Engineers admit retaining wall was not designed to prevent truck rollovers after fiery fatal crash 

An investigation into a highway’s infrastructure is underway after a trucker died in a fiery crash off an overpass this week, raising questions about the design of the barrier walls. 

The crash happened Tuesday afternoon at the intersection of U.S. 75 and Stacy Road in Allen, Texas earlier this week, not far from a wreck last week that killed another driver after he fell out of his cab as it dangled off the same interstate.

As police investigate Tuesday’s crash, questions are being raised over the design of the 7-year-old barrier wall that engineers admit was not even designed to contain a vehicle the size of a semi truck, reported KVUE ABC.

A Texas Department of Transportation spokesperson said that the section of U.S. 75 at Stacy Road where the accident was widened in 2015, and the current barrier was installed at that time. 

“The purpose of a barrier wall is to prevent drop-offs,” TxDOT said in a statement.  “All barrier designs have been crash tested before installation. All fatal crashes are reviewed to determine if any infrastructure actions are warranted.”

During investigations, William Williams, a research engineer with the Texas A&M Transportation Institute, identified the barrier in both crashes as a 32-inch TL-4 structure. TL, or Test Level-4. These barriers are designed to contain a “single unit truck, car or pickup.” Williams said this barrier was the standard in 2015, but that “It’s not designed and intended to contain and redirect large 18-wheeler vehicles. It can in some cases. But it’s generally not designed and intended for that purpose on this particular bridge.”

Tuesday’s incident is still under investigation.