In the last post I touched on the idea that vehicles such as ULTra could be driven by “joystick”. This idea of driving by electronic controls (as opposed to the current practice of having actual mechanical connections between the pedals, steering wheel and the engine and brakes,) is not new. The use of electrical motors and regenerative brakes starts us down that road, which leads to the “skateboard concept.” (scroll down to post 50 for a picture)
Let’s take this line of thinking a step further. If the Ultra vehicles are guided by some kind of laser system that centers them on the track (with accuracy of less than a centimeter, I understand) such a system could presumably be fitted on private, steerable cars as well. An example of a steerable car which could presumably be easily modified for the ULTra control system is this Michelin concept car. The idea is that you drive your car to a ramp (or car “elevator”) and driver control is switched off and automatic control is switched on. Voila! You are now in a fully automatic PRT system until you are dropped off.
That Michelin video raises an important point however. People are really in love with their cars. The very best selling point of this electric car seems to be its muscle. Then there is the addition of luxurious creature comforts, such as adjustable seats, high-end music, etc. It seems to me that private vehicles will always become more and more loaded with features and power until something or someone steps in to halt it. Electric vehicles, in themselves, are not without environmental costs. The electricity they use must be generated, and this, itself, generally involves combustion. The prospect of hundreds of millions of Chinese cars being recharged by way of coal (their principle source of energy) power plants is truly frightening. Coal is, of course, 100% carbon, so there is no fuel on earth that is worse for global warming. Anyway, the point is that there would need to be some kind of societal decision as to how much to limit the power and weight (and therefore luxury) of these vehicles. We can’t afford a guideway network for Hummers. Because any vehicle on the system would need to be meticulously maintained, (combined with the necessary luxury limitations noted above) perhaps some type of leasing model would be the way to go.
This scenario does not eliminate “ordinary” PRT operations. Fully automatic “taxis” could still populate the track. PRT vehicles could come down to ground level and use a special lane to get to stops which cannot be served by raised stations. This would, of course, create the same interferences with vehicular and pedestrian traffic that plague other forms of surface transportation.
The main problem with the whole idea is the same problem that plagues all supported PRT systems. All supported systems inherently discourage true point-to-point travel compared to hanging systems. If they come to the ground they interfere with other traffic and pedestrians. Ramps must be fenced off for safety and are ugly. Stations must be positioned so that ramps won’t block driveways. If elevators are used to raise the passengers or lower the vehicle, the station is considerably more expensive. This is a big deal if you consider the economics of the network. I believe that in many cities the ridership figures are such that a great percentage, maybe even most, of the city would go unserved by the PRT network unless simple “bus-stop” type boarding areas are employed. I think this is a point worth repeating. It is a very big problem if the cost of stations precludes their use in large areas of a city. PRT needs the “network effect” to fulfill its promise as a transformational technology. Of course this is just money problem. If the government wanted to switch some road funds into PRT that would be a different matter. From a business perspective though, there will always be a number of riders under which it becomes unprofitable to create local service.
For the time being I remain very wary of any system that can only take the “low hanging fruit” to market.
Merry Christmas!
15 comments:
The problem with owning vehicles is this creates the parking problem. It also means you cannot board the vehicle in the station. You must wait for your own vehicle to be retrieved from some kind of storage. It also vastly increases the total system cost, as there is great inefficiency in vehicle utilization. Then there is the problem you mentioned of maintenance, which is the main sticking point for automated highway driving with platooning (which is an absolutely bonkers idea).
Much better: let people continue to have their BMWs or whatever, but they are going to be stuck on the asphalt like they are presently. Make these people pay the full cost of the infrastructure they are using. For most people, the economic analysis will make it pretty clear: you'd be crazy to own a car. Where I live (not even Europe!), cars can cost upwards of $6000/yr for basic transportation, and closer to $10,000 for something more luxurious. That's actually quite a lot of money, if someone could forego car ownership and rely on a combination of PRT and carshare programs (hourly rentals).
I think it's a question of how to divide up different transportation tasks in order to effect overall efficiency gains.
Example: if you install windows or gutters for a living, an automobile is very useful. So there's a case for maintaining current roads infrastructure. In fact, economic growth is still the primary reason for continued subsidization of roads.
Is there demand for PRT-based services? Could the network generate revenue and facilitate growth? Currently, transit is mostly a liability.
One benefit PRT brings is it takes some of the burden away from roads. So instead of needing more lanes, the current ones will suffice and -still- the growth can go on. Building PRT tracks is cheaper than building more lanes (which may often be impossible).
Still, eventually growth seizes, since we have a limited Globe. Japan hit that in the 90's. US may be hitting it now. Life still goes on, and within the "flat" economy particular fields and companies will grow. Only, the whole of it does not necessarily need to (which is only good, for the citizens anyways).
PRT has some pretty awesome potential for freight transport, as well. Many firms would absolutely love (and be willing to pay quite a lot for) transport that does not require a driver, and does not require large load sizes, and has highly predictable travel time. Manufacturing, retail, etc. -- huge potential!
Dan The Bogger says-
I think you misunderstand me alfransen. Your first three sentences indicate that I didn’t make myself clear. I am just suggesting that PRT capable vehicles could enter and exit the PRT network. I am not suggesting that “your” vehicle is parked anywhere other than your home or final destination. The “walk-up” PRT system would be unchanged. Also, about your last comment, I totally agree. Check my search box for “freight.”
Cmfseattle, I agree that we need roads, and I can’t see the majority of destinations being
convenient to a PRT station for a very, very long time. Who wants to even walk 2 blocks in a blizzard? I kind of like the notion that a light weight, bare-bones certified PRT capable electric vehicle would compete for garage space and travel time with that big family SUV, though. Strict weight limits on the vehicle plus an extensive network would ensure that a super efficient vehicle would get travel time that would otherwise go to that fully loaded hogmobile. It could even have very short range and slow speeds when off the network and still be well worth having.
Akauppi, I can assure you that growth has not stopped in the U.S. The immigrant population from south of our border is simply exploding. (And not just in the southern states) Our road projects have a very hard time keeping up. We are up to ten lanes each way in much of Houston, if you count the feeder and HOV lanes. True, our indigenous population is stable, but that’s sure not the case in the “third world”. Anyway track IS better, if it is simple and so are the required stations. That is not the case with every proposed system though… Food for thought - Self-driving cars lead to PRT as much as PRT leads to self-driving cars.
Self-driving cars, now that you mentioned.
This is a valid argument against PRT, on some people. I like your approach, either will lead to the other. It's not either or but eventually there'll be both. The question is, when.
What I figured last time in an airplane is that self-flying airplanes may come in first. There's a lot less unexpected changes "up there" and many flight companies would be only delighted to get rid of their pilot staff.
Once we have those - and the general public has gotten used to them - then there's place for self-driving cars. Problem is not making a self-driviging car. Problem is making it drive in the midst of us manual drivers.
I like the idea of creating a shared public vehicle like some rent-a-car companies have been testing (hourly online scheduled green rentals with choice parking spots).
The comfort of cars is for long trips and sitting in traffic. Quick transit would make up the difference.
I thought that one reason "light" rail was "heavy" is traffic safety reasons. Could a pod safely get hit by a truck at an intersection? Seatbelts? airbags? I can imagine completely safe and slow automated ground delivery on the pods part (kids, elderly that can't drive). There would need to be some restrictions for driving access.
I found this company supporting pressure membrane bodies and compressed Hydrogen cartridges (which may make a good backup battery). They claim a 3rd of the weight of a Prius. http://www.myxpcar.com/
I'm glad to see that the posted comments have not disappeared.
Dan the Blogger Responds –
Actually, Akauppi, modern autopilot systems can, indeed, take off and land. I can’t help but be reminded, however, of a recent aviation drama in the US. An airliner sucked in a bunch of geese, lost engine power and had to ditch in the Hudson River, right in New York City. No fatalities. The pilot became an instant hero. Stuff happens. I guess the first step would be to have just one pilot instead of two. Anyway safety is partly why I say that self-driving cars lead to PRT, which I will try to explain better below.
Hi, Joey, Thanks for commenting. As I was saying, self-driving vehicles lead to PRT because of safety issues. Since automatic vehicles and regular traffic don’t mix well, there becomes a need for a special lane. This special lane, then, calls for efficient, full utilization of this valuable space. This, in turn, leads to intelligent traffic management. Voila. PRT. (Except for the vehicle ownership issues). Any kind of taxi or rental service that exists within this infrastructure would be “true” PRT.
The business of mixing pods and people or other vehicles is a very messy one. That’s why PRT should be elevated, and is a major advantage of hanging systems. As for the heaviness of “light” rail, it’s notable that there is a design issue with adding capacity in all vehicles. Every bit of capacity means heavier frame, brakes, motor, etc. Now THAT weight adds still MORE demand for extra power, frame stiffness, heavier wheels… It’s the vicious cycle, a continuum, from featherweight bicycles to ocean liners, and it explains a lot about why it’s so hard to make fuel-efficient cars. Also, the road lane is at least 10 ft. wide, can support dozens of tons, luxury extras are nice, and hauling a huge load is something everyone MIGHT do... PRT offers a chance to enforce downsizing everything by more closely matching the track and vehicle capacity with actual occupancy averages.
I find the idea of dual mode PRT highly questionable. It seems unlikely that any roadworthy (able to share roads with 40 ton trucks) vehicle could simultaneously be useful and light enough to run on PRT infrastructure. I think it's just a bridge too far, and a dangerous idea to propagate, as I expect it will lead to calls for heavier, less economical PRT systems.
Thanks, afransen, for that comment.
It seems to me like there's a bunch of kids in the kitchen, none of whom have ever baked anything. But they have an idea of what could come out... SO many different ways to make PRT, it seems. They'll burn some cakes and some recipies may never even get that far. But eventually someone will make it right, and it will be a success.
There's so many analogies to this situation. Early automobiles (around 1905) is one. Early computers (pre IBM PC) is another. We'll only know in hindsight how they were similar to the PRT case and how they were different.
I, too, don't see much sense in hybrid vehicle designs.
But what could actually be the most important change may not be technical. It can be the change in business models that spreading new technology like this may bring about. Think local instead of global (any village wanting to have a PRT can build one, with instructions). Think massive parallel instead of carefully orchestrated business efforts. We've never seen this kind of model in spreading technical solutions. But we need the rapid expansion, to tackle climate change. Traditional company models may not be up to that challenge.
(If the reader has a company saying yes they are up to the challenge, contact me. :)
Dan the Blogger wishes commentors afransen and akauppi a merry Christmas-
I tend to agree, afransen. It is certainly true that self-driving cars should be restricted to special lanes unless the technology gets way, way better. I have also previously argued that autos and PRT vehicles are sufficiently different as to make a hybrid between the two a bad idea. You get a lousy PRT vehicle that is also a lousy car. I have also (sorry ATS) previously pretty much called ULTra a lousy PRT vehicle, so we’re half way there! The operative phrase here is “half-way”. That’s actually a lot better than what the “pure” designs have done.
Being captive on a track is, and always will be, itself a compromise, just like being a vehicle that is “less than roadworthy”. An efficient car is itself a compromise in comfort and speed over its gas-guzzling counterparts. As I get more and more “fine-grained” in PRT design aspects, I see greater and greater mechanical complexity. I can easily see how automotive engineers could go so many years without a consensus on whether front or rear wheel drive is better, and how, after a hundred years or design refinement, cars have become more, not less, complex. Cars, (and PRT) are studies in compromise.
I agree with of what Akauppi has said here. There is a screaming need to bring transportation technology into the present. Clearly the weak links are the human drivers, the wasteful locomotion means, (fossil fuel engines) and the wasteful, congested infrastructure they are confined upon. Tackling the three together spells PRT in any language, and I think that all of these parallel efforts are a good thing.
I also agree with your assessment about heavier, less economical designs. The track and vehicles MUST be kept light. This is partly why I maintain this blog, and often play “devil’s advocate”. It is important for guys like you to speak up. What Akauppi didn’t emphasize is the costs of “burning those cakes”. It has occurred to me that someday a PRT company or municipality may reference our comments in their decision making process. Maybe we are all collectively helping to bake that better cake.
Another key point about inexpensive guideway is that it makes for a less risky pilot. If it only costs $100 million - $200 million to get a critical mass of network in a mid-sized city, then it is a risk that could be taken. It might be underwritten by a larger jurisdiction, perhaps at the state or national level since the results of such a pilot have far-reaching implications. If the pilot network reveals some design flaws, then we will not have spent more than $250 million in development and contstruction costs, which is relatively cheap as these things go. The city I live near, Toronto, is in the process of spending billions on light rail. There are many skeptics who say that light rail may not be the best technology for the routes being served, or that some routes ought to be given higher priority, yet we are spending billions anyway, without all that rigorous study on the matter (though local planners will disagree). The plan is largely a political project, rather than a technical one.
Perhaps PRT won't truly take off until some of the bigger aerospace firms such as Siemens or Bombardier see the opportunity. I don't think it is as important for the developed world to rapidly deploy this technology. Better to start early and iron out the bugs before wider deployment. It is the developing countries that could see the biggest return from PRT. Much as with telecom infrastructure, the likes of China, India and Brazil would do very well to leapfrog the majority of elaborate highway infrastructures and associated car-oriented subdivisions and go more directly to denser, more livable (and more efficient) PRT-oriented communities. North America has already been cast in the mould of car-oriented development, and reversing that will be a slow, costly, and difficult project. The rapidly urbanizing developing world has the most to gain from PRT as a disruptive technology.
Afransen, a fine comment on the developed vs. developing world point of view. I agree.
http://www.ewebevolution.com/transtec/
I agree. Good comment, afransen. The flip side is that we often have problems with urban decay or inefficient land use. City planners realize that being on a transit route is good for an area, but something like light rail costs billions. It would seem like a PRT loop would be a pretty cost effective tool to help turn an area around.
I've come to agree that dual mode is not going to be the way to start a PRT system.
Initially it seemed so attractive in terms of requiring less personal change, which in theory would have correlated to less political resistance, but the arguments of station complexity convinced me that dual mode won't be able to take off on it's own.
Where dual mode does shine is that if combined with an initial system that has walkable stations in a dense environment introducing dual mode in that area could capture traffic and investment that were still directed toward roads and cars. Since the incremental cost of a few dual mode stations on an existing system is much less than a whole system those costs should provide positive value in many more situations than an initial dual mode system would.
I would like to see many sprawl zones condense into urban areas, but where they refuse to do so for one reason or another, dual mode expansions would provide another means to capture additional traffic and revenue.
Post a Comment