Traffic Congestion Paradoxes

When everybody tries to crowd onto the highway, everybody slows down. Beyond a certain point, throttling usage actually makes everybody get to their destination faster. Imagine a roadway with some kind of nasty merge which gets severely jammed up if there are too many cars. If ten cars all try to go through at once, everybody could be stuck for quite a while. If you throttle them so they go through one by one, everyone gets to their destination faster. The same thing can apply to real roa

Interestingly by Braess's paradox adding more lanes can increase congestion, and removing lanes can speed up the traffic.https://en.wikipedia.org/wiki/Braess%27s_paradox

Yeah it's a known thing now that widening highways / adding more throughput does not ease congestion etc.https://www.nytimes.com/2023/01/06/us/widen-highways-traffic....

The people driving at a constant speed are not the problem. They keep traffic flowing smoothly, even if it is slightly below the speed limit. The ones who create the problem are those changing lanes to gain 5 mph and get to their destination one minute sooner. They cause people in the lane they move into to have to pile on the brakes, causing slowdowns which can form a standing wave and turn into traffic jams. If people would just pick a lane and a speed and stick to it the overall throughput of

This used to bother me, then I realized that under heavy congestion conditions, you probably get higher overall throughput on the highway if no one tries to keep a lane free.

Traffic doesn’t work like that. You seem to have a mental model where traffic is modeled like a liquid (traffic has a definite volume and does not expand to fill its container) while many studies show traffic behaves more like a gas (traffic expands to fill its container). Basically, more lanes doesn’t mean less traffic, it generally means the same amount of traffic.

Try less, and smaller roads:https://en.wikipedia.org/wiki/Braess'_paradox

Could be related to Braess's paradox? In this case "adding lanes" would be "increased routing"> [The] idea was that if each driver is making the optimal self-interested decision as to which route is quickest, a shortcut could be chosen too often for drivers to have the shortest travel times possible.https://en.wikipedia.org/wiki/Braess%27s_paradox</a

Slow traffic is created non-linearly, i.e. if a road has a capacity of 100, it will be totally fine 0-90, but traffic will rise sharply after that point. If you could reduce the amount of cars by 10%, you could massively reduce the traffic that everyone is experiencing. So in that example, 90% of commuters will still be driving and paying tolls, but with far less traffic, and the other 10% may be on public transit/bike/walk/wfh and also experiencing far less traffic.

When have traffic woes ever been alleviated by adding more lanes?