Data-Driven Approach to Targeted Bridge Foundation Repair and Rehabilitation
Written by: Donald Green & Linda Krueger, Michael Baker International
The Leo Frigo Memorial Bridge opened in 1981. As essential route for commerce, tourism and local commuters, the bridge carries approximately 40,000 vehicles per day on I-43 over the Fox River just south of its confluence with Green Bay. The bridge experienced a sudden, unexpected pier settlement of approximately two feet, which led to an emergency closure of I-43 in Green Bay in September 2013.
Following the necessary repairs, the team focused on creating a new approach and concept for forecasting the remaining service life of a bridge foundation. Work on the project spanned more than seven years and included three main components:
- Identifying piers susceptible to higher-than-normal corrosion rates but were not animmediate safety concern.
- Installing a corrosion monitoring system at seven pier locations, representing 16 total piers.
- Creating and implementing a software program to predict a future date when a corrosion threshold (i.e. remaining service life) is exceeded at each pier.
Michael Baker created the Leo Frigo Software for Pile Deterioration to successfully equip WisDOT with a comprehensive data-driven understanding of the remaining service life of the bridge. The software allows for targeted monitoring and recommendations of potential retrofits.
The data from each Electrical Resistance Probe is plotted and a power regression equation is determined using an intrinsic non-linear regression function. Additionally, all probe data is evaluated together to produce an average regression which are used to predict the rate of corrosion. The rates of corrosion, coupled with the controlling corrosion pit size, are used to forecast a date where corrosion will exceed a previously determined and accepted reduction. If the forecasted date is before the planned obsolescence of the bridge, then a date to implement corrosion mitigation techniques is produced.
The corrosion monitoring software is a forecasting toolbox to be used bridges across the state.
This corrosion monitoring program is now a critical piece of WisDOT’s bridge inspection program. The portion that is buried is now just as important as what you can see above. This software tracks corrosion occurring below the ground surface, where it is out of sight and cannot be seen during a routine bridge inspection.
The data generated allows WisDOT to make targeted repairs and more accurately account for the safety and service life of the bridge, enhance asset management, and provide more cost-effective delivery of the transportation network.
About the Guest Bloggers
Our guest bloggers are from Michael Baker International. Donald Green is Project Manager – Geotechnical and Linda Krueger is Department Manager – Bridge. Michael Banker International is a member of ACEC Wisconsin.