; (B) the horizontal or vertical realignment of a highway; (C) the installation (as distinguished from cleaning, repair, or replacement in kind) of a bridge, culvert, or other drainage structure or conduit; or (D) any upgrade in the surface composition of a highway. (11) Maintenance The term maintenance means the preservation of an existing highway, including but not limited to— (A) the physical upkeep of the highway; (B) the repair or replacement of wear or damage to the highway, including to bridges, culverts, or other drainage structures or conduits, from natural or other causes; (C) the restoration of the shape or path of the highway; and (D) the gradation of the highway or other measures to ensure that the shape of the highway permits drainage or safe passage over the highway by the public. (12) Public land The term public land means land— (A) that is owned, controlled by, or subject to the jurisdiction of the Federal Government for the benefit of the public; and (B) that was not reserved other, specific public purpose on the date on which a R.S. 2477 right-of-way grant was accepted. (13) Public or public user (A) In general The terms public or public user mean all natural persons authorized or otherwise allowed to enter or use public land, and includes Federal lessees, permittees, licensees, and invitees. (B) Exceptions The terms public or public user do not include any Federal agent or employee acting within the scope of their agency or employment. (14) R.S. 2477 The term R.S. 2477 means section 2477 of the Revised Statutes ( 43 U.S.C. 932 ) repealed by section 706 of the Federal Land Policy and Management Act of 1976 ( Public Law 94–579