Bridge ‘MRI’ Uncovers Hidden Heat Damage

The relentless summer sun, once a harbinger of carefree days, is now a silent, insidious assailant, baking America’s aging infrastructure to its breaking point.

Our nation’s bridges, the very arteries of commerce and community, are showing alarming signs of distress, their structural integrity compromised by temperatures they were never designed to endure.

This isn’t just about cracked concrete or buckled steel; it’s about the future of our mobility, the safety of our commutes, and the escalating costs of neglect.

Enter Suyun Ham, an engineering professor from the University of Texas at Arlington, who is pioneering a diagnostic tool that could revolutionize bridge inspection.

Forget the antiquated hammer-and-ear method; Ham’s mobile-scanning system is a sophisticated “MRI” for bridges, designed to peer into their very bones and uncover the hidden ravages of heat.

His urgency is palpable, especially in a place like Dallas-Fort Worth, where summer temperatures routinely breach 100 degrees Fahrenheit.

“If temperatures are out of range, bridges can get damaged unexpectedly,” Ham explains, the data flooding his computer screens echoing his concern.

“With our ‘MRI,’ we can see what’s inside a bridge quickly.”

The science behind this silent destruction is straightforward, yet devastating.

Bridge materials, primarily steel and concrete, expand and contract with temperature fluctuations. While engineers once accounted for this movement, the historical temperature ranges they used in their designs are now woefully inadequate. Heat effects on concrete structures

Paul Chinowsky, a professor emeritus of civil engineering at the University of Colorado Boulder, paints a stark picture: when record-high temperatures hit, bridges can behave in ways never intended.

Heat-swollen steel joints can immobilize a swing bridge, preventing it from opening or closing.

Concrete, too, expands, and once it exceeds its design limit, it cracks, inviting moisture to corrode internal metal components.

This isn’t a localized problem; it’s a global phenomenon.

In 2022, a concrete bridge in China fractured under brutal heat.

That same year, London’s iconic Hammersmith Bridge was swathed in giant foil to prevent overheating.

And closer to home, Chicago’s DuSable drawbridge seized up in 2018, its steel joints expanded by the blistering sun, until firefighters doused it with cold water.

“Bridges are very susceptible,” Chinowsky warns.

“The hotter it gets compared to what typically it is, the more danger you have.”

The timing couldn’t be worse.

America’s bridges are already fighting a losing battle against time. Of the nation’s 600,000-plus bridges, nearly half have surpassed their intended 50-year lifespan. While proper maintenance can extend their lives well beyond a century, the reality is grim: roughly one in three bridges needs repair or replacement, according to a recent analysis. Importance of bridge maintenance

Hussam Mahmoud, a Vanderbilt University professor, has found that countless steel-girder bridges have aged prematurely, largely due to the heat-accelerated malfunction of their expansion joints.

These expansion joints, critical connectors between bridge spans, are under increasing strain.

As heat waves grow more frequent and severe, these joints expand more often, compounded by the accumulation of debris and dirt.

The result? Increased pressure, elevating the risk of cracks and buckling.

While these defects may not pose an immediate collapse risk, they demand attention. Neglecting them leads to “a lot of headaches,” Mahmoud notes, both literally and economically.

The implications are staggering.

With over 4.9 billion trips taken across US bridges daily, closures translate directly into economic disruption and lost commerce. Preventing infrastructure damage from climate change

More damage means spiraling maintenance costs, adding to an already daunting $373 billion funding gap the American Society of Civil Engineers projects over the next decade.

The human cost is also very real; just this past June, a South Carolina swing bridge, incapacitated by sweltering temperatures, couldn’t open for ships, delaying rescue efforts for a fatal boating accident.

For Ham, the solution lies in proactive, frequent monitoring.

“Just like it is difficult to heal a human patient with stage-four cancer, it’d be too late to repair a bridge when there are a lot of defects,” he asserts.

His frustration stems from firsthand experience with conventional, manual inspections – a time-consuming process that often requires lane closures, a significant hurdle in bustling states like Texas with its 56,000-plus bridges.

Federal mandates typically require highway bridges to be inspected every two years, but Ham and his team at the University of Texas’s Smart Infrastructure and Testing Laboratory in Arlington envision a future of drive-through inspections, drastically increasing that frequency.

Ham’s innovation is a marvel of mobile engineering: a trailer packed with electronics, hauled by a pickup truck.

As it traverses a bridge, the machine generates mechanical waves that penetrate the concrete.

Sensors capture the resulting vibrations, while a GPS device precisely logs their origin.

Ground-penetrating radars emit pulses to create subsurface images, and GoPros record surface conditions.

The goal is a comprehensive data mosaic, revealing cracks, voids, and other anomalies. Engineering solutions for heat damage on bridges

On a recent scorching July afternoon, Ham’s machine scanned a 5-foot bridge in seconds – a task that would take hours conventionally.

The initial results are compelling.

Ham points to computer images ablaze with bright orange dots and stripes, signaling surface damage, and a red rectangle highlighting a cluster of tiny cracks.

Artificial intelligence then refines the analysis, filtering out “noise” like passing cars.

The findings are then relayed to bridge overseers for safety assessments and future repair work.

Mark Burwell, a bridge inspection coordinator at the Texas Department of Transportation, praises the technology’s efficiency and safety benefits.

His agency has deployed Ham’s system on dozens of bridges since 2019, noting that it eliminates the need for inspectors to work precariously close to moving traffic.

For now, Ham’s “portable MRI,” partly funded by the Texas Department of Transportation, is confined to the Lone Star State.

Scaling up requires continuous refinement.

Ham recounts learning moments: a rough ride once dislodged sensors, cutting an inspection short (the machine now has a lift system).

Software struggled to interpret signals from concrete bridges patched with asphalt.

To overcome these challenges, Ham’s lab has become a hub for creating artificial defects: metal sticks soaked in brine to simulate corrosion, holes drilled in concrete slabs to mimic cracks.

By correlating these known defects with sensor and radar signals, the AI learns to interpret real-world damage.

While the machine may not detect all heat-induced stress until physical damage manifests, the data it collects holds immense promise.

By comparing damage patterns across bridges built with different methods and materials, the technology can inform future design, helping regulators create structures more resilient to a hotter planet. Future of bridge engineering

“We’re like a medical doctor,” Ham concludes, “We can help them make a decision.” In a world increasingly defined by climate extremes, such guidance is not just helpful; it’s essential for safeguarding our vital lifelines.