The LOCOMOTIVES Act proposes to amend the Clean Air Act to establish federal preemption over emission standards for locomotives. This bill specifically modifies section 209(e)(1) of the Clean Air Act, which currently prohibits states from setting emission standards for certain nonroad engines and vehicles, including new locomotives. The core provision of this amendment is to extend this prohibition to existing locomotives and engines used in locomotives that are engaged in commerce, defined as providing common carrier railroad transportation for compensation. By expanding the scope of federal preemption, the bill aims to prevent states from imposing their own emission control requirements on these vehicles, thereby ensuring a uniform regulatory framework for all commercial locomotive operations nationwide.