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Old June 10th, 2008, 04:08 PM   #21
thatchio
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As for the stations, unless they are integrated into buildings, they will take up a lot of overhead space. I also imagine that building out stations would be expensive (system-wide) due to the nature of PRT. PRT is about flexibility of your trip, being able to go from one station to any other as directly as possible. That means there should be a lot of stations to pick from. Each station would need an elevator to allow for wheelchair, stroller, etc. access. That takes up valuable room and costs a lot. Granted, it's a no different situation than elevated rail or subway other than the number of stations.

Another oddity is that the Minneapolis model that was suggested was a series of one way loops that were about half a mile to a mile a part. It struck me as odd to think that if people wanted to go a mile south they may have to ride north, east, and south, and then west to their location...likely going 2 miles to get there. Then again, they should have just walked to begin with.
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Old June 10th, 2008, 10:14 PM   #22
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Quote:
Originally Posted by UrbanBen View Post
PRT headways have been projected to go down to 1.0 seconds for fifty years. The problem isn't the technology, it's that a fully automated control system *does* go down eventually, and none of the PRT companies have actually managed to accept that and plan for it - so 1 second simply isn't safe.
I'm a full-time employee for ATS, makers of the ULTra Heathrow PRT system. I would agree that building a reliable control system is a significant effort. PRT vendors do have to plan for control system failures. We have to make a strong argument that our solutions will work, or else we would not be able to obtain insurance or regulatory safety approvals. Our solutions take a number of approaches, including redundant design.

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- New guideway is not cheap. PRT has to be elevated for it to be automated, which means you have to buy right of way and sink columns. PRT vehicles are lighter than LRT, so you get a small cost savings from having a physically smaller structure, but most of the costs are the same.
Elevated guideway cost is a function of vehicle weight squared. Our vehicles are lightweight, so our guideway is inexpensive. I am using actual Heathrow costs to make this claim - I am not using cost estimates.

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- Station on/offs take longer than on fixed route, due to station selection and what have you, as well as the unhurried nature of personal systems. This drastically limits the capacity of any given "bay", making the number of bays at a station much higher, and increasing right of way costs.
Station capacity per berth is high. Be sure to see the ULTra diagonal berth operation in the youtube video in the first thread post. Diagonal berths increase capacity. A two-berth PRT station can serve 300 vehicles per hour, a twelve-berth PRT station can serve 1,300 vehicles per hour

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- In a situation in which the tax recovery is possible for PRT, and the political will exists for transit, LRT will be cheaper and serve more people.
It's a bit difficult to generalize about transit project funding. PRT enjoys a very high level-of-service, so is competitive with private auto travel. For Heathrow, BAA considered all transit technologies and chose PRT. For Masdar City, all transit technologies were considered and both PRT and mass transit won - other parts of Dubai have LRT.

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Sorry. Peter Calthorpe is an urban planner, not an engineer, and he likes anything that can help promote his low-density "new regionalism". He's eschewed economics in favor of style, and while I applaud that, in practice things turn out differently.
At the last Calthorpe-led public meeting I attended a few months back, Calthorpe advocated 10 story buildings in a two-story area. Even his oldest projects produce more density compared to adjacent areas. I think you should take a second look at Calthorpe.

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ULTra is a 25mph rubber tire system, and can't scale to anything more than connecting a parking garage to a few terminals. PRT advocates are going to keep going along talking about how great their system is and not understanding why politicians don't choose them. They're great for airports, but the points I've made above are the real reasons we don't choose them for urban areas. Those points aren't going to change, because they're inherent to the personal nature of PRT. We build mass transit because personal vehicle storage and right of way (parking and highways) severely limit growth, and PRT doesn't scale well.
Masdar City PRT is an urban application connecting to mass transit. I prefer the use of PRT as a complement to other forms of transit. There's plenty of market out there for all transit modes. PRT is going to follow an "adoption curve" just like other new technologies. Politicians don't choose new technologies for various good reasons, but new technologies still get adopted. In 1888, the electric trolley was a very risky idea. By 1905, it was the dominant mode of transit.
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Old June 11th, 2008, 02:05 AM   #23
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Elevated guideway cost is nothing of the sort. In addition, you're basically ignoring my points. You sound like the Seattle Monorail Project staff sounded...
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Old June 11th, 2008, 03:09 AM   #24
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too many variables to work out, with the first and formost being maintinance and what happens when one of these break down in the middle of the path.

not gonna fly, ever. In the next three decades that is.
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Old June 11th, 2008, 03:57 AM   #25
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The Light Rail Now website features a fairly virulent attack on PRT:

http://www.lightrailnow.org/facts/fa_prt001.htm

About the WVU system, Light Rail Now states the following:

"Originally estimated at $14 million by Prof. Samy E. G. Elias, an engineering professor at WVU and a major advocate of PRT technology, in the end the WVU system, 3.6 miles end-to-end with 8.7 total miles of guideway and 5 stations, cost over $126 million (as of 1979) – about $319 million in 2004 dollars."

This is only $89 million per mile, which is actually quite competitive with light rail. Some light rail lines are actually substantially more expensive. For instance, the initial 13.9 miles of the Central Link light rail line presently under construction in Seattle will cost $2.44 billion, or about $176 million per mile. The daily ridership of the WVU PRT is about 16,000, which is quite remarkable for a line that is just 3.6 miles in length.

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Old June 11th, 2008, 06:07 AM   #26
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ah, greg_christine, how did I know you'd weigh in?

$89m per mile not including right of way costs. WVU built this on property they already owned.

$89m per mile with no tunneling - which has nothing to do with the system, rather the terrain.

You are seriously the king of completely flawed comparisons. From the costs you've quoted (and as usual, although I see you've made some effort, you're not comparing dollars from the same year), this system would cost quite a bit more than Link - especially per passenger mile.

Last edited by UrbanBen; June 11th, 2008 at 06:14 AM.
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Old June 11th, 2008, 03:04 PM   #27
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I try to imagine what the WVU PRT system would have looked like if they had tried to build it as light rail. Tunnels might have been necessary as the maximum grade of 10% is well above the grades for which modern light rail systems are designed. The steep grade is enabled by the use of rubber-tired vehicles and a heating system that prevents the formation of ice on the guideway.

The high ridership of the WVU PRT is due in part to the rapid response of the system. The typical wait times of 10 to 15 minutes seen on most light rail systems would have been longer than the typical ride time on the WVU PRT.

The WVU PRT was one of the first peoplemover systems. Many aspects of the system are similar to the peoplemover systems now seen at large airports around the world. Two features that are common to all these systems is that they operate at close headways and they are completely automated with no onboard staff. Peoplemover systems such as VAL are now seen in urban transit applications. I am not aware of any conventional rail vehicles with human drivers being used in airport peoplemover applications.
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Old June 11th, 2008, 05:43 PM   #28
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Quote:
Originally Posted by greg_christine View Post
I try to imagine what the WVU PRT system would have looked like if they had tried to build it as light rail. Tunnels might have been necessary as the maximum grade of 10% is well above the grades for which modern light rail systems are designed. The steep grade is enabled by the use of rubber-tired vehicles and a heating system that prevents the formation of ice on the guideway.

The high ridership of the WVU PRT is due in part to the rapid response of the system. The typical wait times of 10 to 15 minutes seen on most light rail systems would have been longer than the typical ride time on the WVU PRT.

The WVU PRT was one of the first peoplemover systems. Many aspects of the system are similar to the peoplemover systems now seen at large airports around the world. Two features that are common to all these systems is that they operate at close headways and they are completely automated with no onboard staff. Peoplemover systems such as VAL are now seen in urban transit applications. I am not aware of any conventional rail vehicles with human drivers being used in airport peoplemover applications.
Instead of "trying to imagine", I looked at it. The 10% grade is only necessary because the lower station is at-grade. If the lower station was elevated, the grade between them would be less than 7%.

Which brings me to an interesting point. Before, when we talked about costs, I assumed that Morgantown's line was entirely elevated. It's not! It's 35% at-grade. So per mile, it's even less cost effective than I thought.

You guys have fun over here. Someday, perhaps, you'll realize that you can get something done if you don't decide you have to do it differently.
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Old June 12th, 2008, 12:47 AM   #29
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Quote:
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... The 10% grade is only necessary because the lower station is at-grade. If the lower station was elevated, the grade between them would be less than 7%.

...
Yes, if the grade had to be limited to 7%, the engineering of the line would have been more elaborate and the cost would have been higher. The ability of the rubber-tired vehicles to climb steeper grades simplified the design of the line and reduced the construction cost.
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Old June 12th, 2008, 03:44 AM   #30
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Yes, if the grade had to be limited to 7%, the engineering of the line would have been more elaborate and the cost would have been higher. The ability of the rubber-tired vehicles to climb steeper grades simplified the design of the line and reduced the construction cost.
Reduced the construction cost to something closer to the cost of light rail, you mean?
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Old June 12th, 2008, 02:50 PM   #31
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Light rail can be constructed cost effectively where there is an existing at-grade corridor that can be exploited. The existing corridor can be an abandoned rail corridor or the median of a highway or wide street. Where there is no such corridor available, tunnels and viaducts are required with the result that light rail costs as much as any other system.

Given the terrain along the route of the WVU PRT, light rail would not have been any cheaper to build. Additionally, the WVU PRT system offers significant advantages over light rail in that the wait times at stations are minimal and the vehicles are fully automated with no onboard staff.
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Old June 12th, 2008, 05:45 PM   #32
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An $89m/mile average for 65% elevated 35% at-grade without including right of way, especially in 2004 dollars, is absolutely not cost-competitive with a similar split in elevated/at-grade light rail construction. With the money left over, you could run trains every 5 minutes for decades.

You keep comparing to Link construction costs, but you keep your mouth shut when I point out that those costs include RIGHT OF WAY, and things like completely rebuilding adjacent roadway and major utilities, like the primary water mainline into the city of Seattle. It's dishonest. Stop being dishonest in your comparisons.
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Old June 12th, 2008, 07:32 PM   #33
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Quote:
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An $89m/mile average for 65% elevated 35% at-grade without including right of way, especially in 2004 dollars, is absolutely not cost-competitive with a similar split in elevated/at-grade light rail construction. With the money left over, you could run trains every 5 minutes for decades.

You keep comparing to Link construction costs, but you keep your mouth shut when I point out that those costs include RIGHT OF WAY, and things like completely rebuilding adjacent roadway and major utilities, like the primary water mainline into the city of Seattle. It's dishonest. Stop being dishonest in your comparisons.
As far as expensive ROW costs for elevated transit, could you please provide an example of high-cost ROW? In Indianapolis, for their large-vehicle, large-guideway cable-drawn Clarian people mover system, annual ROW cost is $5 per foot or $26,400 per mile.
“Clarian Health will pay the City an annual franchise fee in the form a ‘Linear Charge’ for each linear foot of public right-of-way that the system occupies on the first day of the period to which the payment relates. The initial linear charge will be $5.00 per foot and will be adjusted every five years by an amount equal to the rate of inflation.” From "Franchise Agreement with the City of Indianapolis: A New Approach to People Mover Implementation In American Cities," by Andrew S. Jakes.

For PRT, 18” diameter columns are usually placed every 60 feet, with one-meter cubed column foundations just below the surface.

As far as applying the per-mile costs for the Morgantown ground rapid transit system to current advanced transit systems, this is not appropriate. Morgantown was an Urban Mass Transit Administration DEMONSTRATION program. Cost was not a major consideration, whereas having the system ready in time for President Nixon to take a ride was a consideration.

A popular, peer-reviewed academic paper on the Morgantown system can be found here: http://www.cities21.org/morgantown_TRB_111504.pdf
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Old June 12th, 2008, 07:35 PM   #34
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The Heathrow PRT headway is something like 4 seconds. PRT headways are projected to go down to 1.0 seconds over time, creating higher capacity than you have calculated. On freeways, the headway between cars going 70 mph is about 0.6 seconds for fast-reflex drivers and 0.8 seconds for slower-reflex drivers. If you drive on a freeway with 1.0 second headway, then other cars cut in front of you.
The legally mandated headway for all car traffic here is 2 seconds (suggested 4 seconds in the wet and for heavier vehicles). If you travel 0.6 second headways and someone infront brakes, you will hit them, no fast reflex driver issues. It takes 0.5 seconds at least for you to even realise they've braked let alone react.

I can see this working for a secondary transport system the same way an elevator is a secondary transport system. A limited number of people a limited distance. Capacity issues are neither here nor there because if you had enough usage to require the frequent usage of multiple cars you might as well make it one bigger car as that would be far more efficient. Works great in places like Airport transfers where you have people that can't afford to wait for the next service but you might see a long time between people actually using the service so you don't need to run a larger service continually.

A city like Masdar would be testing the absolute capacity limit of such a system, and then only because most people wouldn't be using it.

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This is only $89 million per mile, which is actually quite competitive with light rail.
If you're competitive with light rail for a system that provides lower capacity you're doing something wrong, you should run it into the ground absolutely if you want to have a hope of winning. For instance here they're putting in a busway that's costing 1/6th as much as light rail and provides the same end capacity. That's 6:1 for the same ROW/Capacity/Grading and for most routes an increased performance over what light rail could deliver, as well as delivering sooner and allowing capacity to grow with demand. One of the advantages of rubber tyre vehicles is that you don't need to all leave single file and follow a track exactly, if one breaks down, and you've provided the ability to pass for the whole length (even if in some parts that involves slowing and using the other direction of roadway) you create a system pretty much immune to failure effecting more than the immediate area.

It's all fine to have a sytem that's a testbed or a university project, but when it comes to the real world, the cost effectiveness of the system counts over

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This is only $89 million per mile. The daily ridership of the WVU PRT is about 16,000
The cost of the busway here per distance was less than half of that (and that included tunnels, elevated sections and property resumptions in a major urban area), and it moves 15,000 people per HOUR in peak. Headway is less than 24 seconds, wait times for core routes is less than 5 minutes, and there are plenty of express routes in addition to that. Granted running costs are probably more, but people are looking at systems cost over 20-30 years, by the time you start to replace vehicles again.

The reality is PRT in 1-4 user vehicles is going to approach taxi's in terms of cost effectiveness for a citywide system, 10-20 user automated vehicles may have a chance in particular applications with sporadic use required at all hours. I'm sure it works great for airports and educational institutions, as well as fairly small networks, you're not going to do anything city wide with 1-4 user vehicles for a very very long time, you might as well have people take cars. Besides, many countries already have an obesity problem associated with people not doing enough activity, the last thing we want is to encourage everyone to be delivered within 10m of their door everwhere they go.

The irony is what will kill alot of PRTs won't be failure, it will be success to the extent that the system no longer has the spare capacity to expand. Anyway it's good these are getting built because nothing even has a chance at success without at least one commercial example that works far better than expected.
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Old June 13th, 2008, 12:38 AM   #35
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An $89m/mile average for 65% elevated 35% at-grade without including right of way, especially in 2004 dollars, is absolutely not cost-competitive with a similar split in elevated/at-grade light rail construction. With the money left over, you could run trains every 5 minutes for decades.

You keep comparing to Link construction costs, but you keep your mouth shut when I point out that those costs include RIGHT OF WAY, and things like completely rebuilding adjacent roadway and major utilities, like the primary water mainline into the city of Seattle. It's dishonest. Stop being dishonest in your comparisons.
Only a small portion of the $176 million per mile cost of Central Link is due to right of way acquisition. The main problem was that there was no existing right of way available for the project with the result that a new tunnel had to be built through Beacon Hill plus several miles of viaduct had to be built and some adjacent roads had to be rebuilt. The result was that Central Link light rail line is being built at a cost per mile higher than the recent Largo Town Center extension of the Washington Metro ($456 million / 3.1 miles = $147 million per mile).
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Old June 13th, 2008, 12:50 AM   #36
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...

The cost of the busway here per distance was less than half of that (and that included tunnels, elevated sections and property resumptions in a major urban area), and it moves 15,000 people per HOUR in peak. Headway is less than 24 seconds, wait times for core routes is less than 5 minutes, and there are plenty of express routes in addition to that. Granted running costs are probably more, but people are looking at systems cost over 20-30 years, by the time you start to replace vehicles again.

...
That light rail supporters are so sensitive to the idea that systems such as PRT and monorail can offer significant advantages is ironic given that the real threat to light rail these days is BRT. BRT systems in Brisbane, Jakarta, Curitiba, Bogota, Los Angeles (Orange Line), and many other cities have demonstrated that BRT can 1) attract large numbers of commuters to transit and 2) can be built at a fraction of the cost of rail systems.

I have seen light rail supporters on other forums agonizing over the fact that the light rail line being built in Norfolk, Virginia may be the last new light rail system started in the United States. Existing light rail systems continue to be expanded plus several cities are contemplating new streetcar lines; however, there does not appear to be any city in the United States with a credible effort to start a new light rail system.
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Old June 13th, 2008, 02:04 AM   #37
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Only a small portion of the $176 million per mile cost of Central Link is due to right of way acquisition. The main problem was that there was no existing right of way available for the project with the result that a new tunnel had to be built through Beacon Hill plus several miles of viaduct had to be built and some adjacent roads had to be rebuilt. The result was that Central Link light rail line is being built at a cost per mile higher than the recent Largo Town Center extension of the Washington Metro ($456 million / 3.1 miles = $147 million per mile).
That would be no different from PRT in the same corridor, or any other system. You're also trying to compare costs with a tunnel to costs without a tunnel, AGAIN. Stop using location-specific costs to mislead people about the difference between systems. Stop being dishonest.
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Old June 13th, 2008, 02:07 AM   #38
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That light rail supporters are so sensitive to the idea that systems such as PRT and monorail can offer significant advantages is ironic given that the real threat to light rail these days is BRT. BRT systems in Brisbane, Jakarta, Curitiba, Bogota, Los Angeles (Orange Line), and many other cities have demonstrated that BRT can 1) attract large numbers of commuters to transit and 2) can be built at a fraction of the cost of rail systems.

I have seen light rail supporters on other forums agonizing over the fact that the light rail line being built in Norfolk, Virginia may be the last new light rail system started in the United States. Existing light rail systems continue to be expanded plus several cities are contemplating new streetcar lines; however, there does not appear to be any city in the United States with a credible effort to start a new light rail system.
No one is seriously suggesting building BRT anywhere anymore. It's hardly a "threat" here on the west coast, with nearly $5/gallon diesel. King County Metro's "Rapid Ride BRT" service improvements simply disappeared - they're talking the talk, but adding no new service.
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Old June 13th, 2008, 02:40 AM   #39
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I am a newcomer here. I have an academic interest in PRT and I often comment on PRT-related threads.

There are many misconceptions about PRT technology and economics in the comments above. A few corrections:

1. Headways down to 1 second are more than feasible in an automated system. Sensor reaction times are on the order of a few hundred milliseconds, and anyone who understands checked-redundant systems knows that safety is simply a matter of good design. That's why European regulatory authorities have already approved 2.5 seconds and are willing to consider shorter headways with more real world testing.

In fact, there has been significant research on even shorter headways - J.E. Anderson has done extensive work at half-second separation. In his extensive analysis, he showed that the absolute worst case scenario (a tree falling on the guideway during rush hour, the so-called "brick wall stop") would not incur any fatalities in follower vehicles even at half second separation. His research involved extensive analysis of both PRT system dynamics and automotive impact testing. So one second is more than achievable today, and half second may be a realistic long term goal.

Consider: if a fully loaded semi runs a red light and collides with a bus or light rail train, dozens of passengers will likely suffer fatal impacts. So are they any safer than PRT at 1/2 second?

2. ULTra has real cost figures (~$15M/mi), and they compare quite favorably with most light rail installations. And if you consider grade-separated light rail, the savings are nearly an order of magnitude (how much is that Seattle light rail line per mile?)

Also, if you compare apples to apples, PRT cost/capacity ratio is as good as or better than rail:

- PRT, 2 second headway 1.2 per vehicle - $15M, capacity 1500pph
- PRT, 1 second headway 1.2 per vehicle - $30M, capacity 3000pph
- streetcar, 5 minute headway 100 per vehicle - $30M, capacity 1200pph
- grade separated light rail, 1 minute headway 150 per vehicle - $100M-$200M, capacity 9000pph
- metro rail, 1 minute headway, 600 per vehicle - $500M+, capacity 36000pph

Look at the costs per capacity, and PRT measures up quite well. Streetcar is $25000 per pph, grade separated light rail is $11,000 per pph; PRT is $10,000 per pph. If PRT is too expensive for the capacity it provides, then so is rail.

3. PRT is much more efficient to operate than rail even while providing more convenient and comprehensive service. True, rail may be a little more efficient for 2 hours a day when it is full, but for the rest of the day it is underutilized and much less efficient than PRT would be. On balance, PRT wins out in all but the most dense of cities (Manhattan), and even in those places, a complementary PRT network to augment the metro lines would cut operational costs.

The analogy I like to use is this: if milk is $3 per gallon and $2 per quart, the gallon seems to be a much better bargain. But if you only consume a pint per week and throw the rest away, the quart is better.

4. Buses may have small startup costs, but they run on fossil fuels and will therefore become more and more expensive to operate as oil prices skyrocket. A well designed PRT system will have a higher startup cost, but can make it up with greater energy efficiency and the use of cheaper grid power, which is less susceptible to oil price surges. And PRT does this while providing more convenient service to more areas with less waiting, no downtime, no transfers, and full disabled accessibility.


These are all indisputable facts. Whether the commenters above wish to believe them is their business, but it doesn't change the fact that these characteristics would make PRT the best transit option for many (not all, but many) urban problems.
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Old June 13th, 2008, 03:30 AM   #40
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Oh, god, here come the crazies. The moment anyone types PRT online, these same couple of people who Google for PRT every single day come and talk about how awesome it is.

Look at those ridiculous costs. $15m/mile? Yeah, RIGHT.
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