European practice for bridge scour and stream instability countermeasures

FHWk, AASHTO, and TRB sponsored a scanning review of European practice for bridge scour and stream instability countermeasures in October 1998. The review involved a panel of representatives from six state highway agencies (California, Illinois, Maryland, Minnesota, Oregon, and South Carolina), FHWA, two universities, and the private sector. The review included visits to hydraulic research laboratories, highway research institutes, and field sites in four countries-Switzerland, Germany, the Netherlands, and the United Kingdom. Findings during the scanning review can be classified as general observations and observations of specific countermeasures. General observations of European practice include design philosophy, risk analysis, environmental policy, river geomorphology, scour prediction, modeling, and inspection and monitoring. Observations of specific countermeasures include riprap design and construction, filter design and construction, river-training structures, riverbed degradation countermeasures, bioengineering, and flow-altering devices. These observations are contrasted with U.S. practice. The panel's recommendations, for modifying U.S. practice on the basis of the European experience and findings that deserve further evaluation are also presented.