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A howe truss bridge design includes vertical members and diagonals that slope up towards the center. Its diagonals are under compression under balanced loading. It was invented in 1840 by Massachusetts millwright William Howe. Howe truss design proved to be instrumental not only in the development of several notable bridges at the end of an era of fully wooden bridges but also as an inspiration for the creation of other popular designs.
A viaduct is a bridge composed of a series of spans or arches that carries a road or a railway across a valley or a gorge. A viaduct usually refers to long bridges or series of bridges connected to one another by arch structures.
One of the first modern bridges to be made were truss bridges. They could be made of wood which some places had plethora and could withstand larger weights. They were later made of iron and steel. Many of those old modern bridges still stand.
Modern cantilever bridge is one of the safest bridge variants because it can carry largest load. Since the dawn of the modern bridge, in 19th century, they were used to carry railroads.