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Old June 16th, 2008, 10:24 PM   #81
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Quote:
Originally Posted by UrbanBen View Post
Excuse me, but that elevated highway carries an order of magnitude more people than that elevated PRT.
Well, I don't think it's an order of magnitude difference, but OK, let's try to make it an apples-to-apples comparison - one highway lane vs one PRT guideway.

The PRT guideway is probably around 7x3ft cross section, 21ft^2 cross section. Now look at that exit ramp to the left of the highway interchange image - I would estimate 20ft by 8ft cross section, 160ft^2. So, I stand corrected - it's not a full order of magnitude difference - PRT infrastructure is only smaller by a factor of 8. We'll call it an octal order of magnitude.

BTW, it's nice to see you arguing in support of freeways for a change, Ben.
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Old June 17th, 2008, 06:02 AM   #82
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You're making exactly the nitpicky "size of lane" comparison the failed monorail project tried in Seattle. Nobody can tell the difference between monorail and light rail guideway unless they're a transportation geek - here, where we're building a fair amount of elevated light rail, people ask me if that's the monorail.

Nobody cares about what you're saying - nor would that elevated guideway design even work, considering there are federal safety guidelines requiring any stalled vehicle have a walking path to a pedestrian stairway.
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Old June 17th, 2008, 07:16 AM   #83
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1 track of fictional PRT vs 7 directions of roadway... right. As if PRT won't a) require multiple tracks and b) have wider footprint than that to allow for escape in event of fire etc. A fictional system doesn't have to worry about things like safety and human lives, it is just content for people to burn to death or fall off the guideway trying to scramble to safety.

And still the comment was made that air space was 'free' the highway picture looks appalling, but the amount of space it takes up on the ground with those elevated sections isn't particularly large, but the space 'in the air' still counts for space taken up.

Remember those roads are built to be able to handle heavy rigs, buses and all manner of transport. The guideway only has to handle the lightest of PRT vehicles. If you were to restrict heavy vehicles from roads as well you could have their elevated sections with much less impact at ground level.

Just in the one picture of PRT, the maximum people in the picture using PRT is 18 (assuming 6 per car max), and the maximum people using cars is around 90. All the 'less impact' pictures of PRT are for 'less capacity' services. Once you add it back up to the same capacity you get almost identical impact. And a duplication of that impact is unacceptable.
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Old June 17th, 2008, 09:07 AM   #84
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To have elevated guideways is probably most of the time a major drawback. I would not like anything elevated in my historic city center. Nothing against it at the airport but the space under anything elevated many times looks dirty, dark and not very hospitable.
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Old June 17th, 2008, 11:28 AM   #85
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Quote:
Originally Posted by UrbanBen View Post
You're making exactly the nitpicky "size of lane" comparison the failed monorail project tried in Seattle. Nobody can tell the difference between monorail and light rail guideway unless they're a transportation geek - here, where we're building a fair amount of elevated light rail, people ask me if that's the monorail.
Are you implying that the general public can't tell the difference between those two photos I posted? Did you look at the photos?

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Nobody cares about what you're saying - nor would that elevated guideway design even work, considering there are federal safety guidelines requiring any stalled vehicle have a walking path to a pedestrian stairway.
The ULTra guideway I posted is walkable - did you not see the railing? You've been making the same flawed arguments for several years now, and you lash out at anyone who has the gall to correct you. Are you ever going to open your mind to the fact that there can be good transportation solutions which don't have 2 steel rails and big heavy trains?
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Old June 17th, 2008, 12:31 PM   #86
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To have elevated guideways is probably most of the time a major drawback. I would not like anything elevated in my historic city center. Nothing against it at the airport but the space under anything elevated many times looks dirty, dark and not very hospitable.
Masdar City is building PRT below the street level. Underground PRT is always an option for historically sensitive areas. Or, PRT can serve as a feeder for streetcars (or whatever) which can serve the historic district.

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1 track of fictional PRT vs 7 directions of roadway... right. As if PRT won't a) require multiple tracks and b) have wider footprint than that to allow for escape in event of fire etc.
Fictional? They are currently building that very system at Heathrow Airport. Is fictional transport permitted in the UK? (Hey, maybe it is - remember those cool trains in Harry Potter? )

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A fictional system doesn't have to worry about things like safety and human lives, it is just content for people to burn to death or fall off the guideway trying to scramble to safety.
This is silly. The UK transport authority has approved this system for use. I seriously doubt that "burning passengers falling to their deaths" was included in the safety profile.

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Remember those roads are built to be able to handle heavy rigs, buses and all manner of transport. The guideway only has to handle the lightest of PRT vehicles. If you were to restrict heavy vehicles from roads as well you could have their elevated sections with much less impact at ground level.
So you're suggesting they start with existing elevated highway designs, remove all vehicles except the light personal ones, and then use a much lighter guideway.

Congratulations, you just invented a PRT guideway. Add automated fail-safe vehicles for maximum safety, and you have the ULTra system being built at Heathrow. I'm glad to see you've come to my way of thinking.

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Just in the one picture of PRT, the maximum people in the picture using PRT is 18 (assuming 6 per car max), and the maximum people using cars is around 90. All the 'less impact' pictures of PRT are for 'less capacity' services. Once you add it back up to the same capacity you get almost identical impact. And a duplication of that impact is unacceptable.
No, you're incorrect. Highway lanes carry about 2000-2500 vehicles per lane per hour. That's well within the capabilities of a single PRT guideway. The exit ramp in that photo (to the left) is the highway capacity equivalent of a PRT guideway. Are you seriously suggesting there is no difference in impact?
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Old June 17th, 2008, 01:22 PM   #87
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Quote:
Originally Posted by UrbanBen View Post
You're making exactly the nitpicky "size of lane" comparison the failed monorail project tried in Seattle. Nobody can tell the difference between monorail and light rail guideway unless they're a transportation geek - here, where we're building a fair amount of elevated light rail, people ask me if that's the monorail.

Nobody cares about what you're saying - nor would that elevated guideway design even work, considering there are federal safety guidelines requiring any stalled vehicle have a walking path to a pedestrian stairway.
People can tell the difference, especially for rail systems that use overhead wire for power. If third rail power is used, it is common to have separate viaducts for each direction. If overhead wire is used, it is common to have a single viaduct structure for both sets of tracks so that the overhead wire can be carried by a single set of pylons at the center. Some light rail systems have short segments with separate viaducts in way of center platform stations, but the greater part of the viaduct structure generally is a single structure that carries both sets of tracks.

In addition to the shading of the street, there is also the issue of noise. All steel-wheeled vehicles squeal on curves and low-floor light rail vehicles are some of the worst.

There is talk that a plan to extend Seattle's Central Link light rail system will be on the ballot this fall. The baseline plan for the segment through Bellevue is to put the line on an elevated viaduct. I expect that these issues will be thoroughly explored during the election campaign.
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Old June 17th, 2008, 09:26 PM   #88
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Elevated guideays are of course ugly.

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Originally Posted by UrbanBen View Post
Nobody cares about what you're saying - nor would that elevated guideway design even work, considering there are federal safety guidelines requiring any stalled vehicle have a walking path to a pedestrian stairway.
Maybe not in the matter you mean but elevated guideways are common for traditional rail today and have been for a very long time. It is possible to build safe elevated guidelines. Of course these features increase the cost. Going to the second point

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1 track of fictional PRT vs 7 directions of roadway... right. As if PRT won't a) require multiple tracks and b) have wider footprint than that to allow for escape in event of fire etc. A fictional system doesn't have to worry about things like safety and human lives, it is just content for people to burn to death or fall off the guideway trying to scramble to safety.
That's because these pictures come from prt advocates who want it to look nicer and be cheaper. In reality things would of course not built that way. Even so what about 2 lanes on two levels? All prt vechicles are the size , people want lorries on motorways off common roads . It's not just the weight of these big vechicles but also the size.
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Old June 17th, 2008, 09:38 PM   #89
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Are you implying that the general public can't tell the difference between those two photos I posted? Did you look at the photos?
I'm telling you that the general public wouldn't be able to tell the difference between one lane of PRT and one lane of light rail, because a PRT guideway in actual use would look about the same as a light rail guideway.

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The ULTra guideway I posted is walkable - did you not see the railing? You've been making the same flawed arguments for several years now, and you lash out at anyone who has the gall to correct you. Are you ever going to open your mind to the fact that there can be good transportation solutions which don't have 2 steel rails and big heavy trains?
Um... the guideway you showed me both wouldn't stand up, and doesn't have a safe walkway.

And yes, I've been tearing down your nonsense for several years. For how many have you been peddling this PRT joke, thirty? Next year Link light rail opens in Seattle, and we break ground for two more subway stations. This year we go to ballot for expansions without being dragged down by an attached highway expansion package.

Has a magical personal rapid transit system ever been to ballot in a US city? Has a transit agency ever selected it as a viable alternative? Perhaps we're building our big heavy trains for a good reason?
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Old June 17th, 2008, 09:53 PM   #90
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No one will ever begin to build something like that because failure would mean the ruin for every transit agency ever trying to build anything like that. Traditional trains have been built since a very long time. Also when the first people were thinking about prt I don't think technology was as advanced as today. Today people can build a better prt than even a few decades ago. People are looking backward not forward. It may be more uneconomical to buils than traditioal rail but if it really functioned like people imagine it would be better than traditional rail or cars.
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Old June 18th, 2008, 12:01 AM   #91
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I'm telling you that the general public wouldn't be able to tell the difference between one lane of PRT and one lane of light rail, because a PRT guideway in actual use would look about the same as a light rail guideway.

Um... the guideway you showed me both wouldn't stand up, and doesn't have a safe walkway.
Ben, the guideway I showed you is ULTra, which is under construction in its current form at Heathrow Airport, and under serious consideration for several other locations.

So answer me this Ben: is Heathrow building an unsafe system? Has Her Majesty's Railway Inspectorate approved an unsafe guideway? Why hasn't the media exposed this? Is this another one of your vast global conspiracies to kill transit?

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And yes, I've been tearing down your nonsense for several years. For how many have you been peddling this PRT joke, thirty? Next year Link light rail opens in Seattle, and we break ground for two more subway stations. This year we go to ballot for expansions without being dragged down by an attached highway expansion package.

Has a magical personal rapid transit system ever been to ballot in a US city? Has a transit agency ever selected it as a viable alternative? Perhaps we're building our big heavy trains for a good reason?
No Ben, you've been attacking PRT proponents, not their arguments. Face it, you have no valid arguments against PRT, never had, so you call them names and cook up anti-transit conspiracy theories. You don't even bother responding with facts anymore (because you know you have none) - you just launch right into ad-hominems like "Here come the crazies".

Face it: they are building ULTra as we speak. It's approved and under construction. And yet you still call it "magical" - how can you possibly justify that position? I can only conclude that you must be in denial.

I think you are far too attached to your own preference. You prefer trains above all else (and those trains better have at least two rails - monorail trains need not apply ). And you continue to attack all modes that threaten that preference. Perhaps if you really supported effective transit, rather than just trains, you would open your eyes and look at the facts.
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Old June 18th, 2008, 12:08 AM   #92
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No one will ever begin to build something like that because failure would mean the ruin for every transit agency ever trying to build anything like that.
Yes, absolutely. PRT's failure to get built has always been about risk averse transit agencies not wanting to be the first one to fail. Public transit is not set up for risky innovation.

But honestly, in retrospect I think that's been a good thing. In the decades since PRT was invented there have been many bad attempts, and if one of those attempts went into a city it could have destroyed the whole concept. The delays in implementation have not only allowed technology to catch up, but also allowed implementors to finely tune the designs and weed out bad choices. ULTra, Vectus, Taxi2000, and other modern designs are the result of that "natural selection".

And now ULTra has opened the door for everyone, by finally getting a pilot built, so people can actually see it in action. Without Heathrow (notably, a private installation) we might have waited another 2 decades for PRT.

Last edited by TransportEnthusiast; June 18th, 2008 at 12:11 AM. Reason: expand a bit
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Old June 18th, 2008, 12:30 AM   #93
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You showed me a rendering, not Heathrow. Heathrow's PRT has a bridge with a similar kind of guideway - and earth embankments on each end. Heathrow's system is mostly on the ground, not elevated! US requirements are different from British requirements, as well. I didn't make a statement about safety, I made a statement about requirements.

And again, your system's top speed is 25mph.

We already have pods between airport terminals in Seattle - they're a Bombardier system. Nobody's considering that for urban transit, for the reasons I've discussed at length. Maybe you missed my first comment on the thread?

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So, to begin with, you can't serve extremely high density destinations with PRT, because the maximum capacity (people per hour per direction) of a trackway would be tiny - a few thousand at most. A car with 2 people in it every 5 seconds, which is extremely generous both in headway and in people per vehicle (as this would be viewed as "personal", you'd likely see a 1.2 average), you get about 1500pphpd. A subway or even a high capacity light rail system has on the high end of an order of magnitude higher capacity.

For lower densities - places like the sprawl of LA - the tax base necessary to build a system like this is nonexistent - the dollars you get from your community for each mile of track you need to serve them doesn't even come close. This is the same reason even bus service gets crappy in the suburbs. With this thing, you have all the cost of monorail or light rail guideway and stations, but much higher maintenance costs (per-vehicle maintenance is similar no matter what the person capacity of the vehicle). And your stations are generally more granularly spaced, which means even more right of way costs!

There's a reason people have talked about this since the 1950s (or earlier) and done nothing. It's dead in the water as soon as right of way and platform costs are calculated - you can simply carry ten or twenty (or more) times as many passenger-miles for the same amount of money using the transit systems that have evolved in the last two centuries.
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Old June 18th, 2008, 02:13 AM   #94
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The delays in implementation have not only allowed technology to catch up, but also allowed implementors to finely tune the designs and weed out bad choices. ULTra, Vectus, Taxi2000, and other modern designs are the result of that "natural selection".

And now ULTra has opened the door for everyone, by finally getting a pilot built, so people can actually see it in action. Without Heathrow (notably, a private installation) we might have waited another 2 decades for PRT.
This words made me thinking about the maglev technology. It has been tested for decades but only one real world track (Shanghai) is existing. And it does not look good for the future.

The problem may be that these new technologies are only substitutes for existing technologies with way more risk and investment involved without giving a breakthrough advantage in comparison to old technology.

In a good public transport infrastructure with commuter trains, metro, light rail and bus there is no need for prt. Cars and taxis (or bicycles) are enough to drive the kilometers to the next park & rail parking space and get on the mass transport. And in city centers you are at most 500 m from the next station.

Although I have read that public transport in the USA is getting to the limit due to the high gas prices.

Also in my opinion only a combination of different transport methods make good public transport. Bus, light rail or even prt alone just will not cut it.
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Old June 18th, 2008, 03:07 AM   #95
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Substitutes for other technologies with more risk is a great way to put it. Cars already do most of this, with existing infrastructure.
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Old June 18th, 2008, 03:40 AM   #96
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Substitutes for other technologies with more risk is a great way to put it. Cars already do most of this, with existing infrastructure.
So, you're advocating more highways to support the cars?
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Old June 18th, 2008, 04:02 AM   #97
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You showed me a rendering, not Heathrow. Heathrow's PRT has a bridge with a similar kind of guideway - and earth embankments on each end. Heathrow's system is mostly on the ground, not elevated!
Ben, that's completely wrong. Earth embankments on each end? Where did you get that idea?

Here's an actual image from Heathrow that proves my point:

ULTra Heathrow

Perhaps you should check your facts before making such proclamations.

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US requirements are different from British requirements, as well. I didn't make a statement about safety, I made a statement about requirements.
Huh? Doesn't safety drive the requirements? Are you suggesting that the UK system is unsafe?

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And again, your system's top speed is 25mph.
Ben, listen carefully now, because I've already explained this to you several times:
In a non-stop system, average speed equals line speed.
Go ahead, repeat it to yourself several times so you don't forget again.

Now, since ULTra is a non-stop system that spends 98% of its journey running at line speed, it effectively has both a top speed and an average speed of 25mph. (The other 2% is the 8 seconds it takes to accelerate/decelerate in the stations).

OK, now that we have that down, what is the average speed of light rail? Answer: 15.2mph. Why? Because light rail has frequent stops. (Source: APTA)

Conclusion: ULTra is 66% faster than the average light rail line.

Point debunked. Try again.
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Old June 18th, 2008, 04:07 AM   #98
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So, to begin with, you can't serve extremely high density destinations with PRT, because the maximum capacity (people per hour per direction) of a trackway would be tiny - a few thousand at most. A car with 2 people in it every 5 seconds, which is extremely generous both in headway and in people per vehicle (as this would be viewed as "personal", you'd likely see a 1.2 average), you get about 1500pphpd.
No. Wrong. PRT headways are targeting 2 seconds as conservative, 1 second or lower long term. ULTra is proof of this, yet you still quote 5 seconds as "extremely generous".

But don't let facts get in the way of your campaign.

(Since your entire further analysis is based on this misrepresentation, there is no need to respond to it further.)
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Old June 18th, 2008, 05:02 AM   #99
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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.

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.

I'm sure 2 second headways are targeted. Okay, now you have 3600pphpd (2 seconds, 2 people, again giving you .8 extra people) - not competitive with the 6400pphpd minimum capacity on Link when it begins service, or the 20,000pphpd at capacity. I quote 5 seconds as generous because no government agency has authorized you to drop much below that (4 seconds at heathrow, which is not a normal operation minimum, I believe), for safety reasons.

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.

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Old June 18th, 2008, 05:14 AM   #100
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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.

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!
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