Embodiments relate to producing a plan of a route in a transportation system. The method receives route requirements, including a starting location and an ending location. The method builds a model of the transportation system from data about vehicles. The model abstracts a “prospect travel” between two locations using any of a range of choices of vehicles and walks that can transport between the two locations. Given anticipated wait durations for the vehicles and their ride durations, the method determines an expected minimum travel duration using any of these choices. The method combines the expectations for various locations in a scalable manner. As a result, a route plan that achieves a shortest expected travel duration, and meets other requirements, is computed for one of the largest metropolitan areas in existence today. Other embodiments include a computer system and a product service that implement the method.