I-40 Hernando de Soto Bridge

What happened?

The Hernando de Soto bridge is a 3.3-mile-long strech of Interstate 40 (I-40) that connects Memphis, Tennessee and Arkansas.This bridge carries more than 41,000 vehicles across the Mississippi River on a given day.

In 2021, a contractor working for the Arkansas Department of Transportation (ArDOT) observed a crack in one of the steel beams running the length of the bridge deck. The fracture was significant enough that the bridge risked collapse, leading the contractor to contact 911 and traffic to be shut down within hours.

Investigations of this incident revealed that the crack was a result of flawed welding. They also revealed photographs showing that a visible crack was discovered to have been taken by a kayaker in 2016, but annual inspections had not located the breach before it became dire. According to reporting published in 2022 by Benjamin Hardy for the Arkansas Nonprofit News Network, “inspection missteps on the bridge may date back four decades.”¹

Detailed forensic analysis of the crack by Wiss, Janney, Elstner Associates, a Chicago-based engineering firm, noted that the problem with the weld dates back to the original fabrication of steel plates in the late 1960s or early 1970s.¹

What were the costs?

The I-40 bridge remained closed for three months during emergency repairs, costing roughly $10 million. However, it’s impossible to know what the full cost of both life and property had the crack not been addressed when it was.

The need for more investment in NDT

Initially, the failure to detect the crack at an earlier stage was attributed to the negligence of one inspector, but Hardy’s reporting complicates this explanation by demonstrating that warnings of potential failure were present before this inspector’s tenure. Even if the failure could be solely attributed to one inspector, according to Grady Hillhouse ², this explanation just further demonstrates the need for more investment in NDT and quality control. “If your ability to identify a major defect in a fracture-critical member of a bridge hinges on a single person, there’s something very wrong with your inspection process.”²

The takeaways from Hardy’s reporting indicate a need for more resources, more thorough procedures, and more collaboration between inspectors and engineers to be in place for critical infrastructure, such as the I-40 Hernando de Soto bridge. According to Hardy, ArDOT now requires professional engineers to be on site for inspections of bridges like the I-40 bridge. Additionally, ArDOT has helped 29 of their professional engineers become certified to be team leads for inspections and has expanded its use of drones. An action memo was also released by the Federal Highway Administration in December 2021 referencing the I-40 bridge and “requiring state transportation departments to use ultrasonic testing methods to search for weld problems on bridges with similar vulnerabilities.”³

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Sources: 

1. Hardy, Benjamin. “How Authorities Missed the Flaw That Nearly Brought Down the I-40 Bridge.” UALR Public Radio, February 21, 2022.
   https://www.ualrpublicradio.org/local-regional-news/2022-02-21/how-authorities-missed-the-flaw-that-nearly-brought-down-the-i-40-bridge

2. Practical Engineering. “What Really Happened at the Hernando de Soto Bridge?” Practical Engineering, June 15, 2021.

   https://practical.engineering/blog/2021/6/9/what-really-happened-at-the-hernando-de-soto-bridge

3. Banner photo credit: Trevor Birchett, HernandoDeSoto Bridge Pyramid.jpg, photograph, May 1, 2015, Wikimedia Commons, https://commons.wikimedia.org/wiki/File:HernandoDeSoto_Bridge_Pyramid.jpg