Over half of the country’s 623,218 bridges are facing considerable decline. Through an on-site case study executed in western Massachusetts, a group spearheaded by the University of Massachusetts at Amherst, in partnership with investigators from the MIT Department of Mechanical Engineering (MechE), has recently illustrated that 3D printing could offer an economical and minimally invasive remedy.
“Whenever you drive, you pass under or over a decayed bridge,” states Simos Gerasimidis, associate professor of civil and environmental engineering at UMass Amherst and former visiting academic in the Department of Civil and Environmental Engineering at MIT, in a press release. “They are ubiquitous. It’s unavoidable, and their state frequently indicates substantial deterioration. We recognize the statistics.”
The statistics, according to the American Society of Civil Engineers’ 2025 Report Card for America’s Infrastructure, are alarming: Nationwide, 49.1 percent of the country’s 623,218 bridges are rated as in “fair” condition, while 6.8 percent are marked as “poor.” The estimated cost to rehabilitate all these failing bridges surpasses $191 billion.
A proof-of-concept restoration was conducted last month on a minor, rusted section of a bridge in Great Barrington, Massachusetts. The method, known as cold spray, can prolong the lifespan of beams by reinforcing them with newly applied steel. This technique propels particles of powdered steel using heated, compressed gas, after which a technician employs an applicator to spray the steel onto the beam. Repeated applications form multiple layers, thus restoring thickness and other structural aspects.
This technique has proven an effective solution for other large constructions such as submarines, airplanes, and ships, yet bridges pose a challenge on a larger scale. Unlike movable vessels, stationary bridges cannot be brought to the 3D printer; the printer must be transported to the site. Additionally, to minimize systemic disruptions, repairs need to be executed with minimal interference to traffic, which the new method facilitates.
“This represents a remarkable collaboration where innovative technology is applied to tackle a crucial infrastructure requirement in the commonwealth and nationwide,” remarks John Hart, Class of 1922 Professor and head of the Department of MechE at MIT. Hart, along with Haden Quinlan, senior program manager in the Center for Advanced Production Technologies at MIT, is guiding MIT’s initiatives in this project. Furthermore, Hart serves as faculty co-lead for the recently launched MIT Initiative for New Manufacturing.
“Merging digital frameworks with advanced physical processing is the future of infrastructure,” emphasizes Quinlan. “We are thrilled to have transitioned this technology beyond the laboratory and into practical use, and we appreciate our collaborators for making this endeavor achievable.”
UMass states that the Massachusetts Department of Transportation (MassDOT) has been an essential research ally, aiding in identifying the issues and offering significant support for the development and demonstration of the technology. The MassDOT Highway Division and the Research and Technology Transfer Program provided technical direction and financial backing.
Resources for this initiative were supported through the Massachusetts Manufacturing Innovation Initiative, a statewide initiative managed by the Massachusetts Technology Collaborative (MassTech)’s Center for Advanced Manufacturing, aimed at bridging the gap between innovation and commercialization in hard tech manufacturing.
“It’s a quintessential Massachusetts success story,” Gerasimidis states. “It entails MassDOT being receptive to new concepts. It includes UMass and MIT combining their expertise. It involves MassTech in revitalizing manufacturing within Massachusetts. Therefore, I believe it’s a win-win for all parties involved.”
The bridge in Great Barrington is slated for demolition in a few years. After the demolition, the recently treated beams will be transported back to UMass for evaluation and measurement to investigate how well the applied steel powder adhered to the structure in the field compared to a controlled lab environment, assess if it corroded further post-application, and underlay its mechanical characteristics.
This demonstration builds on several years of research conducted by the UMass and MIT teams, including the development of a “digital thread” methodology to scan deteriorated beam surfaces and determine material deposition profiles, alongside lab studies of cold spray and other additive manufacturing techniques suitable for field deployment.
Overall, this undertaking showcases a collaborative effort among UMass Amherst, MIT MechE, MassDOT, the Massachusetts Technology Collaborative (MassTech), the U.S. Department of Transportation, and the Federal Highway Administration. Research reports can be accessed on the MassDOT website.