How does the Iowa Department of Transportation (Iowa DOT) know when flooding threatens a road or bridge?
The Iowa DOT is responsible for maintaining the 9,373-mile Primary Road System (interstate and numbered Iowa and U.S. routes, and 3,975 bridges). To ensure the public’s safety on these roadways, the department relys on a number of programs designed to assist with protecting the public from flood-related dangers. Information about two of the programs are listed below.- Streamflow-Gauging Program
Information on the flow of rivers is a vital national asset safeguarding lives and properties, and ensures adequate water resources for a healthy economy. The U.S. Geological Survey (USGS) operates about 7,000 streamflow-gauging stations that keep watch on the nation’s rivers — 147 of those are in Iowa.
USGS’s real-time gauges provide important information that the Iowa DOT utilizes when monitoring scour-critical bridges. The data is incorporated into a Web-based program called ScourWatch™ that was developed in conjunction with USEngineering Solutions. ScourWatch monitors National Weather Service’s Doppler radar rainfall accumulation, as well as USGS streamflow-gauge data.
The program alerts Iowa DOT maintenance personnel when the potential for flooding at a scour-critical bridge occurs. This allows the Iowa DOT to be proactive in protecting the public from the potential danger of flooding at scour-critical bridge sites.
Scour-critical is when the bridge foundations have been determined to be unstable for calculated scour conditions. Scour conditions for each bridge was developed using an interdisciplinary team of hydraulic, structural and geotechnical engineers created a criteria used to analyze each bridge site. When a structure was identified as scour-critical, an action plan was developed for monitoring and inspection requirements. Scour countermeasures — riprap or articulated block mats — were constructed at various bridge sites to reduce the monitoring level and allow the bridges to stay open to traffic during a flood.
For more information about the streamflow-gauging program, see the January 2008 issue of Research News. - Iowa DOT’s ScourWatch™ Flood Management System — a real-time, Web-based warning system
ScourWatch helps protect the public from potential catastrophic bridge failure during a flood. Iowa DOT engineers evaluated all 2,100 state waterway bridges in the state and has classified approximately 180 of those as scour-critical.
For more information about ScourWatch, see the January 2008 issue of Research News.
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