William J. Mallett
Specialist in Transportation Policy
Nicole T. Carter Specialist in Natural Resources Policy
Peter Folger
Specialist in Energy and Natural Resources Policy
The 9.0 magnitude earthquake that struck off the coast of Sendai, Japan, on March 11, 2011, renewed concerns about the seismic risk to America’s infrastructure, including its highways. Concerns about the U.S. highway system’s seismic risk stem from interest in protecting public safety, facilitating response and recovery efforts, and minimizing economic loss and social disruption. Seismic resilience of the U.S. highway system has improved in recent decades as investments have been made to build new, more resilient infrastructure and to retrofit existing structures. However, not all existing highway infrastructure has been retrofitted, and no infrastructure can be constructed in a cost-effective manner to be immune from the most intense earthquakes, so some seismic risk to the U.S. highway system remains.
Although earthquake hazards in the United States generally are well documented, little national or federal data exist about the seismic risk to U.S. highway infrastructure. Instead, seismic highway risks typically are assessed and addressed by state and local entities which are generally responsible for building and maintaining that infrastructure. The federal government supports these nonfederal efforts by providing data on the seismic hazard for different locations, assisting in the development of construction standards and guidelines, and undertaking research, training, and the development of tools to assist in risk reduction. In limited circumstances, the federal government invests directly in improving resiliency of specific highway structures.
This report addresses frequently asked questions about the risk from earthquakes to highway systems, including bridges, tunnels, pavements, and other highway components. Particular attention is given to highway bridges, which often are the most vulnerable highway structures.1 The report also discusses federal and nonfederal actions to reduce seismic risk to the U.S. highway system.
Japan is generally regarded as the country with the most earthquake-resilient infrastructure. Research into the performance of Japan’s highway structures and systems during and after the massive Sendai earthquake and resulting tsunami is ongoing. Japanese and U.S. earthquake science and engineering researchers have well-established collaborations aimed at gathering empirical data and drawing lessons from significant events. It is too soon to know how the events in Japan will affect understanding of the seismic risk of U.S. highway infrastructure, and whether changes in U.S. seismic highway design standards and guidance will result.
Date of Report: June 5, 2013
Number of Pages: 10
Order Number: R41746
Price: $29.95
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