When used in this subchapter, unless the context indicates otherwise -

The term ''alteration'' includes changes of any kind, reconstruction, or removal in whole or in part.

The term ''bridge'' means a lawful bridge over navigable waters of the United States, including approaches, fenders, and appurtenances thereto, which is used and operated for the purpose of carrying railroad traffic, or both railroad and highway traffic, or if a State, county, municipality, or other political subdivision is the owner or joint owner thereof, which is used and operated for the purpose of carrying highway traffic.

The term ''bridge owner'' means any State, county, municipality, or other political subdivision, or any corporation, association, partnership, or individual owning, or jointly owning, any bridge, and, when any bridge shall be in the possession or under the control of any trustee, receiver, trustee in a case under title 11, or lessee, such terms shall include both the owner of the legal title and the person or the entity in possession or control of such bridge. The term ''Secretary'' means the Secretary of Transportation.

The term ''United States'', when used in a geographical sense, includes the Territories and possessions of the United States