"During high-flow stages streambed materials around bridge piers are frequently removed by floodwaters. This process, referred to as bridge scour, can compromise the structural integrity of the bridge and in extreme cases, lead to failure or collapse. Assessment of seasonal erosional and depositional patterns in the proximity of bridge piers is essential to studying and understanding the bridge scour process. If studies suggest that a specific site is susceptible to excessive scour and possible undermining of the bridge piers, effective remediation can be applied. The University of Missouri-Rolla conducted a geophysical study for the Missouri Department of Transportation to evaluate the utility and cost-effectiveness of ground- penetrating radar as a tool for investigating bridge scour. The data were analyzed to assess the capability of the radar tool to delineate both riverbed topography and in-filled scour features. This information is prerequisite to understanding local erosional and depositional trends, and for designing effective remediation methodologies. Ground- penetrating radar data were collected with a Geophysical Survey Systems Incorporated SIR-10b unit equipped with a 200-megahertz monostatic antenna. Radar data were collected at ten bridge sites characterized by differing water depths and channel properties. The logistics of each site required maneuvering the antenna either from a boat, the bridge deck, or by wading into the water. Calculated water depths were accurate to within half a foot. Although in-filled scour features were identified confidently on several processed profiles, noise generally made interpretation tenuous. Much of this noise was in the form of water bottom multiple reflections. The interpretation of the processed profiles indicated radar is an effective tool for estimating water bottom topography and extent of in-filled scour in shallow water environments (

This report summarizes efforts initiated and sponsored by the New Hampshire Department of Transportation related to location-specific predictions of corrosion and freeze/thaw induced deterioration on existing bridge decks scheduled for rehabilitation. In 1998, twin 842-ft (257-m) interstate bridges spanning the Connecticut River between Lebanon, New Hampshire and White River Junction, Vermont were surveyed using a combination of horn and ground-coupled antennas. These surveys, supplemented by an underside inspection and limited coring and chloride testing, were successfully used to estimate and locate repair areas prior to a deck rehabilitation project on the structures. In 1999, four structures located along I93 in Thornton-Woodstock, New Hampshire were surveyed without the use of supplemental, destructive testing or lane closures. Contour maps were produced on all structures, showing varying degrees of predicted deterioration.