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Systems doomed to fail: ULTra mass transit

December 29, 2008 1 Comment

Over at Futurismic (one of my daily science blog reads) is this post about the ULTra light transit system.  The system is quite clever and takes a demand-based (vs. a schedule-based) approach to transit. But as you watch the accompanying video, ask yourself: why will the ULTra system likely never grow beyond small, custom installations (such as London Heathrow Airport or not-yet-constructed office complexes)?

Here are what I see as being some of the core classic problems with a system such as this.

The “No Room for the Infrastructure” problem. While the elevated tracks are vastly cheaper and easier to construct than, say, corresponding subway tunnels, they still require above-ground space and a regular footprint at ground level. Most existing urban and even suburban areas simply don’t have the room available, either in the air or above the ground. The political and economic costs of purchasing such room (via eminent domain and other takings) would be prohibitive in most urban/suburban settings.  And while everything in the video looks clean, light, and airy, you simply need to spend a little time around most mass-transit stations to see how they act as magnets for vandalism, graffiti, and litter.

The Last Mile problem. Because of the room problem above, the ULTra network would not likely achieve much network density except in limited and constrained locations (such as an airport or a newly-constructed office park). In actual urban/suburban settings, ULTra would likely end up having a sparse network feeding into existing mass transit systems (subway, buses) or leaving you to walk the rest of the way. As such, it is unlikely to reduce car usage.

The Pay As You Go problem. Mass-transit systems are notorious money pits, heavily subsidized via unrelated taxes and federal subsidies (but I repeat myself), since actual rider fees are not enough to pay for the system’s on-going operations, much less the original cost of construction. My wife and I lived in the DC area for a total of nearly 8 years (six of which were in the District itself), and I was a great fan (and heavy user) of the DC Metro subways. But WMATA is always struggling financially, and that’s true of most mass transit systems. Here in Colorado, where we’ve lived for the last 3 1/2 years, the Denver Light Rail system found itself looking at cutting back services this year — due to reduced sales tax collections and higher fuel costs — even as rider volume was going up as gas prices passed $4/gallon.

The Hidden Costs problem. Somehow, much of the public discourse over (electric) mass transit assumes or implies that electricity is free, or at least carbon neutral. It’s neither. Most electrical generation in the United States comes from burning hydrocarbon-based fuels: coal, natural gas, and a bit of oil. And even if the electricity comes from wind, water, geothermal, solar or (my favorite) nuclear, it still costs money and it still has a carbon footprint.

The Scalability problem. Paul Raven, who blogged about ULTra over at Futurismic, raised this issue himself. The ULTra system shown in the video relies on relatively small cars — four seats each, with some standing/storage room between them — that are spaced apart by the controlling software. Assuming a spacing of 3 seconds between cars, that sets an upper limit of moving 4800 people/hour. This is better than, say, busses on a given route, but it’s less clear how competitive it is over existing train, light rail and subways systems, and it doesn’t begin to approach what the automotive infrastructure can carry.

The Coordination problem. One of the long-standing complaints about the automotive system is its high inefficiency, that is, you have millions of cars on the road, the overwhelming majority of which are carrying one or maybe two individuals. ULTra, by being demand-based, sets itself up for the same problem. If I read the video and website correctly, I can walk up and select an unused ULTra car, punching in my desired stop, and go straight there. By so doing, I may tie up an ULTra car all by myself, going from Point A to Point B. This reduces the overall capacity and efficiency of the system; to overcome that, I must then choose to announce my destination, interact with others (“Who else in going to [Destination X]?”), and decide who else I want getting into that rather small car with me. This leads to…

The Safety problem. Personal safety on mass transit is usually provided by the presence of other people; that is, you are less likely to be mugged or assaulted on a crowded subway car or bus due to the presence of all the other people around you. (Hence the classic drama/horror trope of being on a subway car with just one other, sinister-looking person on it.) Should I let another person into my ULTra car, presumably because that person is going to the same destination, I am then trapped alone with that person in that car all the way to that destination. I suspect there will be a “let me off at the next possible stop” button in the car, but that may not be enough. Likewise, there will likely be an inboard camera, but a second or two of spray paint will take car of that. On a less dramatic note, vandalism of the interior of the cars themselves will likely be increased  for that same reason of isolation (no one around to see what you do to the car).

OK, that’s what I came up with on the top of my head. Can you think of others, or do you have counter-arguments to what I’ve listed above?

Again, I’m a great fan of usable mass transit systems. When I lived in Washington DC, I regularly went to New York City on business without once climbing into a car or a plane; I’d walk down to the nearest Metro stop (Cleveland Park, Red Line), take the subway to Union Station, take an Amtrak train to Penn Station in NYC, then walk crosstown to my hotel or business destination. I’d then reverse the whole process to go home again. But I was also quite aware all that time of the financial struggles and subsidies of both WMATA and Amtrak.

Likewise, ULTra will only succeed in small, constrained settings, such as airports and office parks. The video itself references those two settings, but the ULTra website references grander uses. I just don’t think they’ll happen, at least not without massive government spending, and even then they won’t make a real impact in automotive use.

As always, your mileage may vary.  ..bruce..

About the Author:

Webster is Principal and Founder at at Bruce F. Webster & Associates, as well as an Adjunct Professor for the BYU Computer Science Department. He works with organizations to help them with troubled or failed information technology (IT) projects. He has also worked in several dozen legal cases as a consultant and as a testifying expert, both in the United States and Japan. He can be reached at 303.502.4141 or at

Comments (1)

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  1. pmuller says:

    Bruce, you have obviously given this some thought, but I am afraid you are missing the mark in many places.

    No room for infrastructure – a PRT guideway is 7′ wide and carries same traffic as a freeway lane at 12′ or 4 city streets at 48′.

    Last mile- PRT is designed to have stations on a 1/2 mile grid – average 1/4 mile max walk.

    Pay as you go – PRT operating costs are typically LESS than fare box revenues.

    Hidden costs – PRT uses less than 1/3rd energy per passenger mile of cars, buses and trains and requires much less infrastructure.

    Scalability – PRT scales easily to city-wide.

    Coordination – this is where modern computer technology helps out. PRT requires much less empty vehicle movement than conventional transit.

    Safety – the antiquated Morgantown “PRT” has done over 140 million injury-free passenger miles – regular transit would have injured over a hundred and probably killed someone in that many miles. PRT will be (already is) two orders of magnitude safer than cars.

    I agree that PRT will start in niche markets but as speeds increase and headways (time between vehicles) reduce, it will expand throughout cities. Masdar in the UAE is being built to be totally reliant on an 80 station PRT system with thousands of vehicles.

    Visit our website to learn more about PRT.

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