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More than half of the nation’s 623,218 bridges are showing visible signs of deterioration—and now, researchers from the University of Massachusetts Amherst and MIT’s Department of Mechanical Engineering (MechE) have demonstrated a powerful, cost-effective way to extend their lifespan using 3D printing technology.

This breakthrough comes at a crucial time. According to the American Society of Civil Engineers’ 2025 Report Card, 49.1% of U.S. bridges are in “fair” condition, while 6.8% are rated “poor.” The price tag to repair them? Over $191 billion—and that number keeps rising.

A Nationwide Crisis on Our Roads

“Anytime you drive, you go under or over a corroded bridge,” says Simos Gerasimidis, associate professor of civil and environmental engineering at UMass Amherst and former MIT visiting professor. “They are everywhere… their condition often shows significant deterioration. We know the numbers.”

And the numbers don’t lie:

• 623,218 bridges nationwide
• 49.1% fair condition
• 6.8% poor condition
• $191+ billion in projected repair costs

Traditional repairs are expensive, highly disruptive, and often require long-term lane closures—something cities and transportation departments are eager to avoid.

Cold Spray: A 3D Printing Method Reinventing Bridge Repair

The research team turned to cold spray technology, a specialized form of additive manufacturing that deposits metal at high velocity without melting it. This allows steel to bond to corroded bridge sections in the field, in real time, with no major disassembly required.

How Cold Spray Works

1. Fine powdered steel is loaded into a specialized applicator
2. Heated, compressed gas accelerates the particles to supersonic speed
3. The particles strike the corroded beam surface
4. The impact bonds steel to steel—layer by layer—like a metal 3D printer
5. The technician passes the applicator repeatedly, restoring thickness and strength

Because the steel is never melted, the repair is safer, faster, and more structurally consistent than many conventional welding or replacement methods.

Real-World Proof: A Massachusetts Bridge Gets Reinforced

Last month, engineers performed a proof-of-concept repair on a small corroded section of a bridge in Great Barrington, Massachusetts.

The cold spray method:

• Restored missing material
• Reduced corrosion-related vulnerabilities
• Reinforced structural beams
• Caused minimal traffic disruption
• Delivered results at a fraction of traditional repair costs

This demonstration shows that cold spray has the potential to extend the life of thousands of aging bridges—buying cities time and reducing the financial burden of full replacements.

The Future of Infrastructure Repair

Cold spray 3D printing could transform how we maintain transportation networks:

• Rapid field restoration without removing beams
• Lower repair costs, especially for widespread corrosion
• Safer for workers—no high-heat welding
• Sustainability benefits through structural life extension

• Scalable for nationwide adoption

With more than half of America’s bridges in declining condition, this technology introduces a practical, scalable roadmap for infrastructure resilience.

UMass Amherst and MIT’s work may soon influence state and federal repair strategies—ushering in a new era where 3D printing is deployed directly on aging structures to keep roads safe and open.

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Cold spray metal deposition strengthens a deteriorated steel bridge beam with layered 3D-printed metal. Image for illustration only.

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