More than half of the 623,218 bridges in the US are experiencing significant deterioration. Through an in-field case study conducted in western Massachusetts, a team led by the University of Massachusetts at Amherst in collaboration with researchers from the MIT Department of Mechanical Engineering (MechE) has just successfully demonstrated that 3D printing may provide a cost-effective, minimally disruptive solution.
“Anytime you drive, you go under or over a corroded bridge,” says Simos Gerasimidis, Associate Professor of civil and environmental engineering at UMass Amherst.
“They are everywhere. It’s impossible to avoid, and their condition often shows significant deterioration. We know the numbers.”
The numbers, according to the
American Society of Civil Engineers’ 2025 Report Card for America’s Infrastructure, are staggering: across the United States, 49.1 percent of the nation’s 623,218 bridges are in “fair” condition and 6.8 percent are in “poor” condition. The projected cost to restore all these failing bridges exceeds $191 billion.
A proof-of-concept repair took place last month on a small, corroded section of a bridge in Great Barrington, Massachusetts. The technique, called cold spray, can extend the life of beams, reinforcing them with newly deposited steel.
The process accelerates particles of powdered steel in heated, compressed gas, and then a technician uses an applicator to spray the steel onto the beam.
Repeated sprays create multiple layers, restoring thickness and other structural properties.
This method has proven to be an effective solution for other large structures like submarines, airplanes, and ships, but bridges present a problem on a greater scale.
Unlike movable vessels, stationary bridges cannot be brought to the 3D printer – the printer must be brought on-site – and, to lessen systemic impacts, repairs must also be made with minimal disruptions to traffic, which the new approach allows.
“Now that we’ve completed this proof-of-concept repair, we see a clear path to a solution that is much faster, less costly, easier, and less invasive,” says Gerasimidis.
“To our
knowledge, this is a first. Of course, there is some R&D that needs to be developed, but this is a huge milestone to that.”
“This is a tremendous collaboration where cutting-edge technology is brought to address a critical need for infrastructure in the commonwealth and across the United States,” says John Hart, Class of 1922 Professor and head of the Department of MechE at MIT.
“Integrating digital systems with advanced physical processing is the future of infrastructure,” says Haden Quinlan, Senior Program Manager at the Center for Advanced Production Technologies at MIT.
“We’re excited to have moved this technology beyond the lab and into the field, and grateful
to our collaborators in making this work possible.”
The bridge in Great Barrington is scheduled for demolition in a few years. After demolition occurs, the recently sprayed beams will be taken back to UMass for testing and measurement to study how well the deposited steel powder adhered to the structure in the field compared to in a controlled lab setting, if it corroded further after it was sprayed, and determine its mechanical properties.
This demonstration builds on several years of research by the UMass and MIT teams, including the development of a “digital thread” approach to scan corroded beam surfaces and determine material deposition profiles, alongside laboratory studies of cold spray and other additive manufacturing approaches that are suited to field deployment.