Braess Paradox in the Laboratory : An Experimental Study of Route Choice in Traffic Networks with Asymmetric Costs

The Braess Paradox (BP) in traffic and communication networks is a powerful illustration of the possible counterintuitive implications of the Nash equilibrium solution. It shows that, paradoxically, when one or more links are added to a weighted network with linear costs that depend on congestion with an attempt to improve it, and each user independently seeks her best possible route, then the equilibrium cost of travel of all users may increase. Extending previous research by Rapoport et al. (2005), we report the results of a new experiment with a richer topology and asymmetric link costs of travel designed to assess the descriptive power of the BP. Our results show that with experience in traversing the network players' choice frequencies approach the equilibrium solution as implied by the BP