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When I first learned about computer networking, I remember being blown away when I learned that network congestion dynamics also explained how freeway traffic w
by kaycebasques 9y ago
When I first learned about computer networking, I remember being blown away when I learned that network congestion dynamics also explained how freeway traffic worked. It’s cool to see the same idea in this article!
Specifically, I thought it was amazing how it explained why if someone stops abruptly on a crowded highway, every subsequent driver will have to experience that pause, even hours later, so long as the highway maintains the same level of congestion.
You network folk will undoubtedly explain it better than me, but I think that's the correct gist of the idea?
- kps 9y agoI wonder whether any of the large networked navigation software does random early drop.
- paulmd 9y agoI've always had this odd feeling that traffic is actually a Bernoulli flow, where instead of "pressure" you have congestion. eg if you have two lanes merging and the system is at capacity, then the "pressure" across the streamline increases and traffic slows down as a result. And when you have very little pressure (or diverging arterial roads) traffic tends to speed up. Of course there is a secondary problem of "phantom" traffic jams where the system is not really slowing down due to traffic merging or anything, you just have spots where traffic is not flowing at all for no real reason (the optimal solution being that everyone puts their foot on the gas and accelerates together). I suppose the physical analogue might be cavitation or non-laminar/turbulent flow? I can't find any academic references on this but it's always made intuitive sense to me.
- lainga 9y agoThis is exactly why traffic regimes are sometimes described as "laminar" or "turbulent". https://en.wikipedia.org/wiki/Fundamental_diagram_of_traffic_flow https://en.wikipedia.org/wiki/Fundamental_diagram_of_traffic...
- yc-kraln 9y agoHere's one for you: https://www.fhwa.dot.gov/publications/research/operations/tft/chap5.pdf https://www.fhwa.dot.gov/publications/research/operations/tf... I seem to remember a statistic that said, essentially, traffic waves propagate backwards at approximately 12mph. There are a set of circumstances where you can set up a "standing" wave of traffic where cars will have to tap their brakes at the same place for hours, for no reason.