Road Buckling From Heat Is an Engineering Problem, Not Just a Weather Problem. The Fix Will Be Costly.

Since the I-97 concrete buckle south of Baltimore forced a lane closure over the July 4th weekend, engineers and transportation officials have been laying out why that kind of failure is likely to repeat — and why the repair bills will keep climbing.

The short version: American roads were designed around historical temperature ranges. Those ranges no longer hold.

What Actually Causes a Road to Buckle

Concrete fails differently than asphalt, and the distinction matters for both repairs and prevention.

Concrete — called "rigid" pavement in engineering terminology — expands when it heats up. Engineers account for this by building in expansion joints between panels and reinforcing slabs with steel rebar. According to Amit Bhasin, professor of civil, architectural and environmental engineering at the University of Texas at Austin and director of the university's Center for Transportation Research, the problem is a design tradeoff: too many expansion joints and the ride quality degrades (that familiar clack-clack sound on concrete highways). Too few, and the pavement expands beyond what it was designed to handle and buckles.

The I-97 failure fits that pattern exactly. Charlie Gischlar, a spokesperson for the Maryland Department of Transportation, pointed to the combination of prolonged intense heat and heavy traffic load as the proximate cause. Both conditions are now more common than they were when the road was engineered.

Water makes it worse. Charles Marohn, founder and president of Strong Towns, a Minnesota-based nonprofit focused on urban infrastructure resilience, describes how moisture infiltrating the sub-base turns firm pavement into something that moves slightly under load. Once that stability is gone, thermal expansion has nowhere to go but up.

Asphalt behaves differently. It softens and ruts rather than buckles, but it also degrades under sustained heat, creating its own set of surface failures.

The Design Standard Problem

The design standards engineers worked from assumed a climate that is no longer reliable.

Bhasin notes that adding more expansion joints is technically straightforward, but every engineering choice has a cost — in money, in ride quality, and in maintenance cycles. Road agencies set their specifications based on what temperatures they expected a pavement to face over its lifespan. When actual temperatures exceed that envelope repeatedly, failures accelerate.

As Marohn puts it: "Any time you design an asphalt or concrete mix, you're designing for a certain range of temperatures. Extreme events expose the limits of those assumptions."

The I-97 buckle was predictable, not a fluke.

The Opposing Concern, Stated Fairly

Skeptics of large-scale climate adaptation spending point out that infrastructure budgets are already stretched, and committing billions to redesign roads for temperature scenarios that remain probabilistic — rather than fixing the known backlog of deteriorated bridges and pavement — could mean trading one set of failures for another. If climate projections shift or the adaptation designs themselves prove over-engineered for actual conditions, the cost falls on taxpayers with nothing to show for it.

The engineering response, represented by Bhasin's research, is that the adaptation measures themselves — modified expansion joint spacing, updated material mix designs, better sub-base drainage — are not speculative moonshots. They are incremental adjustments to existing techniques. Bhasin puts it plainly: "Engineers have figured this out, and they can design it. They just need to know what to go off of." The question is whether those adjustments get incorporated into standard specifications before the next wave of failures, or after.

What the Money Looks Like

No dollar figure for a national retrofit appears in the available engineering assessments — because no such comprehensive estimate exists yet. What does exist is a pattern: the Houston road damage photographed in June 2023, the Chicago street failure the same weekend as I-97, and several state departments of transportation warning motorists to watch for additional heat-related road damage during the July Fourth weekend heat wave. Each incident carries its own repair cost, and none of those costs are budgeted in advance.

Mikhail Chester, a professor of engineering at Arizona State University, told NPR's All Things Considered that the country has "designed our infrastructures over decades, if not centuries, for temperatures that have been relatively milder" and that the current approach "doesn't seem to be sufficient" for the future. "That's going to require us to innovate, which we are doing. It's going to require us to share that knowledge, which we're starting to do."

What Happens Next

Whether engineering reviews produce updated pavement standards — and whether federal highway funding formulas get adjusted to cover higher-spec construction — remains an open question with no announced timeline.

Bhasin's Center for Transportation Research at UT Austin is one of the academic bodies whose findings feed into those specification updates. The gap between research findings and adopted standards has historically been measured in years, sometimes decades. As temperatures continue to exceed the design thresholds built into existing infrastructure, that gap is becoming harder to defend.