Le Havre agglomeration (CODAH) includes 16 establishments
		classified Seveso3 with high threshold. In the literature, we construct
		vulnerability maps to help decision makers assess the risk. Such
		approaches remain static and do take into account the population
		displacement in the estimation of the vulnerability. We propose a
		decision making tool based on a dynamic vulnerability map to evaluate
		the difficulty of evacuation in the different sectors of CODAH. We use
		a Geographic Information system (GIS) to visualize the map which
		evolves with the road traffic state through a detection of communities
		in large graphs algorithm.