Section: New Results

Selfishness vs efficiency in traffic networks

Empirical studies in real-world networks show that the efficiency ratio between selfishly and socially optimal states (the so-called price of anarchy) is close to 1 in both light and heavy traffic conditions, thus raising the question: can these observations be justified theoretically? In [17] we showed that this is not always the case: the price of anarchy may remain bounded away from 1 for all values of the traffic inflow, even in simple three-link networks with a single O/D pair and smooth, convex costs. On the other hand, for a large class of cost functions (including all polynomials), the price of anarchy does converge to 1 in both heavy and light traffic conditions, and irrespective of the network topology and the number of O/D pairs in the network.