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Old June 18th, 2008, 09:19 AM   #101
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Quote:
Originally Posted by UrbanBen View Post
Er, Link light rail will have an average speed of 28mph (see the bottom of the second page, in the blue box). That's also with initial station dwell times, which will become lower as the system matures.
http://www.soundtransit.org/Document...ail_070718.pdf

The "average" across many systems doesn't matter. What's being built today? Link. If we're worried about average speed and we have the money to do it, we can build light rail like Link anywhere. If we don't have the money to do that, we don't have the money to build PRT, either.
Does the 28mph include transfers for those who don't live or work along the line? What is the average speed including transfers? For reference, the average speed of a mature ULTra network is 25mph including transfers (NB: a comprehensive PRT network wouldn't require any transfers).

How much is Link Light Rail costing per mile? It is more than the ~$15M per mile that ULTra projects? Are fares projected to cover operating costs?

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Originally Posted by UrbanBen View Post
I've never advocated highways and never will. The fact that you keep trying to pull arguments like that is hilarious. I advocate mass transit in various forms - subways, intercity rail, light rail, streetcars, buses in some situations - and bicycles, and of course trucks and cars for some circumstances, just not in the percentage of trips we use them today.
You mention pretty much everything but PRT - including cars. And earlier in this thread, you twice defended cars and highways when compared to PRT.

So is it safe to say then that you would prefer expanding the highway network to building a PRT network? If it came up for vote: PRT or highways, which would you choose, Ben?

Nevermind, I think I know the answer, and it's a very puzzling position for a so-called transit advocate to take.

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I'm sure 2 second headways are targeted.
No, Ben, ONE second headways are targeted. Longer headways will be used during the initial breaking in period; once there is a comfort level with those headways, they will come down.

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If there's no way to exit a vehicle in case of an emergency and walk to stairs, and it sure doesn't look like that for Heathrow, the FTA would consider it unsafe. I don't have an opinion - but they do.
There is an emergency exit on the vehicle.

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I guess you don't have any way to deal with the fact that the real estate costs and construction costs would be close to that of light rail, except that any high capacity stations would have to be much larger and more expensive than light rail to move the same number of people.
No, you're wrong. Daventry (UK) has studied city deployment of PRT in great detail, and they have quoted cost numbers similar to what ULTra claims. I'm sorry Ben, but your claim that PRT is expensive as link light rail simply does not hold water.

As for stations, PRT stations can go where they need to be, and they don't have to be high capacity because you can just add more stations if (and when, and where) you need them. E.g., 4 small stations spread out over an area rather than 1 huge one in the middle.

Contrast that with rail stations: they must be large, they must be located along the line, and that line must be located along the most dense corridors. Therefore, you are constrained to getting large swaths of land right in the middle of the most dense areas of the city.

PRT has none of these constraints. PRT stations are small and can be located almost anywhere, and can thus be positioned to minimize ROW costs. This combined with the miniscule footprint of PRT makes your ROW claims quite puzzling.


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SteveraneyC21, the employee of ULTra, said that "a twelve-berth PRT station can serve 1,300 vehicles per hour" - so with two people per PRT car, you get 2600 pph (and that has to serve both directions). Twelve berths is already a bigger footprint than a light rail platform. Link will carry 10,000 pphpd to and from Stadium station on game days in the first year of operation during peak times - that would require something like 50 berths!
PRT can have 6-8 smaller stations spread around the stadium instead of one big one. We've been over this before.
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Old June 19th, 2008, 03:29 AM   #102
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Er, construction costs for 6-8 stations as opposed to 1 station are higher, and you still have the real estate cost issue even when you split the station up, which is one of the fundamentals that kills PRT.

You can't address that, as I said. If you meet it head on, you have to accept that PRT can't serve urban centers - which makes it pointless, because those are the only places that will vote for transit.

When you talk about the "miniscule footprint" of PRT, you make the same mistake Seattle's monorail advocates did - you assume that aerial ROW costs less than at-grade. It doesn't. You also need more ROW for the same number of people, just because you want your system to be all-inclusive. You'd be talking about hundreds of billions of dollars to serve the same number of trips as a few billion for a light rail system - the cost of the guideway is a small portion of the overall cost when you're talking about radically different approaches as you are.

I love your assertions about me and highways. I write for the Seattle Transit Blog. I don't even have a driver's license, and I'm proud of it! I would never be put in a position to vote for that - I wouldn't make a mark for either!

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Old June 19th, 2008, 04:22 AM   #103
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No, Ben, ONE second headways are targeted. Longer headways will be used during the initial breaking in period; once there is a comfort level with those headways, they will come down.
What happens at crossings?

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PRT has none of these constraints. PRT stations are small and can be located almost anywhere, and can thus be positioned to minimize ROW costs. This combined with the miniscule footprint of PRT makes your ROW claims quite puzzling.
I am using a tram station existing in form of a sign only. I do not think PRT could beat that .

I am looking forward to the Masdar PRT. I think Masdar is about the size PRT could function (50.000). But I wonder how they move in without a car .
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Old June 19th, 2008, 05:39 AM   #104
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Regarding the design of PRT stations, the West Virginia University system has multiple routes or "channels" through the intermediate stations. Vehicles follow different routes through the stations and stop at different platforms depending on the direction from which they are arriving and their next destination. This is explained in the paper at the following link:

http://www.cities21.org/morgantown_TRB_111504.pdf
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Old June 19th, 2008, 06:12 AM   #105
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You're right, I hadn't thought about that! So even more right of way is necessary, for passing tracks!
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Old June 19th, 2008, 09:03 AM   #106
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Er, construction costs for 6-8 stations as opposed to 1 station are higher, and you still have the real estate cost issue even when you split the station up, which is one of the fundamentals that kills PRT.

You can't address that, as I said. If you meet it head on, you have to accept that PRT can't serve urban centers - which makes it pointless, because those are the only places that will vote for transit.
I have addressed it Ben, multiple times. You continue to compare apples and oranges. You quote Link numbers for capacity without mentioning Link's astronomical price tag that is an order of magnitude greater than PRT would be.

If you want to talk about less expensive street-level rail, capacities are going to be in the 2000-4000 pph range, right in line with PRT capacities.

If, on the other hand, you want to talk about elevated light rail at 12000pph, costs are much higher and stations look like this, or this, or this. That first station is the Sea-Tac airport station and will cost $95M - yes, $95 MILLION.

Let's compare the Sea-tac station to PRT. According to the Daventry PRT study, a 2-way elevated PRT station would cost $800,000 not including real-estate. Let's be ultra-conservative and assume a factor of 5 increase for real estate costs, that's $4M per station. Realize that this assumes $3.2M in real estate costs per station, for an elevated station that is a tiny fraction of the size of the equivalent elevated rail station, and which can be located just about anywhere (PRT is not limited to a line).

Even with that extremely conservative assumption, you can build 24 bidirectional elevated PRT stations for the price of that one Sea-Tac station. Again, your arguments are just spectacularly wrong.

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When you talk about the "miniscule footprint" of PRT, you make the same mistake Seattle's monorail advocates did - you assume that aerial ROW costs less than at-grade. It doesn't. You also need more ROW for the same number of people, just because you want your system to be all-inclusive. You'd be talking about hundreds of billions of dollars to serve the same number of trips as a few billion for a light rail system - the cost of the guideway is a small portion of the overall cost when you're talking about radically different approaches as you are.
This is positively absurd! Hundreds of billions? Are you serious Ben?

Allow me to illustrate the folly of your numbers. According to the Daventry study - which, by the way, was conducted by independent consultants - PRT is estimated to cost $28M for 1.67 miles, or around $17M/mile - including all vehicles, stations, and maintenance facilities. Let's again assume a factor of five error in cost estimates.

"Hundreds of billions" - I assume you meant at least $200B. $200B at $85M/mi comes to TWENTY FOUR HUNDRED miles of PRT. Just for some perspective, 2400 linear miles of PRT would cover an area of 20 miles by 60 miles with a PRT grid at 1.0 miles spacing - dense enough that there would never be a station further than 0.5 miles away from any given point.

Since we're comparing to Seattle here, sixty miles long is the distance from Everett to Lakewood, and 20 miles wide is downtown Seattle to Duvall. The entire Seattle/Tacoma area within 1/2 mile of a transit station - that's what you'd get for your $200B, even assuming a factor of 5 increase over estimated costs. And your claim is this would be no better than 20-odd miles of rail? Absurd.

See Ben, this is why I have so much trouble believing you are sincere. When you throw out ridiculous claims like "hundreds of billions", you prove how desperate you are to discredit this form of transit. Hundreds of billions? Ha! The real fact is that you love rail and will say just about anything to protect your preference. You did it with monorails and now you're doing it with PRT.

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I love your assertions about me and highways. I write for the Seattle Transit Blog. I don't even have a driver's license, and I'm proud of it! I would never be put in a position to vote for that - I wouldn't make a mark for either!
Of course you wouldn't vote for PRT, because you would rather have no transit at all if it means you have to accept something that doesn't fit your own preconceived notion of what transit should be. You are not pro-transit, you are pro-train.
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Old June 19th, 2008, 09:05 AM   #107
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You're right, I hadn't thought about that! So even more right of way is necessary, for passing tracks!
I guess that'll be another $200 billion, right Ben?
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Old June 19th, 2008, 12:02 PM   #108
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You're right, I hadn't thought about that! So even more right of way is necessary, for passing tracks!
To further underline the absurdity of comparing elevated rail stations to PRT stations, take a look at this article:

Sound Transit begins buying land for link to UW

The map shows an area where 19 parcels were purchased for one Link station. The area exceeds an entire city block, 300ft by 600ft total, and the acquisition will displace 44 business and 87 apartments. For one station!

Now, since you brought up Morgantown PRT, here is what one of their stations looks like. Now remember, this is a 40 year old system that is much bulkier than modern PRT.

The station in that photo is about 90ft by 50ft, or 4500 sq.ft., compared to 180,000 sq.ft. for the Link station. In keeping with our conservative estimates for PRT, let's say that a PRT station of that size can load 600 passengers per hour, and Link can load 12000. You'd need 20 PRT stations to equal the capacity of that one station. Total area: 20 * 4500 = 90,000 sq.ft. - half the area of the Link station.

But there's an even more important difference: the PRT stations come in bite-sized chunks of 4500 sq.ft. and can be spread out all around the area. To give you an idea of the importance of that fact: I counted at least a dozen parking lots within 3 blocks of that Link station location, and each of them could house an elevated PRT station while consuming no more than 4 or 5 parking spaces.

Many of those lots are much larger than 4500 sq. ft., so that larger stations could be put there. So PRT would likely provide equivalent (or even greater) service to that neighborhood without acquiring a single building or displacing a single resident, and the worst impact would be that the cars in the lots are parked in shade.

So tell me Ben, are you still going to claim that a PRT network would have the same real estate acquisition costs as elevated rail? Will you still claim that purchasing and demolishing an entire city block of buildings is no different than buying space over a dozen parking lots?

How many times do I have to completely debunk your points (using conservative assumptions no less) before you give up your campaign?
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Old June 19th, 2008, 06:53 PM   #109
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...you talk about apples to oranges, and then you compare the size of a construction staging area (from which we are launching a tunnel boring machine and extracting two others) to a station area? The Link station is actually going to be in chunks at ground level about the same size as your PRT stations, the rest of the space is only staging.

Check out "Capitol Hill Station neighborhood context", or the site plan, on this page:
http://www.soundtransit.org/x7757.xml

I don't need to give anything up. See, we're building light rail in Seattle. We're not building PRT, in fact, we're putting more light rail on the ballot, and now that the vote won't be weighed down with highway projects, we'll likely pass this year.

When will you give up your crusade? You try to explain away the real reasons PRT gets rejected by transit agencies. I mean, do you just think they're out to get you? What's your explanation?

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Old June 19th, 2008, 07:39 PM   #110
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...you talk about apples to oranges, and then you compare the size of a construction staging area (from which we are launching a tunnel boring machine and extracting two others) to a station area? The Link station is actually going to be in chunks at ground level about the same size as your PRT stations, the rest of the space is only staging.
OK, fine, I'm not going to quibble over minute details about one specific image, especially when I have so much more evidence that is more compelling. So let's strike that one from consideration.

Now, please explain the $95M price tag for the airport Link station, which would cost more than 100 elevated PRT stations, according to the indepedent consultants who studied PRT for Daventry.

And then, when you're done explaining that, explain to me how a dozen or so tiny 4500 sq.ft. PRT stations sprinkled about a neighborhood can possibly cost as much as the the 180,000 square foot acquisition of the city block at 10th Ave E & E Denny Way, which requires purchase and demolition of 19 separate parcels, displacing over 130 tenants (business and residential). Tell me how you could consider those two scenarios to be even within an order of magnitude of comparable.

Are you going to address these points, or ignore them like you always do?
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Old June 19th, 2008, 08:56 PM   #111
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You think an elevated PRT station would cost less than a million dollars? Really? Do you really not realize that just the ADA required elevator would cost more than that?

And then you go on to talk about the footprint of a completed station versus the footprint of a construction staging area, when I just pointed out to you that the footprint of the completed light rail station will be about the same as the footprint of your system...

I think this is fundamentally why you guys can't be taken seriously. Start comparing apples to apples, start looking at things head on, and your system would cost more to serve the same number of people in the same corridors. The only way you can argue otherwise is to make arguments like "SEE? My elevated system costs less than your tunnel!" - when of course, political realities would prevent an elevated system through a dense residential area. Or "SEE? My system costs less per mile!" - when you're talking about building many times the amount of guideway to carry the same number of passengers. But that's not convenient for you.

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Old June 19th, 2008, 10:06 PM   #112
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Something else that's just a fundamental problem - the reason urban areas really happen, the reason density happens, is pedestrian. When you're talking about putting a little station on every streetcorner, you end up preventing a lot of the interaction that creates innovation and development. I think a decent city planner would shoot this down out of hand because it exacerbates the isolation problem that cars already create in cities.

Oh, yeah, and I was thinking more about your 25mph issue. Because a bunch of our heaviest load stops are going to be the University of Washington stop and the GIANT CAPITOL HILL STATION (and we're going to see a lot of trips just between those stops), you have a much higher average - 37 or 40mph - as you're not including any of the 35mph top speed sections in south Seattle.

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Old June 19th, 2008, 11:01 PM   #113
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You think an elevated PRT station would cost less than a million dollars? Really? Do you really not realize that just the ADA required elevator would cost more than that?
OK, Ben. Multiply the PRT station by 5 if you want, even though that was an independent consultant's estimate and I'm inclined to believe them over you. But fine, I'll play along.

So, say $4M per PRT station - that's still 20 PRT stations for the same cost as the Link airport station. You arguments are still completely baseless.

By the way, I support any transit project, including Link. I only oppose your completely ridiculous claims that PRT would cost one hundred times more. My comments about Link are only intended to point out the folly of your arguments.

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And then you go on to talk about the footprint of a completed station versus the footprint of a construction staging area, when I just pointed out to you that the footprint of the completed light rail station will be about the same as the footprint of your system...
Then please explain to me: why is Sound Transit acquiring 180,000 square foot swaths of land if it only intends to use 1/40th of it (which is what PRT uses - 180k vs 4.8k)? Maybe I'm completely missing something, so please explain it to me.


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I think this is fundamentally why you guys can't be taken seriously. Start comparing apples to apples, start looking at things head on, and your system would cost more to serve the same number of people in the same corridors.
See above. Please explain how you can say $95M stations and 180,000 square foot land acquisitions are less expensive than PRT multiplied by a factor of TEN to account for capacity differences. I'm sorry, Ben, but when I see PRT stations that are 1/40th the size of Sound Transit's land acquisiton, and reliable cost estimates that are 1/100th the cost of Sound Transit's station, even an order of magnitude increase in PRT infrastructure is not enough to close the gap. Now I've cited reliable sources for all my numbers here; please tell me which of those sources is wrong and why.


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The only way you can argue otherwise is to make arguments like "SEE? My elevated system costs less than your tunnel!" - when of course, political realities would prevent an elevated system through a dense residential area. Or "SEE? My system costs less per mile!" - when you're talking about building many times the amount of guideway. But that's not convenient for you.
Here are some convenient numbers for you Ben: Sound Transit acquired land big enough to hold 40 PRTs stations, for construction of one Link station, and is paying 20-40 times more for the airport link station than even the most conservative third party station estimates for PRT.

That's a factor of 20-40 times more cost for Link over PRT; now, is Link 20-40 times higher capacity than PRT? Answer: no, absolutely not, unless link can run at 100k-200k pph.

Therefore, there is absolutely no basis for your repeated claim that Link is more efficient in terms of space or cost. According to all the sources I cited, it's quite the opposite.

Do you dispute these numbers? If so, please explain why because they're clearly well sourced.

(One more thing: are you really talking about political realities of elevated transit while Link is forcibly displacing hundreds of people from their homes? Now that's the ultimate irony. )

Last edited by TransportEnthusiast; June 19th, 2008 at 11:05 PM. Reason: political realities
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Old June 20th, 2008, 01:56 AM   #114
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Just to show you a light rail station:

Where is it?



The other direction:



It just shows how flexible you can use light rail in existing cities. Outside of the center the light rail has a seperated track for faster service. I do not think PRT can deliver this yet (except you ban all cars in the center).
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Old June 20th, 2008, 03:05 AM   #115
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It just shows how flexible you can use light rail in existing cities. Outside of the center the light rail has a seperated track for faster service. I do not think PRT can deliver this yet (except you ban all cars in the center).
Wonwiin, those are street level light rail, which has nowhere near the capacity of a separated grade rail line.

So Ben is comparing apples to oranges - when he talks capacity he references Link at 12000 pph and demands 6 times more PRT lines to match that capacity. Then when he talks cost and ROW, he shows street level rail with its street level stations, without mentioning the fact that those kinds of systems don't even approach 3000pph typically.

Apples:
street level rail vs PRT 1-to-1. Street-level rail is maybe $40-50M/mile, has small stations and will move ~1500-3000 pph. PRT is ~$20M/mi including stations and vehicles, and will move ~2000 pph; no real difference here.
Oranges:
grade-separated rail vs PRT multiplied by 6. Grade separated rail is $150-200M/mi and requires large 180,000 sq.ft. stations; for PRT, there would be 6-10 times more PRT lines required to match that capacity, so PRT would be $120-200M/mile including many more stations that would add up to a total area of significantly less than 180,000 sq. ft. - again, no real difference except that the stations would be much less impact for PRT
The point: all rail lines are not created equally. Ben wants to compare PRT to Link for capacity (ignoring cost differential), but compare PRT to streetcars for impact (ignoring that streetcars have much less capacity). Apples to oranges.

When you truly compare apples to apples, as I did above, PRT fares very well, and will probably be as (or even more) efficient in terms of impact and cost per capacity - even while providing much better long term service (nonstop, no transfers, 24x7 service, reduced travel time, closer stations, more destinations, always a seat, accessible, bicycle-friendly, etc etc). But you have to consider apples to apples.

As for station impact, PRT stations can be extremely lightweight if you consider they don't have to be on the street. They can be inside buildings, in an alley next to the main street, or one street down from the main street.

Or consider this: there is almost always parking in cities, even the most dense. PRT stations could easily go over an open air parking lot or (more likely) attached to the side of a parking garage. For places too aesthetically sensitive even for parking, PRT might be a poor choice (streetcars, perhaps?), but those locations are rare. I never said PRT was the only choice (I endorsed Link earlier).
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Old June 20th, 2008, 05:15 AM   #116
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Wonwiin, those are street level light rail, which has nowhere near the capacity of a separated grade rail line.
Actually it is combined. In the city center there is most of the time no space for grade seperation but whenever possible, they seperate the track from the street. The most modern trams can transport 220 passengers. That moves about 1500 - 3000 pph as you have said.

Quote:
Apples:
street level rail vs PRT 1-to-1. Street-level rail is maybe $40-50M/mile, has small stations and will move ~1500-3000 pph. PRT is ~$20M/mi including stations and vehicles, and will move ~2000 pph; no real difference here.
I have looked for the cost of new light rail projects in Munich (the city where the station is located): from about 30 mio € to 50 mio € for 4 kilometers (including a nice bridge for the 50 mio €). That comes to about 10 to 20 mio € per mile. Not included is the rolling stock. One tram costs about 4 mio €.


Quote:
The point: all rail lines are not created equally. Ben wants to compare PRT to Link for capacity (ignoring cost differential), but compare PRT to streetcars for impact (ignoring that streetcars have much less capacity). Apples to oranges.
I think it is really difficult to compare even light rail to light rail projects because every city has its own priorities and therefore the costs can be very different. Alone geography (necessity for bridges, tunnels, etc.) can double costs.


Quote:
As for station impact, PRT stations can be extremely lightweight if you consider they don't have to be on the street. They can be inside buildings, in an alley next to the main street, or one street down from the main street.

Or consider this: there is almost always parking in cities, even the most dense. PRT stations could easily go over an open air parking lot or (more likely) attached to the side of a parking garage. For places too aesthetically sensitive even for parking, PRT might be a poor choice (streetcars, perhaps?), but those locations are rare. I never said PRT was the only choice (I endorsed Link earlier).
You will not find many open air parking lots in an european city center. To much houses around. They are very different from north american city centers. (And they are historic. And full of nimbys. And mayors ride bikes. And are comedians. And do not like the transrapid. )

Street level light rail is the perfect link between buses and the metro. It has more capacity than buses but can be embedded in the existing infrastructure. The "suburbs", the towns and villages around Munich, are served by the S-Bahn, a commuter train providing fast service to the city center. Would one system be missing the public transport in Munich would really suffer. The combination and integration of different systems seems to be the way to a good public transport system. And PRT can play a part, but propably never in an european city center. It can't easily be embedded into the street (yet) and going underground is propably way to expensive for the transport capacity.

Another thought:
Maybe being similar to a car may provide an image problem for PRT in the form of "It is not mass transit so it is a plaything for rich people". Are fares higher than for normal mass transit?

---------

Some trivia I found about the Munich system:
Average speed: metro 36.7 km/h, tram 20.2 km/h, bus 18.1 km/h.

Building cost for the metro till now (about 100 km): 4.181 billion € (first openend 1971, so most investments are propably not priced in todays €)
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Old June 20th, 2008, 06:56 AM   #117
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Originally Posted by wonwiin View Post
Actually it is combined. In the city center there is most of the time no space for grade seperation but whenever possible, they seperate the track from the street. The most modern trams can transport 220 passengers. That moves about 1500 - 3000 pph as you have said.
Right. But any line-oriented system that has both elevated and at-grade sections will be capacity-limited by the at-grade line. The elevated sections may run at higher speed, but there is no capacity benefit. Only fully grade separated rail lines can run large trains at frequencies necessary for 10k pph and above.

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Originally Posted by wonwiin View Post
You will not find many open air parking lots in an european city center. To much houses around. They are very different from north american city centers. (And they are historic. And full of nimbys. And mayors ride bikes. And are comedians. And do not like the transrapid. )
Yes, Europe would seem to be less friendly to PRT, but ironically it is Europe which has taken the lead in PRT development (UK, Sweden, Poland).

Quote:
Originally Posted by wonwiin View Post
The combination and integration of different systems seems to be the way to a good public transport system. And PRT can play a part, but propably never in an european city center. It can't easily be embedded into the street (yet) and going underground is propably way to expensive for the transport capacity.
This is pretty much the view of most PRT advocates these days (myself included). PRT designers are generally targeting medium-high density or lower as an exclusive system, or as feeders for high-density metros.

My problem is mainly with people who spread misinformation about PRT, like "PRT would cost hundreds of billions of dollars". That's just pure hyperbole which taints the entire debate. I will always react strongly when someone makes such ridiculous claims (not you, of course, but others on this thread).

These are the facts: PRT construction costs would be competitive with light rail at equivalent capacities; PRT operating costs would be lower than both light rail and buses; PRT passenger service would be much better than both; but, there are places where streetcars or buses might be preferred (e.g. the aesthetically sensitive city center). With those facts in mind, people can make intelligent judgements about the best mixed-mode solution for cities.

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Originally Posted by wonwiin View Post
Another thought:
Maybe being similar to a car may provide an image problem for PRT in the form of "It is not mass transit so it is a plaything for rich people". Are fares higher than for normal mass transit?
No, absolutely not! That is one of the biggest misconceptions about PRT, that it would be inefficient in practice. In fact, fares can be lower for PRT, and fares can realistically cover operating costs. Most systems project break-even fares of $1.00 or less per vehicle-ride in a mature system (note: not per passenger-ride; extra passengers in a vehicle ride for free).

PRT can operate very efficiently because (a) it is very energy efficient due to lightweight design and non-stop service, (b) there are no driver costs, and (c) PRT is on-demand, so it doesn't waste energy moving empty up and down the line.

This last point is very important, because it goes to the fundamental benefit of on-demand vs scheduled transit: operational costs for on-demand systems are proportional to demand, whereas scheduled transit system costs are proportional to the schedule.

In other words, to maximize efficiency in buses and rail, schedules must be set to closely match the predicted demand; otherwise, those big vehicles will waste energy (and cost) running nearly empty with little or no farebox revenue to offset those costs.

But demand is inherently variable and unpredictable, so there is a fundamental tradeoff between cost efficiency and passenger service as transit planners adjust schedules to maximize the competing requirements of cost and service level. Generally, cost is what suffers in this tradeoff, as planners must provide a level of service that will attract passengers, even if that means very cost-ineffective service during non-peak times.

For PRT, vehicles don't move if there is no demand, and only move proportionally when there is demand, so there is no such tradeoff. That is how PRT can provide 24x7 on-demand service even while covering costs with fares.

All of this runs counter to our inherent belief that bigger must be more efficient, so people have a difficult time believing PRT's break-even projections. What they don't get is that bigger may be a little better during the 3 hours of peak travel, but it is significantly worse for the other 21 hours of non-peak; and the overall balance favors PRT.

My analogy is: let's say milk is $3 per gallon or $2 per quart; the gallon is a better buy per unit, but if you only consume less than a quart per week, the quart is more cost-effective. Trains may be more efficient per seat, but if those seats are empty for 85% of the vehicle's total travel time, PRT is more efficient.
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Old June 20th, 2008, 08:07 AM   #118
UrbanBen
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I'm sorry, but you're just talking past me. You can't seem to grasp what I'm saying, you just keep repeating the same things. It doesn't fix your problem.

You have all sorts of misunderstandings. In your last comment, you said that the at-grade portion of a line limits the whole thing. That's not true at all - there are lots of lines where the system only goes at-grade farther out of the city, and many trains turn around closer in. With Seattle's East Link project, we'll interline more trains per hour in the downtown core, but those trains will run to Bellevue instead of running in the at-grade portion of Link south of downtown.

You make a lot of theoretical arguments about capacity and ridership, but in practical situations, most of the problems you assert for regular rail systems are long solved. On the other hand, a lot of the ideas you have for PRT (attaching to parking garages?) are unlikely at best, except in a system on wholly owned property like an airport where your developer has full control.

The surface level buildings I showed you (Capitol Hill station in Seattle) are entrances to an underground station, not an at-grade system. Part of your problem here is that you don't understand what I'm showing you - you just decide you have a reason your system is better, and run with it. In Sound Transit's long range plan, that station will have four car trains with comfortable capacity of 800, running every 2.4 minutes, for 20,000pphpd, in the same surface footprint as a few PRT stations. You can't come close to that - and you'd be operating a lot of elevated guideway to try - and that's why PRT gets shot down for urban environments. That was my original point, you just seem to be too hard-headed to realize it. Good thing the people actually making decisions aren't...

Last edited by UrbanBen; June 20th, 2008 at 09:52 AM.
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Old June 20th, 2008, 05:35 PM   #119
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Quote:
Originally Posted by UrbanBen View Post
You have all sorts of misunderstandings. In your last comment, you said that the at-grade portion of a line limits the whole thing. That's not true at all - there are lots of lines where the system only goes at-grade farther out of the city, and many trains turn around closer in. With Seattle's East Link project, we'll interline more trains per hour in the downtown core, but those trains will run to Bellevue instead of running in the at-grade portion of Link south of downtown.
If you have turn-around points, then you can have sections of the line that run higher capacity, but the overall capacity from one end of the line to the other is limited by the lowest capacity section; more generally, between any two points on the line, capacity is limited to the lowest capacity section between those two points.

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Originally Posted by UrbanBen View Post
You make a lot of theoretical arguments about capacity and ridership, but in practical situations, most of the problems you assert for regular rail systems are long solved.
Does rail operate without subsidy? Why not? Is rail's average energy usage per passenger lower than a Toyota Prius? Why not?

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Originally Posted by UrbanBen View Post
On the other hand, a lot of the ideas you have for PRT (attaching to parking garages?) are unlikely at best, except in a system on wholly owned property like an airport where your developer has full control.
Attaching stations to the side of a parking garage is "unlikely at best", even as Sound Transit acquires entire city blocks and evicts 130 tenants from their homes/businesses? I find it amusing that you continue to say these things without any hint of irony, Ben.

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Originally Posted by UrbanBen View Post
The surface level buildings I showed you (Capitol Hill station in Seattle) are entrances to an underground station, not an at-grade system. Part of your problem here is that you don't understand what I'm showing you - you just decide you have a reason your system is better, and run with it.
OK, but even if the end result is underground, in order to build it they still have to acquire an entire city block! Remember, we started talking about this in the context of real estate acquisition costs, where you made one of your absurd claims that PRT's acquisition costs would be the same as Link's.

This is yet another example of your obfuscation of the issue: you originally made the claim that PRT would have similar ROW costs to Link; I responded with concrete evidence that Link's acquisitions are an order of magnitude beyond PRT's acquisition needs; you respond by changing the subject away from ROW costs and start talking about street level footprint.

Sound Transit needed to acquire an entire city block to build a single station. PRT would never need to acquire anything remotely approaching that much real estate; therefore your oft-repeated claim that PRT acquisition costs would be the same as Link's is complete bunk.

Quote:
Originally Posted by UrbanBen View Post
In Sound Transit's long range plan, that station will have four car trains with comfortable capacity of 800, running every 2.4 minutes, for 20,000pphpd, in the same surface footprint as a few PRT stations. You can't come close to that - and you'd be operating a lot of elevated guideway to try - and that's why PRT gets shot down for urban environments. That was my original point, you just seem to be too hard-headed to realize it. Good thing the people actually making decisions aren't...
More "proof by assertion" from Ben.

OK, I'll spell it out for you again. The 17mi Link line will cost about $4B for 17 miles along a line, right?

$4B would get you roughly 235 linear miles of PRT at $17M/mi (the Daventry consultant's esitmate, including vehicles and stations). If you arrange this mileage as parallel 17-mile lines going into the city, that is more than 13 separate lines, so we'll assume 6 bidirectional lines. At 1-second headway and 1.1 passenger per vehicle (both reasonable), each bidirectional line could theoretically move 3960 pphpd, for a total of 23,760 pphpd.

Is 12 lines "a lot of elevated guideway"? Not if you put a line every few streets. Let's assume there is one unidirectional guideway every other street leading into the city. If streets are 300 ft wide, that's one line every 600 ft; see my earlier image for what a single elevated PRT guideway would look like on a street - guideway and support posts which are a tiny fraction of those for elevated highways or rail.

12 guideways would be just about a mile wide area. Because the guideways and stations are spread out over an area rather than a line, more people would have close access to a station, and more destinations downtown can be served. All lines would be available 24x7, and would allow non-stop travel in 2 dimensions over a 17mi long, 1mi wide corridor.

"You can't come close to that" - bunk.
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Old June 20th, 2008, 09:56 PM   #120
UrbanBen
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If you can build PRT with any of the features you're talking about in an urban area, prove it. Not an airport - we have airport trams everywhere. In a city. Until then, I will repeat myself: You can't come close to the capacity or cost per rider of the light rail systems we're building today.

Until then, all you do is try to explain away reality. It's really sad. You make all these cost arguments, but none of them are borne out in reality. The seattle monorail project made similar claims, and their costs just inflated right up to reality. Morgantown came in for five times the "outside consultant" price.

You just can't understand that right of way costs money, no matter how "heavy" the guideway on top of it is.

Last edited by UrbanBen; June 20th, 2008 at 10:10 PM.
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