Highway guardrails are, in theory, designed to keep drivers safe. But the Missouri DOT has banned a certain rail after safety concerns cropped up during an ongoing investigation, Ozarksfirst.com reports. Officials say a malfunction in the ET-Plus system made by Trinity Industries can jam a guardrail's head when a car crashes into it, causing the guardrail to "become a bayonet that can pierce the vehicle and any person in its way," the New York Times reports. There are up to 30,000 ET-Plus rails in Missouri, and a study by the Safety Institute found that the newly designed version of the guardrail is about 2.86 times more likely to cause death in Missouri and Iowa than the earlier incarnation. Lawsuits allege five deaths from the guardrails and "many more injuries," notes the Times, though Trinity emailed that it's "impossible to draw broad conclusions from individual accidents."
Internal memos and other documentation reviewed by the Times show that one of Trinity's engineers questioned the guardrails' safety, emailing that it's "hard to ignore the fatal results" to an outside safety expert. And indeed, that previously mentioned redesign is part of the problem: In 2005, Trinity made a change to the width of the steel channel behind the rail head without disclosing it to the Federal Highway Administration as required, notes the Times. The redesign wasn't discovered until 2012, when Trinity sued a guardrail manufacturer for patent infringement, but by then, "tens of thousands" of the new rail had been put into place around the country. Ozarksfirst.com reports no time estimate for removing the guardrails, nor an estimated cost.