An extensive quantitative risk assessment applied to the land transport of dangerous goods through the territory of Sicily has been outlined. A complete inventory of dangerous substances was the basis of a complete risk analysis. In this paper a quantitative risk analysis has been applied to a large area and then, in order to evaluate the risk associated with the transport of dangerous goods including scenarios caused by terrorist attacks, attention has been focused on an urban area. The study has been applied to the area of the Straits of Messina, focusing attention on two types of incident, explosions and toxic dispersions. It has been possible to define emergency procedures appropriate for those.