The buckling occurred when prolonged high temperatures caused the concrete highway to expand beyond its structural limits, according to CDOT.
BROOMFIELD, Colo. — Crews with the Colorado Department of Transportation (CDOT) are working to fix a section of U.S. 36 that buckled Sunday.
The section of westbound U.S. 36 in Broomfield buckled near the Flatiron Crossing Drive exit due to extreme heat, prompting a temporary repair by CDOT crews.
The buckling occurred when prolonged high temperatures caused the concrete highway to expand beyond its structural limits, according to CDOT. Crews responded quickly to address the damage, implementing temporary measures while preparing for a permanent solution.
"As temperatures rise and stay above 85 degrees, concrete pavement can either break or buckle," CDOT spokesperson Tamara Rollison said. "Concrete pavement is often more durable and can have a lifespan of up to 30 years. This is largely due to the fact that concrete is constantly moving, allowing for heavy traffic without causing major damage. With extreme heat, however, the concrete starts to expand and the expansion joints meant to allow the concrete to move lock up. If the concrete expands too much, it has nowhere to release the pressure and ultimately breaks or buckles."
Steve Long, who teaches transportation engineering and highway design at Metro State University Denver, explained the phenomenon.
"Just think of it as this big, long ribbon that starts to expand and it just blows out," Long said.
The buckle was small enough to avoid creating a dangerous launching effect for vehicles, though Long warned that such incidents can pose serious safety risks.
"They can be dangerous," Long said. "If the thing buckles a foot or two, you can launch cars."
The incident highlights a recurring problem for Colorado's concrete roadways during summer months. Long says it's not uncommon.
Unlike asphalt roads, which remain flexible under heat, concrete highways are particularly vulnerable to this type of failure.
"You don't have that problem with asphalt because asphalt is flexible," Long said. "Asphalt, you might get some bumps, but you aren't gonna get a major crack or upheaving."
This weekend's incident marks another chapter in U.S. 36's history of heat-related problems. Nearly six years ago, three lanes of traffic in each direction were closed for months on the highway after what CDOT called a "slope failure."
The problem extends beyond U.S. 36 to other Colorado roadways too though.
In 2021, 9NEWS reported on a stretch of Parker Road that buckled five times in six years.
Heat-related buckling differs from other road damage like potholes, which result from water infiltration and freeze-thaw cycles, Long said.
"A pothole is usually created by water infiltrating and then freezing and thawing," Long said. "And the buckling is really related to just heat and expansion of that big long ribbon of highway."
The current conditions make the problem particularly acute. "It's only about the heat," Long said. "We haven't had cold temperatures in months, and when you have those colder temperatures, you can have hot days, but the ground stays cool and it keeps that surface at a more constant temperature."