Date of Award

Spring 2005

Document Type


Degree Name

Doctor of Philosophy (PhD)


Mechanical Engineering

Committee Director

Charles B. Keating

Committee Member

Andres Sousa-Poza

Committee Member

Resit Unal

Committee Member

Willie J. McFadden II


Military and civilian leaders have the responsibility to protect our Nation's critical infrastructure, communities, and symbols of American power from terrorists, home and abroad, as well as from natural disasters. To this end, assessments are conducted to reduce vulnerability. The literature offers multiple definitions of vulnerability and measurement has not been adequately addressed. Thus, the purpose of this research has been to develop and deploy a systems-based model that quantifies vulnerability to critical infrastructure. This research defines critical infrastructure vulnerability as a measure of the susceptibility of critical infrastructure to threat scenarios. Vulnerability is a function of (1) threat scenario, (2) protection and (3) importance. Critical infrastructure vulnerability is measured by a system's (1) deterrence, (2) detection, (3) delay and (4) response capabilities. Importance implies that some subsystems are more critical to overall system performance than other subsystems. A value model was used as the logic construct for quantifying vulnerability. Subject-matter experts were queried to establish the shapes of value functions and importance (weights) in the model. Another set of subject-matter experts are queried to assess a notional clean water system with respect to each protection measure within the vulnerability value model. To accomplish this, two simulations are executed in the model. The first simulation aggregates expert assessments into one assessment. The results are then used as inputs into the vulnerability value portion of the model for use in the second simulation where vulnerability is quantified. Results of this research demonstrate that vulnerability can be quantified and that quantifying vulnerability is useful to decision-makers who prefer quantification to qualitative treatment of vulnerability. This research is a novel contribution to the body of scholarly work by: (1) providing a rigorous method to quantify vulnerability to critical infrastructure, (2) introducing the theory of vulnerability, and (3) specifying the theoretical relationship between risk and vulnerability. Subject matter experts conclude that there is value in the approach put forward in this body of research as it is applied to clean water systems, so it may be useful in other critical infrastructures. The research closes with directions for further research.