18> PRT Motor-in-the-Wheel Design

This illustration shows how a motor can be mounted inside of a PRT “Pod-Car” wheel.
I was first inspired by a design from an electric “concept car” where the wheels were actually motors. The idea is simple. If you plug in a motor but hold the shaft, it will spin, (winding up the cord until it unplugs itself). So why not feed the cord through the shaft somehow? That way the motor itself would be a wheel, instead of mounting a wheel on the shaft? (Or more likely, a sprocket, gear or pulley) It turns out this idea is actually widely used. A Google search revealed that the concept is commonly employed to move conveyor belts, (drum motors) and to electrify bicycles in China (hub motors) and in fans, especially computer and ceiling fans.

Despite the obvious simplicity (and efficiency) of the idea, apparently the motors don’t perform well in terms of torque, as compared with a much higher speed motor fitted with a reduction gear. Also they are not exactly cheap or easy to find, so I bit the bullet and researched some more conventional motors.

My switching design calls for hard wheels, so I put in a bunch of them to have the traction to climb steep smooth slopes. I don’t really know how many is really optimum, at this point, but I checked out some “NEMA” standard sized brushless motors, and found that the NEMA 42 standard comes with sufficient torque that if each or the wheels had a motor within they could pull (together) with between 300 and 800 lbs. of forward power, while having a top speed of 60 mph. (Sorry, younger and euro readers, I am not natively metric and feeling lazy) Obviously, reducing the top speed increases torque proportionately, but it also worthy to note just how much of a trade-off is required between the weight, the steepness of the climbs and the top speed. There is no free lunch. For example a combined vehicle/payload weight of 1600 lbs. will probably not make a 45-degree climb.

It is also worth noting that the separate motors solve the fact that my system has no differential gears. For those who do not know what a differential gear is, here is a brief explanation – On car, when turning a corner, the outside wheels have further to travel than the inside wheels. Therefore they have to revolve faster, making more revolutions than the inside wheels. The differential gear accommodates this, preventing one or both wheels from slipping on the pavement, which would create wear and partial loss of control. Even though the right and left wheels in my PRT design are fairly close together, the same phenomena would apply to a lesser extent. With separate right and left motors, however, the RPMs of the wheels can be precisely controlled to actually create the appropriate steering forces.

17> The Role of a PRT Standard

A good PRT standard would
1. Give all decision makers (city, state, federal) the security of knowing that the system design was not rushed, coerced, short changed, tailored by self-interest.
2. Give those decision-makers the assurance that the design is suitable for competitive bidding in initial construction, expansion, and maintenance and therefore they are not utterly dependent on the initial contractor.
3. Give PRT contractors a vetted design more likely to be accepted by the public.
4. Reduce PRT contractor’s liability risks.
5. Make a PRT project easier to manage and subcontract.
6. Give customers more faith in the system
7. Allow innovation in system components outside of the standard.
8. Be divisible so that variations can be introduced without scrapping the entire standard. (A proprietary car for a standard track, for example)
9. Be designed with altruistic intent, including benefit to the environment, local contractors and other vendors, as well as commuters and the communities they pass through.
10. Be continuously updated
Did I leave anything out? Anyway, A good set of open-source specifications would greatly enhance the chances of a truly ambitious implementation. Let’s remember, a scaled down test will always go from a place where people congregate to different, similar place. In other words, companies with millions tied up in engineering and marketing and testing and selling have to recoup costs by jacking the cost of track so high that only a loop is affordable. Meanwhile cities have to ensure usage by placing stations only in congested areas. Almost by definition, then, a simple shuttle service will always be more cost-effective. Only confidence and optimism can produce a first implementation that is scaled for success.

So what would a first standard be? I would think that the first stage would be (for example) to standardize a track profile, switching and control protocol and weight limits. If there are deep-seated divisions in these matters, there could branching specifications. For example, I outline, in the last post, a method of using external power to lift cars up very steep (to vertical) slopes. A “podcar” designed for the track, weight, and switching specifications but incapable of this adaptation might be called PRTSO 100.2 compliant, but not PRTSO 100.2.5 compliant. A city could look at a proposal and decide whether this would be an issue or not. At any rate, they would know what kind of track to buy.

It is interesting to consider that, for design Darwinism to occur, one needs a number of competing designs. It is therefore not the function of this site to design a single system, but a number of competing systems to see what common threads emerge. None-the-less, it is equally important that each idea be critiqued, as though it is the one and only alternative.

16> How to Lift a Podcar

I want to start by noting the obvious difference between the designs I have shown and those of the other two hanging pod designs I am aware of, Beamways and MISTER. Neither has the vertical connecting beam I have illustrated. Besides the obvious advantages of having the track being high and out of reach, the connecting beam has one other advantage.

I have long wondered if PRT vehicles, (OK, Podcars), would need a transmission of some sort. Clearly the advantages that have led to their universal adoption in automobiles would seem to apply here as well, although I am led to understand that electric motors are a bit more forgiving in this regard. Anyway, my concern was about the on-board power needed for steep ascent, and my thoughts went to roller coaster design, where the cars are pulled up the track by a means outside of the vehicle, so there is no need to carry around a heavy motor.

I have taken a design philosophy that is consistent with open-source by seeking to not foreclose options that someone else might find useful, and the roller coaster method seems to have enough merit to at least keep as a possibility, Then the question becomes, “how steep?” Obviously straight up is as steep as possible, so my attitude is “why not?”
One problem that our societies must someday face is our land usage footprint. The future is UP!

Since vertical ascension, however, is not part of any immediate plan, I will not explore the matter further, other to say it’s not challenging, engineering-wise. Now you know another reason for the “beam”. This design also has some comfort (g-force) advantages, and possible collision safety advantages. One challenge, however, is with how to deal with loads that are highly unbalanced, front to back. Inventors, engineers,.. we need you!

By the way, that brings up one obvious problem with this site and format. You can’t post pictures. For the time being, if you have a pic that you think would help out the cause, send it to me at danverhoeve@gmail.com and if it’s worthy, I’ll make a post out of it. Meanwhile, I would be interested in suggestions on how to get a past this problem for good. Wiki? Forum? Tell me what you think!

15> The "Podcar" and the PRT Dream

First, I HATE the term “Podcar” or “pod”. Unfortunately, Since the PRT thing in Ithaca last summer, it seems that a lot of “PRT” Googling results in this awful term. Are people who ride “pods” considered “Pod-People”? (Anyone remember that movie?) Anyway, I use it here in the title solely for the cynical reason that it might bring in some (Googled “POD”) readers, and some of them might become contributors to the cause. I would like to reiterate that cause now, as many people might tend to scan the site, without realizing it’s purpose, which is buried in the end of the “About this Blog” section
The ultimate dream would be to realize the world’s first large-scale open-source mechanical, software, legal, environmental and social engineering project, with a full set of blueprints, contracts, position papers, environmental studies, etc. provided by the masses, for the benefit of humanity and the planet. A “Wikipedia” of how to build a truly 21st century transportation system with local talent and resources, with a hefty “how –to” section on every possible situation. A framework by which primitive “model T” iterations of PRT are skipped, leading to successful and ever more efficient and beneficial implementations worldwide.
But on a much more humble scale, a bunch of us are “second-guessing” each other, on the topic of the day, or week, and our thoughts are being archived in the “cloud.” Anything we say may provoke a design breakthrough, or cut off some bone-headed approach that would only be a setback. In other words, it’s all good, as long as we get enough contributors to be a real resource that can, at least, be found.
I am not free to work toward this full time, but it is my passion. I wish I could post daily, but I can’t. I have many more ideas than I have posted so far, but I have to meter them out. I don’t want the best ideas buried too deep. So to any readers out there- Please post your thoughts about anything I write or any comments you read. Please spread the word! At some point I will start an email campaign to known advocacy groups and academia, but I need a blog gushing with comments, arguments, and ideas. If we, the people, reach a definable consensus, that is powerful stuff. It is the stuff of dreams.
Last but not least . Enjoy the illustration. I would like to note, however, the motor units shown don’t represent any particular design based on inner parts, size of the inner workings or anything else, for that matter. It’s hard enough just making them look shiny. But sometimes a picture says a thousand words, (and one blog address). I wanted to get this out sooner rather than later.

14> Personal Rapid Transit and Streetlights

I heard, the other day, about a proposal whereby streetlights would be turned off to save energy but could be switched on by cell phone. Odd idea, but it gets the old mind working. I was mostly working in Tucson, AZ for the last few years, and they have a number of observatories near town, so they are keenly aware of what is called “light pollution.” I fly a lot, and have for many years, and I must say the brightness below is really getting out of hand. Remember a barrel of oil saved domestically is as good as a barrel of oil produced domestically. Energy is wealth, and the celestial glow of the city is the glow of would-be prosperity diffusing into space.

So how does this apply to PRT? Well let’s imagine the ideal street lighting. First, it wouldn’t blind you, so your eyes could see more with less of it. It would be more uniform, softer. It would shine away from you, not at you. It would be directed mostly toward important things like signs and curves in the road and blind driveways, If there was no one to see it, it would go out, or at least cut back. Intelligent street lighting is an idea whose time has come. PRT could be the platform and catalyst for that change. . This is just one more selling point to PRT that shouldn’t be ignored.

13> A Mid-afternoon Dream

I was sitting in traffic the other day behind a Wal-Mart truck. We both were creeping along together, both going to the same place. Actually I was going to Northern Tool, but still in the same “mixed use” retail area, kind of a mall of sorts, but with no coordination and lots and lots of traffic. The fact is that 75% of that traffic was bound for one of the many sprawling parking lots in this area. It occurred to me that Wal-Mart had two problems. First it was burning Petro-dollars, engine life and driver salary trying to make a delivery, and second, the traffic Wal-Mart alone generates tends to keep potential customers away. If there was a place I could park my car, grab a PRT and be dropped at their front door, I might just stop in for a six-pack of socks. But what if delivery pod cars brought those socks right into the building, maybe right to the correct aisle from a warehouse that also was fitted with indoor PRT style track? Well for one thing, out of stock items could be replaced in a matter of minutes, even during rush hour. And Wal-Mart would be the king of “green.” (environmentally AND cash wise) Now the big question. What would Wal-Mart pay? Would they buy or share track? Contract for rights of usage? Subsidize a station? And what about McDonalds? (Hmmm… refrigerated pod cars. Now there’s a thought.) Can you imagine NOT having a station just down from Wal-Mart? And what about the other merchants? I could see an area I like this becoming a much more attractive destination because of PRT. And wouldn’t a track going to the nearest high density residential area be a logical next step?

This is one reason I believe that “pods just gotta hang.” They are much more parking lot and warehouse friendly. It is also why I now believe reverse is a must for any standardized drive unit. PRT is only as useful as the network of tracks is extensive. Finding uses other than public transit and adding alternative sources of funding can only be a good thing.

12> Station Safety and Sinking Santa

First of all, I wish to thank alert readers timote and Dave Smith (TO?) for their valuable contributions. (Also Transportation Enthusiast, who I have since witnessed eloquently correcting a (less-than-enlightened) anti-PRT blog.
The question of collisions at the loading zone/station is a very real one. I had originally imagined “pods” as being very small, probably just 2 seaters, as the idea of building miles of track gauged for third and forth passengers, which statistically don’t exist seemed wasteful in terms of steel, and would make the track and supports thicker and therefore more visually intrusive. There is also the matter of safety, as heavy objects obviously carry more inertia, particularly at cruising speed. At the time, however, I hadn’t given much thought to light freight usages nor traffic density control. My current thinking is that the possibility of freight delivery could be lucrative. As I have written in a soon to be published post, delivery in gridlock is an expensive fact of life for many companies. These entities might have some influence towards PRT adoption. For them bigger is better. Also claustrophobia is an issue with some people, and a little extra space and larger windows would help. Personally, a port-holed coffin sized pod is fine for me, but I’m not your average person. Anyway, as for collisions at stations, I had always thought of a total load (pod, motor, and payload) of less than 750 lbs, traveling at walking speed. This is probably one half of the actual weight I’m comptemplating now, although I am still for excluding four “large” adults. So the question is, “how slow would a (beeping) object of, say 1500 lbs. have to move to not require an expensive station infrastructure?”
My guess mix is 10 ft. per 20 seconds, with striped pavement, possibly cordoned off with chains, a low to medium volume beep-alert, and tilt/bumper sensors on the pod, so that it will cut power if it hits an obstruction that can’t be pushed with just a few pounds.
Part of the reason that open-source PRT is superior to waiting for a company to sell us the solution is that the safety decisions don’t require the overkill that we would want from a corporation whose decisions are primarily profit-based. Certain risks are assumed to exist. Sidewalks are more dangerous because they’re close to streets. So what? I have yet to see the lawsuit requiring cities to move them or demanding damages. Trains and subways and buses and, yes, PRT can’t stop on a dime. But safety parameters designed by a non-profit open-standards organization are not particularly tasty bait for litigation, and PRT could get very slow as it descends.
Finally, Happy holidays! Here is a depiction of me Photoshopped into a Santa Claus photo that went on to consider the ramifications of global warming on the Santa’s base of operations. Imagine Santa’s waterfront property. And the cats? Hey, Everyone loves cute kittens…

11> Personal Rapid Transit Drive Unit

Here is a sample drive unit. I have left off the track-switching units for clarity. There would be one on each end. (I don’t say “front” or “back” because the unit can move forward or backward equally) I know that my earlier renderings show a “car” with a front and back, but I have evolved my thinking. Notice how the vehicle weight pinches the track between the wheels. Most of the complexity is due to need for sharply turning track, both vertically and horizontally. Note the dual motors. This is because with the unit hinging in the middle the power transmission would be extremely complicated. Also note the offset bearings, which enable dimensional changes. Furthermore, because I envision brushless motors, (RPM is externally controlled and very precise) they may work reliably in tandem. Brushless motors are commoditized products anyway, and this adds a level of redundancy. Furthermore, it occurs to me that half of this unit could be used for light parcel or mail delivery. If six-wheel drive seems a bit excessive, remember that the wheels, being long wearing solid hard rubber, do not have the traction of pneumatic tires. That is just as well, as this design has no differential gears. I envision a track insert designed for slight slippage on curves.

10> A Couple of Issues

I need to address a couple of issues. First the matter of getting exposure. As I Google “PRT” I find that this acronym stands for more than Personal Rapid Transit, or Personal Rail Transit. I find this blog is nowhere to be found. But then again, did I even say “Personal Rapid Transit” in previous musings? If I say “Personal Rapid Transit” again and again, will it come up in a search? PERSONAL RAPID TRANSIT! PERSONAL RAPID TRANSIT!

Now on to other business. So far I have rejected the notion that “pods” sit on top of a track… Well my opinions go way further than that. So here’s a little something to chew on..

1. Cars shouldn’t be just one size. They should be sized and in quantities based on need.
2. Cars shouldn’t just carry passengers. They should carry parcels as well.
3. Cars shouldn’t just go one way…(on each track) Why not go both ways? It would be handy when backing out of private property, good for third lane options where the third lane flows tward the city in the morning, and away from the city at quitting time.
4. I believe that vehicles can go both ways on larger streets. (The “one way” assumption seems to be based on problems making tight turns, spacing of cars, making elevated stations, and other issues connected with cars that ride above the track. I believe that PRT could share stops with buses, on both sides of the street.
5. Unlike previous models, I believe cars should be spaced dynamically, based on weight and speed. I do not think this is too complicated for present technology.

I think cars should be able be able to ascend and descend very steeply, even if the means is external. (roller coasters are easily and reliably grappled and lifted, so why not PRT vehicles?) They should also be able to turn (right, left, up, down) very tightly. This is just common sense, because the system should be as versatile as possible, and that should include track that can be constrained to placement over existing easements.

9> SWITCHING TRACKS

Here is a sample switching system that requires no moving track parts. In reality, the track would be pinched between upper and lower wheels, as in the previously posted pencil rendering, but the lower wheels are not shown here. The wheels should be solid and of a hard rubber-like material. Multiple drive wheels overcome the traction deficit inherent in these solid tires.

8> No eyeballs, No Surrender

So far my blog seems to be lost in the sea of others. I have had only a single comment so far, and I thank that reader for his observation. I have made several renderings, both because I believe in the hanging vehicle concept and because I had hoped that having the images online would bring people to the site, via Google’s image search feature. As far as my belief in an open source PRT design is concerned, it remains undiminished, although I have to admit that my compulsion to re-examine the design fundamentals of PRT may be a bit unusual. This is not the first time I have tried to “re-invent the wheel.” But then again, I am an inventor, and I guess that’s just what guys like me do…So this is what I am going to do next. First, I want to re-examine the definitions and assumptions surrounding PRT, or rather give the reader that chance, for I already have my own opinions. Next, I will re-invent PRT piece by piece. If I am speaking to a vacuum, so be it. I will do it anyway, because sooner of later I will be heard, and I might as well have a body of work on record. Anyway, one thing I was considering was how any reader, even if he/she was a closet engineer, could post design ideas. I tried drawing a design idea on paper, to see how well it could be digitized with a simple digital camera. Here is that effort, from a Sony Cybershot camera. I am not sure if Google compacts the images or not, but they seem to come out pretty well. For anyone who hasn’t tried it, clicking any picture on this blog enlarges it.

7> PODS JUST GOTTA HANG..

It’s been a while since my last post, as I have been very busy. I have, however, given considerable thought to my little project here. I have decided that hanging the PRT vehicles is really the way to go, unless switching is more of a problem than I think.A close look at the PRT 2000 drawing (posted earlier) shows a elegantly simple means of switching tracks. By not having any moving parts on the track itself, such as is the case with ordinary railroad trains, the whole scheme of things is greatly simplified. As I have stated earlier, the track is everything, since the network is everything. I have prepared a list of reasons why hanging is better than on top of, or straddling a track, but it’s a little long. I’ll try to abbreviate it in a later post. Sometimes a picture is worth a thousand words. Here’s one that shows just how simple and versatile hanging PRT is. Note that the station pictured here could be in a parking lot or on any city street. It’s better to have more stations that are cheaper, rather than a few expensive ones. Again, the network is everything.

Table Of Contents

1. IT'S THE ROADS, STUPID! 
2. NO WONDER WE HAVE TRAFFIC 
3. First, there is the track 
4. Here is My Idea of PRT 
5. Like-minded Engineering in Poland
6. Table of Contents
7. Pods just Gotta Hang
8. No eyeballs, No Surrender
9. Switching Tracks
10. A Couple of Issues
11. Personal Rapid Transit Drive Unit
12. Station Safety and Sinking Santa
13. A Mid-afternoon Dream
14 .Personal Rapid Transit and Streetlights
15. The "Podcar" and the PRT Dream
16. How to Lift a Podcar
17. The Role of a PRT Standard
18. PRT Motor-in-the-Wheel Design
19. A More "Mature" PRT Track Design
20. Podcar Control and Encoders
21.1.4 Billion?
22. Link text
23. Podcar Control part 2
24. One Little Problem
25. Just Some Thoughts...
26. Linear Induction Motor Tractor Unit
27. Designing For the U.S. Market
28. An "AH-Hah!" Moment
29. Thinking Outside the Box on Earth Day
30. Active Wheels
31. Fired Up!
32. I Just Can't Let This Stand Unchallenged
33. In Defense of the "Track-on -the-Bottom Design
34. Access for the Disabled
35. Troubled
36. Back to Designing
37. Coming...Soon?
38. The 16th Rule
39. Progress on theTrack
40. PRT: The Best Idea that Nobody Knows About
41.The Future Revealed!
42.Design Time!
43. Crash Tests, Anyone?
44. Going, Going, Gone
45. A Critique of PRT International's Design Approach
46. Many Vehicles, One Track
47. Serial vs. Parallel
48. PRT Stations...Continued
49. In Search of Gridlock and Opportunity
50. Dualmode and Modular Design
51. A New Kind of Motor
52. 3D,2D and Skyhooks
53. SMARTS
54. SMARTS Part 2
55. Chasing Trucks
56. High Speed
57. Roads, Roads and More Roads
58. Defining the Problem 
59. A Milestone and a Call to Arms
60. Prestressed Concrete Track for PRT
61. Classification if PRT, PAT
62. Mission and Miscellanea
63. ULTra - Architecture and Iteration
64. The ULTra Architecture, Continued
65. The Efficiency of Absence and Angled wheels
66. "Luucy! We got some 'Splainin to Do!"
67. Motorized Steering Guide Wheels
68. Haiti and Thinking Small
69. About that Angled Wheel Design...
70. Speaking of...
71. Switching Tracks
72. Stop That!
73. Overwhelmed by an Underpass
74. Tilted Design, Motorcycle Tires
75. Happy Tails to You...
76. Autonomy
77. The Times, They are a Changin'...
78. I've Got Control Issues
79. Something's Buggin' Me...
80. Twisted
81. ZZZZZZZ.......
82. A Sermon for Earth Day
83. Get Smart
84. Leaking Oil Solution?
85. The Enemy if the Good
86. Can't We All Just Get Along?
87. PRT Track and Bridge Design
88. Gone Fishin'... Sort of...
89. On the Road Again...
90. Let's Take It From The Top
91. Dan the Blogger was Writing... 
92. Crack in the Track, Jack...
93. In Search of PRT's "Killer App"
94. Say Cheese!
95. Call the Cable Guy!
96. Control Issues, Part II
97. PRT and Suburban Sprawl  
98. SPEED UP! SLOW DOWN!
99. Pic of the Week
100. One Hundred and Counting
101. PRT Merge Control
102. The PRT Business Model
103. A Little Something...
104. Pondering Infrared
105. A Voice from the Woods!
106. Simple Circuits
107. An App for That
108. Putting a Foot Down for PRT
109. Harnessing "Anti-Gravity" for PRT Control
110. Google's Robocars
111. Capacity
112. Interview with Santa
113. 2010- Historic!
114. In Search of a Cheap Lunch
115. Swing-Low-Sweet-PRT
116. Parkin' on the Hill...
117. Snow Day Musings
118. GM and Segway's Unintentional Dual Mode Platform
119. Further Thoughts on Dual Mode
120. Back to the Drawing Board
121. Solving traffic with 3D PRT
123. Thoughts on Track Size and Switching
124. While We're Still on the Subject...
125. What's in a Name?
126. A Few Good Destinations
127. Really, Really Fast
128. Learning from Roller Coaster Design
129. Emergency!
130. Progress Report
131. Climbing a Chain
132. Forward Compatibility
133. Maglev Mania
134. Good Tidings!
135. In Search of a Parking Space
136. Hot Rod
137. Playing Monopoly
138.  Imagine
139. PRT and the Art of Cabinet Making
140. Piping Hot Ideas
141. GOT IT!
142. Dodging Bullets
143. Waiting for SkyTran…
144. Compromise
145. How fast is fast?
146. Big Wheels
147. Pearls of Wisdom
148. Off-the-Shelf PRT
149. Tower of Babel
150. A Little Present for Myself...
151. Forward Compatability ans extensibility
152. Standardizing for the Future
153. Railbotics!
154. Fractals!
155. For Example...

5> Like-minded Engineering in Poland

Wow. What I’ve just learned…. I really didn’t think anyone would ever find my blog, let alone read it, so I’ve been doing my other things, which, for the last month and a half, has been living “off-the-grid” in a cabin in New Hampshire. No cell signal, no internet, solar and car battery energy only. It’s something I do. Anyway…
I got a comment, just one, that said, “looks like the “MISTER” system”.. with a link http://www.mist-er.eu/home-page.html
Now I suppose anyone who has seen this blog probobly has figured out that I’m a bit of a closet engineer; How gratifying, then to find, out of the blue, that someone else has taken the same info, looked at the same problem, and come up with the same answer. I get it. They get it. There’s hope!
I am still in NH, with Wi-Fi internet only available at the town library, and me far from there, so “bear” with me (pun-fun) if I have missed something they said on one of their pages. I haven’t even read them all yet… but…
I’m a real fan of Bucky Fuller, even built a geodesic dome or two, but the use of the tetrahedron based track, I believe, is impractical. It may suit their purposes, as they, (wanna-be track suppliers) can bid track multiplying truss pieces, but there are, in my mind, real questions about assembly in the real world. Perhaps they want to be the only vendor for track, and feel that this design gives them a leg up, as any competing firm would need to duplicate work which they have already done. If the object is to help the world through PRT, then this is wrong-headed thinking. This is why this blog exists and why meaningful PRT implementations don’t. The flaw is in the business model. The previous and current model is “This is what you need, and we make and sell it”. The superior model is, “This is what the latest concensous is on this type of transportation solution, and we are vendors designing, building, problem-solving, into that evolving environment.”
I am also puzzled by how they expect to switch tracks. As a matter of fact, all of the really challenging engineering details are left out. What type of motors? How is electricity transferred? How does the computer system know where each car is?
None-the-less, I believe they are on the right “track”.

4> Here is My Idea of PRT

Notice the doubly articulated swing arm. This enables steep, even vertical ascension and dissention, as well as speedy, tight turns and rapid starts and stops. An adjustable hydraulic mechanism (similar to a door-closer) would dampen the swinging movement.

3> First, there is the track

First there is the track. This is the most important part, and is half the reason the world needs to “open source” PRT design. I have not seen a single PRT system that I think will ever find any success in the U.S. and here is why. PRT can not compete with buses or light rail in situations where people can aggregate at a point A in order to make a straight line journey down a main drag to points B, C, etc. It is simply inefficient to load and transport many small vehicles as opposed to a few large ones.
As we all know, however, mass transit has real problems competing with cars because it can’t effectively reach less trafficked areas. Yet many people are coming from a less trafficked area, and are destined for a less trafficked area, and are effectively forced to commute through highway and intersection bottlenecks. Mass transit though these bottlenecks is unworkable because there is no infrastructure on either side of that bottleneck that would enable a commuter to complete the journey.
The answer is cheap, go-anywhere, go-over-anything, rails, and go-exactly-where-you-want cars to compliment them. We don’t need a couple of loops. We need a network. This is a critical mass situation. The system needs to have more destinations than is practical with the alternatives or else the alternatives should get the funding.
One problem with the current development model is that the companies hoping to build a PRT system covet the idea of the never-ending construction job that would be the track. It is no wonder that they tend to envision more grandiose guide-ways than the needs would seem to indicate. The same is true of the cars. Just like GM liked the business model of producing SUVs, instead of compact cars, so does the potential sole supplier of PRT “pods” covet the endless production of larger, more expensive vehicles.
Here is a picture of the Raytheon’s idea of a PRT vehicle.

PRT 2000

Is it any wonder that the cities that Raytheon approached eventually rejected it? Note the 72” x 72” track size. Clearly minimal cost was not the object here. The use of a 36” horizontal tubular support beam is a particularly odd choice, as ordinary “I” beams are cheaper, stiffer, less resonate, easier to handle, easier to bolt to, and more available.

2> NO WONDER WE HAVE TRAFFIC

Here is a little picture I drew to show how inefficient our road/car system is for transporting individual commuters during rush hour. The extravagant use of space really harkens back to a bygone era. They are even more spread out when they are moving!

1> IT'S THE ROADS, STUPID!

We urban dwellers know we have a big problem every time we try to get to work. For what seems like hours we become zero efficiency machines with the many horses under our hoods jumping up and down going nowhere. Well maybe not ZERO efficiency..after all we are making some impact...we are obstructing others while spewing emissions from our tailpipes. We are taking up what could otherwise be productive space. We are depleting the world's supply of oil. We are empowering hostile governments...
It's easy to blame the cars......but let's consider, for a moment, another culprit. The roads.
One often overlooked point is that it’s not just that there are too many cars, but rather there are too few roads. While this may seem to be obvious and counter-productive, it raises a couple of important points. First of all, there is traffic because it is too difficult to add lanes in a timely manner. It is too expensive. There may be insufficient space. Now let’s think outside the box and be the three year old who just keeps asking, “why?”
“Well, Junior,” you say, “you need at least ten feet all along the way to add and extra lane..”
“Why?”
“Because it needs to be big enough for cars and even big trucks.”
“Why?”
O.K. now I’m even annoying myself. The point is that we forget that we have a road system designed for big heavy trucks, not the 1.2 person average occupancy of an average car. If you designed roads for commuters in gas sippers only, the lanes could be narrow, the asphalt thin, etc. More lanes, more throughput, faster construction, less money.
One of my main gripes with previous PRT designs is that they seem to forget this lesson. PRT needs to go everywhere a car can go without encountering the “we can’t afford more lanes” problem. It needs to be cheap with a capital C. It must not try to compete with other forms of mass transit between, say two points with only one or two stops in between. That is the realm of trains, or trolleys or buses. PRT should supplement these means by going to where ridership is insufficient to justify larger vehicles. A prime example of where PRT would seem to be less than a great choice is the only active (to my knowledge) program out there, the system to serve Heathrow Airport in London. If you already have people aggregated, and you are transporting them to a single destination, why use PRT?
P.S. Perhaps I shouldn’t use this as an example. In all fairness I haven’t really studied the specifics of that project. Perhaps there are enough terminals on one end and a massive enough parking lot on the other to justify personalized routing. I really don’t know..The point is that PRT needs an extensive network, not just a circular route. That means cheap track, as opposed to the huge cost of expanding truck capable roadways.

Index

Accidents- 72 43
Anderson, Dr. J Edward- rebuttal of Anderson's arguments for supported vehicles- 32 paper on PRT control- 23, comments regarding "rules for engineering"- 38
Active Wheels- Michelin's active wheel -30
ATSC-Automated Transit Systems Classification - 61
Angled Wheels- 65
Braking- 43 72
Bumper- in track hydraulic- 43 72
Business model - trouble with- 35
Climbing Slopes - 31
CO2 in a gallon of gas- 40
Control - 23, 20, 104, 105, 106, 109, 98, 100, 101, 77,
Concrete- prestressed concrete track - 60
Control System and Software- 41
Crash Tests -  43
Dualmode- 50, 110,  64
Electrical Lines- cost of burying 21
Encoders- 20
Freight- track and bogie design - 54, delivery of -55
Future- the future of PRT- 41
High-Speed- conceptual system design - 56
Linear Induction Motors- bogey design - 26
Magnetic Braking- 43
Passenger Preferences - 41
Roller Coasters, Wheels of- 65
SVN - Instructions for collaboration - 59
Safety - looking ahead - 23, 12
Skateboard- a modular auto design concept- 50
SketchUp - design repository instructions 59
Skyhook - concept of- 52
Software - 41
Slopes - cog design for- 31
Stations - 47, 48, 49 12
Status Quo - comments on the continuation of dysfunctional transportation systems- 40
Street lighting - 14
Suburban sprawl -27, 97
Switching - redundant switching mechanism design - 42 traditional "in vehicle" switching designs- 36
Torque Motors - 51
Tortoise - SVN program for Open PRT- 59
Track - industrial and freight 54, switching, 36 design profile, concrete-60, high-speed-54, impact on station design-47, 48, 49, see-through for dual 4 wheel bogies- 42 , profile analysis- 39
suspended vs supported 33, 32
Traffic- PRT traffic management 41
ULTra- hidden design attributes63, 64
Wheelmotors- 44, 31

INDEX OF LINKS

Backyard Monorail Just for fun-
Bubbles and Beams 2 - Many PRT concepts are illustrated in this great YouTube animation 
Control of Personal Transport Systems - Anderson
Flyway Beamcars - Don't leave this site without checking the index. It's huge.  
Headway Limitations - Dr. J E Anderson describes his approach to this and some control issues.
Linear Induction Motor (AC) -general description and guidelines for use, from Baldor
Linear Induction Motors (LIMS)- Force Engineering's Website, links to how they work, etc.
MAIT- (Modular Automated Individual Transit) Non-Profit, promoting multi-modal approach
MonicPRT - This animation shows a ULTra-like system but with some twists
OKI Study   Ohio, Kentucky, Indiana' study which included assessment of a Taxi 2000 PRT proposal.

PRT Activism - Koren  (reasons for PRT's slow adoption)
PRT Consulting - As the name suggests
Rack (or Cog) Railways - using toothed track for slopes- Wikipedia
Station Design - Muller. Concentrates on "open-guideway" types, so would apply to autos as well.

Transportation Research Board
Wheel Motor - Wikipedia entree

X Prize - Big money for innovators