New Report on Channel Bed Erosion Helps Assess Bridge Stability in St. Louis

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A new assessment of channel bed erosion near 13 highway bridges in the greater St. Louis, Missouri, area is now available in an online report from the U.S. Geological Survey, produced in cooperation with the Missouri Department of Transportation.

This information is used by the MoDOT to help assess bridges for stability and integrity with respect to scour, or the erosion of channel bed material caused by flowing water. Scour can worsen during flood events and is the leading cause of bridge failures in the United States.

“The Missouri Department of Transportation is pleased that the USGS has partnered with us in our bathymetric survey program since 2010,” said Scott Stotlemeyer, Assistant State Bridge Engineer at MoDOT. “This program provides stream bed and flow data at all 40 of the state’s Missouri and Mississippi River bridge crossings over a four-year cycle.  Such data helps us identify any scour concerns in the vicinity of the bridge piers and to ensure the vitality of our highway infrastructure.”

Scientists used sophisticated instruments to study channel beds and collect water velocity, or speed, information at 13 bridges at eight locations. This study is the second round of routine, non-flood surveys at the highway bridges across the Missouri and Mississippi Rivers near St. Louis. Results were compared with previous surveys from 2009 and 2010, as well as those taken during the July/August 2011 flood on the Missouri River. These comparisons illustrate changes over time and the difference between flood and non-flood conditions.

Scientists also compared results from before and after construction at the Stan Musial Memorial Bridge on Interstate 70. Results also showed that countermeasures designed to resist scour at a bridge pier site may limit or prevent additional scour.

The USGS, in cooperation with MoDOT, began assessing scour at waterway crossings throughout the state in 1991. Previous studies can be accessed by searching the USGS Publications Warehouse, or by contacting Rick Huizinga or Jennifer LaVista.

Survey of the Missouri River channel on Highway 40 near St. Louis. 
Survey of the Missouri River channel on Highway 40 near St. Louis. (Public domain.)
Sonar equipment used to conduct channel bed erosion survey in St. Louis.
Sonar equipment used to conduct channel bed erosion survey in St. Louis. 
Map of areas surveyed in St. Louis
Map of areas surveyed in St. Louis. 
Stan Musial bridge in St. Louis, Missouri
Photo of the Stan Musial bridge in St. Louis, Missouri. Credit: Richard J. Huizinga, USGS.