Critical Infrastructure systems provide the basis for modern urban life. While they deliver the material and services we have come to depend upon for daily survival, they are as extended network systems vulnerable to both large-scale threats such as earthquakes and hurricanes and to specific attack at key nodes. Risk and Resilience management of regional infrastructure systems requires detailed understanding of the vulnerabilities and dependencies of the constituent assets that make up individual systems and the dependencies and interdependencies between systems and the consequences of cascading failures across systems. Regional resilience management requires tools for the identification and prioritization of coordinated investments at a range of points across regional infrastructure systems. This requires the understanding of both the physical and administrative dimensions of regional infrastructures. This research is directed to the development of such analytical tools.