The finding comes as the maker of the guardrail system, Trinity Industries, faces a federal investigation into its dealings with state and federal safety officials and is fighting a state Department of Transportation over new crash tests for the embattled guardrail system. The Federal Highway Administration and the American Association of State Highway and Transportation Officials had created a task force to investigate crashes in which vehicles hit guardrail end terminals after it was revealed in 2012 that one of the guardrail makers, Trinity, had modified one of its end terminal models, the ET-Plus, years before and failed to notify state or federal officials as required.