Volume 11 (2015) Pages 557-565
When a road network is broken by a large-scale disaster, we have to immediately restore some links and connect the whole network as a first-aid restoration for transporting relief supplies. This study proposes a model to determine the optimal facility locations and routes for working vehicles. The feature of the first-aid restoration is that travel time of a link changes before and after the link is restored. In order to represent the change of travel time, we employ a time-space network and formulate the model as an integer linear programming. The objective function consists of required time taken until all nodes are visited by at least one working vehicle, sum of all working vehicles' travel time, and sum of required time taken until a node is visited by a working vehicle. By applying the model to some example networks, we show the features of the optimal state for first-aid restoration.