Guarding Against Scour

Scour causes 60 percent of all highway bridge failures in the United States. Tragic stories of bridges collapsing and causing fatalities prompted the Federal Highway Administration to establish the National Bridge Inspection Program, which requires that bridges be inspected for scour every 2 years. This article describes recent bridge failures, reports on the national response, and reviews the latest scour-monitoring technology. Two instruments--magnetic sliding collar and sonic fathometer--have emerged as promising devices to measure maximum scour depth at bridge piers and abutments. The cost of the devices is expected to be reasonable for state departments of transportation.