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Train Rule
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this post was submitted on 30 Dec 2023
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I read in a book that the current system of drivers acting on their own without something coordinating their every move is actually 75% as efficient as a fully coordinated system.
Therefore, the benefit obtained with all people using self driving cars is nothing compared to just improving public transit or improving car infrastructure.
I don't know what book that was or what metrics its using, but my local intersections could easily pass 3x the current number of cars per green light if they accelerated together, and right away.
The number of people who poorly merge and cause traffic shockwaves, how slow cars drive in the fast lane, the accidents caused by human error. Really curious how they came to that 75% number.
I was slightly wrong. From page 237 of Algorithms to Live By, The Computer Science of Human Decisions by Brian Christian and Tom Griffiths, further referencing the paper How Bad is Selfish Routing? by Roughgarden and Tardos, it says that
"...the "selfish routing" approach [of cars] has a price of anarchy that's a mere 4/3. That is, a free-for-all is only 33% worse than perfect top-down coordination."
Anyways, the way they got to that number is mathematical game theory. In this case people will choose the fastest route which happens to not be so bad.
It's also very possible that what they're concluding is significantly abstracted, but I haven't read the source reference to know for sure.
Just the number of people being moved on a bus or light rail for a given amount of space tosses that efficiently number away.
Exactly. The point it was making is that perfect top-down coordination takes a ton of resources for a whole lotta nothing.
That's on the macro level with decision making. I think, coordinated has another advantage on the micro level, the traffic jams will move as one without waiting for information spread from the head, the accidents are less likely to happen and jam even more.
Having said that, I'd still prefer a good and technologically advanced tram network to any amount of cars 🥲
I don't think cars are ever going away, even if public is the main transportation method. Which obviously sucks, but it's the way it is.
I've always imagined a protocol that lets cars communicate their planned speed. I'm pretty sure this is how cars will work in the future. A decentralized mesh of coordinated vehicles. This means that cars can:
Public is obviously the best option though. Imagine a city with no streets, only subterranean public transportation. You wouldn't even need such a large public transportation system, cities would be a fraction of the current size. I wonder what percentage of the area of a city is wasted on streets.
In the 90s in school, I did a report and imagined computers would be too expensive to have in every car, so the road itself would have wireless infrastructure to control the cars.
Sounds like a use case for SOLAR FREAKING ROADWAYS!
A hybrid system would be cool. I could see a future where electric vehicles could link up to a pod like train cars for long trips along standard routes, and schedule automated disembarkation for their "stops" to continue the rest of the way to their destination. Full autonomous driving is a difficult problem be a lane pods of this nature could be quite efficient and easier to automate
PRT is kinda like this, but they don't link together.