부산대학교 도서관

A structure that crosses over a body of water, traffic, or other obstruction, permitting the smooth and safe passage of vehicles. In highway transportation systems, the term “bridge” is usually reserved for structures over bodies of water. However, many other structures are generally considered highway bridges. An overhead is a structure carrying a highway over a railroad and an underpass is a structure providing passage of a highway under a railroad. An overcrossing is a structure carrying a county road or a city street over a state highway and an undercrossing is a structure providing passage of a county road or a city street under a state highway. A separation is a structure separating into two state highways. A connector ramp is a structure connecting intersecting highways and roads. An interchange is the group of ramps and structures providing connections for traffic between intersecting highways (Fig. 1). A viaduct is an elevated structure carrying a highway over streets, railroads, or other features. Highway bridges can be made of steel (Fig. 2), concrete (Fig. 3), timber, stone, metal alloys, or advanced composite materials and may have different structural systems such as girder (beam), truss, arch, cable-stayed and suspension.