A case study on graph-based planning for emergency evacuation

We present a pilot study on the implementation of a software, based on declarative knowledge representation and logic-based automated planning, which assists the management of severe Chemical hazard events, e.g. fire or emissions that may require the evacuation of the area surrounding the affected Chemical plant. We model the geography, the road network and the population of the chemical plant and the surroundings by weighted, labeled graphs, which are updated as the hazardous situation develops. Intervening factors, e.g. the spread of toxic in the air, are represented in the graph in terms of their effects. Risk for the resident population and possible evacuation plans are evaluated and re-evaluated as the accident develops. Also evacuation plans are contingent and as conditions change may be re-evaluated from scratch; moreover, they may involve complex coordinated actions among the rescue units. Both the evaluation of the emergency scenario and the evacuation planning phases have been prototyped by means of an Answer Set Programming planner.