Excavator on Trailer Decimates Highway Overpass at Interstate Speeds

I am short. I never have to think or worry about hitting my head on anything. Not even the underside of airplane overhead bins (feel free to hate me if you didn’t already). In Lordsburg, New Mexico, a transporter must’ve spaced out on their taller-than-average vehicle height because they failed to clear an overpass, leaving the bridge’s now-crumpled underbelly exposed in construction morbidity.

The Hidalgo County Fire Rescue District 1 reported that Exit 24 on Interstate 10 westbound was critically damaged due to a commercial vehicle hauling an excavator on a trailer. Not only did it not meet the height clearance, but the load was oversized. Fire officials say there were no fatalities but they must mean of the human kind. Both the excavator and the bridge are dead at the scene.

The damage to the excavator is apparent. Colliding into the overpass at highway speeds (75 mph in this area), the mangled vehicle is a total loss. The bridge doesn’t look great, either. The structure is bowing, for goodness sake. But is it repairable? In addition to not being tall enough for most rides, I also do not have an engineering degree. So, I called someone who does. 

According to my contact, a principal engineer licensed in California and Nevada, the I-10 overpass is a post-tension bridge. In official engineering speak, the bridge would be deemed “catastrophically damaged; unrepairable.” 

Those dangling cables seen in the images are high-strength steel “tendons” laid out before the concrete is poured. When the concrete is cured, the cables are tensioned (pulled), and then anchored. This creates an internal compressive stress that counters the external stress (e.g., the repetitive load of moving vehicles). Because the cables here are ripped apart, there’s little tension and structural support. The girders, which are responsible for most of the bridge’s stress support, are also beyond saving.

“I’m surprised it’s still standing, to be honest,” he said. When I asked if retrofitting was possible, he quickly shut down that idea. “I wouldn’t. I wouldn’t touch that with a 10-foot pole.”

When the interstate highway system was constructed, the minimum vertical height clearance was 14 feet, per the U.S. Department of Transportation. However, in later years, the U.S. Department of Defense recommended a 17-foot clearance to accommodate larger military equipment that couldn’t be transported via rail, such as the Atlas intercontinental ballistic missile. The compromise was 16 feet, but clearances can be higher. The New Mexico overpass is cleared for vehicles up to 16 feet and 9 inches. So, this wasn’t a case of low bridge-high truck.

There aren’t enough poop emoji to describe how deep in it the driver is. The transport company shouldn’t be absolved of the bridge destruction, either. Although the overpass didn’t collapse and potentially injure others traveling along the interstate, the structure will have to be demolished and rebuilt. The construction will take more than a year (think plural), with costs in the millions.

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