From 2004 to 2007 as a modeler I was involved in the Critical Infrastructure Protection-Decision Support System (CIP/DSS) project, a project funded by the US Department of Homeland Security. The main focus of this project is to develop a risk-based decision support system to provide insights for making critical infrastructure protection decisions.

CIP/DSS simulates the dynamics of individual infrastructures and couples separate infrastructures to each other according to their interdependencies [1]. For example, repairing damage to the electric power grid in a city requires transportation to failure sites and delivery of parts, fuel for repair vehicles, telecommunications for problem diagnosis and coordination of repairs, and the availability of labor. The repair itself involves diagnosis, ordering parts, dispatching crews, and performing work. The electric power grid responds to the initial damage and to the completion of repairs with changes in its operating characteristics.

Dynamic processes like these are represented in the CIP/DSS infrastructure sector simulations by differential equations, discrete events, and codified rules of operation. Many of these variables are output metrics estimating the human health, economic, or environmental effects of disturbances to the infrastructures.