Eli5 How are carpool lanes supposed to help traffic? It seems like having another lane open to everyone would make things better?

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I live in Los Angeles, and we have some of the worst traffic in the country. I’ve seen that one reason for carpool lanes is to help traffic congestion, but I don’t understand since it seems traffic could be a lot better if we could all use every lane.

Why do we still use carpool lanes? Wouldn’t it drastically help our traffic to open all lanes?

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Anonymous 0 Comments

The technical term is [induced demand](https://en.wikipedia.org/wiki/Induced_demand). More lanes = more and worse traffic.

Closely related is [Braess’s paradox](https://en.wikipedia.org/wiki/Braess%27s_paradox). Adding capacity actually slows down traffic.

The better solution would be to instead close the non-carpool lanes and put rail lines in their place. But this is America. Land of individualism. Nobody really wants it to be better. They just want more lanes of worse bumper-to-bumper traffic.

[Please stop adding more lanes to busy highways—it doesn’t help](https://arstechnica.com/cars/2021/08/please-stop-adding-more-lanes-to-busy-highways-it-doesnt-help/)

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