Equilibria in Routing Games With Connected Autonomous Vehicles Will Not Be Strong, as Exclusive Clubs May Form

Abstract

We examine whether route-choice equilibria remain stable once connected autonomous vehicles (CAVs) can coordinate their decisions. In classical traffic assignment, a user equilibrium is interpreted as a Wardrop or Nash-type equilibrium where no traveler can improve by changing route alone Wardrop (1952); Nash (1950). We show that this will be no longer sufficient when autonomous vehicles can communicate and deviate jointly. We formulate route-switching coalitions (clubs), define their internal and external stability, and demonstrate the formation mechanism in a microscopic mixed-traffic network with adaptive traffic signals. Starting from a user equilibrium, a three-vehicle CAV club can profitably deviate to another route, reduce each member’s travel time, worsen conditions for excluded users, and increase the total travel time in the system. The results imply that CAV coordination may generate inequitable and strategically unstable traffic states on public road networks.