In this section, we consider the information design problem for urban traffic ( Fig. 4 ). Instead of selecting from two routes, as dis- cussed in previous sections, we consider the routing problem in a urban road network denoted by a directed graph ( V, E ). Here, V is the set of nodes (intersections) and two special nodes, the source (starting point) s and the sink (destination) t , and E = (e ) is the set of edges. Vehicles departing from the source follow a point pro- cess ( Daley and Vere-Jones, 2007 ). Each vehicle, upon departure, chooses a path to the sink. Let P be the set of all paths from the source to the sink.