Podcars

http://www.nytimes.com/2008/09/21/nyreg ... ar.html?hp

This is a pretty interesting article on the viability of podcars in the US, using Ithaca, NY as a test case environment.

What about using these devices to connect NJ's sprawling corporate parks to local railroad stations? I once worked as a network architect at a company based on Sylvan way off route 10 in Parsippany and I had to commute in by car each day because there was no easy way to get to and from the local train station.

If the train stations had vegetable markets as well, the commuters could be dropped off at the train in the morning (car pool or spouse) and then when coming back from work pick up fresh food for dinner. The key is making transit part of the culture and making it preferable, logistically to the automobile.

Any thoughts on this?

sc

I used to live in Ithaca, NY, and I find this proposal most bizarre.

Downtown Ithaca is in the flatland at the southern end of Cayuga Lake, but Ithaca's two colleges are up some steep hills from it, Cornell University to the east and Ithaca College to the northeast. Hills as steep as some of San Francisco's hills.

So to connect downtown Ithaca, Cornell University, and Ithaca College, those podcars would have to be cable cars.

There's some populated area to the north of Cornell University that is less hilly, but it's mostly residential. A line from Cornell University to Pyramid Mall in northern Ithaca might certainly be feasible, but it would not get many riders.

There was no mention of Ithaca's troublesome geography in that article, which makes me suspicious.

In any case, lightrailnow.org has a slam on this concept: Personal Rapid Transit – Cyberspace Dream Keeps Colliding With Reality

The hills are relatively easy to handle IF you use compression of the driving rail rather than relying on the weight of the car multiplied by the coefficient of friction (which is, um, variable).

No, the problem with podcars is that they combine the worst aspects of cars with the worst aspect of trains. Cars have high loading times, which leads to station congestion. Trains, you don't own, so everything you want to transport you have to carry in your hands.

A better system is the RUF, http://www.ruf.dk/, which combines the best aspects of cars with the best aspect of trains. A car, you own, and you get a single-seat ride from source to destination, with as much cargo as you can fit. Yet while on the guideway, RUF vehicles combine to form themselves into a train.

And anyway, the RUF is just a special form of narrow gauge.

RussNelson wrote:The hills are relatively easy to handle IF you use compression of the driving rail rather than relying on the weight of the car multiplied by the coefficient of friction (which is, um, variable).

I don't see how that is supposed to work.

In any case, there was a conference on podcars held at Cornell University Sept. 16-19. It's a bit hard for me to find news stories on what transpired in it, because may of them were about the announcement of it. However, I've found a Cornell Daily Sun story about it.

There's supposed to be some pro-podcar organization in Ithaca, "Connect Ithaca", but its website, http://www.connectithaca.com is now dead. Some cached pages of it survive in Google's cache, but there is nothing substantial, not even a proposed routing for Ithaca.

lpetrich wrote:

RussNelson wrote:The hills are relatively easy to handle IF you use compression of the driving rail rather than relying on the weight of the car multiplied by the coefficient of friction (which is, um, variable).

I don't see how that is supposed to work.

The forward propulsive power of a train is the torque the engine is capable of supplying multiplied by the radius of the wheel. Unfortunately, that power is limited by the fact that the wheel will slip if you try to apply more force than the weight of the engine multiplied by the coefficient of friction of steel on steel, which ain't real great. What if, like the RUF, there was a vertical vane which the engine could compress with as much force as it was able to muster? You'd still have the coefficient of friction, but you wouldn't be limited by the weight of the engine.

Once you can do that, of course, there are other constraints on something that weighs as much as a train, like deforming the rails every time you accellerate or brake, but we're talking about 1 to 2 ton vehicles.

Vertical vane? Would it be like a pole for pushing the train? Or would it be something like San Francisco's cable cars, which move by gripping a moving cable? Do you have a URL of a page describing the mechanism that you have in mind?

One might get improved traction by using rubber tires, though the podcars would likely also use a central guide rail in the fashion of many airport railcars. I remember such rolling stock from the Las Vegas, Denver, and San Francisco airports.

BTW about Ithaca:
East Hill - Cornell University
South Hill - Ithaca College

Here's what the RUF guideway looks like: http://www.ruf.dk/guideway/index.htm

Hi,

I just want to point out to the forum that the "Vectus" PRT system pictured in the NY Times article uses linear motor propulsion, i.e. magnetic motors like those used in the Vancouver Skytrain. Thus, wet conditions do not factor into acceleration and braking.

The American PRT design "Skyweb Express" is another using linear motors; they list 15% as its maximum grade.

-David

A tall, thin vertical rail that sticks into the interior of the vehicle?

I can't help but be skeptical about that -- it would be hard to make turns, and the RUF site does not address that question.

I think that this sort of vehicle would be more practical: the Bombardier CX-100, which runs on rubber tires, but which has a low central guide rail that also supplies electricity. That's the sort of vehicle I had mentioned earlier, a vehicle used in several airports and in the Miami Metromover.

It's hard to find numbers on Ithaca's elevations, but I've found this answers.com article, which gives 814 ft (either the downtown flatland or an overall average), and this Wikipedia article on Ithaca's airport, which gives 1,099 ft / 335 m.

That's about 300 ft / 100 m difference, and a CX-100 or similar vehicle may be able to make it, at least if it uses a somewhat roundabout route, like

Ithaca Commons - State St. - Mitchell St. - College Ave. - Cornell University

I think podcars are a symptom of a sick culture.

The problem is that people aren't willing to be near each other, so cars become preferable. This is the sickness that manifests itself in divisions throughout society. This problem needs to be fixed, then lightrail and more practical means of transport become more viable.

This being said, I still wonder if this type of technology could be useful for NJ's corporate parks.

lpetrich wrote:A tall, thin vertical rail that sticks into the interior of the vehicle? I can't help but be skeptical about that -- it would be hard to make turns, and the RUF site does not address that question.

There's a limit on the radius of the turns, and they're banked. So, no, it's not hard to make turns. But both accelleration and braking are independent of the weight of the vehicle because the car can compress the vertical rail. Plus the rail has a pattern of holes in it which allow the car to determine its location and position, and the cars communicate with each other, so that car spacings of less than an inch are reasonable.

"I think podcars are a symptom of a sick culture.
The problem is that people aren't willing to be near each other, so cars become preferable."

I think you are ascribing a values judgment to the podcar concept that isn't there, and that it's not possible for a technology to have.

The Podcars/PRT idea arose in the Fifties and anticipated the later trend of 'lean manufacturing' developed by industry, which achieves economies of scale in a different way. The old way, companies would build, own and operate huge expensive warehouses to keep materials on-hand. Under the lean philosophy those materials are ordered from supplies so that they arrive 'just in time' to be put into the manufacturing process.

Similarly, PRT uses automation and elevator-like operation in order to move vehicles only in response to demand or anticipate demand, and to move a minimum practical amount of vehicle weight per passenger, saving energy.

I realize that the mind tends to leap to ultimate conclusions, and that some rail advocates may see PRT as a 'threat' to their favorite transit mode. I also admit that PRT advocates often present an idealized, what-if scenario of entire cities served only by PRT. Those are conceptual, designed to show what PRT might be capable of. The reality is that public policy will require PRT to be implemented like any other mode -- it will have to coexist with trains and buses within multimode networks.

For once, I agree with Russ. The podcar thing is a joke, it would probably be more expensive than a Monorail or Even Light Rail. And if I am going to spend that much money for a piece of transportation, I'd rather have someone else drive. (Assuming that you have to do your own Braking/Acceleration Commands.) Also, it's UGLY. I don't necessarily like the RUF either, but If I had to choose a City transportation which is not Light Rail, or BRT, I'd go with RUF.

Chessie GM50 wrote:I don't necessarily like the RUF either, but If I had to choose a City transportation which is not Light Rail, or BRT, I'd go with RUF.

You might like it more than you think. I went on the VRA's NYS&W speeder run last weekend, and come to think about it, riding a RUF would be a lot like riding a speeder except that setting on is done at speed. And I can tell you that riding in a speeder didn't stink!

Chessie GM50, you're not being asked to choose between LRT, BRT or PRT.

What if you lived 2 miles from the LRT or BRT station? Now suppose you could leave your home, walk down the street, and catch a horizontal elevator to the LRT. Suppose you could choose to either go to the station nonstop, or stop on the way to run an errand. This is an example of PRT as you are more likely to experience it in the medium term future -- intermodal transit service.

And like an elevator, all you have to do is push a button. The system does all the driving.