What is Bridge?

Legal Definition
A bridge is a structure built to span physical obstacles without closing the way underneath such as a body of water, valley, or road, for the purpose of providing passage over the obstacle. There are many different designs that each serve a particular purpose and apply to different situations. Designs of bridges vary depending on the function of the bridge, the nature of the terrain where the bridge is constructed and anchored, the material used to make it, and the funds available to build it.
-- Wikipedia
Legal Definition
A building constructed over a river, creek, or other stream, or ditch or other place, in order to facilitate the passage over the same. 3 Harr. 108.

2. Bridges are of several kinds, public and private. Public bridges may be divided into, 1st. Those which belong to the public; as state, county, or township bridges, over which all the people have a right to pass, with or without paying toll these are built by public authority at the public expense, either of the state itself, or a district or part of the state.

3. - 2d. Those which have been built by companies, or at the expense of private individuals, and over Which all the people have a right to pass, on the payment of a toll fixed by law. 3d. Those which have been built by private individuals and which have been dedicated to public uscs. 2 East, R. 356; 5 Burr. R. 2594; 2 Bl. R. 685 1 Camp. R. 262, n.; 2 M. & S. 262.

4. A private bridge is one erected for the use of one or more private persons; such a bridge will not be considered a public bridge, although it may be occasionally used by the public. 12 East, R. 203-4. Vide 7 Pick. R. 844; 11 Pet. R. 539; 7 N. H. Rcp. 59; 1 Pick. R. 432; 4 John. Ch. R. 150.
-- Bouviers Law Dictionary
Legal Definition
A structure erected over a river, creek, stream, ditch, ravine or other place, to facilitate the passage thereof; including by the term both arches and abutments. Bridge Co. v. Railroad Co.., 17 Conn. 56, 42 Am. Dee, 716; Proprietors of Bridges v. Land Imp. Co.., 13 N. J. Eq. 511; Rusch v. Davenport, 6 Iowa, 455; Whitall v. Gloucester County, 40 N. J. Law, 305.

A building of stone or wood erected across a river, for the common ease and bsneflt of travelers. Jacob. Bridges are either public or private. Public bridges are such as form a part of the highway, common, according to their character as foot, horse, or carriage bridges, to the public generally, with or without toll. State v. Street, 117 Ala. 208, 23 South. 807; Everett v. Bailey, 150 Pa. 152, 24 Atl. 700; Rex v. Bucks County, 12 East, 204.

A private bridge is one which is not open to the use of the public generally, and does not form part of the highway, but is reserved for the use of those who erected it, or their successors, and their licensees. Rex v. Bucks County, 12 East, 192.
-- Black's Law Dictionary