Evacuation problems and dynamic network flows

We report our recent work about basic studies on crisis management systems for reliable communication/transportation network design and evacuation guidance of residents against large-scale disasters. We survey recent developments in modeling of evacuation problems and consider an evacuation problem in tree networks and flows such that all the supplies going through a common vertex are sent to a single sink, since everyone has to evacuate fairly and without confusion. We show that the evacuation problem can be solved in polynomial time if the number of sinks is bounded by some constant.