April 2006 (UTC)
Well actually, a PRT might be the perfect system for someplace like London, where all the groundspace is used up. That is one of the many reasons PRT is designed to be elevated. Space not required : ) . As for the "designed to be" thing, I don't find it to be that much of a problem. Replacing "designed to be" with "would" would be shorter, but as it stands, the one or two places with "designed to be" is simply a style choice. Fresheneesz 19:33, 3 April 2006 (UTC)

Speculation about costs

I have remoived this, pending discussion here:

PRT developers and advocates claim that operational costs will be substantially lower than for other modes of transit. For comparison, private automobiles cost approximately $.40 - $.50 per passenger-mile; light rail costs between $1.40 - $6.00 per passenger-mile (depending on utilization); and the Morgantown People Mover — widely recognized as most closely resembling a true PRT system — costs roughly $1.00 per passenger-mile. Most PRT developers claim that their systems will have an operational cost in the same $.40 - $.50 range as the private car, but some have claimed that their systems would be dramatically cheaper — as low as $.10 per passenger-mile, or even less. Some PRT developers have claimed that this would allow the PRT system to operate profitably, without public subsidy. Critics of PRT systems are dubious of these cost claims, and particularly skeptical about the ability to operate without subsidy.

The cost figures for private cars (automobiles) excludes the cost in man-hours of cars stuck in traffic. In London, even for workers on the UK minimum wage, the cost in lost working time can exceed the running cost of a typical car. In addition, the congestion charge exceeds the cost of running the car. And finally, the expense of land in the city has pushed the cost of parking above the cost of driving a car. PRT aims to reduce travel times significantly and remove the parking cost.

There are two problems here to my mind: first, that these figures are entirely speculative - they have no basis in reality because we have no idea how much real systems wil cost (major projects almost always have cost overruns, especially compared with initial budgetary estimates). Second, the comments about cars and congestion miss a very real point: a PRT system which could replace meaningful numbers of cars would have to be very big indeed, much bigger than the models we've seen here. Also, other methods can address the costs of congestion without any significant expenditure. London's congestion charge saw an immediate substantial reduction in motor traffic, massive increases in use of bicycles and existing transport modes, and raised money to buy more buses and fund developments of the Underground, all without the need for new, unproven technology. As far as congestion goes, Tokyo is a better example than Londond anyway.

Be that as it may, I see these two paragraphs as pie in the sky. If these arguments go in they need to be stated in much more neutral terms, and with named sources not weasel phrases. Just zis Guy you know? 09:02, 2 April 2006 (UTC)

The second paragraph does indeed seem to speculative for my tastes, however there is nothing at all speculative about the first paragraph. The text does not state what PRT costs "are" or "would be" — it states what PRT proponents claim that PRT costs would be, and it clearly identifies the source of that claim. This is not "speculative" (PRT proponents really do claim this, or are you saying that you don't?), and is in strict conformance to NPOV guidelines. What is the problem with it? I understand that it is unacceptable to make speculative claims within Wikipedia, but if it was unacceptable to report on speculative claims that other people are making, then you might as well just delete the entire article. Skybum 17:53, 2 April 2006 (UTC)
Any cost projection is, by its very nature, speculative. But so are statements like "Actually, the PRT concept combines two mutually incompatible elements of these two systems: very small vehicles with complicated guideways and stations." This is the Vuchic argument, and it is no less speculative than the cost argument above. And yet it is allowed to stand unchallenged (even though it has been challeneged) while similarly well-documented arguments (i.e. cost) from PRT proponents are suppressed.
The London "congestion charge" debate is orthogonal to the PRT debate -- the money raised from the toll could have just as easily been spent on a new PRT system instead of buying buses and improving the underground. And, of course, the "need" for PRT in London (or anywhere else) is immaterial. Technically, PRT is not "needed" anywhere, just as any public transit option is not needed. Cities have gotten along without PRT, just like many get along OK without trains. The question isn't whether there's a need, but whether a different approach might provide a better solution to a given problem. That's what the debate is about. Why are we afraid of portraying that debate from both sides? A Transportation Enthusiast 16:43, 2 April 2006 (UTC)
Perhaps because an encyclopaedia is supposed to document known facts, not speculation and opinions. Stephen B Streater 16:58, 2 April 2006 (UTC)
Then the speculative criticisms in the critical section should be removed as well. Vuchic's article is an expert opinion. Regulatory arguments are hazy at best. If we are going to ban all speculation then it should be banned from both sides of the debate. Include both sides, or suppress both sides. I'd prefer inclusion of both, but suppression of both is OK too. Inclusion of one side and not the other is unacceptable, IMO. A Transportation Enthusiast 17:26, 2 April 2006 (UTC)
I think PRT would have to be big to make it worthwhile. If it wasn't going to take me door-to-door, I may as well go by train to avoid the traffic. I can find stats to show that the "cost" of running a car is not the significant part of the cost to the user (as in parking, wasted time and congestion charge), but this is less relevant if the previous paragraph is also removed, or is corrected to include these costs. As we don't know what delays there might be on this new system, time savings are themselves speculative, but are clearly a major point in the proposed designs. If the first paragraph is included in some form, I'll find the citations to back up the second. Stephen B Streater 09:44, 2 April 2006 (UTC)
It's also worth mentioning that a major part of the cost for cars is tax: petrol tax, road tax, congestion charge, publicly run parking etc. Public transport, OTOH, is subsidised by taxes. It is far from clear to me whether PRT would be taxed or subsidised. If it replaced cars, it is bound to be taxed. If it replaced buses, it is bound to be subsidised. Stephen B Streater 09:52, 2 April 2006 (UTC)
Thank you for taking out the claim that PRT is cheaper than conventional transit. Although you don't see it much on PRT websites, it is one of the most repeated claims I've heard from anti-rail transit proponents and politicians like Michele Bachmann, Mark Olson and Dean Zimmermann. Yiou can hear that claim on the audio archives of the Minnesota Legislature. Avidor 14:03, 2 April 2006 (UTC)
I think this misses another point though: people are getting richer and require a better service than that provided by buses and trains. I see PRT as faster and more expensive than buses, but more efficient than taxis as the utilisation rate will be higher and it doesn't need drivers. And cheaper than a private car which is hardly ever used, so ties up capital inefficiently. I still believe what I said earlier: PRT will only come about when the early systems can work on existing infrastructure ie roads. The step to a new infrastructure is too expensive for stage 1. Stephen B Streater 17:05, 2 April 2006 (UTC)
The first paragraph is simply inaccurate. I'm not at all sure where these operations and maintenance cost estimates are coming from, but for many light rail systems costs per passenger-mile are MUCH lower than $1.50. Like $0.15 to $0.55 per passenger-mile. See the tables at the bottom of this page: .
Also, the claim that PRT will be cheaper to operate than other transit modes depends entirely upon labor costs, which ammount to around 75% of O&M costs for most transit systems, whether bus or rail. That means that, compared to rail, PRT's driverless automation systems need to be sufficiently efficient and reliable so that the money saved by eliminating drivers isn't swallowed by the need for increased monitoring, control, security, and maintainence personnel. That's an entirely speculative proposition. -- Transit Guest 17:00, 3 April 2006 (UTC)
Here is a paper that discusses expected reliability of PRT vehicles and systems. Since the vehicles are small with few moving parts and they have redundant systems, they are expected to be reliable.

Why don't we just re-add the Pros Section, so that "speculative arguments in favor of PRT" can be properly represented as claims there, just as "speculative arguments against PRT" are already fully represented in the criticism section? As I've argued at least four or five times now on this talk page, there should be a "pro" argument in addition to the criticism, and since JzG objects to it being interspersed in the criticism section, then maybe the "Pros" section should be re-added. History and design are purely factual and do not (should not) document the pro position. Pro would list the common arguments in favor of PRT, like the cost argument (which, for the most part, is speculative until a real system is built), just as criticism currently lists stuff like the speculative statements of Dr. Vuchic. I've brought this up several times now and it's been summarily rejected by JzG because it violates his view of how this article should be balanced. I continue to argue that facts should always supercede one particular editor's subjective view of balance. The facts of the debate are indisputable and well known; we should not be suppressing half of it. A Transportation Enthusiast


I'm not as extreme as JzG - many fictional things have articles about them, so idealisic ones could have too, as long as the titles fully reflect that the contents are unproven as yet. I do agree with JzG that until PRT systems have been shown to work in practice, the article in WP should err on the side of caution/sceptical. Partly the problem is that there are infinitely many dreams, which may take an instant to think up, but hours to prove ineffective. How can the sceptics argue against a many headed Hydra which each argument can be countered by a new person saying: "But of course HIS idea wouldn't work, but mine is much better!". This root cause of this caution is that PRT schemes are being represented as viable in reality, rather than interesting ideas. WP doesn't contain original research, and the: "Here it is working!" example is what will make all the difference. Stephen B Streater 17:15, 2 April 2006 (UTC)
PRT is more than just idealistic ramblings. Companies and governments have spent $millions ($billions?) developing the technology. Fully engineered prototypes have been built and tested. Companies are still today working on it, and one is specifically targeting delivery of a production system. This is not some abstract idea in someone's head. And it is very clearly documented at the beginning of the article that there are no PRT systems currently in real world operation, so I see no evidence that the article attempts to imply that that this is real-world proven. That's what the debate is about!
As for "erring on the side of skeptical", I have an entirely different take: we should err on the side of factual presentation rather than factual suppression. Where debate exists, it should be presented as debate, not one-sided criticisms. We are currently suppressing one side of the dialog in the name of some abstract notion of "neutrality" and it is inappropriate for an encyclopedia. A Transportation Enthusiast 17:35, 2 April 2006 (UTC)
PS On a related topic, WP is not a soapbox, or here to educate people on what is possible. It is here to say what has verifiably happened. So as a reader, I would like to know what informed people have said about PRT (pro and con), but for it to be represented as hypothetical. Also, a short article with external links to opinions may be preferable to slogging it out here. Stephen B Streater 17:18, 2 April 2006 (UTC)
Stephen, thank you - that has been my view all along. The article was long, and spent much time rehashing the arguments. That is not what Wikipedia is for. The pro and con section mentioned above was an example of just that: a he-said-she-said session. If you want to prune the article further please be my guest, I am sure it could be shorter without reducing the encyclopaedic content. You don't get a neutral encyclopaedic article by repeating the zeal of the convert followed by the shouts of those who oppose, you get it by documenting what can be verified, which is what I've tried to do. See the section above: PRT proponents may well claim that it will cost ten cents a mile or whatever, but that is just the sales pitch. The few full-scale triels have not, as far as I can tell, approached that, and there are serious unanswered questions about the fundamental workability of the schemes which would yield such low costs. To say nothing of the fact that pretty much no public transport project in living memory has been built to budget. It does seem to be the case that there is an external agenda being pushed here (and I am not ascribing motives to any individual). There is pressure to support PRT and there is strong oposition to PRT from proponents of alternative more proven modes. I remember the "Salter duck" and Severn barrage renewable projects being pretty much killed by the nuclear lobby, who were given the job of doing the return on capital forecasts for the Government - they were practical, but killed by proponents of a competing extant technology. I know these problems. But in the end Wikipedia reflects reality, WP:NOT a crystal ball. Just zis Guy you know? 21:33, 2 April 2006 (UTC)
There is no way this article should prune all speculative pro content while still containing an entire section with speculative criticism. That is completely unbalanced and factually incorrect. If that's the way this article is to remain, then I'm going to apply the POV tag to the criticism section and request formal arbitration. A Transportation Enthusiast 22:30, 2 April 2006 (UTC)
I'll see if I can improve anything - but it may take a few days to untangle the arguments. I also remember Salter's duck. As it happens, I have a great interest in renewables. Stephen B Streater 07:40, 3 April 2006 (UTC)
Stephen, if you like you can take a look at the technical feasibility section of this history entry which shows both sides of the debate, rather than giving just the opposition. I thought it was very fairly stated. JzG removed it with the comment "Remove he-said-she-said, that was precisely what got us into trouble in the first place!)". He also removed the links to references to the responses, so there is no indication at all that there is a formal response to these points. My complaint is, if we don't want a "he said, she said" then we should remove both, not just the "she said". If we don't want debate on this page, that's fine, but if we have debate we shouldn't be representing only one side. To me, I can't understand how suppressing this information somehow improves the article. It's factual, it fairly portrays both sides, and it's neutrally presented. The only argument against it seems to be that it violates one editor's sense of balance, and I don't think we should be suppressing vital information just to satisfy such a subjective requirement. A Transportation Enthusiast 13:54, 3 April 2006 (UTC)
I'm still forming my opinion, but my first impression is this. If we have all the pro and con arguments in the article itself, it will be as long as the talk page, which is too long and detailed for something which cannot yet be pointed to as a tried and tested system. I would prefer the main article as the proposition. By its very existence it is giving credibility to the concept. This would say how it is anticipated the system would work, including general responses to potential criticisms. Then the criticism section would be much shorter than the main article, saying the main problems detractors envisage about the ideas. Then the external links will point to detailed arguments of both sides, some of which can be referenced from the main article. This avoids direct conflicts between the pros and the cons being mixed together, which breaks the flow of both, and allows the reader to get into the frame of mind / world view of each side. For example, the main article would say something like: "The X design envisages that advances in computer power and engineering would allow pods to travel close together at high speed in safety, giving high capacity even with a relatively slow pod speed compared with trains."[Cite] The detractors section could say something like: "Small pods at train-like separation would give such low capacity that the system would not be economically viable"[Cite].
Your approach sounds promising. I would not have a problem with your capacity example, because the Proposition would explain how PRT calculates capacity (as well as the use of short pod separation). Readers would decide for themselves if the detractors' claim is correct. -6:04pm CDT

I don't think that paragraph should be removed. This entire article is basically a big educated guess, and saying that the cost analysis should be removed because its *speculative* seems rather badly thought out. The main reason PRT is proposed in the first place is because it is supposed to be cheaper to run and maintain than any other viable system. It seems ridiculous to me to remove cost analysis which is the largest part of PRT's reason for being. Fresheneesz 19:48, 3 April 2006 (UTC)

To be fair, it has been removed pending discussion here. The idea is to reach a consensus before editing the main article. On the plus side, there does seem to be more reasoned argument and even agreement than I was expecting, so I'm a lot more hopeful now that we can agree on the article at some point. Stephen B Streater 20:14, 4 April 2006 (UTC)
I dunno how deleting it is waiting for concensus before editing.. but ok. I don't care if we reach a consensus, but ... It seems people have stoped listening.. Fresheneesz 07:06, 5 April 2006 (UTC)
Where did you get your cost figures from? Stephen B Streater 07:51, 5 April 2006 (UTC)
My cost figures? I didn't get them.. I have no idea where they're from. But I do know for a fact that SkyTran claims cost estimates of 1 cent per passanger mile energy cost, and that the accepted tax deduction rate for bussiness is around 40 cents. They seem like reasonable numbers to me, but I can't support them with a source. Maybe whoever wrote it can. My suggestion is that those costs are left up, until someone can find some more accurate figures, with a source. Otherwise we might just forget about it until someone random puts up some less well-researched figures somewhere on the page. Fresheneesz 02:55, 6 April 2006 (UTC)

Urban Integration

I would like to see the source of the following info:

"On most routes in mass transit with scheduled service, vehicles are normally 85% to 95% empty."

I think the above is too vague, too general. weasel wordy and just plain wrong.

The following is not true of Ed Anderson's Taxi 2000 design:

"PRT attempts to address the fixed cost issues by .... only running in response to demand"

From the Light Rail Now article[27]

"As PRT proponent Dr. J. Edward Anderson readily acknowledges, "about one third of the operating vehicles will be empty." Anderson presents a scenario of constantly "recycling empty vehicles", bustling over the network of guideways, waiting to be "recycled" and diverted to passengers waiting in a station."-J. Edward Anderson, Ph.D., P.E., "Personal Rapid Transit: Matching Capacity to Demand", Advanced Transit Association (ATRA),February 1998

That's why they call it Taxi 2000; If most of the fleet were dormant during off-peak hours, the fleet could not re-distribute itself in order to be on-demand everywhere in the system.Avidor 14:46, 2 April 2006 (UTC)

The 1/3 empty vehicles is proportional to demand. This means if there are 1000 vehicles moving, about 333 are empty to resupply stations. If 100 are moving, 33 are empty. If it's 5am Sunday morning and 5 are moving, then maybe 2 are empty. The point is, overhead is proportional to the number of vehicles in service to passengers; as such, from a cost perspective, it can be built into the per-passenger cost.
This is in contrast to the line haul model, where a bus is moving on schedule regardless of whether it is empty or full, and therefore overhead costs are independent of demand. This may make it cost-ineffective to run at 5am on Sunday when demand is extremely low, because overhead costs are not justified to serve the low demand.
Conceptually, even during rush hours, buses would be less than half full, on average, because most people are travelling in one direction and the bus is empty for the return trip. During non-rush hours, the percentage occupancy is even less, as both legs of the trip are at significantly less than capacity. This is one reason why buses and trains run less frequently during non-busy times -- in an attempt to fill up the trains and avoid running empty.
This is much of the basis for the claims that (a) PRT can run cost effectively 24-7, and (b) per-passenger costs can be controlled while providing a high level of service. A Transportation Enthusiast 16:13, 2 April 2006 (UTC)
The text is wrong. It needs to be removed. I cited a source-Ed Anderson himself. What's your source for the above?Avidor 17:29, 2 April 2006 (UTC)
Let me explain again. The direct quote is: "about one third of the operating vehicles will be empty." In other words, if 667 vehicles are carrying passengers, then approximately 333 will be moving empty. If 67 are carrying passengers, ~33 will be moving empty. If 7 carrying passengers, ~3 will be moving empty. If zero are carrying passengers, zero will be moving empty. The statement "PRT attempts to address the fixed cost issues by .... only running in response to demand" is an accurate description of this fact. If there is no demand, there are no vehicles moving, not even empty vehicles. What are you disputing? A Transportation Enthusiast 17:55, 2 April 2006 (UTC)
Let's let the mediator decide about this section...Avidor 18:08, 2 April 2006 (UTC)

What exactly is the issue here? You want to remove that quote you wrote up at the top of this section? I think its pretty clear though. Most public transportation vehicals are mostly empty most of the time. Are you saying that it implies something false about PRT? I want to emphasize that we should not use such a controversial article as that LRN article as a source. Please leave that article out of the rest of this page. Fresheneesz 21:04, 2 April 2006 (UTC)

What is your source for the "fact" that trains and buses are empty "most of the time"?Avidor 21:54, 2 April 2006 (UTC)
Freshneesz wrote "mostly empty most of the time" (bold added), i.e. >50% empty. The times when trains and buses have a chance of being 'mostly not empty' would be during rush hours. Rush hours are not a majority of a day's 24 hours, so "mostly empty most of the time" makes perfect sense. Perhaps you, Avidor, can supply us with evidence showing that trains and buses are in fact 'over 50% full most of the time'?

"Mostly" used in this context (twice) is a weasel word.Avidor 00:32, 3 April 2006 (UTC)

Fine. How about "Trains and buses make scheduled runs regardless of actual demand, therefore movement of empty seats is inevitable. Minimizing inefficiency calls for reducing operation during non-peak travel periods, reducing capacity and leaving the system unable to meet unexpected demand." ?
I don't need a source for everything I say. Are you trying to tell me, Avidor, that I'm either lying or saying a falsity when i said "that trains and buses are empty "most of the time"" ? Do you think trains and busses are *not* empty most of the time? I see busses and trains empty all the time. I rode one today, it was what I consider mostly empty (less than 50% full). Its well known common-knowlege that this is true for most public transit. Do you disagree with this? Or are you asking for a source just to be an asshole about it? Fresheneesz 07:20, 3 April 2006 (UTC)

Evidence for the "reduced support for other alternatives" Question?

Regarding this line:

"There is some evidence that advocacy for PRT has reduced support for other alternatives to private motoring, with the result that neither alternative has been implemented."

What is the specific evidence you are referring to? A Transportation Enthusiast 22:36, 2 April 2006 (UTC)

Prominent PRT promoters like Minnesota Senator Michele Bachmann were never serious about PRT. She has been a staunch foe of funding the Northstar commuter rail line and the Hiawatha LRT line. Although she has sponsored PRT legislation and has promoted PRT in the media, she has not worked all that hard to get PRT advanced through the legislature. Her grandstanding for the media on controversial issues like PRT, the Taxpayers Bill of Rights and the Marriage Amendment has earned her condemnaton even within her own party [28] There are many other examples of anti-LRT , pro-PRT proponents walking away from PRT. Avidor 23:03, 2 April 2006 (UTC)

This proves nothing. A Transportation Enthusiast 23:16, 2 April 2006 (UTC)

Not to mention that the other alternative, Hiawatha, was implemented. Does that mean Avidor agrees the sentence is inaccurate and should be removed?
If it wasn't for the PRT delaying tactics of Sheffer Lang, and Ed Anderson and other PRT proponents we might have gotten LRT ten years ago. Detroit still doesn't have LRT in part because Ford promoted its PRISM PRT as a better alternative to rail transit...and where is PRISM today?Avidor 00:13, 3 April 2006 (UTC)
In 2003 Ford reps wrote, "Recently we have proposed a new transportation system called PRISM"[29] Uh, how long has Detroit been trying to get LRT?
PRT promoter Emory Bundy has been a prerrenial foe of rail transit in Seattle which is only now building its first LRT line....where is Bundy's Pathfinder PRT?Avidor 00:17, 3 April 2006 (UTC)
Where's Skyloop? After all the distraction of Ed Anderson and the $625,000 flushed down the loo, they are more likely to resume building the Cincinnati Subway[30]Avidor 01:16, 3 April 2006 (UTC)
Who? What??? If Seattle LRT had political problems, maybe it was because the cost is 35% higher[31] than promised. I've read about Seattle's light rail, it looks like the city was rejecting new light rail systems starting in the 60s, and Bundy isn't mentioned[32].

None of this constitutes "evidence". There's nothing to indicate that support for PRT resulted in delay or cancellation of any of those projects. This line should be reworded: :"Critics claim that advocacy for PRT has reduced support for other alternatives to private motoring, with the result that neither alternative has been implemented." A Transportation Enthusiast 01:46, 3 April 2006 (UTC)

Google Emory Bundy and Light Rail Transit [33] Emory Bundy and CETA, an anti-rail group [34] Bundy was part of a group that sued to stop the LRT...and there is this article:

Light-rail foe has rival-rail link Conflicts? May 19, 2002 David Quigg- The News Tribune

"Since the 1980s, years before he emerged as a civic-minded general in the battle to kill light rail, Seattleite Emory Bundy has been a corporate officer of a fledgling transit company that touts itself as a low-cost alternative to light rail. This financial stake - in what the influential critic dismisses as a corporation with no product, no venture capital and no payroll - surprised longtime friends and foes alike last week. Most wished he'd disclosed it all along. Then the public could judge its effect, if any, on his credibility as a critic, as a plaintiff in a federal lawsuit against light rail and as a dissident member of the official citizen committee that reviewed and endorsed the 1996 ballot measure that created Sound Transit. Members of that committee say - and meeting notes and minutes confirm - Bundy didn't tell his fellow panel members about his stake in Pathfinder Systems Inc., a developer of so-called personal rapid transit, or PRT. Not on Feb 8, 1996, when he talked up PRT at a committee meeting. Not on March 5, 1996, when he arranged for a business partner to brief the committee about the PRT concept. The committee's chairman, Seattle attorney Dick Ford, said it "troubles me" to have been unaware of the business relationship. Other light-rail backers, including state transportation commissioner Aubrey Davis, also see Bundy's silence as problematic....."Avidor 02:24, 3 April 2006 (UTC)

Yeah, I looked at CETA. They're pro-bus. I thought Avidor liked buses. Avidor, WHY must someone like LRT to be pro-transit in your book? Google also found numerous instances of Avidor repeating the Emory Bundy refrain.[35] By the way, Seattle LRT is being built, right? How did Bundy cause "reduced support for other alternatives"? If a majority still supported it, what do you care? Do you need LRT to have 100% support? Does public debate of policy options play a role in Avidor's republic, or is the ballot just a rubber-stamp formality delaying the laying down of rails?

So, an individual who happened to be against Sound Transit, also happened to support PRT at some point. What does this prove? A Transportation Enthusiast 02:41, 3 April 2006 (UTC)

The PRT proponents here bring arguments ...I bring facts and an article from neutral source-a newspaper article that says Bundy, a "corporate officer" in a PRT company was a "general in the battle to kill light rail"....they respond with more arguments and personal attacks.Avidor 13:23, 3 April 2006 (UTC)
Huh? I'm just asking questions. Is it so wrong to inquire into the groundings of your arguments? Your response makes me wonder. It's interesting in this thread that you have brought up CETA, by all appearances a pro-transit group, and Emery Bundy, a pro-bus person who seems to have done nothing to offend you other than exercise his rights as a citizen, and lend his support to one PRT company that shows no sign of life. You oppose him even though he is pro-bus and therefore pro-transit. And above you called CETA "anti-rail"--not anti-transit.
Can't you see why a lot of people here are perplexed by you and your claims? When I ask about these contradictions, you claim you're being attacked. Which ducks the questions.
You don't seem so much pro-transit as pro-technology-- Light Rail Technology. Which makes you, in spirit, as much a gadgetbaaner as the PRT people. -5:40pm CDT

I think the line should be changed to something like "Critics claim". I've seen no evidence that PRT has reduced support for other alternatives. Bundy is an individual who (apparently) happens to have supported PRT in his past. If, hypothetically, he also happened to support universal health care, would you also say that advocacy for universal health care has reduced support for transit?

Since no one has come up with evidence for There is some evidence that advocacy for PRT has reduced support for other alternatives to private motoring, with the result that neither alternative has been implemented, I am going to change it to "Critics claim." Although this objection is so unsubstantiated that it probably should be removed entirely. -08apr06 6:47 CDT


If we have an artist's rendering of a system done for its proposers, is there any particular reason we should not include the artist's rendering of a system done by opponents? Image:PRT-Guideway.jpg.

There is a difference. No one is proposing the design drawn in the opposers' representation. So they are attacking a design not proposed by anyone - a straw man. Stephen B Streater 09:47, 3 April 2006 (UTC)
The design is Taxi 2000's. The plan is Zimmermann's.[36] Where has Skytran been proposed? Superimposing images like this is a commonplace practice in the transportation is not fakery. Furthermore, the illustration is from an article critical and skeptical of PRT which is why its in the Criticism and Scepticism section. Avidor 12:51, 3 April 2006 (UTC)
Regarding the image, it's drawn by a critic, and it exaggerates proportions to make a point. Avidor himself admits this is supposed to represent the Taxi 2000 proposal, yet it looks nothing like Taxi 2000 designs (it's Raytheon). Even for Raytheon it's a bit exaggerated in size. So it's deliberately misleading, in order to make a point. Now, having said that, I have no problem including it as long as (a) it is noted that it is an exaggeration intended to disparage PRT, and (b) references to LRN be removed -- that article is already linked through the LRN root page. A Transportation Enthusiast 14:13, 3 April 2006 (UTC)
In a way that the artist's renderings by companies selling the product do not? I see these as two compeitng visions of the visual impact, with the reality probably somewhere between the two. Just zis Guy you know? 14:28, 3 April 2006 (UTC)
There's a big difference here. Companies may present their product in a favorable way, may even exaggerate its appearance in some way (McDonald's hamburgers come to mind :-)). But they don't show a completely different design. This image shows Raytheon as a representation of Taxi 2000, and even then exaggerates dimensions on the Raytheon design. The analogy would be Chevrolet promoting the Cavalier with a picture of a Corvette. So all I'm saying is, it should be noted that this was a misrepresentation that was created and used by the anti-PRT political campaign. A Transportation Enthusiast 14:46, 3 April 2006 (UTC)

I removed the picture simply because it overemphasized the LRN article, and added nothing to *this* page. This article is about PRT, not about its opponents. Also, the LRN article is probably the most biased site I've ever seen, and thus its information isn't fit for being on this page. I really don't think its at all appropriate that an affiliate to the LRN article (avidor) is pushing it upon this article. Once again, the *main* reasons I removed it is because 1) it had no attachment to this article, 2) it is not fit for being a full half of the pictures on this page. Perhaps it *would* have a place on this page if it was explained, if there were many other pictures on this page, if it was actually accurate, and it if adds useful information to the page. As it stands, it was simply an advertisement for the LRN article - and that is simply inappropriate. Fresheneesz 19:06, 3 April 2006 (UTC)

So we are only allowe dpropaganda pictures form one side? ;-) Just zis Guy you know? 14:02, 4 April 2006 (UTC)
As I've said, I have no problem including it, as long as it's labelled as deliberately misleading. I also would prefer to have an actual image in place of the Skytran rendering, which I believe does not represent a typical design. I think Skybum was going to try to get an ULTra image to replace it, but I don't know if he did. It might be useful to include a picture of Morgantown or Cabintaxi in the history section. And if Skyweb releases its images, I think either this or this would be a good representation, because they seem to be rendered with the appropriate scale. Of course, I would have no problem labelling them as promotional images. A Transportation Enthusiast 15:33, 4 April 2006 (UTC)
SAGE PERLs of wisdom, ATE?--Avidor 19:09, 4 April 2006 (UTC)
"So we are only allowe dpropaganda pictures form one side?"
This is not a propaganda page. The best pictures would be entirely neutral. I definately agree with replacing the skytran picture with a real photograph. Sure, labeling them as promotional pictures isn't a problem. My problem with the *specific* picture I removed is that it advertised LRN's article. Fresheneesz 02:16, 5 April 2006 (UTC)

Just a note: Avidor added the LRN picture back in with the old caption. Based on our discussion here, I've changed the caption to: "An anti-PRT illustration from a Light Rail Now article, showing a Minneapolis street with disproportionately large PRT guideway." I believe this is a NPOV statement of what that image is: a misrepresentation of a guideway used in a political campaign against PRT, by a web site promoting a competing technology. If anyone has a better way of saying this, feel free to edit, but it should mention that this is an intentionally exaggerated view. A Transportation Enthusiast 14:01, 5 April 2006 (UTC)

Can't let people make up their own mind... right, Trey?Avidor 14:19, 5 April 2006 (UTC)
Avidor, A Transportation Enthusiast isn't me... I did a null edit on his or her user page because the redlinks in my watchlist were annoying me. Sorry for the confusion. --TreyHarris 17:58, 5 April 2006 (UTC)

OK, I notice the caption is once again bland. This caption has got to reflect at least one of: incorrect proportions; created by anti-PRT campaigner; no one is promoting the design depicted; no one is promoting the design in the location depicted. I would even accept a caption "What critics say PRT might look like." -13apr06 8:00 CDT

I've put something in to say this is not a real photo (which one might assume given no other information), and that it is there to make a point for one side of a debate. Personally, I think that having the picture there gives credibility to PRT (as it looks real) and sets expectations of size and intrusiveness which should be quite easy to meet. Stephen B Streater 12:26, 17 April 2006 (UTC)


I keep finding absurd math errors!

"In theory, if the peak speeds of PRT and trains were the same, PRT should be two to three times faster, simply because the PRT vehicles do not stop every few hundred yards to let passengers on and off, yielding two to three times as many trips per seat as a bus or train. PRT vehicles have lower seating capacity than trains and buses, but can achieve equal or greater capacity by running at shorter headway distances."


  • PRT peak speeds are NOT the same as trains. PRT top design speeds are 40 mph. Light rail top speeds are 55 mph - 37% faster. Heavy rail or commuter rail top speeds are almost 80 mph!
  • At two-second headways, with full-capacity six-person vehicles, a single PRT guideway could carry 10,800 passengers per hour (6 people/car * 30 cars/min * 60 min/hr). BUT... LRT capacities easily exceed 12,000 per hour (4 car trains, 150 per car, 3 min headways), and heavy rail capacities can exceed 30,000 per hour (8 car trains, 140 per car, 2 min headways).
  • PRT can't move three times as fast. PRT's top speed in around 40 mph - but /average/ rail commute speeds are 22-30mph! Given that PRT designs regulate vehicle speeds to allow merges from stations, it is unlikley that 40mph speeds could be maintained full time - and so PRT can't even be twice as fast as rail. Let's keep it at 50%-80% faster than rail?
  • Finally, the whole point of PRT is that it goes where YOU want to go - it's like a car, not a glorified van-pool. So what happens to system capacity when most PRT vehicles are actually carrying only one or two occupants? Three-occupant vehicles reduces capacity to 5400 per hour. Two-occupant vehicles reduces capacity to 3600 - scarcely more than an HOV lane.

Thus, the paragraph is bunk. Speeds are NOT equal, PRT is cannot be twice as fast, and headway reductions are insufficient to provide rail-equivalent capacity. -- Transit Guest 18:00, 3 April 2006 (UTC)

Thats a very good point. That paragraph probably had data grounded in inner city transit, where average speeds of trains and rail are really really slow. It should be noted that "speed" and "capacity" are very very different, and although they are mutually related, they aren't the same. PRT might be 2 to 3 times as fast, but capcity per mile of guideway may not be that much. Also, since we're talking "theory" we shouldn't mix the realities of light rail with the theory of PRT. Its best to compare theory, or compare reality. Light rail never carries 12'000 per hour with those assumptions, and neither would PRT carry its theoretical maximum. I'll change it a bit, and you're welcome to do the same. Fresheneesz 18:56, 3 April 2006 (UTC)
I mostly agree with this response. In a downtown area, where LRT or subway stations are less than a mile apart, PRT might be faster. But that's exactly the environment where PRT's low capacity limitations are most severe, because that's where transit demand is highest. -- Transit Guest 13:38, 4 April 2006 (UTC)
According to this, the Taxi 2000 design is capable of up to 60mph, while in other contexts Taxi 2000 has been quoted at lower speeds. It may be that the lower speeds were quoted from a specific application where high station density and limited siding lengths would not permit a high main guideway speed. But if Taxi 2000 is engineered for up to 60mph, then that would imply that less dense applications could likely take advantage of the higher speeds.
"But that's exactly the environment where PRT's low capacity limitations are most severe" - that is essentially the Vuchic argument, and it implicitly relies on the assumption that PRT is low capacity. But if you have sub-second headways and a dense 2-dimensional grid of PRT (rather than a single "line"), then the low-capacity argument doesn't hold water. That's the basic problem I have with the Vuchic argument: it is presented as a proof, but it is based on an unproven premise: that PRT cannot achieve high capacities. Rather than debating capacity, Vuchic just dismisses it outright. A Transportation Enthusiast 15:05, 4 April 2006 (UTC)
Who in the world is goign to invest in that much infrastructure when we already have afunctional road network and an installed base of millions of private cars and other vehicles able to use the same roads? That really is cloud cuckoo land. It's far more likely that any practical system on that kind of scale will be based on wire guides in the roads and additional technology in existing vehicles, not least because what people want is not really public transport they don't have to share, but private transport door to door with their own clutter and their own music. Just zis Guy you know? 21:44, 4 April 2006 (UTC)
You do realize that this is basically just the classic anti-transit argument, and applies to every form of public transit, right? (well, except maybe buses) A Transportation Enthusiast 03:19, 5 April 2006 (UTC)
I agree, I thought you were more objective than that JzG. Obviously people have invested in "that much infrastructure" when talking about trains, airplanes, light rail... Even bicycles have had their own infrastructure made. PRT is simply another design that doesn't use the road system. But, this is not the place to discuss your opinion, this is discussion about an encyclopedic topic. Fresheneesz 05:45, 5 April 2006 (UTC)

The other mistake is calculating PRT capacity according to cars/hour on one piece of guideway. It is tempting to do this because that is how train capacity is measured, passengers/hour/direction. But because PRT is a network, the cars travel the most direct route from station to station, they don't all travel the same line. So a better way to express PRT capacity would be to calculate the number of trips each car can make in an hour, then multiply by the number of cars in the PRT fleet. Of course, some assumptions have to be made-- how far is the average trip? What average speed? How many riders per trip? Someone with the time should try a number of scenarios.

No, that it is incorrect math. Calculating by a one-mile "piece of guideway" has nothing to do with being in a straight line or not. Capacity is "how much room" there is on the guideway at any given moment. By using your method, you would have more trips per *instant* than vehicals that could fit on the guideway - which is obviously impossible. In calculating capacity one should calculate the number of people PER distance of guideway PER amount of time. Obviously 2 miles of guideway can carry twice as much as 1 mile of guideway (in theory with the given idealities). The type of capacity you seem to be talking about requires that guideway space NOT be a limiting factor. If space wasn't a limiting factor, capacity would be infinite. That is one of the reasons many PRT designers want to make it possible for zero-headway, or "bumper-to-bumper" style travel. (the other reason is air resistance)Fresheneesz 19:18, 3 April 2006 (UTC)

for god's sake write new discussion responses at the BOTTOM of the headered section

But if you have sub-second headways and a dense 2-dimensional grid of PRT
  • 1. You again assume sub-second headways - an essential design feature which has yet to receive regulatory approval anywhere. And again, this discussion is in the context of PRT capacity with respect to rail capacity - so if regulators were to approve PRT with sub-second headways, they'd also approve rail with sub-2 minute headways, with concommitant increases in rail capacity. So PRT would still have LESS capacity than rail.
  • 2. A "dense" grid - that means lots of parallel guideways in the same narrow corridor. First, that's not clear from the article. Second, if you need two guideways to supply the same capacity as one rail line, then you need to DOUBLE your cost estimates for both capital installations and operations & management. You also need to double the amount of land for rights of way and stations, etc. Saying "a single PRT guideway is smaller than a single rail line" is irrelevant (if not deceptive) if you need to build two or three guideways for every rail line. That's apples and oranges again - although 'bait and switch' seems more descriptive.
  • 3. What about return travel? All the estimates and models are only for uni-directional guideways. So double AGAIN the costs (capital and O&M) for return trips. Sure the loops are nice for local routing, but you need to be able to go both ways. And if the answer is, "you just loop around on another track", then you might travel 60 miles an hour, but you're only going in circles.
  • 4. You're still overlooking station size as a bottleneck. The Sky-web website says that a small three-berth station can only handle 450 Vehicles per hour. Even at 2 persons per vehicle (i.e. every commuter is PRT-pooling), that's only 900 passengers per hour to a destination. And, of course, only one-way, because those 3 berths only face one direction on the uni-directional guideway. Note that Skyweb also says that doubling station size is insufficient to double capacity - a 6 berth station serves only 750 vehicles per hour; you'd need an 8 or 9 berth station to serve 900 vehicles per hour, or nearly three times as large!
That's the real bottle neck - how may stations does it take to replace the capacity of a rail system? Washington's Metro has 86 bi-directional stations and carries 150,000 or more every week day, mostly at rush hour. That would require four to six guideways on most lines (double or triple, each direction), and more than 400 3-berth stations - without any additional benefits. When the additional usage of PRT emerges from traffic on cross-route lines or loops, you'll need to increase capacity again. -- Transit Guest 15:17, 5 April 2006 (UTC)
  • The automated control of PRT vehicles allows for short headways. Within milliseconds of detecting a slow vehicle or problem on the track, all other vehicles along the same guideway will be slowed simulatenously. The vehicle weight of a PRT vehicle is small, and so the mechanics of the braking system could stop them in a short distance. Trains can't stop in a short distance because of the vehicle weight (momentum) vs. braking friction problem, communication time for indication of the problem, and human reaction time to engage the brakes. An automated, lightweight PRT vehicle has much different operating characteristics than a heavy train or human-driven automobile, so different safety regulations must be applied.
  • A trip on a PRT system is a trip, regardless of the direction. Because of the grid of guideways, each station would not be far from a junction to allow the vehicle to travel in whatever direction is necessary to reach it's destination. Since a PRT system would be deployed to cover a significant geographic portion of a city, "extra" guideways won't need to built, since the system would already include them. Sure, a greater distance of linear guideways would need to built for a PRT system, but the point of a PRT system is to provide the convenience of no-transfer-travel to any station, any point in the city (within 1/4 mile). This is a different goal than trains that have a limited number of stations.
  • Let's do some math. Let's assume that in the near future, Washington's Metro 150,000 is split between the morning rush and evening rush, and each rush lasts 3 hours, so 25,000 trips per hour. Using Skyweb Express's numbers from your link above, at 450 vehicles per hour per 3-berth station and 1.2 average occupancy per vehicle, the number of stations needed is (25,000 / 450 / 1.2) ~= 47. Surely you agree that the coverage area of Washington's Metro system could contain 47 PRT stations. If we say 75% of the people are travelling to downtown, that gives us about 35 stations needed in the downtown area. If we include stations with more berths, the number of stations needed is reduced: all 6-berth stations -> (25,000 / 750 / 1.2 * 0.75) ~= 21 stations. This isn't unreasonable.
Clearly, the use of sub-second headways is crucial to the success of PRT. That's why discussions of regulatory concern and safety are so important to the article. I'd note that such close spacing means that if a vehicle stops suddenly, the vehicles behind must stop equally suddenly. But can a PRT vehicle decelerate from top speed to full stop in under a second? And even if the vehicle can, can an unrestrained passenger inside do so? Sure, cars travel closer than two seconds apart, but that's how multi-car pileups occur. Even professional drivers (belted in) rarely exceed 1g decelerations, and at 1g, it takes nearly two secods to come to a complete stop. So the regulators' concerns are real. But even sub-second headways doesn't get around the problems of station bottlenecks.
You miss the point. Transit demand isn't uniform because commuting patterns aren't uniform. Very few people commute from downtown homes to suburban jobs - the traffic goes one direction. If there's only four guideways into the business district where you work, and they're all FULL in rush hour, it doens't matter how many other lines there are or how fast you're going because you can't got to work! That's why you'll need more guideways, or double-wide guideways, or somehing. Likewise, if the station close to your work is jammed, just going to a nearby station doesn't help because it's a half mile away! You need bigger stations, or more stations. And that's the capacity problem: you only get sufficient capacity in a PRT system to handle rush-hour traffic when you spend more on the system than an equivalent capacity of light rail will get you! -- Transit Guest 20:56, 6 April 2006 (UTC)
What happens when a light rail train stops suddenly? A Transportation Enthusiast 23:24, 6 April 2006 (UTC)
  • You again assume sub-second headways
For PRT to show any benefit at all it must be built. Thus the efficiency estimates take for granted that when PRT is built.. it will be .. built... Along these same lines of thinking, estimates assume that they're built to their design specifications they should assume this, otherwise what good is their design? Its irrelevent whether PRT will happen, whether regulatory agencies will allow sub-second headways or anything else about PRT. This is simply not an issue for an encyclopedia to handle.
If the article is going to include statements about cost, capacity, and speed, and implied comparisons to existing transit options, then I think you better include discussions of the assumptions involved - including whether the system would be legal to operate as designed! That would be like an article on highway design that presented a theoretical capacity of highways based on "platooned" tailgating cars moving at 85 mph, without mentioning that tailgating and such speeds are illegal. -- Transit Guest 20:56, 6 April 2006 (UTC)
And yet, we don't know if it will be illegal until regulatory agencies address the issue. There is some evidence that regulatory agencies will not allow it (CVS) and some other evidence that they will (Cabintaxi, ULTra). It's an open question, which is why Ldemery's section properly documents the debate: there are current regulations that appear to contradict the PRT design, but it's unclear whether those regulations would apply to PRT, or whether PRT would be evaluated as a different system. A Transportation Enthusiast 23:20, 6 April 2006 (UTC)
  • A "dense" grid
"that's not clear from the article" -
you can go ahead and make it clear if you want to.
"you need two guideways to supply the same capacity as one rail line" -
I assumed that "one rail line" means one line of tracks.. meaning only one direction. Some PRT guideways include both directions in their calcuations (some even have both directions using the same supports). My gut feeling is that you're misunderstanding what "one rail line" is. But maybe its me thats confused.
I'll be more clear. An LRT line can carry double the capacity of a PRT guideway. Rail construction costs per mile are expressed as "per mile of bi-directional track" because nobody builds commuter systems that only go one way. If you want to build a PRT system that can move as many passengers as an LRT line, you need 4 guideways - two each direction. If PRT costs $10-$15m per unidirectional mile, it costs $40m-$60m per mile of LRT-equivalent guideway, still excluding purchase of rights of way for four guideways and all the stations, under the best-guess assumptions of the companies trying to sell it. And that's without ANY crossing routes - i.e., no grid. -- Transit Guest 16:43, 6 April 2006 (UTC)
  • What about return travel?
I think i addressed the issue above.. hmm. Unidirectional estimates are fine, as long as those aren't compared to bi-directional esitimates for something else. And about the capacity of stations/berths - that looks pretty intersting and probably a good addition to the article. You wanna add it?
Fresheneesz 03:15, 6 April 2006 (UTC)
Done. -- Transit Guest 20:56, 6 April 2006 (UTC)
  • In response to You miss the point. Transit demand isn't uniform because commuting patterns aren't uniform.: PRT directly addresses the point that communiting patterns aren't uniform. Typically during daily commutes, people are travelling individually or with 1 or 2 other people. PRT's small vehicles taking individuals to a destination unique to that person is the most convenient and most direct way for that person to travel.
  • Also, not everybody that travels during the peak times is going from suburbia to downtown. Sure, there are a large number that do that, but there are also people already in the downtown area going to another part of the downtown area, people in downtown are going to the suburbs, etc.

If a downtown area is large enough to accomodate the number of people commuting into it, it would probably have a large enough PRT grid (read: enough guideways entering the downtown area) to handle the load. It wouldn't make sense to put only one automobile lane to handle lots of traffic; why argue that a small number of PRT guideways can't handle it either? PRT still has physical limitation; any good design will be engineered to be successful at it's goal.

Excuse me, Transit Guest, please *do not* write inside my responses. Its hard enough to read this talk page without individual sentences of people's response being cut up with other response.
"including whether the system would be legal to operate as designed!"
Let me make this clear, it is NOT illegal as it stands. There are *NO* laws about this concerning PRT. Speculations about its future legality is something I don't think this article should have.
"An LRT line can carry double the capacity of a PRT guideway."
Like I said, some PRT designers give cost estimates per bi-directional mile. I'm truely not sure about the others. I know for a fact that SkyTran's estimates of around $1 million/mile (~1990s) is for a bi-directional track. I also know for a fact that SkyWeb Express's estimates of "$16-$24 million" is for unidirectional tracks. ULTra also does this at estimates of $8-$12 mil. So yes, if there are bad comparisons, we need to address them. Perhaps a table of uni-directional cost (uni-directional LRT costs as well) would be a good addition.
Fresheneesz 06:35, 7 April 2006 (UTC)

side conversations:

Yet nearly all PRT designs and companies claim speeds around 40 mph (45 is the usual upper limit). Keep in mind that we're comparing actual operational characteristics of rail systems to hypothetical design specs of PRT - I think we need to be realistic when speculating about PRT.
This says up to 60mph for Skyweb Express. What makes you believe the vehicles aren't capable of travelling at that speed?
I've ridden enough roller coasters to know that I don't want to ride one to work every day. 60mph, in a small wind-buffeted box 20 feet above the ground is gonna make a lot of people very nervous. And what about motion-sickness for the suspended-cab designs? Those swaying little cars are gonna smell real bad real fast... -- Transit Guest
The train I commute on has a top speed of 125 mph. Just zis Guy you know? 14:11, 4 April 2006 (UTC)
  • .
  • What about less-than-2-second PRT headways? For example, if you assume 1 second headways, the PRT capacity is double.
    Also, how often do 8 car LRT trains travel at 2 minute headways? That seems pretty often for such large trains.
PRT has not been approved anywhere with less than 2-second headways. I agree that short headways (and platooning) would increase capacity, but if regulators ever approved PRT on sub-2 sec headways, there's no reason rail operations couldn't do the same and run closer together.
Is this true in general? I was under the impression that trains could not run at shorter headways because the stops are online. If trains could run at shorter headways, why don't they allow it today? And, this only applies to grade-separates systems, right? Because at-grade systems are inherently limited by the fact that they mix with traffic...? A Transportation Enthusiast 04:13, 5 April 2006 (UTC)
As explained by another user below, because regulators want all trains to be able to come to a complete stop without risk of collision with another train. That safety concern applies equally to PRT and rail. -- Transit Guest 15:17, 5 April 2006 (UTC)
Is there somethat that makes you believe it won't be approved at sub-2 sec headways? Isn't it reasonable to have the first large scale trail at something more safe, then improve the performance as the system proves itself?
Don't trains of this size have a very long stopping distance that would prevent them from running at short intervals?
As for rail capacity, I referred to heavy rail. Washington's Metro now runs 8 car trains. The Red line runs 29 six car trains during peak rush, while the Orange-Blue line was running 29 trains at peak through the Rosslyn Tunnel (that has been cut back as Metro tests 8-car trains on the Orange line to reduce congestion). The Red line has *actual ridership* of over 15,000 per hour at rush, and the Orange-Blue lines move over 20,000 per hour at peak through their shared tunnel. -- Transit Guest
  • .
  • Why do you think PRT designs regulate vehicle speeds to allow merges from stations? Some designs reserve a "slot" along all guideway sections from origin to destination for a PRT vehicle to travel in, so there is no slowing down during merging, etc. So, yes, the average speed of PRT vehicles can be very close to the cruising speed. (Acceleration, deceleration, etc will reduce it slightly)
  • .
  • Are we talking about single guideway capacity or system capacity? A PRT system, as you allude to, is able to transport many people to diverse destinations simultaneously. LRT, etc, can only transport people to the relatively few stations along it's tracks.
I mis-wrote - I meant per guide-way, at peak rush hour. And clearly, the demand for transit (and for congestion relief) is strongest along specific corridors of suburb-downtown traffic. So while PRT offers the ability to move people in other directions, across the flow of normal rush traffic, it's not clear that reducing such traffic will do much to reduce rush-hour congestion. The point is that if a single PRT guideway only has the same rush-hour capacity as an HOV lane, well, HOV lanes are a LOT cheaper to build and operate. And rail has far higher rush-hour capacity. One solution for PRT is to build more guideways into downtown - which is what the Seattle plan suggested: 3 inbound guideways from each direction (except over the water). But if you're going to have 9 inbound guideways, that's a really expensive system - not to mention an implicit admission that a single PRT guideway can't handle the rush hour capacity. -- Transit Guest
Let's compare apples to apples here. If we're referring to at-grade LRT that shares the road system, capacity is not going to be in the tens of thousands per hour, right? In fact, propably no more than 5000 per hour per line, correct? A single PRT "line" along the same corridor would be able to handle that same capacity, and costs would be in the same ballpark. Now consider grade separated light or heavy rail: this can move much larger capacities, and you would need multiple PRT guideways from each direction to match that capacity. But the cost of grade separated light or heavy rail is almost an order of magnitude higher than an at-grade system! Let's say grade separated rail costs 4x more than at-grade light rail or a single "line" of PRT -- for that much money you could build four times the PRT guideway! And, not only that, the 4 PRT lines could be spread over a larger area if necessary, to give more people close access to a station. So if you're a mid-to-large city spending $billions on tunnels and elevated rail... well that amount of investment in a PRT system could cover a larger area AND provide equivalent capacity. When you compare apples to apples, the capacity argument against PRT doesn't look so compelling. A Transportation Enthusiast 03:37, 5 April 2006 (UTC)
Indeed - let's do that comparison. Because actual installed LRT costs per mile for systems requiring minor capital construction (i.e., limited on-street, ground-level grade-separated, pre-existing rights of way, etc.) average less than $25m per mile, often including rolling stock. More intensive construction, i.e. full grade separation with short tunnels or elevated spans, averages less than $50m per mile. See charts here. Heavy rail costs range $50m - $200m per mile or more for complete grade separation, third-rail power, larger stations, bulkier bridges and rights of way, and lengthier elevated or tunneled spans. Those costs are bi-directional, including stations. And how much does PRT cost? The article says $.8 to $20m per mile of guideway - but the lower end is for dual-use RoW (i.e. PRT over public roads), not including stations, control centers, or vehicles. What do the companies say? Their complete costs are collected and estimated here, routinely falling into a range of $10-$15m per mile, one way. And all those costs exclude RoW. So even before RoW, PRT advocates' glossy-eyed predictions of cost are $20-$30m per mile of bi-directional guideway. And you still need RoW and land for stations (you can't put those on the roadway). What are the actual total costs? Probably 20%-50% larger, plus rights of way. And that's for systems that only follow an LRT route, with the same number of miles of guideway (albeit more stations), and which can't carry LRT capacity. To get LRT capacity, you need to double or triple the costs, and double or triple the rights of way ($$)! To get "true PRT" - i.e., the "dense" city-wide grid, costs will increase rapidly. -- Transit Guest 15:17, 5 April 2006 (UTC)
Would PRT be more expensive than other systems that would provide non-stop, on-demand service? Trains aren't non-stop, and probably won't get you as close to your destination as PRT could. Buses are the same, and get stuck in traffic. Cars can take you close to your destination, but you have to park them, and they are restricted by traffic problems also.
That's the problem - "non-stop on-demand no-parking" transit is unrealistic. The best is the enemy of the good. -- Transit Guest 15:17, 5 April 2006 (UTC)
PRT's "system design" is based on having many stations spread throughout the city. Many stations -> many guideways connecting the stations -> multiple guideways into the city. Your argument about having to "build more guideways into downtown" -- what is that based on? More than LRT?
See above. A grid is nice, but if most of the traffic is going in one direction, you need extra capacity on those routes. If everyone wants to go downtown in the morning, you need to get them there. That means the radial suburb-city-center routes need to be double or triple size compared to other cross-town or circumferential routes. -- Transit Guest 15:17, 5 April 2006 (UTC)

Some points in response:
  • "PRT peak speeds are NOT the same as trains." The line clearly states if PRT runs at the same speed as trains. Clearly, some trains have a higher top-end speed, but some lines (especially at-grade) do not. The point is, for equivalent top speeds, PRT has a greater average speed because there are no stops. I see no problem with that statement. A Transportation Enthusiast 04:13, 5 April 2006 (UTC)
Yes - but the "if" is irrelevant because PRT does not move as fast. *IF* wishes were horses, then beggars would ride.
The point is, for equivalent maximum speeds, PRT has significantly higher average speeds because there are no stops. And as you add more stops, LRT average speed decreases while PRT average speed remains constant. I think the wording in the article is fine, but if you feel it is misleading then change it. A Transportation Enthusiast 04:13, 5 April 2006 (UTC)
  • "LRT capacities easily exceed 12,000 per hour" -- is this true of all light rail? I've read that at-grade light rail lines are limited by mixing with traffic: smaller trains, slower speeds and longer headways.
Apples and oranges. Comparisons to LRT should only be made to grade-separated LRT. Otherwise, the severe imbalance in construction costs swamps any benefits from PRT. After all, on-street LRT only needs wires and rails and a bench at each stop - no dedicated ROW, and no dedicated stations. -- Transit Guest 13:38, 4 April 2006 (UTC)
Well, what are the typical costs of grade separated LRT, per mile? I was under the impression that grade separation gets quite expensive for rail systems -- on the order of at least a hundred million per mile. And at-grade systems are typically $20M-$60M. This would make PRT systems competitive with at-grade LRT, wouldn't it? A Transportation Enthusiast 04:13, 5 April 2006 (UTC)
See above - your estimates are too high. At-grade LRT averages $25m per mile, with many systems costing less. Grade separated costs average $50m per mile. Again, PRT designs (not actual costs) average $25-$30m per mile for bi-directional guideway without including RoW, at lower capacity. So the best-case estimates of the PRT companies are only barely competitive with the actual real world costs of LRT - and what about real world costs of PRT? -- Transit Guest 15:17, 5 April 2006 (UTC)
  • Your calculations for PRT capacity assume 2-second headways are the lower bound of headway. In fact, sub-second headways are technologically feasible; the only barrier to sub-second headways are political (regulations might not allow it without significant operational experience and testing at longer headways). This regulatory/political concern is properly documented in the criticism section. Some designs have been engineered for shorter headways, as low as 0.5 seconds, which quadruples the max capacity. Now, I fully understand that this is very controversial (and as I said, the controversy is well stated in the criticisms and elsewhere in the article) but as far as I know that controversy does not address the actual engineering and safety analysis of a specific system -- only the current regulatory environment. A Transportation Enthusiast 18:40, 3 April 2006 (UTC)

Regulatory concerns / safety standards

There are two "safety standard" issues that you won't find in California PUC literature because they are basically "judgement calls" - and could well rule out PRT.

(You (probably) won't find an explicit written CA PUC prohibition on wood-bodied subway cars - but see what they do if you propose to use wood cars in an actual subway line.)

Vehicle crashworthiness: The "heavy rail" and "light rail" systems in California have used vehicles similar (or identical) to those in service elsewhere, and so PUC "might" not have explicit specifications (such as how much force a vehicle must withstand in a "squeeze test" without distorting its frame). They "might" simly review the specs of the vehicles you buy as part of their certification process. They might take a closer look, however, if you're planning to deviate from "established" practice. An "ultra-lightweight" vehicle design, for example, would (probably) attract close scrutiny.

Although documentation in English is scarce, Japanese-language sources make clear that the initial AGT lines in Japan cost considerably more to build than estimated initially because vehicles had to be built more sturdy (= "heavier") than originally planned. I have seen an article (in Japanese) that describes the guideway "profile" changes (scaling up) that had to be made.

Headway, aka the "safety limit:" This is the potential "ultimate PRT killer." There is no such thing as a public transit system with "trackguided" or "railbound" vehicles that is permitted to operate beyond the "safety limit." This seems to be an unfamiliar term to Americans, but it simply means that the minimum spacing between vehicles is greater than the "safe stopping distance" at the "maximum permitted speed." Operation "beyond the safety limit" means that the spacing between vehicles is less than the "safe stopping distance." As happens on roads.

Anderson and other PRT proponents have basically ignored these issues, preferring to argue that technology makes collisions so unlikely that they will never happen. Such arguments have not been accepted in the case of fully-automated ("driverless") AGT and metro systems overseas - and might not be accepted by CA PUC.

Thus, it is reasonable to write "the degree to which CA PUC would hold PRT to "heavy rail" and "light rail" safety standards is not clear." This is so because these decisions have not yet been made. Ldemery 05:42, 5 April 2006 (UTC)

Most of that seems reasonable, but I'm unsure of what you're suggesting for this article. One thing I disagree with is that "Anderson and other PRT proponents have basically ignored these issues". One major reason most PRT proponents say that "beyond the safety limit" is safe is that there are no "brick-wall" stopping possibilities because there are no intersections. The only possible brick-wall type stops are if a vehical is stranded on the tracks, or if a bird or airplane crashes into a pod. Many people have also argued that such restrictions on busses and trains aren't warrented because the vehical in front of another vehical can't stop instantaniously. An interesting point that someone in the far past has made on this talk page is that Doug Malawiki proposed 6G emergency stops so that the SkyTran vehicals could meet that "safety limit" requirement. Fresheneesz 06:04, 5 April 2006 (UTC)

About talk page organization

First of all, this talk page is getting cluttered enough to warrent another archive. Second of all, its near impossible to follow all the "side" conversations that occur between people's writing.

  • Everyone, please write your response to people BELOW everyone elses comments. DO NOT write your comments in response to a mere part of somones writing. This talk page gets so ridiculous. Please keep your comments to the point, and keep them organized in a sane way please please! Fresheneesz 05:47, 5 April 2006 (UTC)
If you want to write below a comment that someone wrote way up there, make a header especially for that section, and also header the stuff below what you write. Fresheneesz 05:55, 5 April 2006 (UTC)

Criticism belongs in the criticism section

I'm seeing a lot of critical analysis seeping into the main section of the article. If the history and design sections are to be the "pro" argument, then the critical portions should be restricted to the criticism section. I have no problem interspersing arguments, but it's already been established (unilaterally) that the criticism section is to be devoid of any counter-arguments based on the assumption that the rest of the article is the "pro" case. We can't have it both ways. Either the main article is uncontested pro and the criticism section is uncontested criticism, or we intersperse arguments everywhere. A Transportation Enthusiast 16:28, 5 April 2006 (UTC)

I also think the exposition should not try and argue point by point. It should contain answers to potential questions, but not the questions, which should be raised in the criticsm section. At most, it should refer to the criticsm section for counter arguments. Are there any back-and-forth arguments in particular that might be separated? Stephen B Streater 18:08, 5 April 2006 (UTC)
There is a fundamental misunderstanding here. The main body of the article is not intended to sell the concept. There are phrases repeatedly creeping back in which seem to me to be out-and-out advocacy, and many points are reiterated multiple times for no good reason. How many times do we need to restate that even though they are smaller, they could really carry more poeple, honest they could, it's just those evil regulators not letting them run with sub-second headways. And if not that, then there are not enough guideways. An old friend came in out of town! The car ran out of gas! I got a flat tire! I didn't have enough money for cab fare! The tux didn't come back from the cleaners! There was an earthquake! A terrible flood! Locusts! "We" are removing chunks without discussion for the same reason they are being inserted without discussion. I keep coming back to an article whihc reads like a press release with a handbill pasted on the end. Incidentally, we don't need to have the initialism PRT in every other sentence. Just zis Guy you know? 20:16, 5 April 2006 (UTC)
JzG, you don't understand PRT, and you are sympathetic to Avidor's views (which are based more on emotion and politics than fact). You continue to remove anything that you consider "speculation" that puts PRT in a favorable light, even if it is backed by scientific studies and theory. You just removed a section on ridership that was even confirmed by a study conducted by critics. At the same time, you allow anti-PRT speculation to be added daily. Your bias is affecting your judgement and you should remove yourself from this debate before I call for arbitration. I am very concerned that your sympathy for Avidor's politics is causing you to put a negative spin on this article, in order to satisfy Avidor's oft-expressed concerns about upcoming votes in Minnesota, and this is wholly inappropriate. Your recent statements reveal that you are biased against this technology and you should cease now. A Transportation Enthusiast 21:02, 5 April 2006 (UTC)
No, I am not sympathetic to his views, I think he had a point. The article read like a press release for PRT, and every neuitral statement was balanced by puff. It still needs more work (see below). I have lost count of the number of times people have accused me of supporting one side or another - in this case I get it from both sides - but as usual there is no evidence to suggest why I should care one way or another. After all, the chances of a PRT scheme being built in my town is negligible. It's tough being a rouge admin. Just zis Guy you know? 21:34, 5 April 2006 (UTC)
Oh come on! Anything that makes a claim favorable to PRT is "puff" in your book, and yet you were willing to include a cartoon invoking fear of terrorism as representative of the skeptical case! This shows an extreme level of bias, when scientific simulation is scoffed at while blatant fear mongering is "a light hearted look at the opposotion's argument". Give me a break! A Transportation Enthusiast 22:27, 5 April 2006 (UTC)
The fundamental problem is that there are no real life commerical working examples to show PRT working, so the design is hypothetical for now. I would still prefer a main section on approximately "How it is hoped/planned PRT would work", with a potential problems separated out, rather than each idea being contradicted where it occurs. I think this would lead to much less conflict in editing the article. Stephen B Streater 22:18, 5 April 2006 (UTC)
I think everyone needs to calm down here (well except for Streater). Everyone remember that this article isn't imperative to the survival or demise of PRT. NOTHING on this page is urgent - so noone should get exasperated.
First of all, Up till a couple of days ago (when I looked at it last) this article looked *fine* to me. Not anywhere near perfect, but in terms of NPOV it looks fine. The main reason things are reitterated so much is probably because there are a bunch of people that have made a bunch of unorganized edits, without reading the whole article. Thats what I usually do. If you see cumbersome reitterations - merge em. Fresheneesz 02:39, 6 April 2006 (UTC)

A problem section

Ridership AttractionIf PRT systems can deliver the claimed benefits of being substantially faster than cars in areas with heavy traffic, simulations show that PRT could attract between 35% and 60% of automobile users. This is significantly more than other forms of public transit. The higher ridership spreads the cost of the PRT system over more passengers per day, also causing greater utilization of the PRT system's capacity.

If. A speculation which is unsupported by any real-world examples, including from the small number of model schemes. Are these simulations run by didinterested third parties and published in reputable peer-reviewed journals? Did they take account of the fact that reduced traffic numbers owuld increase the speed of the motor traffic, eroding the differential? Or did some salesman just pluck it out of his guideway? Cite it from a reliable source (i.e. one independent of a company pushing PRT) or remove it. Just zis Guy you know? 21:28, 5 April 2006 (UTC)

Next time, maybe you should check the talk page first. A bunch of studies are referenced on this page, from our earlier debate on this topic! One of the studies is the OKI report itself, which is exhibit A of the anti-PRT argument. I've put the section back in. I'm frankly sick of you removing valid content without checking here first. You continue to play politics with this page, eliminating facts that support PRT while allowing speculative criticism to stand unchallenged. This is inexcusable. I'll repeat again: when you first arrived, you made a lot of improvements to this page. In the past week, however, your changes have been almost exclusively biased to the negative view, and the article is now POV the other way. You should quit while you're ahead. A Transportation Enthusiast 22:13, 5 April 2006 (UTC)
As I've said before, I make no claims to be a great editor, but neither do I have any agenda here, unlike several of the others involved. The ridership estimates in that study are predicated on low/no wait times (i.e. many vehicles), wider coverage than the other schemes compared, and other assumptions which cannot be justified from real-world data. But since I'm being accused of bias by both sides, maybe I'm getting something right, who knows? Just zis Guy you know? 17:36, 12 April 2006 (UTC)
JzG, you keep making the same vague accusation that "some editors have an agenda". Other than Avidor, which editors would you be referring to? I certainly have no agenda. I think if you are going to assume some of us have an agenda, you should be specific about who you are referring to. A Transportation Enthusiast 04:14, 14 April 2006 (UTC)

Regulatory concerns / safety standards - continued

I will reiterate my POV - that's what it is and it does not belong in the article - that Anderson and other PRT proponents have basically ignored the issue(es) - of vehicle crashworthiness and the "safety limit." They prefer to argue that technology and the nature of the PRT concept make collisions so unlikely that they will never happen with "close-headway" operation.

It's true that some have argued that the "safety limit" is not an appropriate standard for trains is not appropriate - especially with driverless operation and multiple "fail-safe" systems.

My point, however, is that to date, no regulatory agency anywhere in the world has accepted such arguments. To assume that CA PUC would make an exception for PRT is, at best, an unjustified leap of faith. Thus it seems perfectly reasonable to write, "the degree to which CA PUC would hold PRT to "heavy rail" and "light rail" safety standards is not clear." Remember: 1. CA PUC has the authority to say "yea" or "nay," and 2. that decision has not yet been made, 3. it is unlikely that such a decision ("ruling") would be made absent a serious PRT project somewhere in CA.

(6G emergency braking rate? I doubt that CA PUC would permit this because it would raise major issues re. passenger injuries.)

I've also noticed that some PRTers appear not to understand that roads and trackguided modes are not identical. Roads have "intersections," but trackguided systems have "junctions" and (if not fully separeted) "crossings." Trackguided modes may also have "fouling points," as Seattle learned late last year - and that "fouling point" wasn't even protected by signals.

There is the (physical) possibility of a collision between vehicles at any junction point. There is also the (physical) possibility of an undetected vehicle stopped along the guideway between stations (or between junctions for "off-line" stations).

"Off-line" stations are not a sufficient condition for "close-headway" operation. If this were so, then Japan's Tokaido Shinkansen "should" have been permitted to operate beyond the "safety limit," because (if I recall correctly) all intermediate stations were "off-line." (They have since added stations which are "on-line"). Ldemery 22:27, 5 April 2006 (UTC)

The focus of most PRT designs is to avoid brick wall stops entirely, and to engineer systems such that this is the case. From what I've read, checked redundancy in these designs ensures that MTBF for brick wall stop scenarios are in the millions of years. In other words, only multiple simultaneous failures plus an act of God would cause a brick wall stop. If the engineering is shown to be valid, then there should be no question as to the fundamental safety of these systems.
So my question to you is: are you disputing the engineering or the concept? For example, if you found a flaw in the safety analysis that produced the MTBF numbers, I could understand your skepticism. But if the engineering is valid, and the MTBF numbers are correct, then any argument that brick wall stops are not safe is invalid.
You refer to "physical possibilities" -- but isn't every system subject to physical possibilities? Trains crossing intersections can collide with fully loaded semis, which would cause catastrophic damage to the train and its occupants. Is this a physical possibility? Yes. Is it an acceptable risk? Yes.
Now, as to the regulatory concerns, you certainly raise valid points. Regulatory conflicts are perhaps the biggest challenge facing PRT, because regulations are the realm of politics, and politics and engineering don't always mix. So certainly your objections in the article are accurate and well stated. But again, the regulatory environment says nothing about the underlying safety of sub-second headways in a given PRT system design. And as more operational experience is gained (maybe ULTra or Dubai?) regulations may very well catch up to the engineering. A Transportation Enthusiast 22:48, 5 April 2006 (UTC)

Sub second headways are already common. Here in Southern California, autos often follow at less than half second intervals. It is certainly not wild speculation that an automated system may be allowed to do this. pstudier 23:47, 5 April 2006 (UTC)

Pstudier makes a good and very real point. I agree with the point, but an obvious counter to that is the horrendously high rate of accidents with cars. Surely a constant speed and automation would cure these problems tho. Although I have 100% certainty that it would be safe for properly designed PRT vehicals to travel 10 feet behind the next one, Ldemery is saying that regulatory agencies do not. What do you want to change about the article Ldemery?
Also, it should be noted that all of this is speculation. Regulatory agencies haven't fully considered PRT if at all. Looking at the article, it seems alright to me. Concerns about regulatory approval are in there, and there are no claims of "probable regulatory approval" of subsecond following distances. Again, what about the article did you want to change? Fresheneesz 02:49, 6 April 2006 (UTC

To answer the question above regarding changing the article, "at this time, nothing."

Skyburn wanted to remove the paragraph about the California PUC, and this I oppose. I am not disputing the "engineering," or the "concept." Nor am I am not addressing the underlying safety of "close-headway" operation. I am emphasizing that regulatory agencies have explicit authority to say "yea" or "nay" to the concepts, crucial to PRT, to ultra-lightweight vehicles and operation "beyond the safety limit." We don't know what they might decide - and so the uncertainty needs to be addressed - explicitly.

With the qualified exception of the British Railway Inspectorate, I reiterate that no regulatory authority, anywhere, has yet to authorize a "trackguided" or "railbound" system to operate "beyond the safety limit." The fact that autos do so today (as they have for decades) is not germane to the matter at hand. As for "automation" - there are a number of automated or "driverless" transit systems in operation overseas - and in this county, at airports. To the best of my knowledge, none are permitted "close-headway" operation.

My POV, but I find the speculation that "regulations may well catch up to engineering" quite naive. The same high-speed trains that have operated safely in Japan and Europe for millions of miles cannot be operated in this country because they do not meet Federal Railroad Administration crashworthiness standards. Furthermore, the high-speed trains that are "FRA compliant" - Amtrak's ACELA trains - have experienced a rash of mechanical failures that have been attributed to the greater mass of these trains. But don't expect any change in "the rules" anytime soon.

OT, but I'll give one example of a "regulatory" fiat that has blocked something that is technically feasible - and has been for decades. A recurring dream in the Seattle area is a bridge across Puget Sound. This would have to be a floating bridge because of great depth (900 feet, and that is reached within half a mile of shore). This could be built - it would be very expensive and would therefore require federal funding, but it is perfectly feasible - technically. However, the U.S. Coast Guard would have to approve such a project - and they have signaled, repeatedly, that they would not.

To conclude: no changes needed, so long as regulatory uncertainty is addressed. California PUC is probably the "best" example because of materials available online. Ldemery 20:53, 6 April 2006 (UTC)

I basically agree with you on all points. I think the regulatory section should stay, as it is perhaps the major hurdle for PRT to overcome.
As to my "naivete", well I just like to think of it as "giddy optimism". :-) A Transportation Enthusiast 15:39, 6 April 2006 (UTC)
Regarding the comparison to automobiles: even though the accident rate is somewhat high, I still believe that the automobile experience proves that close headways work in practice. In the past few months, I've done a lot of "headway timing" while driving in my car, and I've frequently seen 1-second (or less) headways between vehicles. This, without automated control, without constant vehicle positional checks and feedback, and with drivers distracted by cell phones and coffee spills. Automobiles are the best proof of the PRT concept. Now, of course, autos have seatbelts and airbags so that high-G decelerations typical of auto accidents are not fatal, but PRT can avoid almost all collisions or rapid decelerations if it is properly engineered. And, if necessary, for the extremely rare collisions that might occur, seatbelts and airbags could be provided (though I think this would be overkill if accidents are very rare). Of course, regulatory agencies might not agree with any of this, which is the real point of this whole discussion. But, as I said, I'm an optimist. A Transportation Enthusiast 16:01, 6 April 2006 (UTC)
It should be noted - and the article does note - that regulatory agencies did not agree, during the 1970s, in Japan. This killed the CVS project which had reached an advanced state of development. I can think of a number of locations in Japan that (from the ground) appear almost "tailor-made" for PRT.
Also, your observations regarding autos and PRT ignore the issue of automation vs. human judgement. To quote a friend who is a commercial pilot and once worked as a flight instructor: "You can't program human judgement into a computer." Nonetheless, we've reached agreement on the regulatory section. Progress! Ldemery 20:53, 6 April 2006 (UTC)
Your argument about human judgement vs automation does not apply to PRT designs, for the simple reason that PRT algorithms do not require "judgement". Separated guideways basically allow for a very simple control logic that doesn't require the heuristics of human judgement. So while computers may be very poor at recognizing a pedestrian crossing an intersection, they have no problem calculating millions of simple trajectories per second, at very high precision. This is one big reason why grade-separation is an absolute requirement of PRT, so that the control logic does not involve the complex heuristics of human thought, and full automation is therefore safe and practical. A Transportation Enthusiast 07:07, 7 April 2006 (UTC)

PRT Proponents Have Their Doubts...

Deleting this section

From this point on, I will personally remove any talk page text on THIS article, if it does not pertain to WRITING the article. Avidor has repeatedly used this talk page as a push for his anti-PRT campain, and this is not acceptable. I have archived this in the appropriate place, but I will not do this in the future. If you want to spout your opinions and bitch about a controversial subject, wikipedia is not the place to do it.

Also, I DO NOT APPRECIATE Avidor quoting me out of context, and ESPECIALLY when he doesn't give me credit for what I say. Avidor, if you quote me, label WHERE you found that quote at least, and both where and who if you want. Fresheneesz 02:41, 10 April 2006 (UTC)

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