This synthesis report describes the current state of the practice and experience of state and local transportation agencies dealing with the preservation of historic bridges in their jurisdictions. Information for the synthesis was collected by surveying U.S. state and federal transportation agencies and by conducting a literature search. The synthesis is intended to compliment NCHRP Synthesis 101: Historic Bridges-Criteria for Decision Making published in 1983, and draws on that work by reference. Administrators, engineers, and researchers are continually faced with highway problems on which much information exists, either in the form of reports or in terms of undocumented experience and practice. Unfortunately, this information often is scattered and unevaluated and, as a consequence, in seeking solutions, full information on what has been learned about a problem frequently is not assembled. Costly research findings may go unused. valuable experience may be overlooked, and full consideration may not be given to available practices for solving or alleviating the problem. In an effort to correct this situation. a continuing NCHRP project, carried out by the Transportation Research Board as the research agency, has the objective of reporting on common highway problems and synthesizing available information. The synthesis reports from this endeavour constitute an NCHRP publication series in which various forms of relevant information are assembled into single, concise documents pertaining to specific highway problems or sets of closely related problems. This report of the Transportation Research Board provides information on the policies, decision criteria (or models), and administrative practices used to determine which historic bridges to preserve and the specific preservation option to be employed with each. It also emphasizes the experience of highway agencies in administering these polices and practices, describes a number of successful examples, and identifies some unresolved issues. Several case studies are included to highlight the differences between the policies and practices of state transportation agencies and preservation agencies. To develop this synthesis in a comprehensive manner and to ensure inclusion of significant knowledge, the Board analysed available information assembled from numerous sources, including a large number of state highway and transportation departments. A topic panel of experts in the subject area was established to guide the research in organizing and evaluating the collected data, and to review the final synthesis report. This synthesis is an immediately useful document that records the practices that were acceptable within the limitations of the knowledge available at the time of its preparation. As the processes of advancement continue, new knowledge can be expected to be added to that now at hand. (A)
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