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Get On Board!
Personal Rapid Transit
Questions & Answers

Get On Board! PRT


You may send questions, comments and scoops to: prtinfo AT kinetic.seattle.wa.us

About Us

(January 2010) We are honored that J. Edward Anderson PhD, generally regarded as the leading thinker and designer of personal rapid transit, has called Get On Board!PRT "The best independent webpage on PRT," or podcars.

Since our establishment in late 2000 our mission has been to conduct public outreach and education with the goal of encouraging support for the research, development and implementation of PRT.

Today the mission and goals remain the same, but our objectives reflect the evolution of the PRT field over the past decade. Simply put, there is less need today for basic, elementary education about PRT, since good descriptions of podcars have hit the mainstream media. There are also number of robust programs in several countries, they are market-ready and at some stage of initial installation. Governments have endorsed PRT's promise as a tool for urban mobility and reducing oil dependence, and have granted regulatory approval to the most advanced designs.

Therefore over the past several years we have deemphasized educational activities (though any still-relevant writing is still available), and shifted outreach to providing coverage of news and resources about podcars.

Ed Anderson called us independent, and that independence is by design. We are not beholden to any PRT company, and within our outreach and education mission we are dedicated to the principle of neutral objectivity as practiced in the field of public policy analysis.

When we report news we give facts, whether 'favorable' or 'unfavorable' for PRT.

When we editorialize we do not spare anyone, pro- and anti-PRT camps alike.

Our ultimate wish is that there will no longer be pro- and anti- PRT camps at all, but rather just a single transit camp.
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What does PRT look like?

There are several leading designs at or near a ready-for-market stage. This page shows the Taxi 2000 Corp.'s "Skyweb Express" system and describes how it works. The prototype vehicle consists of a passenger compartment mounted atop an undercarriage, which rides inside the guideway. Propulsion and braking are performed by an electric linear induction motor, sort of a rack & pinion that uses magnetism instead of teeth. In the Urban Light Transport (ULTra) system by ATS Ltd., the entire battery-powered cab rides atop a slim, 5 ft-wide guideway. Vectus guideway is built around a 20-inch pipe. Other systems include 2GetThere and Mist-er.

←"Skyweb Express." Taxi 2000 Corp.   •  "ULTra" ATS Ltd.

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Who supports PRT?

A number of pro-Transit organizations, agencies and individuals around the world support PRT efforts or are actively engaged in research of their own, such as:

In addition, Marcy Winograd, 2010 and 2011 candidate for Congress (CA-36) and co-founder of Progressive Democrats of America-Los Angeles chapter, praised the 1970s-era Morgantown PRT project as an example of a non-defense project that can provide green aerospace jobs.

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What would PRT guideway look like?

Guideway would usually be elevated. Here, a digital illustration for a PRT application in Fresno shows Taxi 2000 guideway passing a baseball stadium; the guideway is only 3'x3' in cross-section. Internally, this guideway design could also house public electric, phone and cable TV lines, reducing aerial clutter).
       When supported atop slender pylons PRT guideway takes up little space on sidewalks or street medians. It is so light it can be mounted, sans pylons, on the sides of buildings and bridges. [ Pictures of slim guideway ]. Short turning radii (varies according to system) means PRT can make turns to avoid homes, businesses and nice old trees.
      When necessary, PRT can also operate on the surface or underground in exclusive right of ways. Main guideway and sidings could be mounted on the ground or (depending on the manufacturer) defined virtually (e.g. magnetic or RFID markers)

"Masdar City Peoplemover" (CyberCab) 2getthere
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How can the guideway be so small?

In addition to the weight factor described above, PRT guideways don't have moving parts-- unlike conventional rail and monorails, which must have large mechanical switching devices built into the railbed or monorail beam. Skyweb Express will have a simple switch in each vehicle/pod. At branches ("diverges" in Transit jargon) the inside of the guideway has "switch-rails" on the left and right sides. When a pod is programmed to take a left diverge, the switch grabs the left switch-rail, and the pod is guided to the left; for a right diverge the switch grabs the right switch-rail. Vectus also uses this approach. In ULTra, the vehicle uses lasers to steer along the guideway.
      I read an article in which the reporter wrote that only a short part of ULTra's test track is elevated, and we can't be sure how strong it is because there's only a single support post. That reporter is wrong, the test facility he wrote about actually has two posts [ photo ]. In fact, Britain's Rail Inspectorate has approved ULTra to carry passengers, and its first public system has finished construction at Heathrow. Vectus has also received safety approval, from Sweden's rail agency.
      I've read claims that a PRT guideway would sag under the weight of the vehicles. That is also wrong. Instead of analyzing a PRT design chosen by a Cincinnati citizen committee, a consultant made up its own, bad PRT design and analyzed that. [ Documentation ]
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Why is a grid so important? What's wrong with the way trains are routed now?

Trains are efficient for travel between two locations that are far apart, for instance between two cities. But within a city, rail lines and stations are now so expensive that only a few lines can be built, and it makes more sense to configure Light Rail as a commuter system. But the pattern of where people live, work, shop and play can be anywhere, not necessarily near a rail line; a grid is more conducive to urban transit service. Slender PRT rails configured in a grid network is affordable, and makes it possible to board a PRT pod at any station and ride nonstop across the grid to any other station -- even a train station. Can't buses operate in a grid? Yes, but they must stop frequently and are often slowed by traffic congestion. PRT is what is called 'grade-separated'

Radial: How is this system convenient for someone traveling between the red dots? Grid: Put the red dots anywhere, and the grid makes travel between them convenient.

Transit Grid ©2000 Get On Board! Personal Rapid Transit
See also: How Will You Get to the Train? PRT and light rail together (Google Docs slideshow)

There are plans for an intermodal Transit station at the mall. Doesn't that fix the problem? "Intermodal" means "transfer". In an attempt to create a network, bus and train systems are layered on top of each other. The idea is that you'll be able to travel anywhere by using a series of Transit vehicles, periodically changing mode-- bus to train, train to bus, etc.-- at the intermodal connections. This is called a "seamless network", but this still means users must wait at every transfer point. This is a reason Transit has trouble competing with cars. A multimodal network which includes PRT by definition reduces transfers and waiting.

But if PRT reduces transfers, what about economic development? Shops can be located at or near the intermodal Transit stations and attract the business of people transferring between modes. Because PRT stations are small and relatively inexpensive, it is economically feasible to site them closer together than rail stations, and in areas that are not high density. More commercial and residential areas would be accessible by rapid transit, leading to a single citywide "virtual Transit-oriented development." Learn more

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Can small PRT pods really be a MASS Transit system?

Yes—just as a skyscraper has lots of small elevators running anytime, instead of just a few big ones at fixed times. In other words, the key is eliminating Transit schedules and making service on-demand.
       Imagine a light rail or monorail station in a small-to-medium size retail/commercial district, and suppose the goal is to pick up 500 riders per hour. If the train comes once every 10 minutes, there are only 6 scheduled trip opportunities per hour, and each time an average of 83 people have to wait and then crowd on board. Even if the train runs every 5 minutes, that's only 12 opportunities per hour with 41 riders each time.
       Now consider the way PRT would provide service. With on-demand, schedule-free service, people would ride as soon as they enter the station. Thus, if we assume it takes 20 seconds to enter a PRT vehicle, sit, and have the vehicle get underway, then the number of opportunities for a person to travel on PRT is 180 trip opportunities per hour, PER STATION BERTH. Capacity would multiply with three, four, five, or more berths per station. [ Some more boring math about this ]
       Furthermore, a large PRT network would hold more vehicles than would likely be needed at first. So if your town's PRT system reaches ridership capacity for the fleet size you have, just add more PRT vehicles. Learn more

See also:
      • Skyweb boarding procedure, elapsed time
      • PRT: Matching Capacity to Demand by Dr. J.E. Anderson (zipped .doc)
      • One PRT line can move the same number of people as a freeway

Conventional Mass Transit
Imagine if all these empty seats could run around
separately, providing on-demand, nonstop travel. The
result would still be MASS Transit, but now it would
be individualized-- or PERSONAL.
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More on achieving mass Transit with small vehicles
       If the PRT station has 3 berths, there are (3 berths) x (180 opportunities)= 540 trip opportunities per hour. The capacity of the station is (3 persons per vehicle) x 540= 1,620 riders per hour. And even if actual use is only 1-2 riders per opportunity*, ridership is still 540-1080 per hour if all 540 trip opportunities are used.
       This is just for one PRT station. Imagine a citywide system with 100, 200 or even 300 stations. The number of berths per station would vary according to demand in each station's vicinity. On-demand, non-stop PRT trips are continually taking place between any combination of stations: you get in a vehicle, you go, you arrive at your destination a short time later. Suppose the average trip takes 8 minutes; one PRT vehicle could make more than 7 such trips per hour. If we assume the vehicles have 3 seats, the total capacity of one vehicle is 3x7.5= 22.5 riders per hour. Now imagine there are 2500 vehicles in the PRT fleet: the capacity is 22.5 x 2500= 56,250 riders

* Keep in mind that the average number of people riding in an automobile is about 1.2
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Doesn't PRT just duplicate the road system?

Not really. In Seattle there are 1,691 centerline-miles of streets for the city's 78.75 square miles. PRT needs only about 2 miles of mainline guideway to serve a square mile, so a PRT system reaching every square mile would be only 157.5 miles of guideway— less than 10% of the length of the street system. And this means, obviously, that PRT guideway would not go down every street.
       I heard this guy say that "we already have PRT, it's called the car." What about that? Cars aren't automated to prevent accidents, or on their own track to avoid pedestrians and congestion. Cars burn gas, PRT vehicles are electric. But the fundamental difference is that PRT vehicles are used and reused by different people 24/7. When you're not using your car, it sits idle in your driveway or a parking lot.
       If PRT is Personal, how much will buying a pod cost me? PRT is Personal, but that does not mean "privately owned." Rather, Personal refers to "PERSONALizing" the level of service—the individual, or small group of people traveling together. This basic assumption leads to the appropriateness of demand-responsive service, small stations and vehicles, and low-profile guideways with small spatial footprints.
       But how can PRT replace cars if the rail doesn't go to your house? PRT is not a panacea; the goal is not to replace the car. PRT has been designed to be convenient Transit suitable for many kinds of travel. Think about what kind of trips you usually take by car, bus or train: it's often the rush hour commute, just you and a briefcase or pack. And maybe you even have to transfer along the way, or sit in stop & go traffic.
      Under PRT, every location in the service area would be within easy walking distance of a station— access would just be a quick walk down the street. So in addition to your commute, it would be just as easy to take PRT to the movies, restaurants or events, anywhere in town (—that is, attracting a larger variety of journey types). This would reduce the number of occasions when people would need to drive.
      PRT could even be used as a convenient way to reach light rail and intercity rail stations—helping the overall Transit network function better.
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Sounds like chaos-- won't all those little cars run into each other?

Quite simply: No. No head-on collisions, because each square (or "loop") in the network grid allows travel in only one direction. However, the loops are all connected, allowing PRT vehicles to pass from loop to loop, reaching any station in any part of the grid network [ visualize it ].  No rear-end or merging collisions, because the vehicles are not operating independently. All are communicating with a central computer system that keeps tabs on traffic throughout the network. In principal it works like this: Cars continuously report their positions, and the central computer system tracks their location; the two sets of data are continuously compared. If a vehicle does something it's not supposed to do (such as follow too close, stop unexpectedly, a mechanical breakdown, or even if the vehicle's reporting signal is interrupted), the central system will send commands to fix or avoid problems-- "deccelerate for 3 seconds", for example. This system is always in operation, ensuring safe distances between vehicles whether on straightaways or at junctions.
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What would PRT stations look like?

Stations would be very small, and located off-line on sidings so that stopped vehicles don't get in the way of vehicles going to other stations. The boarding-unboarding area would be at the same height as the guideway, usually about 16 ft. above ground (although some systems also envision placing some guideway in exclusive right of ways at ground level or underground). Stations would have as many berths as arrival-departure demand calls for, so they could be larger in a city's major activity centers. Thus in areas of lesser demand stations might have only one berth, the entire station probably being smaller than a house. Stations could even be integrated into buildings and sports arenas. Station placement is very flexible due to the onboard switches described above, enabling guideway at diverge points to have much shorter turn radii than conventional rail or monorail. Thus, PRT can do things like sharp turns off the main line into a station. [ See a photo album of a scale model PRT station ]
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Hold on, what ABOUT big buildings and stadiums: how could small stations possibly handle the crowds?

Large stations are required for trains because: (1) the platforms must be as long as the longest train; (2) trains must be full to run efficiently, so schedules dictate that large numbers of people must arrive and depart all at the same time; (3) crowding is made worse by total ridership being divided among relatively few stations, each serving population from many square miles as well as people waiting to transfer to and from buses and trains; scheduling means trains actually don't depart very often, once every 10 minutes is only six trains per hour-- even once every 5 minutes is only 12 departures; (4) acres of parking or garages are needed for park-and-riders.
      None of these drawbacks apply to PRT. Vehicles are small, 8-12 feet long. Huge waiting areas aren't needed because service is on-demand, people don't arrive at the station at the same time and don't have to assemble in large groups. Even if the PRT station is part of a stadium, office building or shopping mall, people don't come and go all at once, but over a period of time; by picking up and dropping off riders all the time, PRT doesn't let crowds build up.1 People can get in a PRT pod and depart at a clip of several per berth per minute-- 4 per minute means 240 times an hour (if 3-seat vehicles, the capacity of a 3-berth PRT station could be 720 per hour, and so on).
      Finally, by distributing service across a broad area, PRT also distributes demand. Instead of channeling all riders into a few huge stations, there would be 4-6 PRT stations per square mile. In a city the size of Seattle there might be 300 PRT stations, each one serving only those coming or going in the immediate vicinity, usually walking distance. Learn more
What about heavily-traveled corridors like freeways? PRT couldn't handle the same volume as trains or buses. PRT actually has higher capacity on a head-to-head comparison. A single PRT line could convey 7200 vehicles per hour at half-second headways (25.6 ft. vehicle separation at 35 mph), or 21,600 people if each vehicle has three passengers. Compare to express bus service: by mid-2007, ST Express averaged only 28 boardings per trip.

1. Simulation data for the proposed Cincinnati PRT network: 78 minutes on a Friday evening, prior to a ballgame at Cinergy Field. Average wait is 0 - 2.09 minutes, 0.94 minutes (56 seconds) for the entire system. Even at the station with the most people (21) waiting, the average wait is only 106 seconds.
      Two 15-berth stations at a stadium could transport fans at a rate of over 10,000 in a half hour-- and it would take them to stations closest to their homes. A train would merely drop them at a few stations, they would still have to drive or bus to get home.
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Stations every half-mile? Where will we find room for them, and all the guideway? Won't it be too expensive?

The size, or "footprint", of PRT stations will be small-- because PRT service is on-demand and crowds do not accumulate, huge waiting areas are not required. Some residential areas might only require a station large enough to contain stairs and ADA-compliant elevator, ticket-buying area, and a single vehicle berth. This small size and the economies of scale of a standard, modular design make the number of stations feasible. One strategy might be to add PRT stations onto already-existing public uses, such as fire stations, branch libraries, parks, schools, police stations, etc.
      Typical costs range from $16 to 24 million per guideway mile, including stations and siding.

Is it realistic to have that many stations, that close together?

Close station spacing is common in the world's best subway systems. The New York City MTA has 469 stations, an average of 2,745 feet apart. The Paris Metro has 300 stations, an average of 1,845 feet apart. These translate into maximum average walking distances of 1,373 and 923 feet respectively
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Would people be willing to ride around in a closed, computer-controlled car?

Well... they ride in elevators, don't they? PRT is essentially a system of horizontal EXPRESS elevators. There's little or no wait, you get on, you go straight to where you want to go, you get off. What could be easier?
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Wouldn't PRT be scary to ride, like a roller coaster?

Rollercoasters are scary not because they are small and fast, but because they twist, turn, climb and dive. Imagine a rollercoaster which traveled only in straight lines and gentle turns, and accelerated and braked like a carefully driven car. That wouldn't be scary at all, would it?
      PRT riders are always sitting down—no more standing up on a lurching Transit vehicle! Comfortable limits on acceleration and deceleration are programmed into the control system, and seatbelts are provided for an extra sense of security. One company even includes a dashboard airbag.

[ Example Components List ]
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Can a person in a wheelchair use PRT?

Skyweb Express, Taxi 2000

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What if the first available vehicle has litter, or smells, or has been vandalized?

Good PRT designs include a "Reject" option, a button which will send the vehicle to the central maintenance center and at the same time summon a fresh vehicle for you. Technology to deter other forms of mischief, that are already in use around us everyday, have been incorporated into some or all PRT designs: for instance, video cameras in vehicles, cameras in stations, and two-way voice intercoms. Moreover, if a "smartcard" fare system is used, promptly reported acts of vandalism can be traced back to the perpetrators. Note also that critical vehicle systems are underneath the passenger compartment, inaccessible to the public, and are monitored-- a car is never dispatched which is mechanically unsafe.
      What about comfort? The interiors will be attractive and comfortable but easily cleaned and repaired, comparable to the materials used in buses and light rail.
       Makers with designs at the advanced stage have incorporated air conditioning and heating units into their PRT vehicles. The necessary equipment is common, like that used in automobiles, and lightweight, adding less than 50 pounds to total vehicle weight. Example: Components List, Taxi 2000.

"Masdar City Peoplemover" (CyberCab) 2getthere
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Do I have to share the pod?

Only if you want to, and everyone is going to the one destination encoded on the ticket. You don't have to wait for others—not because they're strangers, but because of on-demand service (like elevators). The odds of another person needing to go to the same destination as you, leaving at precisely the same time, is extremely low.
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Then doesn't PRT discourage social/civic interaction?

You may choose to ride PRT alone if that is most convenient for you, but that doesn't mean it is socially isolating. It seems to be human nature for strangers not to socialize on transit under normal conditions, so the time on PRT wouldn't cause a decrease in meaningful social interaction--especially since it is nonstop, so we expect much less time would be spent riding it. Plus, nothing stops people from sharing a PRT ride, as long as they're all going to the same place at the same time.
       By using nonstop, express Transit service, imagine the time you will save to spend with family, friends, or at a community meeting.
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Isn't it unsafe? Couldn't a criminal jump in with me?

All pods will be equipped with a panic button to alert the central control center. It could even be programmed to reroute the trip to the nearest police station. In addition, there are design choices and service characteristics making loitering in a PRT vehicle or station difficult. But the bottom line is that a criminal wouldn't WANT to hijack a PRT trip. He wouldn't know where he was going, and could change that only by hitting the panic button. But couldn't terrorists use PRT to send bombs? ALL public and private transportation are susceptible to terrorism to varying degrees. PRT could employ the same security methods, as well as something unique to prevent unmanned travel: a Go button inside the vehicle that must be pressed, after the door closes, before a journey can begin.

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Aren't fixed rail systems less flexible? Wouldn't we be better served by improving bus service?

Fixed rail systems are inflexible only if they don't reach many areas. High cost means it is not affordable to build enough light rail or monorail to serve all parts of a city. A bus system would continue to be caught in traffic congestion, would continue to use timetables and require waiting, would still be slow due to frequent stops, would reduce or stop service late at night, would still require transfers, etc.
       By being relatively inexpensive to construct, it is financially feasible to build a city-wide PRT network reaching all districts desiring service. And because PRT has small dimensions, the visual impact of the elevated guideway will not be significant.
      If you're against buses and trains you're anti-transit! Are you part of the highway lobby? The T in PRT stands for Transit. PRT retains the best features of Transit (public shared vehicles, low fares, accessibility), while jettisoning the negatives: waiting, missing your bus or train, slowness due to frequent stops, transfers, etc. PRT's superior features will attract more riders and increase Transit's share of total travel—keeping congestion from getting worse, or even reducing it. Therefore additional highways would not be needed.
       At the same time, PRT doesn't have to be your only Transit, it can also work with the other modes your city already has. PRT can help that system attract more riders. Due to high cost, limited rights of way and geographic obstacles such as steep hills, light rail and streetcars in most cases cannot reach every neighborhood (especially true in cities that have installed starter rail lines only recently). The lower capital cost and smaller physical profile of PRT means it can reach those unserved areas and connect them to the light rail corridor. In such instances, PRT would provide local circulation Transit service and serve as a collector-distributor for rail. [ How the European Union and Sweden plan to use PRT. ]

Three ways to PRT:

Small PRT networks for local circulator Transit, congestion relief, or in anticipation of future density Transit service to and from rail stations Circulators linked together, forming a citywide network
©2005 Get On Board! Personal Rapid Transit and GetThereFast.org
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Is there anything like PRT now?

Yes! The West Virginia University at Morgantown has had an early version, still called "The PRT," since 1975.

Back in the early 1970s the Federal Government commissioned this system, built by Boeing. The Morgantown system is perhaps better characterized as a 'first generation' or 'Version 1.0' PRT because the vehicles are large, with 8 seats and room for 13 standees. Therefore, many prefer the term Group Rapid Transit (GRT). In addition, the guideways had to be larger than today's 21st century PRT designs because the big vehicles weigh 8,700 lbs. empty. But it proved the feasibility of circulating automated vehicles on a guideway network—even with mid-1970s computers.

"The PRT" is still in operation today and has an impeccable safety record. Learn more

[ PRT guideway passing over University Street ] External link

WVU Campus Tour

"WVU Minute" video at wvu.edu; Same video at YouTube

PRT Journey (YouTube) - 1 | 2 | 3

Morgantown PRT (Wikipedia)

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