Talk:Personal rapid transit/Archive 3

message: 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)
replies: text: 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 .  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)
thread_title: Quick question

message: 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)
replies: text: 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)
replies: text: 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)
thread_title: Speculating about Design

message: 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)
replies: text:  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)
thread_title:  Regulatory concerns / safety standards 

message: 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)
replies: text: 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)
thread_title:  About talk page organization 

message: 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)
replies: text: 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)
replies: text: 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)
replies: text: 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)
thread_title:  A problem section 

message: ===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)
thread_title: PRT Proponents Have Their Doubts...

message: 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)
thread_title: Deleting this section