Additive manufacturing has moved from lab demo to field repair: a UMass Amherst–MIT team, working with the Massachusetts Department of Transportation (MassDOT), has shown that cold-spray metal deposition can restore corroded bridge steel directly on site with minimal traffic disruption. In a proof-of-concept performed in Great Barrington, technicians deposited powdered steel onto a degraded section of an I-beam, rebuilding thickness and structural properties layer by layer.
Why the field trial matters
Across the United States, more than half of the 623,218 bridges show significant deterioration, with 49.1% rated “fair” and 6.8% “poor,” and full restoration costs projected above $191 billion. By demonstrating additive repair on a live structure, the team points to a path where engineers can stabilize assets sooner and at lower cost—without removing beams or shipping them to specialized shops.
How cold-spray works
Cold-spray is an additive process that accelerates metal powder in a heated, compressed gas stream. When the particles strike the substrate at high velocity, they plastically deform and bond, creating dense, metallurgically adhered layers without melting the base metal. For bridge repair, a technician uses an applicator to raster over the corroded steel, building back lost thickness through successive passes. Because the process is solid-state, it reduces heat-affected zones and limits distortion relative to conventional welding.
Digital planning meets physical repair
Before deposition, the team captured corrosion geometry and planned additive deposition profiles using a “digital thread” workflow—scan, analyze, prescribe, and print. This integrates inspection data with process parameters so the resulting patch matches the beam’s required geometry and performance targets. The approach aims to shorten time from assessment to repair while improving repeatability across sites.
Collaboration and support
The field work reflects a broad collaboration: UMass Amherst and MIT’s Department of Mechanical Engineering led the research with MassDOT as partner and site host. Equipment support came via the Massachusetts Manufacturing Innovation Initiative through MassTech’s Center for Advanced Manufacturing, with additional participation from the U.S. Department of Transportation and the Federal Highway Administration. The Great Barrington bridge is slated for demolition in the coming years; its sprayed beams will return to UMass for post-mortem testing to compare field adhesion, corrosion behavior, and mechanical properties with lab baselines—closing the loop on additive performance validation.
What this could change for infrastructure
On-site additive repair offers three potential gains: speed (repairs scheduled within maintenance windows), cost (less need for component replacement or long closures), and safety (reduced heavy lifts and traffic diversions). It also complements existing methods: cold-spray patches can stabilize sections until full rehabilitation or replacement, giving agencies more flexible asset-management options.
Limits and next steps
Cold-spray is not a universal fix. Success depends on surface prep, material compatibility, deposition rates, and environmental controls at the job site. The research team plans expanded trials, design guidance for additive patch geometry, and standardized inspection and acceptance criteria so owners can specify the method with confidence.
Conclusion
The Great Barrington demonstration marks a practical step toward integrating additive cold-spray into bridge maintenance. If standards and training follow, owners could gain a faster, less invasive option for stabilizing corroded steel—bridging today’s maintenance gaps while longer-term replacements advance.