PRT Will Save The World

Several progressively minded people have proposed a new transit system called, Personal Rapid Transit. A quick hit on google gives us this link:

http://faculty.washington.edu/~jbs/itrans/prtquick.htm

In short, PRT involves creating a second roadway system, typically above grade, on which only computerized vehicles are permitted. These cars are small, can be individually dispatched, and most importantly allow the user to designate their destination directly.

When fully deployed, it provides a number of excellent advantages:

• The central control of the cars permits a much greater efficiency than the old at-grade, driver-controlling system
• The cars can be run on alternate powersources much easier than switching over the existing at-grade road-system
• Starts/Continues the process of weaning transit consumers off of their expensive vehicles
• Can handle much higher traffic densities due to the 'big picture' central control gives
• Unlike existing transit systems like busses, subway, and Light Rail Transit (LRT, a.k.a. trolley), permit the user a straight-to-destination without having to 'share the ride' if they wish.
• Allows the system to charge users the true-cost (or a percentage there of) of the system, something that the current highway-based system doesn't do.

This is all very well and good, but it all depends on one key thing. The above benefits only are realized when fully deployed. Full deployment in this case means that a PRT station exists within easy walking distance of every user of the system, AND a large majority of the places they wish to go to.

Also, a fully deployed PRT system has the same order of magnitude cost as, LRT, dedicated bus corridors, heavy-rail commuter lines, and interstate highways. I say order of magnitude since a fully deployed system, regionally, for any of those technologies is a multi-billion dollar investment. PRT is cheaper than any of the others, but that doesn't change the fact that it still costs ten figures. At least.

Then factor in the fact that for any of those transit systems the costs will force the deployment to take decades. While a truly massive infusion of cash could force a fully deployed system to be put up in under seven years, the chances of someone ponying up more money than the US paid to put up the International Space Station are slim. Any allocation of public funds will be a yearly, or bi-yearly, ordeal subject to the same pitfalls of public funding any massive non-DoD project gets. The public likes highways. They understand highways. They do not understand PRT.

The two main pitfalls of PRT are not exclusive to PRT, but sink it none the less:

1. It is still mega-engineering, requiring a massive investment of resources to pull off
2. The time-scale for deployment really requires public investment, and all the uncertainty that brings

There are a couple of other problems that raise the cost of PRT. These are things that are actually taken into consideration by some of the researchers in the field, but I've met a few advocates who were not aware of them or chose to hand-wave them away as trivial. For clarity:

• The Americans with Disabilities Act requires that the above-grade stations be accessible to people in a wheel-chair. This will require elevators in each and every station, at least
• The above-grade track has to work around or with existing above-grade items like utility wires. Some municipalities have buried these, but by no means all.
• The above-grade track will definitely change the city-scape, which may lead to "not in my front yard" protests
• Above-grade needs to be earthquake proof in those areas where that is a hazard. We all remember the double-decker highways in California that collapsed during one of their earthquakes, and we don't need PRT pylons toppling into houses
• People are not used to walking very far anymore, so that station has to be within 300 yards of the front-door of people. Or immediately in front for people who have to carry heavy things like groceries for a family of four.

So not only will it take a massive public investment of resources, it will also require a culture shift. The second may be possible once it is proven that the PRT system can get you places faster than you can by car, but that also depends on PRT being deployed far enough that such is provable.

Which leaves us with the alternatives. And that is to upgrade our current infrastructure to work with the future. We've done this a lot in the past. Trolley systems have been paved over and replaced with more flexible busses. Long distance train travel has been replaced by Greyhound and airplanes. Commuter wagons in the inner cities have been replaced by busses and private vehicles. It is clear that what we need now is a replacement for the car, and that's difficult.

There are two technologies that will make the car into something more PRT-like:

• The advent of traffic tracking technologies in our urban centers
• Computer-assisted or computer-piloted cars

These two technologies, once mature, will provide a lot of the benefits of PRT but do so at grade on the existing roadway systems. Something like this is far more likely to catch on that a PRT system would. Yes, we do have to wait until the technology is ready, but we'd have to wait 15-30 years for PRT to be fully deployed anyway, so that's reasonable.

Such a system could be deployed like this:

1. State/Federal law mandates that cars be shipped with a transponder. This transponder can be disabled.
2. The state starts building in transponder readers into the road-system. A lot of states already have passive detectors so they can sense traffic jams, this just provides an active device to identify individual vehicles (note, the transponder can still be disabled).
3. The combination of transponders and readers creates a very nice datastream. Either the State department of transportation or private companies can use this feed to generate a very detailed congestion map. This second generation map, the first gen being what we have now, can be used by drivers as a subscription service (or publicly subsidized system, whichever) to be notified of traffic problems ahead on the route. Cars without enabled transponders are treated as the moving hunks of metal they are.
4. Car manufacturers and Federal safety regs permit the use of computer-driving along transponder-equipped roadways. Such cars can take the feed from the congestion-tracking service and make changes in route and speed to minimize things
5. The next generation of cars actively communicate with Central and with the cars around them in order to move most efficiently. Cars without active transponders, or in 'human driver' mode are given a larger safety buffer.

This provides some free-market incentives to jump on the technology bandwagon, and does not deprive the transit consumer of their much cherished vehicles. In the most densely congested urban centers, they may never actually drive their vehicle, but they could if they wanted to. And that's important.

To the paranoid, this does provide a way for the Feds to track your car through the system and that could be a violation of privacy. The privacy laws regarding the appropriate use of the data of where you are right now will still need to be assessed at some point. Whether or not this data stream belongs in the hands of the Government or some privately held third party I leave as an exercise for the reader. This is why I envision a transponderless option being in place for a good long time. Some states already encourage commercial trucks to have transponders, and encourage this by allowing transponder-trucks to bypass some weighstations.