29 replies to this topic

[Hankster]

I'd like to introduce you to Ultra.  It's a rapid transit system developed in the UK that I think has tremendous promise.  It should be relatively low cost, highly efficient, and offers the closest thing I've seen yet to combine the convenience of a car with a rapid transit system.  Take a look at this website and this video, and try to imagine Nashville with such a system.  Wow!  The first system will be operational at London Heathrow airport later this year.  The system is electrical and the pathways are only six feet wide.  

Ultra Personal Rapid Transit Movie

Ultra PRT Website

[smeagolsfree]

Hank,

I am wondering how low cost it is because it looks as if there is a lot of infrastructure to put in place. I can see where something might replace autos in the Metro areas but it would not in rural areas.

Its an interesting concept for sure.

Edited by smeagolsfree, 10 January 2008 - 11:17 AM.

[monsoon]

Actually this concept was experimented with in the 1970s in the United States with a couple of real systems built.   Generally they cost as much as light rail to construct, they are much more expensive to operate, and they don't carry as many people.   The best known example of an operating PRT is the one in Morgantown, WVa which basically serves the University there.   You can learn more about it here.   The one in the Dallas suburbs more resembles the concept show above, but in these days of funding restrictions, a system like this would never get off the ground in the USA.  

The best bet for Nashville is go to light rail.

[Hankster]

monsoon, on Jan 10 2008, 12:47 PM, said:

Actually this concept was experimented with in the 1970s in the United States with a couple of real systems built.   Generally they cost as much as light rail to construct, they are much more expensive to operate, and they don't carry as many people.   The best known example of an operating PRT is the one in Morgantown, WVa which basically serves the University there.   You can learn more about it here.   The one in the Dallas suburbs more resembles the concept show above, but in these days of funding restrictions, a system like this would never get off the ground in the USA.  

The best bet for Nashville is go to light rail.

Is there any information on how much was spent on UWV's system?  My guess is that this type system (the track is only six feet wide and the cars are only 12 feet long and probably cost not much different than personal cars) would cost far less per mile than light rail and it offers advantages that light rail can't offer.  Right of way acquisition in most cases might not even be required as the system could be located over sidewalks or over medians.  The biggest advantage is the fact that the system always takes you directly to where you want to go using the shortest possible route nonstop.  No light rail system can do that.  This system also offers a more secure environment when your riding.  You and the rest of your party are the only ones in the car.  There are no worries of crime or violence.  The Atlanta MARTA system has never reached its full potential because of that.  Finally, this system offers much shorter waits for passengers to get the started.  Simulation of the Ultra PRT system show average waits of only 15 seconds for a car.  I think people will much more likely use a system like that than light rail.  I look forward to the operation of London's Heathrow airport PRT system and seeing how successful the system might be there.  Maybe this is the best way to do mass transit.

[steveraneyC21]

First off, the Morgantown system is called PRT, but is actually Group Rapid Transit.  21 students fit in the vehicles.  PRT is 3 or 4 persons per vehicle.  I wrote an academic paper on Morgantown GRT, and, for some strange reason, it's wildly popular.  300+ downloads per month for a few years: http://www.cities21.org/morgantown_TRB_111504.pdf .  Morgantown was a demonstration system, so it's a bit unfair to be picky about costs:

"What started out as a demonstration project estimated to cost between $15 to $20 million dollars quickly turned into a political chess piece in the presidential election campaign of 1972. Pressure applied by the administration to complete the project before the next election combined with the uncertainty of any new technology resulted in an approximately $130MM system which took nearly a decade to complete."  That's rougly $319 million in 2004 dollars for 8.7 miles of track, vehicles, and 5 stations - a bit less than $40MM per mile - not bad compared with some $80MM per mile airport automated people movers.

For ULTra PRT, the cost is $10 million to $15 million per mile, depending on the compexity of the system.  This costing comes from the London Heathrow procurement folks.  

A bit more description: ULTra is a battery-driven, 100-mpg-equivalent, elevated personal rapid transit system with many four-person vehicles. First deployment is scheduled for London Heathrow Airport in Spring 2009, to serve Heathrow's new Terminal 5. Working as circulator transit for office parks, airports, universities, and other major activity centers, ULTra is faster than a car. In these applications, ULTra makes carpooling and conventional transit more effective, by solving the "last mile problem."  Hence, the idea is to complement bus, light rail, Atlanta MARTA (by being a circulation system for the Perimeter Center), etc.  The youtube version of the animation Hankster gave is at: http://www.youtube.com/watch?v=B7hgipbHBK8

ULTra PRT places columns every 60 feet or so, and each column is about 18 inches in diameter, so per Hankster's comment, it's relatively easy to come up with a system design that doesn't require acquiring large amounts of expensive right of way.

[monsoon]

steveraneyC21, on Jan 11 2008, 03:07 AM, said:

ULTra PRT places columns every 60 feet or so, and each column is about 18 inches in diameter, so per Hankster's comment, it's relatively easy to come up with a system design that doesn't require acquiring large amounts of expensive right of way.
[/font]

You have to have ROW where ever this goes (doesn't matter if it is raised track) and the FTA is going to require clearance for safety reasons, so expect it to take up as much room as a 2 lane highway.    There are dozens of similiar technologies that have been proposed that also cite the $10M-$15M mile costs but when analyzed it's fond the costs are much much higher.   If you do a search on this site you will find some of them that have been posted over the years.  

As a practical matter if the local transit agency requests federal funding to build a system, then they are going to do a cost/rider analysis of the system and the end result is a PRT would not be funded because they simply don't move emough people in comparison.

steveraneyC21, on Jan 11 2008, 03:07 AM, said:

Morgantown was a demonstration system, so it's a bit unfair to be picky about costs:
...

These systems don't get built without money and I will tell you from experience they public agencies that will have to come up with the funding are going to be extremely picky about costs, especially about untested technology.

[Hankster]

monsoon, on Jan 11 2008, 07:16 AM, said:

You have to have ROW where ever this goes (doesn't matter if it is raised track) and the FTA is going to require clearance for safety reasons, so expect it to take up as much room as a 2 lane highway.    There are dozens of similiar technologies that have been proposed that also cite the $10M-$15M mile costs but when analyzed it's fond the costs are much much higher.   If you do a search on this site you will find some of them that have been posted over the years.  

As a practical matter if the local transit agency requests federal funding to build a system, then they are going to do a cost/rider analysis of the system and the end result is a PRT would not be funded because they simply don't move emough people in comparison.These systems don't get built without money and I will tell you from experience they public agencies that will have to come up with the funding are going to be extremely picky about costs, especially about untested technology.

The Ultra PRT system is based on new technology and let's see if the $10 to $15 Million per mile cost is achieved for the Heathrow system.  If the procurement folks at Heathrow say they expect the system to cost that much, then there's a real chance they will be right.  If cost are that much in London, they would be even less in the Southeast.  This technology is very intriguing to me and I look forward to seeing what the future brings for this technology.

[steveraneyC21]

Monsoon,



1. Cost

You are right to be skeptical of PRT cost per mile

A. One of the last big PRT efforts, the Raytheon Marlboro, MA test track, produced a PRT design that was far more expensive.  Raytheon was never successful in commercializing.

B. I am a full-time employee of Advanced Transport Systems, makers of ULTra PRT.  I should clarify that my cost quote of $10M to $15M per mile is based on Heathrow paid expenses and bids-in-hand – there are no unknowns in the cost, and there are no estimates in the cost.  

C. I’ve heard (second-hand) that a competing system has a cost estimate that is more than $25MM per mile.  Hence, it is difficult, but not impossible to produce low-cost PRT.  It takes staff that can be creative within cost constraints.



2. I don’t see how the first few systems would receive FTA New Starts or Small Starts $ -  that process is exceedingly slow.  The business cases for the first few systems will all be different, but won’t follow the typical federal paradigm.  Often, real-estate economics will drive the process (like the rapid expansion of the electric trolley in the U.S. from 1888 to 1905).  The first few systems will have unique approval and ROW characteristics that allow them to proceed to implementation rapidly.   BAA owns the Heathrow Airport land, so the ULTra system ROW acquisition was rapid.  Heathrow ULTra PRT is 100% funded with private sector funds.  BAA bought a PRT system from ATS and took an equity stake in ATS, hence undertook a more thorough analysis than a transit agency would have budget for.  So, we do have BAA as a happy customer who undertook a very thorough study of ULTra (cost/rider, safety, etc).  No US transit agency will ask for an ULTra system until there is operational data from Heathrow ULTra – but that pickiness will begin to die away once ULTra is proven.

[Shuzilla]

Well, it's an interesting system, but I can't see the actual benefits given the personal aspect. Yes, four can sit inside, but eight can fit in an SUV. Will the cars not move until all seats are filled? If not, it's more of what we have now. Just more exclusive and seemingly all constructed on the government's dime.

I like the possibility of doing away with stopping at intersections and the fact that the cars are electric. I just can't see this putting a serious dent in traffic on any of the major arteries. Enlighten me?

[steveraneyC21]

Shuzilla,



Here’s the main schpiel about PRT applications: Working as circulator transit for office parks, airports, universities, and other major activity centers, ULTra is faster than a car. In these applications, ULTra makes carpooling and conventional transit more effective, by solving the "last mile problem."



This 3-minute animation gives a pretty good explanation of “last mile” applications for PRT:

http://www.youtube.com/watch?v=B7hgipbHBK8



One peer-reviewed research study (by me) showed that the concept of making carpooling and conventional transit more effective could lead to a significant commuting switch away from driving alone:



A five-mile, $50M Personal Rapid Transit (PRT) "shuttle" system is proposed for Palo Alto's Stanford Research Park (SRP), complementing and significantly increasing the attractiveness of commuter rail, carpool, vanpool, bicycle, and bus commutes for the center's 20,000 employees. The office park is transformed into a transit village of two square miles. PRT provides non-stop, no-wait, 30 mph service over the commute's "last mile," and services mid-day trips. In addition to PRT, a very comprehensive "door to door mobility" service is proposed, supplying both high tech (web/cellular) and "high touch" (personal) solutions to meet SRP employees' complex transportation needs. Dr. Susan Shaheen defines "new mobility" service as "a new transportation approach that focuses on pairing clusters of smart technologies with existing transportation options to create a coordinated, intermodal transportation system that could substitute for the traditional auto."

A complex travel demand analysis was conducted on a sample of suburban employees, of which 89% drive alone. When presented with a hypothetical Year 2008 commute alternative scenario, where PRT solved the "last mile" problem and new mobility services solved specific objections, drive alone commutes dropped to only 45%. Extrapolating to the entire office park, 6,600 cars per day are removed, freeing 50 acres of parking for reclamation, conservatively worth $150M. It appears possible to eliminate traffic congestion and air pollution without lifestyle sacrifice. Commuters intend to take 1.32 PRT trips per day for a total of 26,000 trips per day for the entire job center. At $0.75 fare, $5M annual fare box revenue is produced. Additional revenue sources and cost savings total $16.9M per year, profitably covering PRT capital, operating, and maintenance costs. The model for Palo Alto plausibly translates to 200 other U.S. job-rich major employment centers.



Paper: http://www.cities21...._111503_web.pdf

[monsoon]

It's a system for moving people in an airport.   It's not a municipal transit system.  There are a whole host of cost issues, requirements and drivers that will affect the construction of a municipal system vs one that is constructed completely on airport property.  

The system at Heathrow costs $50M and runs 2.4 miles.  This means it costs $20M/mile and they did not have ROW costs, nor are they paying for station construction in this figure.   Furthermore it takes an entire car to move 4 people 25 miles/hour.  Spec this up to something that a municipal system would require and you have costs that would most likely exceed that of LRT.    For example the carriages on the LRT in Charlotte move 265 people at speeds of 55/mph.

[TrEn]

I am a passerby here. I have an academic interest in PRT and I often comment in PRT discussions. I go by the name "A Transportation Enthusiast" in other forums, and ATren on Wikipedia. I have no affiliation with PRT or PRT companies - it's purely academic for me.

To respond to a few points raised here:

monsoon, on Jan 15 2008, 07:14 AM, said:

It's a system for moving people in an airport. It's not a municipal transit system. There are a whole hots of cost issues, requirements and drivers that will affect the construction of a municipal system vs one that is constructed completely on airport property.

There is no transit system that has a smaller street-level ROW requirement than PRT - a single support post every 50 feet and an elevated station every quarter mile. Even bike paths have much greater street-level ROW than this. This is not to say there are no issues with urban integration, but they would be the same kinds of issues encountered for any transit expansion, only on a much smaller scale because of the very small street-level footprint.

monsoon, on Jan 15 2008, 07:14 AM, said:

The system at Heathrow costs $50M and runs 2.4 miles. This means it costs $20M/mile and they did not have ROW costs, nor are they paying for station construction in this figure.

I believe I've read that this discrepancy is due to the added costs of Heathrow being a pilot system, and that future ULTra installations will benefit from greater economies. It is my understanding that their costs would drop to ~$15/mi for later expansion. ULTra has done a remarkable job at keeping costs down, though $20M/mile or more is probably in the ballpark for other designs. Even at $20M/mi, the benefits of a PRT system are compelling, IMO (see below).

monsoon, on Jan 15 2008, 07:14 AM, said:

Furthermore it takes an entire car to move 4 people 25 miles/hour. Spec this up to something that a municipal system would require and you have costs that would most likely exceed that of LRT. For example the carriages on the LRT in Charlotte move 265 people at speeds of 55/mph.

There are several common PRT misconceptions here:

• speed - ULTra PRT has a low maximum speed, but PRT is nonstop, so 25mph is both the maximum and the average speed. Compare this to the typical rail/bus lines: average speeds on light rail lines rarely exceed 18mph (most hover around 12mph average) due to the frequent stopping. This also doesn't include waiting at the station nor transfer time, both of which are eliminated in PRT. Add it all up and PRT is a much shorter trip, even if it tops out at less than half the raw speed of a light rail train.
  
• costs - PRT construction costs are on par with LRT (it's difficult to compare directly because they're very different in their layouts), but operating costs are much more favorable for a PRT system. There are several reasons for this: (1) PRT vehicles are very lightweight and there's no stopping, so there are significant energy savings, (2) PRT vehicles have no drivers, (3) PRT vehicles only run in response to demand, whereas trains must run on a schedule, and therefore PRT consumes much less energy in empty vehicle movement. Which brings us to...
  
• efficiency - scheduled transit suffers from a fundamental performance-efficiency tradeoff: during off-peak times, schedules must be cut back to avoid skyrocketing costs-per-passenger. It basically comes down to this: moving a 265-person light rail train empty is an efficiency nightmare, so schedules must be set to ensure that the trains are relatively full most of the time. That's why trains run less frequently on Sunday evening than on Monday morning. If trains (also buses) ran at the highest level of service frequency all the time, costs would skyrocket. PRT, on the other hand, provides on demand service, and doesn't consume anything sitting in the station waiting for a passenger to arrive. So PRT can be available efficiently 24x7 yet still be very cost effective.
  
• capacity - some PRT designs have been designed for high capacity (by reducing vehicle headways) - see Ed Anderson's HCPRT ("high capacity PRT") for an details of this approach. But the current ULTra design is designed to be more of a mid-capacity feeder system, a complementary system - they freely admit that this would not replace the London Underground. But IMO, PRT scales so much better than other forms of transit that the system can easily grow as capacity needs increase. Other forms of transportation (including automobiles) have physical constraints that limit scalability beyond a certain point, but PRT's ultra-lightweight footprint and low land impact make it much more expandable, even for very high density applications. But this is the long term - ULTra is starting with smaller, moderate density applications. Other efforts have aimed higher right from the start and subsequently failed to get off the ground, so this is probably wise.

I envision two possible directions a city can take with PRT:

• Complementary solution - for cities that already have trains and buses, PRT can act as a complementary mode. Consider the problem with trains: they are horribly inefficient at off-hours operation, so what if a city could run trains only during rush periods? If a small PRT system were added to an existing rail transit infrastructure, not only would PRT provide much greater service off-hours (guaranteeing 24x7 availability with no waiting), but would also greatly reduce the operating costs of other systems which would no longer need to run off-peak schedules. Thus, PRT would make an existing transit system better and cheaper.
  
• Pure PRT solution - for smaller cities that don't have an exisiting infrastructure. Here, PRT can start small and grow as the city grows - and by grow, I don't mean "grow out" but rather "grow in". As the city center becomes more dense, the PRT network density would increase with it, providing both greater destinations and greater capacity. Then, if a specific need arises, a train system could be implemented in the most high-density corridors to augment the PRT; e.g. an express train from downtown to the airport.

When you think about the advantages of such an infrastructure - reduced need for highway expansion, reduced downtown parking, improved transit cost efficiency, vastly better passenger service, not to mention vastly reduced local emissions and greater walkability in the city core - even $30M/mi seems like a bargain.

[monsoon]

TrEn, on Jan 15 2008, 09:14 AM, said:

.....When you think about the advantages of such an infrastructure - reduced need for highway expansion, reduced downtown parking, improved transit cost efficiency, vastly better passenger service, not to mention vastly reduced local emissions and greater walkability in the city core - even $30M/mi seems like a bargain.

It might be a bargain if it were truly this cost, but I continued to be amazed how, in these discussions, significant cost drivers are left out of these discussions.   Furthermore, in most places in the USA, this system is going to complete directly against the automobile and it loses simply because the infrastructure has already been built for it.   So the $30M/mile would be much better invested in something such as light rail that can actually allow for more growth in already congest areas.  

These PRT proposals come of from time to time and never end up amounting to anything.   When the due diligence is done on them, they turn out to be much more expensive than claimed, (the system in Heathrow is a primary example of that) and they don't perform.

[TrEn]

monsoon, on Jan 15 2008, 09:36 AM, said:

It might be a bargain if it were truly this cost, but I continued to be amazed how, in these discussions, significant cost drivers are left out of these discussions. Furthermore, in most places in the USA, this system is going to complete directly against the automobile and it loses simply because the infrastructure has already been built for it. So the $30M/mile would be much better invested in something such as light rail that can actually allow for more growth in already congest areas.

But do you dispute the fact that PRT would be much more efficient to operate than light rail? If the construction costs are similar and PRT has a much more efficient operational profile, why would you choose the less efficient mode?

I do agree that the automobile has an inherent advantage because the infrastructure already exists - but if auto density increases to the point where road infrastructure needs to be expanded, PRT would be a more attractive alternative to more highways, wider lanes on existing streets, and parking garages every two blocks.

Nothing will ever eliminate cars and roads - they're entrenched in our culture. But PRT holds the most promise of drawing enough people out of their cars to eliminate the need for MORE roads and MORE parking in the city center.

BTW, I'd be curious to know more about the significant cost drivers you refer to. It has always been my understanding that the minimal street-level impact of PRT reduces the ROW cost significantly.

Quote

These PRT proposals come of from time to time and never end up amounting to anything. When the due diligence is done on them, they turn out to be much more expensive than claimed, (the system in Heathrow is a primary example of that) and they don't perform.

This is a generalization and an oversimplification of the issue. PRT proposals "never amount to anything" mostly because politicians are afraid to take a risk on a system they are unfamiliar with. It's been a decade since any city has even attempted PRT - and that effort failed for specific, well-documented reasons. Much was learned from that failure (which was due to escalating costs due to poor design choices), and today, streamlined systems like ULTra and Vectus are better for it. There is also the steady stream of technology advancement that has made PRT even more technically feasible today than just 10 years ago.

[monsoon]

TrEn, on Jan 15 2008, 11:21 AM, said:

But do you dispute the fact that PRT would be much more efficient to operate than light rail?

Yes I do.  It incorporates the worst aspects of automobile transit with the costs of LRT infrastructure.   As I said above, it amazes me these proposals keep getting made when the reality of the situation is this is not the way to take transit.

[TrEn]

monsoon, on Jan 15 2008, 04:13 PM, said:

Yes I do. It incorporates the worst aspects of automobile transit with the costs of LRT infrastructure. As I said above, it amazes me these proposals keep getting made when the reality of the situation is this is not the way to take transit.

"Worst aspects" of automobile transit? Are you referring to aspects like convenience, on-demand service, no stops, fast trip times, and round-the-clock availability? Why would we not want those aspects of the automobile? PRT preserves all the best passenger aspects of automobile transit while eliminating local emissions, traffic jams, and highways and parking lots - all of which are cancer for cities. What's not to like?

Rail is OK (I've always been a railfan) but the fact is that it cannot stop the spread of the automobile - rail lines are too slow and incovenient for people to give up their autos en masse. PRT offers a level of convenience that can compete against the automobile behemoth in the transit marketplace - and it can even make rail a more attractive alternative (see my previous post on complementary PRT implementations).

Monsoon, I used to believe as you did - until I got beyond the PRT detractors' literature and studied it for myself. PRT done right is technologically, mathematically, and financially sound - research it in-depth and you will learn what I learned, and you will understand the enthusiasm of those who promote it. The main barriers are now political, as politicians are wary to take the risk on something so different.

By the way, I am an electrical engineer by training and trade, but urban planning and transportation have always been academic interests of mine - that's how I started reading about PRT.

[monsoon]

TrEn, on Jan 15 2008, 05:01 PM, said:

......

By the way, I am an electrical engineer by training and trade, ...

As am I.  I have no idea what that has to do with this subject however.

TrEn, on Jan 15 2008, 05:01 PM, said:

"Worst aspects" of automobile transit? Are you referring to aspects like convenience, on-demand service, no stops, fast trip times, and round-the-clock availability? Why would we not want those aspects of the automobile? PRT preserves all the best passenger aspects of automobile transit while eliminating local emissions, traffic jams, and highways and parking lots - all of which are cancer for cities. What's not to like?....

I would contend that it does none of this and it does not have the capability to make any significant changes to congestion.  You can't remove cars from the road and put them on tracks and have any hopes at all of accomplishing anything.   The claims for it are not proved at all, and all evidence is that it is a very inefficient used of transit resources.  

Furthermore it is a system that continues the isolation of people instead of the mixing of demographics that are important in cities.  Putting in a system such as this is bad urban design of the 1950s mind set.

[TrEn]

monsoon, on Jan 15 2008, 06:09 PM, said:

As am I. I have no idea what that has to do with this subject however.

It doesn't have anything to do with the topic. It's just friendly banter.

monsoon, on Jan 15 2008, 06:09 PM, said:

I would contend that it does none of this and it does not have the capability to make any significant changes to congestion. You can't remove cars from the road and put them on tracks and have any hopes at all of accomplishing anything. The claims for it are not proved at all, and all evidence is that it is a very inefficient used of transit resources.

You certainly may contend that it is an inefficient use of transit resources, but you would be wrong. Check out the Morgantown PRT system, which isn't true PRT but is the closest thing to it currently in operation. It has been very cost effective and efficient in its 3 decades of service, and they are actually looking to expand it. Fifty cent fares cover half of operating costs, despite the fact that Morgantown is a 70s era system with very serious design flaws - flaws that modern systems like ULTra have rectified.

There have also been other fully functional prototypes that have demostrated the efficiency advantage (see German Cabintaxi and Japanese CVS, both from the 1970s, and British ULTra, which has had a prototype for several years).

monsoon, on Jan 15 2008, 06:09 PM, said:

Furthermore it is a system that continues the isolation of people instead of the mixing of demographics that are important in cities. Putting in a system such as this is bad urban design of the 1950s mind set.

This is a fallacy, IMO. Think about this: how many people in NYC consider the subway to be a place for social mingling? Transit is good for cities when it doesn't get in the way - look at those cities with good underground transit networks: NYC, Chicago, London, Toronto. These are cities where transit is a means, not an end, to good urban design.

The basic problem with the automobile is not the isolation, but rather the destructive infrastructure that criss-crosses the city. Traffic, parking, pollution, and highway infestation are what makes cars so bad for cities, not the incidental fact that people are not standing next to each other on a train. PRT could help to eliminate much of this, or at the very least stem the tide, and do so in a very low impact way.

If you doubt that PRT could actually curtail auto traffic, consider that even skeptics seem to agree that PRT would draw people in record numbers out of their cars. The OKI report in Cincinnatti, which ultimately rejected PRT, conceded that PRT would indeed draw a large percentage of people from their cars. I believe the number they came up with was 20-30% switching from their private automobiles to PRT. No train or bus has ever been able to come close to that, even in the very most dense installations, and this was using standard transit ridership modelling techniques.

If a transit system can potentially have such a drastic effect on auto traffic, and do so in such a low impact and efficient way, it deserves serious consideration.

[cloudship]

PRT has it's place. I tend to think of it as a sort of horizontal long distance elevator. It works well in controlled environments, where you aren't going to face  a large problem of safety or vandalism. And it works well where you have a fairly even spread of use. Anotherwords, large campuses and the like.

The problems with PRT conceptually, though, are specifically dues to the fact that it IS personal. First and foremost you have safety issues. In a controlled environment where you can assure everyone will get their own private car, and you aren't likely to have someone who will jump in the car with you, this isn't a huge problem. But can you imagine the first time a single woman is riding gets in, someone at the last minute hops in the car with her and then rapes her? The lack of privacy of a group transit solution also serves as a benefit in this case. You also have a huge issue of vandalism from kids riding around, without anyone being able to see what they do. I could only imagine the problems you would face in a depressed neighborhood with drugs and prostitution (unless, of course, that IS the goal! : ) )

You also face a huge problem if you have peak ridership. A college has peaks between classes, but those peaks are very close and even out. But as a commuter type instrument, you would have to allocate for huge demands in the morning and evening, with low demand middle of the day. In theory, you could easily vary the number of cars available, but by the time you build a system robust enough to handle those high demands, you are too heavy to be efficient with light volume use.

The biggest problem, of course, is that it doesn't address what people really like about their cars. It's not the point to point travl - it's the fact that it is your OWN SPACE. Not something you ride in for a while - but a place where you are in control, where you can store your stuff, leave when you want and remain when you want. It's not about where you are going, but what you are bringing with you - your own little mini-room.

Actually, we already have PRT available, although it really only works from point A to point B. The aerial gondola and chairlift are essentially PRT systems that only operate between two points. Detachable cars or chairs can leave as needed (except for balance) and are only used by one group.

[TrEn]

cloudship, on Jan 15 2008, 09:17 PM, said:

But can you imagine the first time a single woman is riding gets in, someone at the last minute hops in the car with her and then rapes her?

I've seen this argument before, and it doesn't make sense to me. How is this any different than a single woman walking to her automobile in a remote parking lot? I'll tell you how it's different: the remote parking lot is surrounded by other cars where a rapist can hide; the remote parking lot may not be well lit, and will not be covered monitored by surveillence cameras. A PRT station, on the other hand, is not likely located in a remote place; it's well lit; there are no dark corners where a rapist can hide; and there are security cameras.

Furthermore, what rapist would force himself into a vehicle where he is CAPTIVE? Think about it: a rapist would committing a felony in a vehicle which he cannot control and which is taking him to an unknown destination! For all he knows, that vehicle is going to a crowded marketplace where he will be immediately exposed to dozens of witnesses. Hey, it could be going to a station right in front of a police station! He'd have to be incredibly stupid to do something like this.

Compare this to the dark parking lot: once the rapist has forced his way into your automobile, he can gain complete control and go wherever he wants.

So my question is: given these risks, why on earth would a rapist (or any violent criminal) choose PRT over a dark alley or remote parking lot?

cloudship, on Jan 15 2008, 09:17 PM, said:

You also face a huge problem if you have peak ridership. A college has peaks between classes, but those peaks are very close and even out. But as a commuter type instrument, you would have to allocate for huge demands in the morning and evening, with low demand middle of the day. In theory, you could easily vary the number of cars available, but by the time you build a system robust enough to handle those high demands, you are too heavy to be efficient with light volume use.

You are misunderstanding PRT. There is no allocation in PRT; vehicles go when needed, and stay when not needed. When a vehicle leaves a station with a passenger, the system can automatically send an empty vehicle to that station so that one is available for the next passenger. This is all implicit to PRT control algorithms.

And I confess, I don't understand your argument that increasing the number of cars in use would make PRT "too heavy to be efficient". PRT vehicles are all the same size, and only move in response to demand, so they are equally efficient in heavy volumes as light volumes. It is trains, not PRT, that suffer from off peak inefficiencies due to empty trains.

cloudship, on Jan 15 2008, 09:17 PM, said:

The biggest problem, of course, is that it doesn't address what people really like about their cars. It's not the point to point travl - it's the fact that it is your OWN SPACE. Not something you ride in for a while - but a place where you are in control, where you can store your stuff, leave when you want and remain when you want. It's not about where you are going, but what you are bringing with you - your own little mini-room.

PRT will never replace the automobile for most people, and there is nothing about PRT that takes away your ability to own and use a car. But it does give you the option to leave the car at home for certain types of trips. Examples: use PRT for your daily commute, use your car to go to the supermarket. Use PRT to go to dinner downtown; use your car for a day trip out to the country. PRT is complementary to cars and other forms of transit.

And let's face it: as compared to a daily commute in rush hour traffic, PRT would be a compelling alternative: cheaper, potentially faster, and you can read the morning paper instead of trying to merge into an endless line of stopped traffic. And, I might add: PRT is much safer than an automobile.