Personal Rapid Transit (PRT) is getting some attention. NPR has a story.
It’s an interesting compromise between full-blown rail mass transit and personal vehicles. The primary concern is that PRT would only work in compact, high-traffic areas; like connecting the hotels in Vegas, getting around a university campus, or at facilities like airports.
I was talking with someone the other day about a conceptual PRT-like system as an alternative to light rail, where there’d be many cars all evenly spaced apart that would run on a limited-access rail system. To get on and off the cars there could be “exit paths” along which the cars would slow down some and passengers would board from a series of accelerating moving sidewalks, similar to the continuous circuit train rides at Disney World. This idea, of course, is totally half-baked with plenty of flaws, but I don’t think it’s too far from what these PRT studies are exploring in San Jose and Ithaca.
My thinking on it is that you’d want a system that did not stop at each and every stop, like a personal equivalent of an express train. Certain popular stops would have more cars arriving, since more passengers would request that stop, and, inversely, more would want to board there. The intelligent system would know the queue lengths at each stop, and if an empty car rode by a stop with a queue, it would exit and let the waiting passengers board. PRT systems seem more attractive than light rail in certain locations because they could reduce wait times. If the stops along your circuit have similar levels of traffic and are similarly desirable stops, the even distribution of ridership would lend itself well to more small cars, rather than fewer larger ones.
