Sunday, May 27, 2018

The Rollercoaster Line

I thought I was done writing about PRTs because self-driving cars were the new stupid thing, but stupid billionaire Musk has resurrected them and I am mad about it. David Dayen takes a swing in the LA Times.

Even if we buy the semi-plausible claims of boosters about these things (not that we should, but ok), Musk's underground PRT is at best an extremely low capacity subway. If speed is the issue, subways are pretty fast. What keeps them from being fast is boarding and the number of stops. But boarding is pretty efficient! 24 trains 1000 person capacity trains per hour on a modern subway is pretty standard. As for the number of stops, well, it doesn't matter how fast the technology allows your train to go at full speed. Braking and accelerating take time (also given the lack of inertial dampeners in our not very advanced civilization, there are human limits). If you increase the number of stops, or even potential stops, you just slow things down even more. And if you don't have a large number of stops... the system is an improvement over a high capacity I have no idea. Not rubbing elbows with strangers is apparently the draw, but if the price of that is 1/100 of the capacity, optimistically.... take a damn limo, Elon. You're never gonna ride this public transit system, either.