Ian Bicking: the old part of his blog

Re: On the subject of mass transit

The main problem is that cities in the US weren't designed so people could live within walking distance of work and the store and nightclubs and the like. Then people wouldn't need much transportation. A few older neighborhoods are walkable, and -- surprise, surprise -- these happen to be the most desirable addresses and have the highest real-estate value. You'd think the zoning regulators would get a clue and build more neighborhoods like that, enough to saturate the demand and bring the prices down. Especially since people in those neighborhoods use half as much energy per capita as others.

The automobile is so dead. The game is up not when the last drop of oil is used, but when half of it is used. Then the price will rise significantly and rapidly. There's disagreement in the oil industry on when it will occur, but David Goldstein (Out of Gas: the End of the Age of Oil) argues it could come in four years. All the 30-year predictions fail to account for the ever-increasing demand in China and India, and assume the US level will remain steady and not increase (fat chance). Some other countries have good public transportation and walkable cities to fall back on, but the US has pissed away most of its opportunities. This should really worry us. A terror attack is nothing compared to a 15-year depression until alternative-fuel cars become viable on a mass scale. What's going to happen when 80% of Americans can't get to work because they can't afford gas for their SUV, and the public transit line that would have taken them to work was never built?

Low-volume cars really are the problem. See all the empty space around the person that's taken up by the vehicle. Feel the weight of the vehicle, how much power is required to move it. I've heard a double-length bus gets three miles a gallon. At that rate you only need twelve people to compensate for a 36 MPG car -- and the bus has room for forty more people, all within three car lengths. The reason there's traffic congestion is the planners won't dare to build a system that would really accommodate 1.2 cars per person. You'd need freeways a mile apart, and parking lots significantly larger than our current ones. That was already recognized in the 50s, and the freeways were proposed, but even the most freeway-happy cities won't swallow that much roadway. Now several cities including Phoenix and my hometown Seattle are slated to get a million more people in the next twenty years. One extra freeway and a few park and rides won't be enough.

Good public transportation has to be faster than a car, come every five minutes including evenings and Sundays, and cover all portions of the city. Places that do this, like Moscow, London, and NYC, find a significant number of residents don't need cars or want cars. It can be done in small cities too: Germany is doing it. Duesseldorf and even Bielefeld have streetcars that go underground downtown, Duesseldorf has a train station right at the airport that links to any city in Germany, and a 24-hour commuter train to Cologne and Essen. AND comprehensive night buses, at least on Friday and Saturday, so you can get home from the bar without driving.

Unfortunately, so many cities think they can just do one light rail line and that's enough. It's enough if your house, job, and evening activities are all near the line. Otherwise you're stuck in traffic, have to pay insurance on a car, etc. Try three lines or maybe six, and then you'll see half the residents ditch their cars. But it has to be in a grid, not an octapus like the Chicago EL. If Chicago had a half circle connecting all the lines, usage would more than double because there would be many more one- and two-segment trips possible without going downtown and back. Note that a grid (which need not be rectangular or uniform) is similar to PRT loops, although larger. The PRT articles I read said it's not suitable for very large cities like Chicago. The large numbers of people would overwhelm it. But it could complement the El or Metra in outer neighborhoods or suburbs. Seattle (500,000) is considered a good size for PRT.

Chicago and NYC may suck, but they're more convenient than anywhere else in the US if you don't have or don't want a car. Although it's sad Chicago is just letting the infrastructure deteriorate. Why don't they modernize the tracks and use rubber-tired cars so the El wouldn't be so painstakingly slow and loud? I remember sitting in an almost-empty train car at rush hour and being baffled. In DC the metro is full even at 10:30pm.

Decentralized paths is a good point in general. Inner cities are less congested because they have grid streets, so there are several paths to anywhere and each person chooses a different one, and they can detour if there's a bottleneck. But suburban neighborhoods often have only one road going in and out of them, with dead-end streets and cul-de-sacs off it. These get significantly more congestion. I'm not sure decentralized paths is feasable with transit, however.

What's this about light rail using more BTU than cars or buses? That sounds highly suspicious. Five vehicles chained together use less energy than five separate vehicles, and the tracks should provide less resistance than the roads.

Comment on On the subject of mass transit
by Mike Orr

Comments:

The PRT articles I read said it's not suitable for very large cities like Chicago. The large numbers of people would overwhelm it.

I think PRT people undersell it, sometimes for dumb reasons. They still want the mass transit people to like PRT. The die-hard mass transit people can't stand PRT it seems. They love the idea of mass transit. The biggest critics of PRT are mass transit people; they are tedious but incredibly consistent. Hell, I hear Ken Avidor is even trolling Seattle discussions now (he's been a long time Minneapolis troll).

Everything I've seen indicates that PRT can support more throughput for less infrastructure cost, and with less right of way than any mass transit system. Maybe NYC subways pay off better, but NYC has a unique level of ridership (at least in the US). So, putting aside New York, I think PRT has more potential than any other system, regardless of density. If the infrastructure costs are lower, and the experience is better, and the operational costs are lower, then density shouldn't be a problem. It just means you get an even better level of service as the system is built more densely.

That doesn't mean Chicago is the right first location for PRT. It would be an excellent first location -- I'd be delighted of course -- but there are other places more desperate for new kinds of transportation, and without any real alternatives. In those locations PRT isn't just a better choice, but maybe the only real opportunity for a solution.

What's this about light rail using more BTU than cars or buses? That sounds highly suspicious. Five vehicles chained together use less energy than five separate vehicles, and the tracks should provide less resistance than the roads.

This page lists energy for several systems. It actually puts a bus as on par with light rail, and both above cars. Generally speaking, this applies to a non-commuter system -- i.e., one that doesn't just carry a consistent (and high) level of commuter traffic, but also provides service at non-peak times.

Also, light rail is really really heavy. I'd guess that pound-per-passenger it's on par with a car.

Remember also that this is BTU per real passenger mile. Real trains aren't full all the time. They get less full as they reach their terminal point. There is directional traffic, so they are full in one direction and empty in the other. There is varying usage at different times of the day, and you can't get smaller than one car. So all of these numbers are based on the actual ridership seen in real systems. And the nature of mass transit is it can never provide good service while consistently running anywhere close to capacity -- it's just structurally impossible for those systems.

Lastly, five cars isn't that much more efficient. Amount of stopping and starting and the weight of the vehicle mostly determines the fuel efficiency. So five cars isn't that much more efficient than one. And they are just crazy heavy, and they stop and start all the time.

Current PRT systems aren't actually that much lighter than a car (though it's an immature technology and so I would certainly expect systems to get dramatically lighter). I think most designs have 1 ton cars. The advantages are that they travel slower, stop and start less, and operate only on demand. The energy efficiency is partly in the freedom you get in a lighter, simpler, more modern system; but most of the efficiency is in the basic design of the system, the non-mass aspect.

# Ian Bicking

The PRT articles I read said it's not suitable for very large cities like Chicago. The large numbers of people would overwhelm it.

I think PRT people undersell it, sometimes for dumb reasons. They still want the mass transit people to like PRT. The die-hard mass transit people can't stand PRT it seems. They love the idea of mass transit. The biggest critics of PRT are mass transit people; they are tedious but incredibly consistent. Hell, I hear Ken Avidor is even trolling Seattle discussions now (he's been a long time Minneapolis troll).

I was wondering who Ken Avidor is, but he seems to have answered it himself (below).

I'm not against PRT. It's just that we just finished a 10-year debate on light rail vs monorail vs PRT vs more buses, and the worst choice won. A light rail that has traffic crossings in two sections, and whose first phase is not where the bulk of population is. But I learned that in order to get anything done, you have to get everybody to agree, or at least enough of the movers and shakers. That's the problem with PRT. Not that it's intrinsically bad, just that it gets laughed off the table. Nobody wants to commit millions of dollars to be the guinea pig. We got the same complaints about monorail but were able to point to working systems in Japan, Malaysia, and Las Vegas. I would like to see PRT tried citywide somewhere, and Joe who suggested Phoenix may be onto something. Nobody has been able to find a better solution for post-WWII automobile cities, so PRT could be it. But it would take a very forward-looking city to consider it, with much risk.

The capacity argument was specifically directed at London and Los Angeles, saying that PRT could not handle hundreds of thousands of people going downtown all at once. I assumed Chicago was the same size and dynamic, but you know more about it than I do. PRT is like an elevator system or supermarket check-out line. It works excellent when under capacity, but deteriorates rapidly when it reaches capacity. So PRT complements a trunk system rather than replacing it, and would work in individual neighborhoods or districts or medium/small cities (including most of the US). PRT is good if there are five or ten people at a stop, but not for clearing out a baseball game.

# Mike Orr

I agree that traditional transit activists have had an effect on the way that PRT is sold. PRT proponents now tend to shy away from pushing PRT as a replacement for traditional transit.

The problem, it seems, is that traditional rail activists fought back hard, and dirty. A lot of them (Avidor in particular) have resorted to outright lies and scare tactics in their propaganda campaign. So I think that caused PRT proponents to back off the assertion that PRT could replace most rail systems.

I certainly don't think it's a technical limitation. From what I've seen, a mature PRT system could easily serve a large city like Chicago, assuming of course it was extensive enough to cover the whole city. Don't forget, when you look at cities like Chicago and New York, you are comparing PRT to existing systems that would probably cost trillions of dollars to construct in today's network. With that kind of money, a monstrous PRT network could be built, and well-designed PRT scales better than any other form of transit because of the network effect.

So I think the stated PRT limitations are motivated more by political concerns than technological ones.

# A Transportation Enthusiast