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Publication Number: FHWA-RD-02-014
Date: September 2002
For bridge and highway infrastructure engineers, protecting bridges and other structures used to mean guarding against such natural processes as fatigue and scour and events such as earthquakes. September 11 changed all that. Since last fall, engineers have faced the new challenge of how to protect structures from potential terrorist attack. “Bridge and highway engineers are being asked the urgent questions of how vulnerable these structures are and what can be done to reduce this vulnerability,” says Steve Ernst of the Federal Highway Administration (FHWA). To equip engineers to answer these new and complex questions, FHWA is developing a Bridge and Tunnel Vulnerability Workshop and has launched other structural security initiatives.
The workshop is being developed in conjunction with the U.S. Army Engineer Research and Development Center (ERDC) Geotechnical and Structures Laboratory in Vicksburg, Mississippi. For the past 35 years, the ERDC has carried out structural vulnerability research and development work. This work has included conducting numerous full-scale explosive tests on bridges and in tunnels, as well as analyzing complex structural data and developing computer tools. Starting in the spring of 2003, FHWA and the ERDC will present three workshop sessions for FHWA engineers and some State personnel. While the agenda is not yet final, proposed topics include bridge and tunnel vulnerability to explosive attack, structural response to blast-induced loadings, and an overview of vulnerability predictive tools and mitigation methods.
Providing guidance to bridge owners is also the focus of a new FHWA/AASHTO Blue Ribbon Panel on the Safety and Security of Highway Bridges and Tunnels. The panel is being formed this fall and will hold its first meeting in November 2002. The panel will develop short and long-term strategies for increasing the security of critical bridges and tunnels, including implementing design and retrofit techniques and electronic and physical protection systems. “The Blue Ribbon Panel will generate ideas to help transportation program managers make decisions about allocating resources for bridge and tunnel security,” says Ernst.
With more bridges than any other State in the country, assessing and improving the security of structures is a primary concern for the Texas Department of Transportation (TxDOT). The agency has implemented a multifaceted approach to transportation security over the past year. This approach included first identifying the State's most critical bridges. Options were then developed for deterrence of terrorist acts, as well as surveillance and protection of the structures, tailored to each specific location. Deterrence techniques that have been considered include eliminating parking areas beneath bridges, limiting access to important bridge components by securing or removing ladders and inspection platforms, and restricting approach routes from adjacent areas through the use of fences or other barriers. Options for surveillance that have been looked at include clearing of vegetation around structures to improve sight lines and installing motion sensors and other active sensors to monitor sensitive areas. Actions to protect critical bridges being considered include installing barriers around bridge columns.
As part of its security initiative, TxDOT has launched several research projects. In the first one, the Center for Transportation Research at the University of Texas at Austin is examining the design of bridges for security. “Bridges that are hardened for natural disasters such as earthquakes, floods, and wind, are not necessarily hardened for terrorist attack. Solutions are needed that reduce the threat and mitigate the consequences of such attacks,” says Mary Lou Ralls, Director of TxDOT's Bridge Division. Meanwhile, researchers at Texas Tech University are evaluating techniques and incentives for rapid bridge replacement in the event a structure is damaged or destroyed. While the research initiatives started out as internal TxDOT projects, recognizing their value to other States and the advantages of gaining additional perspectives, the initiatives have been changed to Texas-led national pooled-fund projects. A kickoff meeting for the pooled fund will be held September 10 in Austin, Texas.
TxDOT is also working to ensure preparedness to handle the consequences of potential future security threats. For example, the agency has developed an Emergency Highway Traffic Regulation Plan to expedite and facilitate vehicle movements in the event of a national security emergency. In addition, site-specific emergency response procedures are being developed for the State's critical bridges. These procedures will cover such areas as traffic control plans, detour plans, and debris management.
For more information on TxDOT's transportation security initiative or the pooled-fund studies, contact Tom Rummel at TxDOT, 512-416-2254 (email: email@example.com).
FHWA is also participating in a BiNational Security Steering Committee that is studying the security needs of 8-10 major bridges between Michi-gan, New York State, and Canada. Composed of representatives from Canada, the United States, and private bridge owners, this group is working on best practices and standards for identifying critical infrastructure, assessing its vulnerability, and developing countermeasures to potential attacks. Other issues being considered include protocols for identifying which agency should take the lead in an emergency and for coordinating among operators of the different bridges if security risks are detected in the area. The committee has held two meetings to date and will convene again this fall. Jim Steele and Bob Arnold, FHWA's Division Administrators for Michigan and New York State, respectively, represent FHWA on the committee.
For more information on the Vulnerability Workshop or the Blue Ribbon Panel, contact Steve Ernst at FHWA, 202-366-4619 (email: firstname.lastname@example.org). For more information on the Bi-National Security Steering Committee, contact Jim Steele at FHWA, 517-377-1844 (email: email@example.com).
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