But it doesn’t really matter, as has been stated here a number of times, LRT & PRT can co-exist just fine.

“appears to have guideways almost if not quite wide enough” and yet somehow it was built. Perhaps you don’t know quite as much about safety as you think you do. Care to provide some actual evidence of your requirements?

Don’t like a chairlift? Add an elevator at the back, that only adds about 8 feet to the end of the station and no additional width. Sure it adds cost, but far a trivial amount given the costs of the entire system, a 2 story elevator big enough for a wheelchair just isn’t that expensive… as I pointed out much earlier.

“replacing a 120-person vehicle with 30 4-person vehicles running every 20 seconds is not terribly practical” care to explain why? Oh, and PRT can run at much faster headways, anywhere from 1/2 second to 8 seconds depending on the particular implementation.

“the morning collector traffic in particular is diffuse” that’s exactly what PRT is designed for. Since the costs are so small in PRT you can build a grid rather than a single line, but if you bothered to read the posts above, or do any of your own research about PRT you would already know that.

“PRT alignment could be designed with low-capacity vehicles but large stations, so the vehicles could be replaced with larger vehicles as demand grew” There would be no point to this, PRT can support just about any capacity until you need heavy rail, at which point PRT works as a feeder system to the heavy rail.

You obviously don’t know anything about PRT and can’t be bothered to learn about it. Which is fine, many people don’t know anything and don’t care and that’s their right. The problem I have with you is that you somehow think you can make arguments against it while being completely ignorant of it’s basic principles, not to mention that all your arguments have been debunked in these comments and elsewhere.

*This* would be revolutionary, because it would allow driverless systems which aren’t pedestrian-separated.

But it would have to operate correctly in the rain, snow, and sleet, and at night, before it will revolutionize transportation.

At-grade light rail system with same passenger throughput, much lower average speed, worse energy efficiency, and greater danger to pedestrians: $100-$200 million a mile.”

These numbers suffer from being, well, just plain wrong.

A lot of light rail systems have been gold-plated lately, with all kinds of streetscape rebuilds and decorative projects attached to them which have nothing to do with transit. There’s also “ripping up utilities” costs, which make a huge difference; much better to run where the utilities don’t have to be moved, or where they’re being rebuilt by someone else anyway. That’s where you’re getting your inflated numbers for light rail. $8-$15 million a mile is what you’re looking for for a streetcar system. I’m not surprised the price doubles if you build it elevated, that’s close enough to the standard factor.

After checking Heathrow, I find that in fact (unusually for an airport) “the system is not expected to have a high demand”.

This makes it possibly the first reasonable application for PRT yet. Though it does make one wonder how useful it is — it’s a *SHUTTLE BUS TO A CAR PARK*.

A very expensive shuttle bus, at that. Does the savings from not employing a driver for a battery-run minibus outweigh the cost of construction? Perhaps it does; drivers are expensive. However, there are not very many places where frequent shuttle buses are used or needed; perhaps amusement parks as well as airports would find PRT useful.

Shuttle buses are a notoriously inefficient form of transportation, and if PRT can replace shuttle buses then by all means I support it in that application. (How about replacing the shuttle buses to airport hotels, from train stations and airports to Disneyland, and so forth.)

Of course there’s something else odd about this. Since T5 was new, would putting the car park underneath Terminal 5 have made more sense?!?! Would it have made even more sense to just let people arrive by the two separate rail services to the airport, and put the long term parking somewhere other than the Greenbelt?!?!?

I also don’t think a price generalization from a two-stop system is remotely reasonable. One other thing. We don’t know the actual costs of the Heathrow system yet; it appears the final bill hasn’t come in.

—-
On the other questions:

Patrick, I know more than a little bit about the ADA. Those portable stairlifts you keep going on about are allowed for residences and retrofits, but are not legally acceptable for bridging significant height differences in new-build commercial construction in the US. It’s a proper (safe) elevator or a ramp. Maybe they’re allowed in the UK, but having used them they are *not* terribly safe and they shouldn’t be allowed in new construction. On top of that they’re really not durable.

I also know a little about about the health-and-safety regulations. Any elevated guideway now requires a safe walkway alongside for escape purposes if there’s a vehicle breakdown. (If you can safely walk on the tracks, the walkway just has to be wide enough to get to the tracks. Similar rules apply to new tunnel construction, but this is usually achieved automatically by making the tunnels round.) The Heathrow system appears to have guideways almost if not quite wide enough, and should be considered the absolute minimum width for an elevated US PRT system. “Completed ULTra guideway looks like an elevated road.” — sounds about right.

In general — non-airport — applications, the trouble I have is that most of the goals of PRT seem to be met at least as well by electric car-share programs — or by walking. (Or even by travellators/moving walkways, which are heavily used in airports.) Airports, like amusement parks, are a very specialized application.

The PRT company doing the construction at Heathrow doesn’t seem to be presenting it as an alternative to mass transit for high-traffic corridors — and in a “replacement for small shuttle buses” application, it may well actually have a function. This is highly specific. It’s overbuilt for a true collector function (to the home); and it’s underbuilt for the movement of large numbers of people.

A rule of thumb is that you don’t want rail transit (for transportation purposes, anyway) unless you can run your vehicles nearly full every 5-10 minutes at peak times. (Minor exception: cheap line extensions for existing lines.) For those applications, PRT is just not terribly useful; replacing a 120-person vehicle with 30 4-person vehicles running every 20 seconds is not terribly practical, even if technically possible, and is horrendously expensive if your line is of any length, thanks to the huge number of vehicles required (all that steel!).

For most collector/distributor traffic, meanwhile, PRT is overbuilt; the morning collector traffic in particular is diffuse and usually can’t justify any form of grade separation. When the traffic is concentrated, but not concentrated “enough” for mass transit, it’s very unusual. PRT seems to have a crack to fit into here (the amusement park exception); however, if there’s already a rail system, it’s often cheaper to just extend it, and even at an amusement park, there may be enough traffic to justify large vehicles immediately.

I suppose a properly built PRT alignment could be designed with low-capacity vehicles but large stations, so the vehicles could be replaced with larger vehicles as demand grew, for low-traffic corridors believed to be turning into high-demand corridors. This could be an intelligent replacement for the highly questionable “economic development” light rail schemes which never pencilled out as transportation in the first place — because if the demand never grew, you’d never have to increase the vehicle size, and you’re already spending money on something which is questionable as transportation.
Interestingly, these are the sort of schemes where if the developers can’t get the rail they want, they may run shuttle buses (until they’ve sold all the units and don’t care any more).

So I guess you’ve convinced me that there are a couple of obscure niches for which PRT would be useful. Namely, replacing frequent, low-capacity shuttle buses, and for developers who might otherwise run frequent, low-capacity shuttle buses.

http://www.technologyreview.com/video/?vid=338&p=3

http://www.youtube.com/watch?v=3SQiow-X3ko

Another point is that the British society of royal engineering *government body) is predicting that 30% of freight on British roads will be carried by robotic vehicles in ten years.

Very quickly the gain from robotic transportation will evolve in automated people movers on our city streets. BRT, Light Rail, PodCars, and deliverbots will e arriving starting within 12 months. They perform all the functions of mass transit but have zeo infrastructure costs. These robots will utilize any signalling assist, but it is not a requirement.

Robotic vehicles are much safer than human drivers, they mix freely with humans on the factory floor, and there are two systems of robotic rubber wheeled people movers in operation in Europe as well as one in Asia.

The oil savings and convenience of the robocars are great enough that gated communities will adopt them first. Government DMV officers will soon be setting guidelines for Robotic Drivers licenses.

At-grade light rail system with same passenger throughput, much lower average speed, worse energy efficiency, and greater danger to pedestrians: $100-$200 million a mile.

Convincing trusting progressives and TOD supporters that it’s in their interest to support a more expensive and poorer performing system over one that actually has a chance of getting a large number of people out of their cars and thus preventing thousands of fatalities each year: priceless.

Fixed that for you.

Ken Avidor may be an obsessive nut, but he’s our obsessive nut!

“The summary is very simple”… the summary of what? Of the 3 items in your summary only the first is correct. As the private auto has shown, it does not require a large, high occupancy vehicle to move large numbers of people around. PRT is essentially an automated taxi service without the crashes, or crazy drivers. There is no need for large vehicles.

“Oh, by the way, in a complex podcar network, intersections will end up delaying traffic” that statement shows your complete lack of understanding of PRT. PRT intersections are either separated from each other, or merely merges. If grade separated there is no delay, and when a merge the delay is only fractions of a second at most. There are definitely no cross traffic issues.

As I mentioned earlier the station images are perfectly reasonable, ADA requirements can be met by adding a wheelchair lift on the stairs. Exactly what safety requirements are required that would need a bigger station? Safety requires that you have an exit that works when power is lost. Stairs work perfectly well for that.

“and even so PRT isn’t really appropriate because the volumes justify full-size automated trains holding dozens of people”… Heathrow airport (busiest international, 3rd busiest overall) seems to disagree with you as they are finishing a PRT project, it will be available to the public in 2010.

As far as your second post goes, the economics of PRT work just fine with grade separation, the aforementioned haethrow project is coming in at $15million per mile, far cheaper than just about any other transit system out there. Cheaper than highway, light rail or heavy rail. The basic premise of PRT requires grade separation, it is not PRT without grade separation.

(Now, making it an electric car on rails is not necessarily a bad thing, but you still need the driver to watch for pedestrians crossing and hit the brakes. No full automation allowed, driver must look out front window all the time.)

We have LOTS of obsessive nuts with good liberal credentials in Ithaca, many of whom I wouldn’t trust to run a hot-dog stand, let alone build a transportation system.

The summary is very simple: (1) In order to be automated safely, podcars must be fully grade separated. (2) In order to justify the huge cost of grade separation, they need to be able to carry large volumes. (3) If they’re going to carry large volumes, then in order to be efficient they need to have large capacity per car.

This destroys any role for podcars. In Ithaca in particular, a carshare program is very successful. Equip it with electric cars and you’ve provided almost all the benefit of podcars except automation at a fraction of the cost.

Oh, by the way, in a complex podcar network, intersections will end up delaying traffic. It’s slightly better because it has centralized computer control, but after a certain point, you simply have to wait for the cross traffic.

The station images are ludicrous. ADA compliance and safety escape requirements would require much more substantial stations. Not a problem if at ground level… but then you have to bar pedestrians from crossing the tracks (major, major problem) or install a driver (oops, not podcars any more).

PRT has fundamental design flaws; it’s just not good for anything much. Airports are a *very* specialized application with very odd characteristics (no pedestrian traffic outside buildings, need to grade-separate everything anyway, demand for very fast movement of passengers to catch planes, huge pots of government subsidies), and even so PRT isn’t really appropriate because the volumes justify full-size automated trains holding dozens of people!

a light rail system was recently completed here, in seattle. the support posts for the overhead power supply wires look a lot like PRT guideway posts. the trains are loud. i can’t afford the inflated rents to live within walking distance, and there are a limited number of bicycles allowed onboard.

i don’t like being taxed for systems that gobble up 60% of the transportation budget while facilitating only 10% of all trips. please, stop forcing your social-engineering BS down my throat.

If PRT succeeds in taking cars off the road in a way that conventional transit can’t, what will the people at Streetsblog have left to complain about?

Save Streetsblog. Kill PRT.

“Downtown Connecting People

A project to promote the creation of a pedestrian corridor of vibrant businesses, affordable housing, artful street life and shared garden oases through the heart of Downtown, linking the Commons to the Waterfront… a unifying pathway Martin Luther King would be proud of.” Projects – ConnectIthaca.org

One of the people in Connect Ithaca and the PRT effort is Joan Bokaer, who seems to have pretty good liberal credentials
http://en.wikipedia.org/wiki/TheocracyWatch
http://www.talk2action.org/user/Joan%20Bokaer
http://www.podcar.org/ithacaconference/videos/Joan_Bokaer/Joan_Bokaer.html

I’ve made a number of claims on this column, none of them are that PRT will be profitable. If you find flaws in my arguments why don’t you point them out? I don’t feel any need to support claims other than my own.

http://dissidentvoice.org/Feb07/Avidor11.htm

Incidentally, I just read a very eloquent letter about PRT in the Ithaca Times:

http://www.ithacatimes.com/main.asp?SectionID=28&SubSectionID=91&ArticleID=9665

Connect Ithaca, a for-profit company which is paying itself to do this study (it is in their grant application), is proposing an extremely expensive, resource intensive infrastructure layer for the city of Ithaca that has the primary function of shuttling college students to Wegman’s and then to their cars, which will be parked in huge parking lot/heat islands on the edge of town.

Even in the highly unlikely case that their wild assertions about travel times, emissions, and cost were true, Connect Ithaca’s proposal would still be disastrous for our city because of its offensive aesthetics and devastating social implications. To wit: despite their claims to the contrary, if the proposed layout for the elevated PRT were to be constructed the city/state would indeed have to either widen and re-grade roads to accommodate a middle ground for the centerline placed tracks and/ or remove trees and sidewalks to allow the elevated track to travel along the side of the road because closing every street in their scheme to all but emergency vehicles is nearly impossible and impractical, both politically and economically – but even if it weren’t, the sections of the “circulator” that run along NY State Route 96 and NY State Route 79, for many reasons, cannot be closed to daily motor vehicle traffic, so major road widening will have to happen. Just as important, the physical appearance of this concept is reminiscent of the elevated Eisenhower era super highways that destroyed the beauty and livability of many American cities – today we are dealing with the costly results of these poorly designed monoliths in projects such as Boston’s Big Dig.

If the previous weren’t reasons enough to reject this project outright, know this: well trained urban designers and progressive city planners (like Jane Jacobs) know that a transit system in a city like Ithaca must be integrated into the streetscape, not only because such a system is meant to serve short, local trips where station access time is more important than travel time but also because such a system activates street life, enhances vigilance and security, and necessarily engages riders with each other. A city is about engagement with the other, not secluded 5-minute dashes from ivory towers to shopping areas, that, my friends, is a suburb and there are plenty of those to go around.

If Connect Ithaca, were really interested in enhancing public transportation, giving the streets back to pedestrians, bikers, and skaters and reducing vehicle miles traveled (VMTs) for local trips, as they claim, why aren’t they paying themselves to pursue the most obvious, least expensive, most sustainable, and most suitable solution for Ithaca, what is known as the Woonerf or the Living Street: reduce the speed limit on many city streets to 10 miles an hour and make those streets fully shared pedestrian-bike-skateboard-motor vehicle spaces. If a handful of streets remain at the 30 mph limit – and if the lights get timed to enhance traffic flow as they should be–most car trips will be on those routes because the 10 mile an hour shared roads are just too frustrating and many short trips will be on foot (or bike or board) for the same reason–this, of course should all be done with public transit routes in mind. It can be done here and, though it lacks the flash of pod cars and will probably take 20 years to be fully realized, it will work and it will cost very little while reducing VMTs and drastically improving the quality of life for Ithacans – nearly half of whom live under the poverty line and the overwhelming majority of whom will not be well served by the addition of a PRT circulator.

http://www.youtube.com/watch?v=lKiHTiVOF3g