Minnesota Gadgetbahn – When the Future of Twin Cities Transit Was Up in the Air

The Twin Cities is hosting the Rail-Volution conference this week. As I watched the Rail-Volution attendees gathered in the refurbished Union Depot last night, I thought what a long way we’ve come from the dark days ten years ago when nearly every transportation meeting I attended included at least one proponent of Personal Rapid Transit, an iteration of a phenomenon some transit professionals have dubbed “gadgetbahn”.

Personal Rapid Transit (PRT) was loosely defined at the time as a network of pod-like vehicles on an elevated monorail-like structure with many off-line stations. In theory, PRT was supposed to combine the advantages of the private automobile with the efficiency of fixed guideway transit. After fifty-odd years and hundreds of millions of dollars spent on PRT research, there are no true PRT systems in operation anywhere in the world. There are small demonstration projects labeled as PRT but should be more accurately described as APM’s (automated people movers).

PRT had no support from traditional grassroots Twin Cities transit advocacy groups which had resolutions opposing the public funding of PRT. While many PRT advocates claimed PRT was a futuristic, 21st Century concept, in fact it was a crusty relic from the last century. Personal Rapid Transit began as a concept in the 1950’s and ’60’s and found favor among urban planners at the Federal Urban Mass Transit Administration (UMTA) who believed that mass transit could only compete with the private automobile by becoming more car-like. Millions of dollars were poured into PRT research projects. One of these ancient PRT projects was called Uniflo.

From a website history (no direct link) of Rosemount Inc., a Minnesota company:

“Uniflo was a computer controlled, air pressure levitated and propelled personal rapid transit (PRT) system. A Honeywell researcher, who had worked on and then purchased the rights for the project, interested Frank Werner in pursuing its development. Rosemount had hoped to fund the project with public financing or equity participation by another firm, but even with renewed federal interest in public transportation Rosemount had trouble funding Uniflo. A joint effort with Northrup Corp. to win a Department of Transportation (DOT) contract for a demonstration mass transit system at Dulles International Airport failed. The DOT passed over the Uniflo project for more conventional mass transit systems. Uniflo later received two other federal research grants but made no sales. The project, which was abandoned in 1973, cost Rosemount about $1 million.”

Here’s what Uniflo PRT was supposed to look like – (click on the picture to make it bigger)


This was the pitch for Uniflo:

“A personal rapid transit system has been developed, capable of providing urban areas with public transportation service that is competitive with the automobile in speed, availability, accessibility, and comfort. The system contributes no pollution in terms of air, noise, or vibration; it is relatively small in size; and it can be installed elevated, on grade, or below grade. These qualities make it an acceptable addition to a community. Because this personal rapid transit system is highly automated, a significant reduction in the amount of labor required to provide transportation service is anticipated. This could mean that it would again be possible to make money moving people.”

Rosemount pulled the plug on Uniflo after spending a reported million dollars in research.

In 1971 Minnesota Legislature appropriated $50,000 for another PRT proposal. PRT promoters from the Citizens League testified against a Metropolitan Transit Commission proposal to build rail lines as the backbone of a comprehensive transit network. The PRT study, published in 1973 recommended public funding of a project that would demonstrate the feasibility of PRT. The legislature did not fund the PRT project, but the diversion created by the PRT promoters helped to block the MTC proposal and Minnesota had to wait nearly twenty years to get it’s first light rail line.

PRT also played a role in delaying plans for rail transit in other cities. Denver citizens voted for a one-half cent sales tax in 1973. A Congressional report explains what happened next:

“UMTA began backing away from its early enthusiasm for the Denver PRT proposal in 1974. Embarrassing cost overruns in the demonstration project in Morgantown, W. Va. had cast doubt on the financial and technical feasibility of a PRT system similar to the one proposed in Denver. In addition, the Airtrans System at the Dallas-Fort Worth Airport-like Morgantown’s PRT, a technological predecessor of the proposed Denver system-was not performing up to specifications.”

The so-called PRT project at West Virginia University in Morgantown was estimated to cost $14 million and ended up costing $126 million (1979 dollars). At it’s debut, the Morgantown PRT malfunctioned with President Nixon’s daughter Tricia on board. The Morgantown PRT has been plagued by glitches and breakdowns ever since.

Other PRT-style, automated transit experiments ran into the brick wall of reality; CVS (Japan), Cabinentaxi (Germany), Aramis (France), Cabtrack (England) Ford Motor Company’s ACT (Dearborn) all failed to meet expectations and were abandoned after wasting considerable funding that could have been invested in reality-based, conventional transit modes.

In the 1990s, Professor J. Edward Anderson, convinced the Regional Transportation Authority (RTA) of Illinois to fund a PRT project for an industrial park in Rosemount, Illinois. Raytheon agreed to build it. The project was discontinued due to cost overruns and technical problems. Total losses in public and private investment in the Raytheon PRT project were estimated at $67 million.


Undeterred by this massive failure, J. Edward Anderson’s PRT company Taxi 2000 tried to get city after city to fund a PRT testing facility. In Cincinnati, promoters of PRT managed to convince U.S. Sen. Jim Bunning  to release $500,000 in federal money for a monorail project. A PRT project called Skyloop was very likely the intended beneficiary. Skyloop never happened. Skyloop was rejected by a regional planning committee after engineers found the PRT concept to be an unsafe, infeasible eyesore. Downtown Cincinnati business owners objected to the removal of potential customers from the street level. Cincinnati is getting a streetcar instead.

In the 1980’s, Minnesotans took another look at rail transit. PRT enthusiasts again opposed LRT, but this time with a more belligerent tone. A PRT enthusiast disrupted an art seminar my wife and I were conducting, yelling that public officials conspired to suppress PRT and threw Taxi 2000 brochures on the table. Another transit advocate told me of similar meetings disrupted by PRT enthusiasts.

In 2004, bills and amendments were introduced at the Minnesota Legislature that granted bonding, regulatory and tax advantages to develop a PRT industry in Minnesota. Not one of these bills survived the legislative process, but the PRT bills provided a platform for anti-transit legislators to denounce conventional transit as too expensive, inefficient or old-fashioned. Stooping to fear tactics, PRT promoters claimed LRT riders would be “forced to ride with strangers”.  The $4 million PRT bonding bill was passed by the House only to disappear in the conference committee. Things went quickly downhill for PRT promoters after that.

Late in 2005, a lawsuit involving Professor Anderson and the Taxi 2000 Corporation seemed to have derailed chances of public funding of PRT however, a far more important factor in the demise of PRT in Minnesota was the phenomenal success of the Hiawatha Light Rail Line, renamed the Blue Line which has exceeded ridership projections. This year, the Green Line between Saint Paul and Minneapolis was added the Green Line which has already exceeded expectations. Light rail’s success in attracting auto drivers has disproved the notion that transit must be car-like.

A group calling itself Citizens for Personal Rapid Transit (CPRT) keeps the PRT flame alive in Minnesota, According to this PRT website, there are several PRT “niche systems” proposed for Minnesota. A 2012 article in the Fridley Patch asked whether Taxi 2000 could be described as “moribund”. The last attempt to revive interest in PRT was a bill by Minnesota State Senator Torrey Westrom.  Another Minnesota PRT company Jpods claims it is going to build a PRT system in Secaucus, New Jersey.

Nowadays, the citizens of Minnesota seem to understand that the future of transportation in Minnesota is unlikely to resemble the futuristic, Jetsons-style fantasies of yesteryear. The very real challenge of providing transportation choices to Minnesotans requires public officials and citizens alike to make decisions that are based on reality, not science fiction.

Note: Much of this article comes from a 2008 article I wrote titled “A Brief History of Personal Rapid Transit”. Needless to say, not much has changed since then. Below is a photo I  took years ago of a model of Skyloop that was on display at the Crystal Court of the former IDS building in  Minneapolis:

Ken Avidor

About Ken Avidor

Ken Avidor is an illustrator, cartoonist and occasional courtroom sketch artist. Ken Avidor is an active urban sketcher and maintains a daily, illustrated journal. Ken is married to urban cartographer and talented sketch artist Roberta Avidor in the Union Depot in Lowertown, Saint Paul. Follow Ken and Roberta's sketching/bicycling adventures on their travel blog.

27 thoughts on “Minnesota Gadgetbahn – When the Future of Twin Cities Transit Was Up in the Air

  1. Ian Bicking

    Since your original article there has been a launch of a real PRT system at Heathrow airport: http://en.wikipedia.org/wiki/ULTra_%28rapid_transit%29

    Since 2008 it’s also becoming clear that the future of transportation will be self-guided cars instead of self-guided rail; maybe that will even be the future of transit. In the meantime improvements to our transit systems might eke out another 1-5% of trips, which will seem like dramatic growth compared to previous transit share, but will still leave transit a small minority compared to car transportation.

    At the same time our ROI on transit is going down, not up. The field has somehow managed to be immune from technological advance, not even meeting the progress of past deployed systems, with entirely conservative designs and a set of transit advocates that spend more time excusing transits failures on the misdesign of cities and people and pushing back against any attempt to imagine a transit system that was actually better, one that could actually satisfy any substantial portion of our transportation needs.

    There are lessons from PRT. Government, ultimately, is conservative. It doesn’t push hard. The best design is the design that is good enough, or at least common enough. Rail is naturally a governmental affair, it is by design a highly mediated and exclusive right-of-way, and requires governmental support, subsidy, acquisition, and then ultimately management and approval. And so I don’t think PRT had much of a chance. I am pessimistic about progress in rail transit. And I am sure if any progress is proposed that you will be ready with your criticism and conspiracy theories.

    Buses… I think there’s some hope for them, if we were to pay a bit of attention.

    1. John

      I thought the Morgantown WV was a PRT system. While it does primarily function as a scheduled service, in off peak hours it functions as a true prt.

  2. Ken AvidorKen Avidor Post author

    Ultra, the so-called PRT at Heathrow is s an automated people mover that uses battery-powered vehicles connecting a parking lot to a terminal at Heathrow Airport. Since it takes passengers to just two stations it cannot demonstrate whether a true PRT system with multiple offline stations could work in the real world, let alone be “faster, better, cheaper” than Light Rail as proponents often claimed ten years ago.

    That is all moot – Ultra has failed in its bids to build systems in MInnesota, Daventry, Cardiff and more recently Amritsar.

    1. Walker AngellWalker Angell

      I’ve used the system at Heathrow a couple of times. There’s a board there saying that they plan to expand it in 2016 to three additional stations. Not sure if that’s still on track or not.

      I thought San Jose was close to doing something?

      What will be fascinating is seeing deliveries made by these pods. Instead of mostly empty 40′ semi’s from US Foods trudging all over town and nearly hitting bicycle riders (guess what happened to me yesterday on Grand Ave), the delivery for Salut can be put in a much smaller pod and sent on its way.

      1. Karen Sandness

        By that criterion, Chicago-O’Hare already has PRT, only with larger pods. Its people mover already carries passengers to all the terminals in a loop track.

        The problem, as Ken Avidor notes, is that no one has ever succeeded in creating or even simulating a multi-line fully PRT system, one that would handle rush-hour traffic in both directions and transfers between lines without massive pile-ups of pods.

        1. Peter Muller

          Ken – a small correction – the Ultra system at Heathrow has three stations and so does demonstrate direct, nonstop station-to-station travel on demand (average waiting time = 15 seconds). Karen, this is unlike the O’Hare APM which has to stop at very station.

          Karen, you are incorrect in saying no one has even simulated a large multi-line PRT system. Many have. We recently simulated a 30-mile 50-station system in a paid study for a very sophisticated client. We found the system had a line capacity of 6,000 passengers per hour per direction and 13,000 passengers were accommodated on the network in one hour. The simulation was based on technology capabilities already proven in public service (no wishful thinking). I agree that putting this into practice will involve overcoming hurdles along the way, as will any expansion of new technology, but it is very clearly possible.

        2. Walker AngellWalker Angell

          Just because nobody has yet done it wouldn’t mean it’s impossible. At some point nobody had propelled a boat with anything but wind or oars either.

          I’m not a fan of PRT and doubt I’ll see much of it in my lifetime but I’d think the function wouldn’t be extremely different than a data router (except it wouldn’t have the luxury of dropping bits when things got congested). I’d think the biggest issues would be building enough failsafe in that it was routinely a reliable enough alternative and could avoid catastrophic failure.

  3. mplsjaromir

    Thank you for wiritng about the hucksters, grifters and charlatans of PRT. I liken the concept to the gold standard. Even though it has been universally rejected, a small subset of people still think its a viable solution.


  4. Matt SteeleMatt Steele

    One of the coolest gadgetbahns (for cargo) is the pneumatic system between Mayo Clinic facilities under the streets of Rochester, dating back to the 1890s. My friends who work in labs say it’s still used to shuttle specimens from the two hospitals and the clinics, although electronic medical records have apparently replaced the use of the system for moving charts and files.


  5. Andy SingerAndy Singer

    Thanks for fighting this insane pyramid scheme, Ken.

    Public transit works because it can move more people through a given corridor than automobiles. In driving school, one is taught to keep a 2 second following distance from the car in front of you. This turns out to be the average time/distance that people actually maintain, regardless of speed. With two seconds between each car, this means that the average highway lane can accommodate 30 cars per minute or 1800 cars per hour. Because people change lanes and aren’t perfectly efficient, the accepted highway industry standard is about 1,500 cars per hour, per lane. Since most cars are single-occupant vehicles, this means that a highway lane moves about 1500-1800 people per hour. Even if everyone rode in 3-person carpools, the capacity of that highway lane would be just 4500 people, per hour, per lane.

    Now imagine a single track of transit (about the same spacial displacement as a highway lane). A 3-car LRT train holds over 600 people. If you ran them at 5 minute intervals, you can now move 7,200 people per hour through that same amount of space. If you used longer or more frequent trains, you can boost this carrying capacity to over 20,000 people per hour, per lane. PRT is basically a smart car (or Google car) on a fixed mono-rail guideway. It can only compete with transit if it is able to have as little as quarter-second following distances between pods (cars) and tens of thousands of pods, operating simultaneously.

    Imagine tens of thousands of pods, each with their own computer, motors and mechanical systems, all going to different, random destinations, on an elevated monorail system, at quarter second following distances. If even one pod’s computer, motor, brakes or other mechanical system failed, it would shut down the entire system. Bay Area Rapid Transit system (“BART” for short) is a computer-controlled transit system with just 54 trains moving to fixed destinations on fixed schedules. BART trains have lots of redundancy built in– multiple cars, multiple motors, multiple brakes, etc. If one motor dies, the train can keep operating. If a computer malfunctions, a human operator in the train can override it and manually run the train using a redundant signal system. If a train breaks down completely, it can be easily taken out of service. Even with all this, the system has a 1-2% failure rate, leading to delays or brief system outages.

    A 1-2% failure rate would mean, within the first ten minutes of operation, a true PRT system would fail. Building a perfect anti-missile shield to protect the USA from a nuclear attack is an easier engineering problem than building a PRT system that can begin to compete with fixed rail transit. Both PRT and missile shields have been talked about for 50 years but other than simple demonstration projects, both things are so far off as to be engineering fantasies. Universal implementation of self-driving Google cars has a greater likelihood of success than PRT …and Google cars still have a lot of problems.

    Taxi 2000 was a ponzi scheme. The minimum investment was $5000. It snagged a Minneapolis city councilman, an investment adviser in Saint Paul, an ex-chancellor of the UMN and many others who lost tens of thousands of dollars. Its following is cult-like. As Ken said, during the early 2000s, you couldn’t go to a transit event or give a talk about transit without some PRT advocate interrupting or shouting you down. I’m so grateful that Minnesota has finally moved past it and built LRT.

  6. David MarkleDavid Markle

    Rails are a relic of the 19th century, not PRT–although we still need rails. Very recently someone told me of a very favorable experience with a small PRT system on an East Coast campus. I understand that for some reason Mr. Avidor has been a dedicated foe of PRT.

    1. mplsjaromir

      Ahh yes, the PRT system at The University of Doesntexististan. Great system, we should learn from that model and replicate it here,

      All kidding aside David your reputation for proprogating misinformation precedes you. My advice is too heed the words of the great poet Ice Cube “You don’t have to lie to kick it”.

      1. Joseph TottenJoseph Totten

        Oi, the Morgantown PRT has mixed results (how much of that is people pushing PRT yelling success, who knows). But this is not a complete mis-information, and does not seem to be portrayed as such.

        That a single person rode it, and had a favorable experience, and told Mr. Merkle is not far fetched.

        1. mplsjaromir

          The article mentions the Morgantown PRT, so why refer to it as a ‘small PRT system on an East Coast campus’? For what it’s worth West Virgina is not on the East Coast. My guess is that David didn’t even read it.

    2. Ken AvidorKen Avidor Post author

      Mr. Markle, This post is meant to be a brief history of PRT in Minnesota. PRT is no longer being proposed in MInnesota I hope the history I present here explains why PRT has pretty much disappeared in Minnesota and other states. If there are other historical reasons, please let me know in the comments. Thank you.

      For more reasons why the concept has lost traction, there’s this article titled “Personal Rapid Transit Is Probably Never Going to Happen”:


  7. Peter Muller

    Ken, it is good to know you are still alive and well. It seems a long time since you last bashed PRT. It is refreshing to have your thoughts open to debate rather than hidden behind a website closed to comments.

    Here are some facts as I know them:

    1. Heathrow PRT has been operating since 2011 with an availability of 99.7% (about eight TIMES more reliable than transit level of service A). It has three stations and thus is not just a shuttle but a true network (albeit a small one).

    2. The Masdar City PRT system has been operating since 2010 with an availability of 99.5%. It only has two stations but the supplier has a GRT application (since 1999) that demonstrates station bypassing.

    3. The 40-vehicle Suncheon system has been operating since April this year. While it only has two stations, it demonstrates PRT capabilities because the maintenance facility is a third destination.

    4. Morgantown was a political and financial disaster at the beginning, but Trish Nixon’s father pushed the schedule so it would open before his re-election. Once it was opened it has performed very well carrying tens of thousands of passengers every day and unifying a previously divided campus. It has over 160 million injury-free passenger miles. The FTA and the University are currently modernizing the control system (the system is 39 years old). The New York Times characterized it as a “White Elephant turned into a Transit Workhorse”.

    These are small systems but all are true PRT (Morgantown is really true GRT). PRT is thus presently emerging at a rate exceeding a system every two years.

    I wish I could tell you more of what we are working on but suffice it to say that we are being paid serious money to investigate US systems ranging in size from 15 to 900 vehicles. Our clients have airports and communities that are desperate for better solutions and, like Heathrow Airport, are finding, in some cases, nothing else really works.

    Ken, I do not think PRT is the solution to every problem. I do not understand why you continue to think it has no place at all. A community in Brazil is planning a PRT /monorail combined solution. A city in Africa has terrible congestion but no space to widen roads – they are also considering PRT. These people are simply using all the tools available to them to solve their problems in the best way possible. Learning how to use new tools and where they are applicable is only good practice.

  8. Ken AvidorKen Avidor Post author

    Mr. Muller, what I wrote is not a debate, it’s history. PRT is a Minnesota historical artifact.

    I would say you are beating a dead horse, but that would not be accurate – the deceased horse (PRT) has been carted away and you are beating the faintly discolored patch of earth where the dearly departed equine lay motionless for many years.

    PRT is no longer being proposed for funding at the MInnesota legislature as it was ten years ago. If you know of any current, serious PRT bills being proposed in the Minnesota Legislature, please let us know.

    The Minnesota-based group Citizens for PRT group has been largely inactive as their website and Twitter reveals:



    Over and done with = history.

  9. David MarkleDavid Markle

    I stand corrected: substitute “out east” for “East Coast,” and kindly continue to let me know whenever I make an important error.

  10. Karen Sandness

    All the projects Mr. Muller mentions may be people movers with multiple stations, but do any of them have multiple LINES? I have seen a PRT project in a suburb of Tokyo, but it has only one line, like the aerial tramway at the State Fair. Multiple lines? Anywhere? That’s the tricky part.

    You can have 100 stations on a single line, but unless you make every pod stop at every station (thus eliminating the supposed advantage of PRT over conventional trains), you’re going to need the counterparts of on-ramps and off-ramps for people whose destination is Station #3 or #98 in order to allow other pods to pass by non-destination stations without interruption.

    The situation is only worse if you have multiple lines. Either passengers have to get out of one pod and switch to another (thus eliminating a supposed advantage over trains) or you have to think of a way to switch pods from one line to another without causing a traffic jam.

    In either case, the PRT advocates have either not thought the matter through or they believe one or both the following things:

    1) Public transit means having to ride with icky people who are of a different social class or ethnic group
    2) Public transit is bad because it’s public, so the best thing to do is to delay it with proposals that have never worked as real transit systems anywhere in the world.

  11. Lee Sprecker

    What about J-PODS proposed installation in NJ? Is this really going to happen or is it another ‘wisp of smoke with no fire’?

  12. Ken AvidorKen Avidor Post author

    Who knows? The internets are awash with tales of gadgetbahn projects here today & gone tomorrow. Here’s a few articles of Jpod projects of yesteryear:



    Lots of fun Jpods videos – enjoy:


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