Report Documents New Simplified Method To Evaluate Illinois Bridges For Streambed Scour

Streambed scouring during floods is the most common cause of bridge failures in the United States. As a result, transportation officials in Illinois are scrutinizing the flood stability of the more than 13,000 bridges in Illinois. Analysis of bridges for streambed scour by conventional methods is both time consuming and costly. In an attempt to fulfill public safety needs within current fiscal and personnel resources, part of the stability analysis has been simplified with a new streambed scour estimation method developed by the U.S. Geological Survey (USGS) in cooperation with the Illinois Department of Transportation, Division of Highways, and described in a report recently released by the USGS, U. S. Department of Interior. The total-streambed scour for the 500-year flood is estimated with the new method in less time and more conservatively than with conventional methods.

The report, titled "Development, verification, and application of a simplified method to estimate total-streambed scour at bridge sites in Illinois," by Robert R. Holmes, Jr. and Chad J. Dunn, has been released as U.S. Geological Survey Water-Resources Investigations Report 95-4298. Copies are available for inspection at the U.S. Geological Survey, 221 N. Broadway, Urbana, Ill., and at most large libraries nationwide. Paper and microfiche copies can be purchased at cost from the U.S. Geological Survey, Information Services, Box 25286, MS 517, Federal Center, Denver, CO 80225 (telephone: (303)202-4700. Orders must include check or money order payable to U.S. Department of the Interior-USGS and must specify report number WRIR 95-4298.