1. A route planning system comprising the following computer-executable components: a receiver component configured to receive a request for driving directions between two or more points; and a route generator component that outputs driving directions of an optimal route between the two or more points, the driving directions including: directions between the two or more points along the optimal route; a contingency comprising: a contingent branch route; information specifying an observation point visible to a user driving along the optimal route; and a traffic condition at the observation point under which the contingent branch route is recommended; wherein: the route generator component determines the contingent branch route as a function of information about a previously observed flow of traffic with respect to at least one road segment within the driving directions; and the route generator outputs the driving directions in a format configured for presentation to a human with the contingency integrated with the optimal route.