Computing Dynamic Routes in Maritime Logistic Networks

In this paper, we study the problem of finding the path that maximizes the gain toward one of several destination ports subject to uncertain information on the expected gain in each port. Although the cost of a ship trip between two points is usually predictable, some events may happen, thus impacting the cost. The price of goods to be delivered may fluctuate during the trip (thus impacting the gain), or the price to pay at the destination point can be higher than expected (in case of a strike for example). All of this has important economical consequences for the ship-owner and for the port on a long-term basis. In this context, it is important for a ship-owner to be able to react quickly when a destination port is no longer available. When a port terminal is on strike for example, ships are rerouted to other ports to be loaded and unloaded. We propose in this paper a simple and yet efficient algorithm to re-compute the path of the ship, when she is on the way, based on the computation of the longest path in a weakly dynamic graph, in order to maximize the global gain of the trip.