Sunday, January 31, 2016

The Price of Anarchy in Transportation Networks

Great paper with an interesting application of Braess’s paradox to transportation: closing roads can reduce travel delays.

Youn, H., Gastner, M. T., & Jeong, H. (2008). Price of anarchy in transportation networks: efficiency and optimality control. Physical review letters, 101(12), 128701.

Uncoordinated individuals in human society pursuing their personally optimal strategies do not always achieve the social optimum, the most beneficial state to the society as a whole. Instead, strategies form Nash equilibria which are often socially suboptimal. Society, therefore, has to pay aprice of anarchy for the lack of coordination among its members. Here we assess this price of anarchy by analyzing the travel times in road networks of several major cities. Our simulation shows that uncoordinated drivers possibly waste a considerable amount of their travel time. Counterintuitively, simply blocking certain streets can partially improve the traffic conditions. We analyze various complex networks and discuss the possibility of similar paradoxes in physics.
Hyejin Youn also has some more recent and equally interesting papers on urban scaling laws, in case you're interested.

credit: Youn et al (2008)

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