Would Personal Rapid Transit Benefit Anyone but Its Manufacturer?

Picture_9.jpgImage: SkyTran

Some of you saw the Examiner piece yesterday about SkyTran’s personal rapid transit (PRT) project and were probably looking for a response from us (one of you even asked in comments why we didn’t touch it), but I’ve been very leery of the topic since I saw the "Pod People" post over on New York Streetsblog blow up with 227 polarizing and dogmatic comments for and against PRT (Personal Rabid Transit?), before the editors shut comments down. I’m pretty skeptical of anything taken on faith as good or bad, so why get into the fray, especially with a technology that hasn’t been proven at scale?

Then there’s my personal bias against the aesthetic clutter that would ensue with multi-level guideways two stories high running down quiet residential streets to whisk people to their front doors? I don’t know about you, but I like walking those quiet streets and looking up at the sky.

And isn’t a transit system that costs at least five times less than freeways and light rail called a bus? If the problem is competition with traffic from cars, then make a serious policy commitment to segregated roadways for buses. Or why not spend public money for innovations like bike-share, which would have the added benefit of keeping you healthy?

One of the issues the Examiner didn’t touch in its promo for SkyTran was feasibility. Where in the world would the money come from to build a workable system less marginal than the monorail at Epcot Center?

"The most likely source of major public funding would be federal funds
that are targeted toward new rail projects," said Metropolitan Transportation Commission (MTC) spokesperson Randy Rentschler, whose agency would be responsible for finding public funds for PRT, should that ever be mandated by the public. He explained that the New Starts federal fund typically doles out $1.5 – 2 billion annually, though that goes to projects all over the country. In San Francisco, the Central Subway is one of the projects competing for the money, for example.

"On the hurdles faced by any [PRT] project: one
is basic math," added Rentschler. "The number of projects seeking significant money is
long and the ask is very large. Way more than is available. Also, the
way to look at this particular issue is that public money has a very
low tolerance for risk and favors the tried-and-true, so new ideas are
hard pressed to gain favor."

BART Director and general transit buff Tom Radulovich echoed Rentschler’s comment about funding for a huge capital outlay and was skeptical of "silver bullet thinking," but did bring up an interesting angle on how the technology could benefit rail transit.

Some PRT supporters disdain rail, but there are aspects of PRT that could help improve rail transit – especially driver-less operation. More and more metro systems are going driver-less, which reduces operating costs overall, and changes the economics of transport. The main operating cost for most transit is the driver, and transit is most economical when one driver is transporting lots of people. To economize, transit agencies tend to want to run longer trains less frequently. Go driver-less, and the economics change; running three two-car trains costs just as much as one six-car train. Lille’s VAL (automated light metro) operates like this; short, automated trains every 90 seconds. If BART were driver-less, we could run very short trains every few minutes during off-peak hours for the same cost as running longer trains less frequently.

So what do you think? And let’s keep the sermons on topic, please.

  • anonymous

    “We have LOTS of obsessive nuts with good liberal credentials in Minnesota, many of whom I wouldn’t trust to run a hot-dog stand, let alone build a transportation system.”

    Fixed that for you.

    Ken Avidor may be an obsessive nut, but he’s our obsessive nut!

  • anonymous

    Elevated PRT system: $15-$30 million/mile.

    At-grade light rail system with same passenger throughput, much lower average speed, worse energy efficiency, and greater danger to pedestrians: $100-$200 million a mile.

    Convincing trusting progressives and TOD supporters that it’s in their interest to support a more expensive and poorer performing system over one that actually has a chance of getting a large number of people out of their cars and thus preventing thousands of fatalities each year: priceless.

  • Here are two videos that might help. The fist is a robotic vision system cruising through a busy street identifying and tracking pedestrians without mistakes. The second is a robotic vision system following the lane markings perfectly well.



    Another point is that the British society of royal engineering *government body) is predicting that 30% of freight on British roads will be carried by robotic vehicles in ten years.

    Very quickly the gain from robotic transportation will evolve in automated people movers on our city streets. BRT, Light Rail, PodCars, and deliverbots will e arriving starting within 12 months. They perform all the functions of mass transit but have zeo infrastructure costs. These robots will utilize any signalling assist, but it is not a requirement.

    Robotic vehicles are much safer than human drivers, they mix freely with humans on the factory floor, and there are two systems of robotic rubber wheeled people movers in operation in Europe as well as one in Asia.

    The oil savings and convenience of the robocars are great enough that gated communities will adopt them first. Government DMV officers will soon be setting guidelines for Robotic Drivers licenses.

  • Nathanael Nerode

    “Elevated PRT system: $15-$30 million/mile.

    At-grade light rail system with same passenger throughput, much lower average speed, worse energy efficiency, and greater danger to pedestrians: $100-$200 million a mile.”

    These numbers suffer from being, well, just plain wrong.

    A lot of light rail systems have been gold-plated lately, with all kinds of streetscape rebuilds and decorative projects attached to them which have nothing to do with transit. There’s also “ripping up utilities” costs, which make a huge difference; much better to run where the utilities don’t have to be moved, or where they’re being rebuilt by someone else anyway. That’s where you’re getting your inflated numbers for light rail. $8-$15 million a mile is what you’re looking for for a streetcar system. I’m not surprised the price doubles if you build it elevated, that’s close enough to the standard factor.

    After checking Heathrow, I find that in fact (unusually for an airport) “the system is not expected to have a high demand”.

    This makes it possibly the first reasonable application for PRT yet. Though it does make one wonder how useful it is — it’s a *SHUTTLE BUS TO A CAR PARK*.

    A very expensive shuttle bus, at that. Does the savings from not employing a driver for a battery-run minibus outweigh the cost of construction? Perhaps it does; drivers are expensive. However, there are not very many places where frequent shuttle buses are used or needed; perhaps amusement parks as well as airports would find PRT useful.

    Shuttle buses are a notoriously inefficient form of transportation, and if PRT can replace shuttle buses then by all means I support it in that application. (How about replacing the shuttle buses to airport hotels, from train stations and airports to Disneyland, and so forth.)

    Of course there’s something else odd about this. Since T5 was new, would putting the car park underneath Terminal 5 have made more sense?!?! Would it have made even more sense to just let people arrive by the two separate rail services to the airport, and put the long term parking somewhere other than the Greenbelt?!?!?

    I also don’t think a price generalization from a two-stop system is remotely reasonable. One other thing. We don’t know the actual costs of the Heathrow system yet; it appears the final bill hasn’t come in.

    On the other questions:

    Patrick, I know more than a little bit about the ADA. Those portable stairlifts you keep going on about are allowed for residences and retrofits, but are not legally acceptable for bridging significant height differences in new-build commercial construction in the US. It’s a proper (safe) elevator or a ramp. Maybe they’re allowed in the UK, but having used them they are *not* terribly safe and they shouldn’t be allowed in new construction. On top of that they’re really not durable.

    I also know a little about about the health-and-safety regulations. Any elevated guideway now requires a safe walkway alongside for escape purposes if there’s a vehicle breakdown. (If you can safely walk on the tracks, the walkway just has to be wide enough to get to the tracks. Similar rules apply to new tunnel construction, but this is usually achieved automatically by making the tunnels round.) The Heathrow system appears to have guideways almost if not quite wide enough, and should be considered the absolute minimum width for an elevated US PRT system. “Completed ULTra guideway looks like an elevated road.” — sounds about right.

    In general — non-airport — applications, the trouble I have is that most of the goals of PRT seem to be met at least as well by electric car-share programs — or by walking. (Or even by travellators/moving walkways, which are heavily used in airports.) Airports, like amusement parks, are a very specialized application.

    The PRT company doing the construction at Heathrow doesn’t seem to be presenting it as an alternative to mass transit for high-traffic corridors — and in a “replacement for small shuttle buses” application, it may well actually have a function. This is highly specific. It’s overbuilt for a true collector function (to the home); and it’s underbuilt for the movement of large numbers of people.

    A rule of thumb is that you don’t want rail transit (for transportation purposes, anyway) unless you can run your vehicles nearly full every 5-10 minutes at peak times. (Minor exception: cheap line extensions for existing lines.) For those applications, PRT is just not terribly useful; replacing a 120-person vehicle with 30 4-person vehicles running every 20 seconds is not terribly practical, even if technically possible, and is horrendously expensive if your line is of any length, thanks to the huge number of vehicles required (all that steel!).

    For most collector/distributor traffic, meanwhile, PRT is overbuilt; the morning collector traffic in particular is diffuse and usually can’t justify any form of grade separation. When the traffic is concentrated, but not concentrated “enough” for mass transit, it’s very unusual. PRT seems to have a crack to fit into here (the amusement park exception); however, if there’s already a rail system, it’s often cheaper to just extend it, and even at an amusement park, there may be enough traffic to justify large vehicles immediately.

    I suppose a properly built PRT alignment could be designed with low-capacity vehicles but large stations, so the vehicles could be replaced with larger vehicles as demand grew, for low-traffic corridors believed to be turning into high-demand corridors. This could be an intelligent replacement for the highly questionable “economic development” light rail schemes which never pencilled out as transportation in the first place — because if the demand never grew, you’d never have to increase the vehicle size, and you’re already spending money on something which is questionable as transportation.
    Interestingly, these are the sort of schemes where if the developers can’t get the rail they want, they may run shuttle buses (until they’ve sold all the units and don’t care any more).

    So I guess you’ve convinced me that there are a couple of obscure niches for which PRT would be useful. Namely, replacing frequent, low-capacity shuttle buses, and for developers who might otherwise run frequent, low-capacity shuttle buses.

  • Nathanael Nerode

    “Here are two videos that might help. The fist is a robotic vision system cruising through a busy street identifying and tracking pedestrians without mistakes. The second is a robotic vision system following the lane markings perfectly well.”

    *This* would be revolutionary, because it would allow driverless systems which aren’t pedestrian-separated.

    But it would have to operate correctly in the rain, snow, and sleet, and at night, before it will revolutionize transportation.

  • patrick

    got any evidence to support $8-$15 million per mile for light rail? Because the world seems to disagree with you. Here in SF we just built 5.1 miles of light rail for $650 million, about $125 million per mile. No gold plating, no grade separation, just a dedicated lane in the middle of the road. A few lines have been done for about $20 million a mile, but those are few and far between. Sure, if you can pick where you want to run your line and there are no concerns about construction impacting the neighborhood you can built it cheaper, but reality is that most areas where an LRT would be useful are already well built up and the choices of where they are built are limited. That’s why the reality is so much more expensive than your best case scenario.

    But it doesn’t really matter, as has been stated here a number of times, LRT & PRT can co-exist just fine.

    “appears to have guideways almost if not quite wide enough” and yet somehow it was built. Perhaps you don’t know quite as much about safety as you think you do. Care to provide some actual evidence of your requirements?

    Don’t like a chairlift? Add an elevator at the back, that only adds about 8 feet to the end of the station and no additional width. Sure it adds cost, but far a trivial amount given the costs of the entire system, a 2 story elevator big enough for a wheelchair just isn’t that expensive… as I pointed out much earlier.

    “replacing a 120-person vehicle with 30 4-person vehicles running every 20 seconds is not terribly practical” care to explain why? Oh, and PRT can run at much faster headways, anywhere from 1/2 second to 8 seconds depending on the particular implementation.

    “the morning collector traffic in particular is diffuse” that’s exactly what PRT is designed for. Since the costs are so small in PRT you can build a grid rather than a single line, but if you bothered to read the posts above, or do any of your own research about PRT you would already know that.

    “PRT alignment could be designed with low-capacity vehicles but large stations, so the vehicles could be replaced with larger vehicles as demand grew” There would be no point to this, PRT can support just about any capacity until you need heavy rail, at which point PRT works as a feeder system to the heavy rail.

    You obviously don’t know anything about PRT and can’t be bothered to learn about it. Which is fine, many people don’t know anything and don’t care and that’s their right. The problem I have with you is that you somehow think you can make arguments against it while being completely ignorant of it’s basic principles, not to mention that all your arguments have been debunked in these comments and elsewhere.

  • Rob Berger

    I’ve ridden the prototype of Taxi2000 (now Skyweb Express) which is on a 60 foot track in a warehouse in Fridley, MN. I see many uses for PRT. I see no reason why PRT won’t work in many applications. Somehow we accepted freeways in all too many American cities, but a narrow guideway will be aesthetically devastating? I don’t think so, but this is a matter of taste. Ken Avidor points to Michele Bachman (one of Minnesota’s bizarre politicians who continues to be re-elected) support for PRT as a reason to be against PRT. In Minneapolis, we have one LRT line, which I happen to like and use whenever I go to the airport. I take a taxi to the LRT line downtown and then take 20 minutes to get off at a station IN the airport. Very neat. I’d like to see at least four to six light rail lines in the Twin Cities. I would also welcome PRT for the sprawling U of M campus, as a circulator near the downtowns, and to connect suburban passengers to light rail. I see value in many different modes of transit. Frankly, as peak oil becomes more apparent, I think aesthetic issues will become less salient as it becomes more difficult to get around. As far as riding the bus is concerned, I rode for many years, but never really liked riding the bus. The ride is jerky, LRT is much more comfortable and I don’t feel that sense of claustrophobia on LRT. PRT would not be crowded and have the same ride comfort as LRT (perhaps even better if the prototype experience I had is relevant). I am a psychologist in Minnesota who is interested in non-polluting, efficient transit to replace automobiles as much as possible. If I am fanatic, it is about peak oil. I believe that this next twenty years are going to require radical shifts in the way we move goods and people. Most people on peak oil websites align with Kunstler against PRT in favor of rail. I am one who likes both rail and PRT. Let’s see if PRT can be practical for specific applications.

  • Please read: http://www.lightrailnow.org/facts/fa_prt001.htm
    And you will see why PRT will never work!

  • Nice site.The PRT company doing the construction at Heathrow doesn’t seem to be presenting it as an alternative to mass transit for high-traffic corridors — and in a “replacement for small shuttle buses” application, it may well actually have a function. This is highly specific.
    please must visits us:http://www.autobus.co.il/

  • “Speaking of which, how on earth do you get past a breakdown on a single track suspended in mid-air?”

    A typical PRT network design involves a grid shape (closely spaced). If a pod car breaks down, the system can simply re-direct other pod cars to other segments of the grid, taking an alternate route. This may slow down operations slightly but it won’t bring them to a complete stop like heavy/light rail.


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