Load rating is carried out on all bridge structures to ensure that they have the capacity to support the expected vehicular loads, or to appropriately restrict the vehicular loading on older and/or distressed structures by posting load limits. For many of these older structures, including culverts, concrete and stone arches and precast girder bridges, design or as-built plans are no longer available to serve as a reference for the load rating analysis calculations. In these situations, NDE methods are often useful to fill in such missing data as element thickness, depth of overburden (culverts and arches), rebar depth and spacing, and estimated concrete strength. Over the past few years, MassDOT has used these techniques to support load ratings on a number of structures. The paper describes the types of structures that have been investigated, the NDE methods used, the data that was obtained and the methods of analysis, and the resulting information generated for the load rating process.

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