A Survey of Non-arched Historic Concrete Bridges in Virginia Constructed Prior to 1950: Final Report

About the report:

Bridges are among the cultural resources that must be considered for historic significance under the Historic Preservation Act of 1966. The Virginia Transportation Research Council conducted pioneering studies of Virginia's early metal truss bridges and concrete and masonry arch bridges during the 1970s and 1980s, but no comprehensive evaluation of non-arched concrete bridges in Virginia was undertaken. The lack of information on non-arched concrete bridges made the case-by-case evaluation of these bridges in construction or maintenance projects a standard practice. Most of these studies were done by outside consultants, a time-consuming and expensive method which yielded only information about particular bridges, not comparative or contextual data on non-arched bridges as a whole. This study rectifies this lack of information and analysis of non-arched concrete bridges built before 1950 (a cut-off date chosen because, in general, a structure must be 50 years of age or older to be considered historically significant under National Register criteria). Given the average monetary cost of $10,000 per consultants' study, and an average time frame of 90 to 120 days, it is estimated that this project has already saved the Virginia Department of Transportation more than $500,000 and eliminated a typical three to four month delay for each project. Projected savings arising from this project are estimated at approximately $2.5 million over the next ten years. As construction and maintenance projects are initiated on older non-arched concrete bridges, the benefits from this survey in costs and time saved will continue to accumulate. The project consisted of field survey, data tabulation, documentary research into historic non-arched concrete bridge types, and comparison of the resulting information on bridge chronology, technology, and usage during the first half of the 20th century. Criteria for the evaluation of historic significance were developed and applied, and a final review of the results was done with the Historic Structures Task group (an interdisciplinary historic transportation study committee) and the State Historic Preservation Officer. Of 1,420 non-arched concrete bridges built before 1950, fewer than a dozen were found individually eligible for the National Register of Historic Places. This project identified Virginia's few significant bridges of this type for appropriate management, and cleared over 1,400 bridges, the great majority of Virginia non-arched concrete bridges, for necessary maintenance and upgrade.

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