Optimal location of flow intercepting facilities to improve security in urban areas

The problem of the optimal location of control facilities in an urban area for improving security in case of large events or critical situations is presented. The paper focuses on the prevention of threats by the control and/or the interdiction of people and vehicle flows entering an area (restricted zone). In general, limited available resources do not allow monitoring all the access points of the area. So it is fundamental to identify the most suitable points where control facilities should be located. Two flow intercepting facility location models will be presented: the first one is devoted to identify the best location of a limited number of control facilities to maximise the security level; the second one is aimed at computing the minimum number of control facilities able to guarantee a prescribed level of security. Results obtained on test cases representative of different urban structures are presented.