With infrastructure negotiations currently taking center stage in the United States’ political discourse, researchers at the University of Georgia (UGA) have published their findings on how a new approach to infrastructure maintenance would save federal and state governments millions of dollars per year. A study produced by the UGA’s College of Engineering proposes a new model for bridge infrastructure which prioritizes the incremental maintenance of key components, in contrast to current national strategies that favor replacement and rebuilding.

When determining the long-term health of a bridge in the United States, current strategies rely on a basic broad depreciation formula. The researchers believe such a method generates overly conservative assessments of how long infrastructure could last before full replacement. The UGA’s “bridge coactive model” instead considers the interaction of 60 to 80 bridge components in predicting long-term bridge performance, and assesses how regular, routine upkeep of key components can result in major cost and material savings.

To build and test their model, the researchers analyzed data in the Federal Highway Administration’s National Bridge Inventory for Alabama, Florida and Georgia, encompassing tens of thousands of bridges. “Prior to our work, we hadn’t seen a mathematical model that considers the interaction between bridge elements,” said Mi Geum Chorzepa, an associate professor and the study’s principal investigator. “We need a more realistic way to assess bridge conditions and prioritize preventive maintenance, particularly in such a challenging budget environment.”

“Rather than considering a bridge as a monolithic structure, the bridge coactive model assesses a bridge as a system in which changes in the condition of each coactive element not only directly affects the overall bridge performance but indirectly influences the performance of the other dependent elements,” added Brian Oyegbile, one of the study’s authors.

As an example, the researchers point to expansion joints. While replacing a damaged bridge expansion joint is inexpensive and has little impact on the bridge’s short-term performance, a damaged joint left in place over time could allow salt from de-icing or contaminated water to penetrate through the structure, and compromise critical elements such as columns. In another example, debris left to accumulate in an expansion joint may restrict the normal expansion and contraction of a bridge deck over time, leading to more rapid deterioration.

These so-called “butterfly effects” are at the heart of the researchers’ proposed new method. They argue that the periodical replacement of minor elements such as expansion joints, regardless of their condition, can prevent a chain reaction of deterioration across key components in the overall structure, and have a significant impact on the country’s infrastructure health and spending over the long term.

The team estimates that a $10 billion investment over three years in timely preventive maintenance on America’s bridges would generate $20 billion in recurring savings by 2024. In addition, the researchers believe that their approach would increase the average lifespan of a bridge from 75 years to more than 100 years.

The full study, “Novel Prioritization Mechanism to Enhance Long-Term Performance Predictions for Bridge Asset Management,” is published in the American Society of Civil Engineers’ Journal of Performance of Constructed Facilities.