4 ms·
Paradoxically, adding routes can actually make traffic worse for everyone. Suppose you have two equal-time routes between A and B. If a shortcut is added connec
by danteembermage 18y ago
Paradoxically, adding routes can actually make traffic worse for everyone. Suppose you have two equal-time routes between A and B. If a shortcut is added connecting halfway on route A to halfway on route B (obviously these are not direct-as-the-crow-flies routes with identical speed limits or this wouldn't work) Travel time for everyone increases by 50% (whether you take A, B, or A-B).
I read an article before (tried to find it but couldn't) about a mathematician and [his/her] grad student who had calculated the theoretical maximum cost of this sort of thing and that 50% is the worst it gets, but that's still pretty bad.
- mlinsey 18y agoThis is called "Braess' Paradox" http://en.wikipedia.org/wiki/Braess'_paradox http://en.wikipedia.org/wiki/Braess'_paradox
- iigs 18y agoMaybe I'm not understanding the article here, but could this apply to the problem with aggressive lane-changers on a highway? When people (I find this in myself) get on the freeway, it seems like they tend to get clear over to the fast lane right away. Shortly thereafter traffic starts to back up in that lane and the next slower lane looks like it's winning -- so a bunch of people move over, causing that lane to slow and the original lane to speed up. The resultant pattern is an oscillation of stop and go traffic in the lanes in question. It seems like if this doesn't exactly apply that it at least speaks to what might be going on. I wonder if there has been any research in disallowing lane changes in areas prone to stop and go traffic.
- danteembermage 18y agoThe article about the 50% maximal cost used that exact situation as the attention getter.