There is no evidence to support this. In the 1970s, the proposed light rail system was stopped because the transit commission ended up favoring a 40 seat vehicle -- small, but still not PRT. Also because of political infighting not related to PRT.

Most recently, the new Hiawatha LRT was constructed and opened during the term of a councilman who from time to was accused of using PRT to stop LRT.

Proposing PRT does not equal opposing LRT. The Masdar program plans to use both technologies.

Fooled me! Good for us then. I think "we" will be fine as far as transpo is concerned, but we may not be able to stop the suburbs from pumping every last drop of oil out of the ground. I'm not ruling out any options for slowing them down.

"we might have more success increasing transit ridership if we to provided a service that fills that demand"

This is the unicorn we have been chasing the past half century, while our transit systems only fall further behind those in Europe and East Asia. American drivers, addicted to persona-defining cars, have a line of excuses of which "I hate the attitudes on the subway" is just the beginning. If it's not stranger danger, it's the condition of the upholstery or the lack of an award-winning bass system.

"trying to find ways to force people to use a service they don't want to use"

Economic "force" is a fact of life. I'm forced to go to work, forced to not have a maid, forced to live in a small apartment. Except, I'm not really forced in anything. I can choose how to spend the money I have. It's no different with including external costs in automobile ownership and use, and ending public subsidies of failing personal transportation infrastructure. That's the only method of "forcing" people out of cars I've ever advocated.

"Trains and buses are heavy"

We've been over this up-thread. PRT vehicles are "small and light" because they are made out of vapor (do not exist... except in Heathrow airport? soon?). Anyway, we would put these things through a regulatory commission before they hurtle around over everyone's heads like a packet switched network; that's just the way it goes. But I'll be happy to join a coalition for making American rail safety standards less insane, which is the real issue. We're in the same boat on that one. As far as trains running at low capacity, I don't see them nullifying the awesome efficiency advantage that rush hour trains have over PRT. You can make a case for PRT having good efficiency, but you can lord about saying this theoretical system is vastly more efficient in computer simulations than the one that's used in the real world. Not if you want to be taken seriously.

"I would also dispute the idea that surface solar will never be practical"

Oh it will be practical. It may be all we have. But that doesn't mean it will support moving around 2 tons of metal per person just because people want it to. As I understand it the energy that makes it through our atmosphere is not great enough to match what we get from petroleum (built up from millions of years of that same energy), even if we were able harness it without loss (at least not if we leave any square foot uncelled, like if we want to grow food there or keep some natural ecosystems around). In any case solar energy is going to be more expensive than the petrolorgy that birthed the SUV everyman phenomenon.

"Once hard, experience-driven operating numbers are available for PRT, it should be included in any alternatives analysis for a new transportation project."

No disagreement there. Bring in the hard numbers, then let's talk.

Actually, I don't drive either. I ride a bike for most of my trips, transit, air, and car rental/car sharing for the rest. I was speaking metaphorically of "we" as the vast majority of metropolitan-dwelling Americans who drive for most trips, and use transit mostly for park&ride to work type trips, if at all. That is the American norm, not NYC.

"I would suggest that, when there is no cheap energy to move about in personal vehicles (surface solar won't cut it), people will get over their distaste for one another and ride trains."

Since many people do have a distaste for riding with strangers, we might have more success increasing transit ridership if we to provided a service that fills that demand without most of the negatives associated with private auto use, rather than trying to find ways to force people to use a service they don't want to use.

Counting on higher energy costs to force people en masse into conventional transit is a mistake, IMO. Rising energy costs hit transit too, and they hit hardest on a per-passenger basis at the least-used, least attractive suburban services. The net effect of rising energy costs for transit will probably be positive, but not by much, because so many underused systems have terrible energy efficiency, and would need very large increases in ridership to offset the rise in energy costs.

PRT is more energy-efficient than either trains or buses. http://www.atsltd.co.uk/prt/env/
Trains and buses are heavy, and they must move regardless of whether they have many or any passengers, to maintain acceptable headways. So the occupancy ratio is quite low for most transit systems. Conventional transit also stops and starts frequently, which wastes a lot of energy. PRT vehicles are small and light, they usually don't move unless they have at least one passenger (a .25 occupancy ratio), and they don't stop until they reach the destination. The result is the best energy efficiency of any form of motorized transportation.

I would also dispute the idea that surface solar will never be practical. There is plenty of solar energy to tap, more than enough to meet all energy needs, though at a very high price. But the technology is getting steadily better and cheaper. If the technology keeps advancing, solar energy will be cheap enough to support widespread electric car use within 30 years.

Transit investments can help make walkable and bikable communities possible. However, a lot of money has gone into rail systems that rely on park and ride lots, an investment that will arguably worsen sprawl and increase energy consumption and emissions.

"...Nobody is going to scrap the New York City subways or inter-city trains..."

Actually, PRTnut, that's exactly what has happened in Minneapolis and other places. PRT was used as a way to siphon transportation funds and support away from immediately viable light rail and bus projects.

I never said anything about new systems, only the ones that have already been built.

How much public money was actually spent on PRT in Minneapolis? I can understand a reluctance to spend public money on an untried system. But you don't get progress without taking risks. It's a shame that the US has surrendured leadership in public transportation research and innovation.

PRT is far enough along that a pilot project is well justified. And a pilot project is near completion at Terminal 5 in Heathrow airport. Masdar in the UAE will also use PRT. Once hard, experience-driven operating numbers are available for PRT, it should be included in any alternatives analysis for a new transportation project.

I think that once we get past the first two or three successful applications, and people and agencies realize the advantages of PRT in terms of service, energy, construction, and operating cost, there will be a wave of PRT projects comparable to the light rail boom of a century ago.

Actually, PRTnut, that's exactly what has happened in Minneapolis and other places. PRT was used as a way to siphon transportation funds and support away from immediately viable light rail and bus projects.

I say go set up a PRT project in Dubai or some Chinese city where, for the moment, the sky's the limit when it comes to infrastructure spending. If it works there and proves itself to be viable and cost effective, let's try it out in the US. In the meantime, we're going to be busy promoting smart growth and rebuilding our national rail network.

It's a function of the perception gap. You say "we're going to find ourselves in thirty years driving electric cars charged with solar electricity" and I'm thinking, why would I (as a "we") be driving an electric car in 30 years when I don't drive a gas car now? And that disconnect was exacerbated in this thread by someone refusing to accept (until his "clarification") that mass transit does in fact carry more people than all other modes do or could here (this is a New York weblog) and that the congestion on our streets is not overflow from transit but people that prefer not to ride it. Which has some overlap in the defining quality of PRT that no one has to ride with anyone he doesn't want to. That is a pretty deep social question that can easily stoke emotional fires.

I would suggest that, when there is no cheap energy to move about in personal vehicles (surface solar won't cut it), people will get over their distaste for one another and ride trains. This assumption is also part of the perception gap. Car people, including those that advocate PRT, start with the premise that American personal transportation of the 20th century must be accommodated forever. Non-car people, including transit riders, take the premise that energy and spatial realities will dictate human behavior. This is already the case in big cities, where it was never posible for everyone to get around by car. And I'm not trying to be combative by lumping people into car and non-car groups, but it isn't PRT that predicts who will say "we're never going to stop driving" vs "you're going to have to find a way to live without driving", it's the habit of daily driving itself.

As for the physical, non-social aspects of PRT I do have an open mind. But you understand that it doesn't affect cities directly and we've got no more reason to advocate PRT for the suburbs than you have to advocate improving our mass transit. I'm sure we all support both over the status quo, conceptually. My hunch is that it will be cheaper to reorganize the suburbs (where houses are not exactly built for the ages) into many small towns than it will be to lace the existing suburbs with PRT. But that's skepticism, not opposition, and I wish you guys the best of luck.

If you look at the old SEPTA R3 schedule from 1915, shortly after electrification it took slightly LESS time to get to downtown Philadelphia back then than it does now. The automobile and the road system haven't stood still for 100 years. But rail transit is not appreciably faster or more reliable than it was a century ago. The whole industry has become sclerotic, unwilling to try anything new. And since it's publicly funded, it doesn't have to.

Anti-automobile policies strong enough to bring about a real transit revival are politically unlikely, though that doesn't mean we should stop trying to eliminate the public and private subsidies for auto use.

Nobody is going to scrap the New York City subways or inter-city trains. But for extending transit into the suburbs and developing areas, PRT seems to have real promise of providing a level of service and a service area that will be attractive at a lower cost than light rail, and at all hours, not just rush hour. People who want livable, walkable communities, and transit that you can rely on for all your daily trips, not just the daily commute, should take an open-minded look at PRT.

If we don't make transit better and more effective (and not just bigger and more costly), we're going to find ourselves in thirty years driving electric cars charged with solar electricity, on automated highways, through the same soul-deadening suburban sprawl we have now.

And honestly, current generation PRT could not do that without a heck of a lot of infrastructure - dozens of large stations. Perhaps, once PRT is established in other markets, it can fill a circulator role in New York, to complement the amazing capacity capabilities of the subway. But I never suggested PRT could replace the subway any time in the near future, and after researching it more, I'm even more convinced that it couldn't; I only challenged the preconception around here that PRT is a toy system unworthy of serious consideration in any context.

I think the issue here is that "rail" is an overloaded term. There is a huge difference between a 50k pph subway and 7k pph street-level light rail, and I think PRT's current niche is more in the latter than the former.

But remember, it is still a new technology as far as city integration is concerned. PRT opens up so many options for integration into urban environments, because it is truly small enough to go anywhere. If it takes hold in other (smaller) cities, we may see some dramatic new innovations when it comes to integration into existing infrastructure - stations in buildings, PRT in tunnels, even multi-level stations (up and/or down) that can handle many more vehicles per hour than current designs. And I truly believe that people will be much more accepting of the elevated guideway once they get used to it, especially if it reduces street level traffic. We take traffic signals for granted, and some PRT guideway designs are not much bigger than that.

It will be interesting to see what happens in Europe and the Middle East. I hope I've at least convinced some of you that PRT has merit, if not as a replacement for a 100-year-old super-efficient subway in the most dense downtown in the world, then as something that can serve transit needs elsewhere where autos are choking cities to death. And it has tremendous growth potential, so it can scale up in density as a mid-level city grows around it. Think of heavy rail transit in NYC, how it grew as the city grew over the course of 100 years.

By the way, you might like to know, tonight I became an Eli Manning fan. That was the best game I've ever seen. Congratulations, NY.

PRT can be as dense or as sparse as you like. It seems that PRT has been tainted by its association with the automobile, which DOES tend to destroy livable spaces, but in fact, the particular features that PRT shares with the automobile are NOT the ones that are sprawl-inducing.

The two main space-destroying features of automobiles are: the need for an extensive road network, and the need for parking. PRT eliminates both of these.

Consider the parking problem in the context of buses and taxis - both of these require roads, but they do NOT require parking, and both are much more compatible with transit-oriented cities than private automobiles. I've never seen anyone suggest that taxis destroy living spaces, despite the fact that they are very personalized and individualized forms of transit. It's not the privacy aspect of private autos that is destructive, it's the space they take up to move and park.

As for the road network, we all know the tradeoff with cars: build freeways and the city is decimated; don't build freeways and the streets are jammed. But PRT eliminates that, providing the capacity and convenience without touching the street. Look at what they did in Boston with the Big Dig - that misguided effort was an attempt to provide automobile convenience while reducing the impact of freeways, exactly what PRT could have done for a tiny fraction of the price of that mess.

Also consider the fact that PRT can be as big or small as you like. Most PRT designs feature lots of small, densely distributed stations, rather than a few very large, less densely distributed stations. This is not a limitation of PRT, but rather a BENEFIT, because it allows for transit to adapt to both small and large needs - but if you want, you can easily build gigantic station from which multiple guideways diverge in every direction. But then I would ask, why?

This goes back to the fundamental question: what is the END we're trying to achieve here? Isn't it about getting people efficiently into, around, and out of the core of a city without destroying city spaces? If PRT can achieve that with eight small PRT stations in the same area as one huge subway station, then why not? The density is still the same, only people are a little closer to the nearest station for PRT.

The argument I've often seen is that the train itself becomes a gathering place, but to me this has always seemed like a contrived argument. Who goes to the subway station to socialize? The train is a *means* of aggregating people, not an *end* unto itself. IMO, there is no merit idea that we somehow lose something by not having people gather together in large numbers the station. In my experience in transit stations, nobody treats these places like a social gathering. Maybe you have a different experience, but when I'm in a transit station I'm not thinking about socializing.

So if transit infrastructure is not itself a social end (and I don't believe that it is), then what is the difference between a PRT network that aggregates X people per hour into the dense city center using *8* stations sprinkled about that center at 1/4 mile spacing, vs one big station that dumps X people per hour in the center of the area at 1 mile spacing? Is it really so important to have everyone arrive at the EXACT SAME SPOT?

Totally untrue. Freeways were stopped throughout the country and throughout the world during the freeway revolts of the 1960s and 1970s. San Francisco did a much better job than NY of stopping them. Even Milwaukee did about as well as New York.

When people are making personal decisions about their own individual trips, they "prefer the the convenience of cars."

When people are making political decisions about what sort of city they live in, they prefer to reduce use of cars.

I am open minded about PRT. I think, if they can get it to work right, it would be appropriate in many moderate-density cities (such as Berkeley, where I live), and it could help to concentrate new development around PRT stops.

However, I must say that Transpo Enth has made me more skeptical of PRT by claiming that it is a way of perpetuating the automobile mentality - that I care about my immediate convenience more than I care about how livable my city is.

At the risk of sounding redundant: bullshit.

I don't see PRT as reinforcing that kind of density. I am open to your interpretations, I appreciate your detailed response, and I apologize for this slapped-together post here.

I thought I answered this, but maybe I didn't. I'll try again.

PRT will move commuter traffic away from the street level. Studies have shown that a well-designed PRT network would actually draw commuters in large numbers out of their autos and into transit. By large numbers, I mean 20-30% of auto users will switch to PRT. Those numbers have been derived from multiple ridership studies done by various independent parties, using standard transit ridership numbers that have been used for decades to predict ridership for traditional forms of transit. At least one such study was conducted by a group critical of PRT.

Now consider: even the most ambitious rail/bus plan usually draws much less than 10% of commuters from private cars. Most traditional transit projects are pretty good at attracting new passengers but rarely get more than a few percent to leave their automobiles at home. And, at the risk of sounding redundant, I must again reiterate that even in NYC, which has the best transit system in the country, still relies on the road system for the majority of transportation needs (auto, taxi, bus).

Now, if PRT could draw 30% or more people out of their cars - not to mention eliminate buses - that's 30% fewer cars on the road, 30% fewer accidents, 30% smaller parking requirement, 30% fewer local emissions. Do you not see how that would create better livable spaces in cities? Road widening projects would no longer be necessary. Traffic and gridlock would be reduced. Intersections would be less busy, improving walkability. Parking lots could be turned into parks. Think of it: 1/3 of the traffic lanes in the city would become unnecessary - how would that NOT help to improve livable spaces?

If that doensn't answer your question, then you need to clarify what specifically you are referring to, because as far as I'm concerned, there is no better way of increasing living space in a city than reclaiming the street level.

If those words are true, someone will implement it very soon without having to beg for support from cities that don't need or want it. That is realism.

Another thing that's real is free roads being used to their maximum (congested) capacity no matter what alternatives are available. It always seems like the next, great thing will lure people away from the asphalt that costs nothing to use and so much to maintain, but too many people stubbornly prefer to parade around in their own personalized, gleaming metal boxes. You think your community pods are going to "naturally" pull in people that buy Escalades? I'm not investing in your plan. Sorry. I will support national policies that push infrastructure costs back to its users; only after that happens will alternate suburban transit plans have credibility (and investment). And the most practical solutions, I think we will find, are those that reintegrate communities and improve upon the successful transit systems already in use. Time will tell! Bye.

So why not try to increase demand naturally, by providing a better service in public transit? The technology is available today to do so cost-efficiently - the PRT technological feasibility and cost issues have been essentially answered with today's technology - but the very people who should be supporting it are downright hostile towards the concept. What is it about PRT that is so objectionable to you? Is it because it looks too much like automobiles? If that's the problem, then people need to learn to get past external appearances and realize that PRT is nothing like the automobile in any way, except for level of service it provides. PRT retains almost all of the good of the automobile while eliminating all of the bad. What's not to like?

Is it SO important that public transit be huge and familiar, that you would ignore the possibility that another, completely different approach could accomplish the GOAL of low-impact, high capacity, convenient, highly available public transit, and do it better than today's systems? What's more important, the means or the end?

ATE, when you blow off our successful mass transit system and our hope that livable streets thinking will spread (return) across the country, wtf do you expect? You've said all sorts of uninformed, plainly false things about how transit isn't working in our city or can only possibly work here, which isn't the case globally or historically. You've got no interest in congestion pricing, a powerful idea that cuts across the political spectrum. And did you hear that freaking David Frum has endorsed carbon taxes? (Electricity will have to go up in cost too of course.) Paying real money to drive will seem a lot more feasible to Americans when geopolitical realities, and the economic costs of congestion, give them no choice but to do so. Get a sense of history and the world outside our borders and you'll find that the global transit community will take your PRT ideas more seriously.

I've been in many debates like this one, and when people start saying "make the drivers pay their own way" (politically impossible) and the demise of the automobile "will happen" (akin to saying "Harvard WILL win the Super Bowl"), I know that the debate has turned into an irrational turf war.

ATE, you started it by making sweeping generalizations about what "the public" wants or doesn't want, and what they will or won't do.

Tons of Americans have switched from cars to transit just in the past ten years. I'm not just talking Portland, Denver, and other cities that have built decent rail systems, but also the thousands of people that have moved to places like New York, Chicago and Boston and given up their cars. If you read the comments section on blogs like Curbed (and occasionally here), you'll find dismissive references to "hipsters from Ohio" who ride fixed-gear bikes to the L train station in Bushwick. Many people taste "the forbidden fruit" of 24/7 convenient transit and walkable, bikeable streets, and don't want to go back to the expense and drudgery of caring for a car.

The bottom line is that people on both sides of the PRT debate are making pronouncements about what "the public" wants. Until someone pulls out a well-designed representative study that somehow shows which people would choose all other things being equal, then no one really knows.

And by "all other things being equal," I mean if both options had comparable levels of public investment, prestige and familiarity. And if you can get people to stop being blind about the death toll from car use. Good luck finding a case study for that!

There's more to cities than getting places quickly.

In most cities, politicians can't even suggest a $0.25 toll increase without causing a public revolt. The American public looks at free roads and highways as practically a birthright. The idea that this political situation will suddenly change, and that 97% of auto-driving public nationwide will suddenly start paying for something they've always gotten for free, is naive. To merely suggest it is political suicide in most places.

As for stuff like peak oil, we're already seeing how the market pressure of $3/gal gasoline has turned the electric/hybrid automobile from an esoteric novelty to the latest rage. As gas prices continue to go up, we will see a transition from gas-powered autos to electric autos, NOT autos to trains. We can't turn back time - the public has tasted the "forbidden fruit" of convenient, private, non-stop travel, and they're not going back to line haul transit. Places like NYC are the exception.

And there's no reason for New Yorkers to worry - the NYC trains aren't going anywhere for a very long time. The more important task for PRT is to make transit inroads in cities where the automobile rules, to provide a good public option in places where the 98% of people drive to work without giving transit a second thought. That's a noble effort that deserves the support of the transit community, not mocking dismissals.

I guess generally I'm discouraged that mass transit advocates seem to be satisfied with picking up the crumbs from car traffic, based on a theory that cars are ultimately unsustainable and due to traffic, the spiritual flaws of suburban living, peak oil, and whatever other problems come up that people will suddenly give up on cars and come begging for another solution. I just don't see that happening. It *might* happen, but I think these issues are too important to rely on that.

It will happen. I can't speak for the others on this blog, but my goal is to get my neighbors out of their cars sooner rather than later, so that by the time the road warriers come there'll be nothing for them to take.