49 U.S.C. § 20504: Inspection, testing, and investigation

(a) Systems in Use.—(1) The Secretary of Transportation may—(A) inspect and test a signal system used by a railroad carrier; and (B) decide whether the system is in safe operating condition. (2) In carrying out this subsection, the Secretary may employ only an individual who—(A) has no interest in a patented article required to be used on or with a signal system; and (B) has no financial interest in a railroad carrier or in a concern dealing in railroad supplies. (b) Systems Submitted for Investigation and Testing.—The Secretary may investigate, test, and report on the use of and need for a signal system, without cost to the United States Government, when the system is submitted in completed shape for investigation and testing.