By Tony Hunley, PE, SE, PhD
The Bridging Kentucky Program is reaping major rewards in the Kentucky Transportation Cabinet’s (KYTC) initiative to improve the safety and soundness of the Commonwealth’s bridges and reduce the number of bridges with weight restrictions or rated in poor condition.
Maintaining and improving Kentucky’s inventory of more than 14,000 aging bridges is a big task, which grows larger each year. As of mid-2018, Kentucky had more than 1,100 structures with posted weight restrictions or National Bridge Inventory (NBI) ratings of 4 (poor) or below.
Bridges in the state were receiving substandard ratings faster than they could be repaired or replaced. Most of these substandard structures were smaller bridges owned by county governments and other local agencies that could not afford to fix them.
To respond to this growing need, KYTC launched Bridging Kentucky in 2018, one of the most aggressive bridge preservation and replacement programs in the country. It was developed with a goal of rehabilitating, repairing, or replacing critical bridges across the state, and is designed to reopen closed structures, ensure structures meet appropriate weight capacities, and extend the lifespan of bridges.
With significant transportation needs and limited transportation dollars, the team is focused on improving the condition and lifecycle of existing bridges. The structures in the program are smaller, mostly rural bridges spread across every region of Kentucky. On average, these bridges are 18.5-feet wide by 60-feet long, around 60 percent are locally owned by counties or agencies, and they have an average daily traffic of less than 900 vehicles. In many cases, the team is cost-effectively adding at least 30 years of life to the bridges through repairs and improvements. Where a full replacement is appropriate, the team is designing bridges for at least a 75-year design life.
Program management approach
In April 2018, a general engineering consultant team, led by Stantec, was selected to partner with KYTC and assist in the planning, development, management, delivery, and oversight of the transportation program.
To take on a transformational bridge program, Stantec along with partners QK4 and AECOM assembled a large and diverse team of 23 consultants. The team works in collaboration with various divisions within KYTC, integrated into design and construction teams, and with cabinet staff performing program management leadership, bridge design, geotechnical engineering, bridge hydraulics, surveying, right-of-way acquisition, design-build oversight, communications, and construction administration. At its peak of delivery, the program had 24 design teams working on multiple bridge projects concurrently.
To deliver a program of this magnitude within this timetable and budget, it was apparent that there had to be a way to streamline certain activities. The team started by working with the KYTC, the Federal Highway Administration (FHWA), and stakeholder agencies to evaluate every aspect of project development, construction procurement, contracting methods, and construction administration to determine streamlined approaches focused on efficiency. The result was a Program Charter executed between KYTC and FHWA that detailed tools and techniques the program team would leverage to deliver the program, and clearly defined the roles and responsibilities of all parties.
The Program Charter is a living document that reflects the continuous evolution and refinement that the program has undergone. While many of the early processes and procedures have worked well to streamline execution and reduce project development delivery time and cost, KYTC and the program team have continuously evaluated and modified approaches for maximum efficiency. One key to managing such a massive and broad undertaking is a laser focus on continuous improvement and reacting to lessons learned. For Bridging Kentucky, this often meant incorporating improvements across dozens of active design projects and contract packages already submitted for construction procurement in a matter of days.
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 during 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 already 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 distinguish 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 determine 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 estimate 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 design team performing an assessment of the structure in the field. During this assessment, any conditions that differ from the previous documented 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.
As a result of the success to date of the program, Kentucky is currently seeing its busiest period of bridge construction in its history. Over the last two years, 375 bridge rehabilitation, repair, and replacement projects have been let to construction across 167 contracts totaling 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 projects; 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 commitment at the highest levels of the Transportation Cabinet will serve as a model to other states looking to address their aging bridge infrastructure needs in a bolder way.
Tony Hunley, PE, SE, PhD, is Vice President, Bridges at Stantec Consulting Services and Program Manager for the Bridging Kentucky Consultant Program Team.