Abstract: Routing games are used to understand the impact of individual users' decisions on network efficiency. Prior work on routing games uses a simplified model of network flow where all flow exists simultaneously. In our work, we examine routing games in a flow-over-time model. We show that by reducing network capacity judiciously, the network owner can ensure that the equilibrium is no worse than a small constant times the optimal in the original network, for two natural measures of optimality. Bio: Umang Bhaskar completed his PhD in August this year from Dartmouth College, and his thesis work focused on understanding equilibria in routing games. He joined Caltech as a postdoc in September this year.