Evaluation of Historic Truss Bridges

The prioritization of the maintenance and rehabilitation of bridges based on their historic importance is challenging. While the AASHTO Guidelines for Historic Bridge Rehabilitation and Replacement contain guidance on selecting bridges for preservation, there is currently no guidance on how to prioritize historic bridges selected for rehabilitation. A ranking system for rehabilitation prioritization of historic truss bridges is developed based on two levels of prioritization. The first level, Historical Importance, is the primary and most important level of prioritization. A historical importance factor (HIF) is presented to account for the bridge's uniqueness, year of construction, and other factors. Bridges are sorted based on their HIF to identify the ones for rehabilitation prioritization. When several bridges have the same HIF, a second level of prioritization (P2F) is developed to account for the bridge condition and rehabilitation potential. In cooperation with the Kentucky Transportation Cabinet (KYTC), the authors developed a truss bridge database listing the historic, geometric, and other key features of the bridges. 94 candidate bridges were selected as being historically significant for preservation. 8 of the bridges were identified as being of significant historical importance, receiving an HIF greater than 100. 30 bridges had an HIF between 10 and 100, and the remaining 56 bridges had an HIF less than 10. For the bridges under consideration, P2F was not deemed necessary at this stage, since the prioritization based on the HIF provided sufficient clarity for investigating the rehabilitation potential of the bridges. The results generated from the HIF ranking provide the tools for KYTC to maintain Kentucky's truss bridges based on their historical importance.