C+S September 2020 Vol. 6 Issue 9 (web)

design team performing an assessment of the structure in the field. During this assessment, any conditions that differ from the previous docu- mented field inspection or any other mitigating factors are considered to either confirm or change the scope determined during screening. As of the summer of 2019, about 160 more bridges were load posted or closed by the state’s bridge engineers due to unsafe conditions. The program team utilized the life-cycle cost model

to screen the additional bridges and reevaluate the remaining bridges originally screened in 2018 to help KYTC plan, estimate, and prioritize future bridge projects. Progress As a result of the success to date of the program, Kentucky is cur- rently seeing its busiest period of bridge construction in its history. Over the last two years, 375 bridge rehabilitation, repair, and replace- ment projects have been let to construction across 167 contracts total- ing more than $300M in construction value. The program utilizes a variety of delivery mechanisms to address bridges (individual and bundled traditional design-bid-build packages and a large bundled design-build contract). To date 137 bridges have been let to construction as individual proj- ects; 132 bridges have been let in 29 bundled packages ranging from 2 to 16 bridges per bundle; and 106 bridges are being constructed in a single design-build contract. Impressively, the program has represented a true partnership across the state’s bridge industry. More than thirty bridge construction firms have won contracts under the program. And, in less than two years of construction, more than 200 of the bridges have been substantially completed and reopened to traffic. The combination of innovative and efficient approaches, variety of contracting methods, statewide programmatic approach, and commit- ment at the highest levels of the Transportation Cabinet will serve as a model to other states looking to address their aging bridge infrastruc- ture needs in a bolder way.

Data driven bridge asset management approach As a critical first step, the program team was tasked with evaluating and prioritizing the bridge improvements. Stantec developed a data-driven screening process focused on determining the appropriate restoration solution for each bridge. The initial list of bridges included more than 1,000 candidates for the program that were screened by the team dur- ing the summer of 2018. Each bridge was analyzed to determine a unique preservation plan for that individual structure. The team screened each bridge using data al- ready collected by KYTC bridge inspectors in AASHTOWare Bridge Management (BrM) software (including inspection reports, photos, and notes; NBI ratings; load ratings; element-level condition states; and posting results and notes). This process allowed the team to dis- tinguish potential rehabilitations from certain bridge replacements. In some cases, the need for major or only minor improvements yielded an obvious decision to replace or rehabilitate the bridge, and those bridges moved directly to design to expedite projects. The remaining bridges underwent a life-cycle cost evaluation to de- termine the most cost-effective solution. The program team compared life-cycle costs of rehabilitating versus replacing each of these bridges. The analysis included a deterioration model customized for Kentucky’s environment, user costs developed by the program team, and estimated construction costs to restore elements in poor condition. This cost esti- mate was baselined against similar recent work on Kentucky projects. Through this life-cycle cost analysis, bridges with a greater long-term cost advantage of repair or strengthening could be rehabilitated rather than replaced. Ultimately, it was determined that approximately 40 percent of the bridges could be rehabilitated. Bridges within a small band of the unclear long-term cost advantage between rehab or replacement were evaluated in the field by a qualified bridge inspection team to confirm the scope. Further, the initial activity for each bridge design project consists of the multi-disciplinary project

TONY HUNLEY, PE, SE, PHD, is Vice President, Bridges at Stantec Consulting Services and Program Manager for the Bridging Kentucky Consultant Program Team.



september 2020

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