Balancing Engineering Criteria and Historic Significance to Preserve Select Bridges

Abstract

This paper describes Indiana's efforts to prioritize historic bridges for preservation with the use of a systematic analysis that considers both relative historic significance and engineering condition. The state's historic bridge preservation program was initiated in 2006 with the execution of a programmatic agreement (PA) between FHWA, Indiana Department of Transportation (DOT), Indiana State Historic Preservation Officer (INSHPO), and Advisory Council on Historic Preservation. The PA streamlines the Section 106 regulatory process and allows Indiana DOT and local agencies to manage the state's population of historic bridges effectively and programmatically instead of using an inefficient project-to-project approach. The most innovative aspect of Indiana's historic bridge program is the establishment of a prioritization method. Each historic bridge is evaluated and then classified as either select, meaning the bridge is an excellent example of its type statewide and is suitable for preservation, or nonselect, meaning the bridge is not the best example of its type and may not be suitable for preservation. Upon agreement by FHWA, Indiana DOT, and INSHPO, lists of select and nonselect bridges were issued in March 2010. The methodology for identifying and prioritizing individual bridges is explained, highlighting the effort to achieve balance between historic significance and engineering and economic criteria, including functionality, safety, feasibility, and cost-effectiveness. Indiana DOT also developed standards for treating historic bridges on low-volume roads. If historic bridge rehabilitation can meet the standards, then rehabilitation for vehicular use must be implemented.