may cost more than building an underground facility. A cost-risk analysis can demonstrate the most cost-effective approach for obtaining the desired level of protection.

At the request of the Defense Special Weapons Agency, the Board on Infrastructure and the Constructed Environment of the National Research Council convened a workshop on April 6 and 7, 1998, on the use of underground facilities for the protection of critical infrastructure. The workshop, which was held at the National Academy of Sciences, in Washington, D.C., explored how existing UGFs constructed for defense purposes or new facilities might meet the nation's needs in protecting critical infrastructures. Workshop participants possessed expertise primarily in defense and security matters. Members of the commercial underground and tunneling communities also were in attendance.

The views presented in this summary of the workshop are solely those of the participants and do not represent the positions or opinions of the Defense Special Weapons Agency, the Board on Infrastructure and the Constructed Environment, the National Research Council, or the National Academy of Sciences.

Following a welcoming address by Maj. Gen. Gary Curtin, director of the Defense Special Weapons Agency, and a keynote address by Frederick Struble, former commissioner of the PCCIP, four technical panels were convened. Panel 1, "Infrastructure Protection Issues", provided an overview of the threats facing the nation's critical infrastructures. Panel 2, "Needs and Requirements of the Infrastructure Community", addressed issues and protective strategies from the viewpoints of selected infrastructure sectors. The third panel, "Experiences with Underground Facilities: Capabilities, Limitations, and Applications" gave an historical perspective on the use of UGFs and operating experiences with defense and commercial facilities. Panel 4, "Factors Influencing the Decision-Making Process'' discussed the various technical, economic, and policy questions that must be addressed when considering an underground facility option. Donald Woodard discussed the key issues that commercial enterprises consider when contemplating an underground location and Arnfinn Jenssen provided a Norwegian perspective on infrastructure protection in the United States. Following the panel presentations and discussions, the workshop participants divided themselves between two breakout sessions to discuss technical and policy issues.