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(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.
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.
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.
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).
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.
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'
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."
Can small PRT pods really be a MASS Transit system?
Yesjust 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.
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
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
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.
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.
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 ]
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
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.
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.
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
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?
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?
Can a person in a wheelchair use PRT?
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.
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 othersnot 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.
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.
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.
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.
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 networkeven with mid-1970s computers.
"The PRT" is still in operation today and has an impeccable
safety record. Learn more
Morgantown PRT (Wikipedia)