a bridge whose main load-bearing structures are made of natural stone, brick, or concrete blocks. Such a bridge is always arched, with massive supports. The main load-bearing element of a masonry bridge is the arch, over which is built the spandrel, which in turn supports the bridge roadway. The spandrel is made from a gravel or crushed stone backing held in by lateral (side) walls made of concrete masonry or stonework or in the form of an open structure of small arches resting on crosswalk.
The advantages of a masonry bridge are its architectural at-tractiveness and its durability. Masonry bridges are known thathave been in use for more than 1,000 years. The basic shortcom-ings that limit the use of masonry bridges are their complexityand labor-intensiveness of construction. A variation of a ma-sonry bridge is the concrete bridge, which has an arch made ofcast concrete.