Congressman Jimmy Duncan, Senator Lamar Alexander and Senator Bob Corker issued a letter Friday to the Federal Highway Administration urging the them to revoke a letter of eligibility for Lindsay X-Lite guardrail end terminals after several deadly crashes involving the system.

The letter states that while letters of eligibility are not required for states to install safety devices, the existence of such a letter implies certification. A June 2016 study found that 10 states do not have laws requiring crash-tests for roadside safety hardware and four of those wrongfully believed the FHWA required crash-testing.

Authorities say 17-year-old Hannah Eimers was killed in a crash on Interstate 75 in McMinn County in November 2016. She died instantly after hitting an X-Lite end terminal. One other fatality in Cumberland County and in Chattanooga have been identified as being related to the X-Lite system. TDOT removed the model from its approved list in October and has begun the process of removing already installed end terminals.