The Federal Railroad Safety Act of 1970 (FRSA) authorizes the Secretary of Transportation to promulgate regulations and issue orders for railroad safety, and it requires the Secretary to maintain a coordinated effort to solve railroad grade crossing problems. The FRSA also has an express pre-emption provision. One regulation promulgated by the Secretary, through the Federal Highway Administration (FHWA), addresses the adequacy of warning devices installed under the Federal Railway-Highway Crossings Program (Crossings Program). That program provides funds to States for the construction of such devices pursuant to the Highway Safety Act of 1973. According to the regulation, adequate warning devices installed using federal funds, where any of several conditions are present, are automatic gates and flashing lights. 23 CFR §646.214(b)(3). For crossings where those conditions are not present, a States decision about what devices to install is subject to FHWA approval. §646.214(b)(4). Res